Ocmttatlbn3NewstetterVolume I, Number 9 September, 1976

The Occultation Newsletter is published by the International Occultation Timing Association (1.0.T.A.)Editor and Compositor: H. F. DaBo11, 6 N 106 White Oak Lane, St. Charles, Illinois 60174, U. S. A.

IOTA NEWS

David bd. Dunham

The last issue of (jccultation N~3,10e-ter was duplicated by Roger Hoefer ofthe Miami Valley Astronomical Society(MVAS), using the facilities of theDayton (OH) Museum of Natural History.IOTA had to pay for the cost of mater-ials only, a considerable saving ovqtrhaving the job done comnercially.Douglas Sauer, another MVAS member,

who was to have collated and mailedthe issue, was stranded in Kentucky,due to a car breakdown, so Art Hudsontook the un-collated material to the .,convention of the Great Lakes Regionof the Astronomical League in Indian-apolis, where Hudson, Gary and KathyRingler, Rick Binzel, Joan and I as-sembled the mailing Sunday, June 20th.Joan and I were also in a hurry todrive to Silver Spring that day tomake arrangements for our move thenext day, when the issue was finallymailed. This and future issues will beassembled and mailed by Douglas Sauerand other MVAS menbers, to be reim-bursed for materials and postage COStSby IOTA. This should make it unneces-sary to raise IOTA dues for some time,and possibly we could even lower them,if we are too rich when we assessIOTA'S financial position early in1977.

The Spanish edition of OccultationNewsletter (issue #8 only) is now a-vailable free from Guillermo Mal)en,Goya 64-11, Col. Mixcoac, Mexico IB,D.F., Mexico. Mucho gracias to Eduar¢ciPrzyby1, Rafaela, Argentina, for doingthe translation, and to the Institutodc Astronomia of the Universidad Ma-clonal Autonoma dc Mexico for provid-ing duplication and mail services. Asmall fee probably will have to becharged when the ntnber of observerswanting the Spanish edition becomestoo large.

During the last three months, we havereceived two requests for IOTA'S mail-ing list. As a temporary policy, wehave decided to sell our mailing listto such requesters for $25, if theyare willing to buy it. This shouldfilter out some requests, but even ffwe offered the 1fst for free, it isdoubtful that your mail box wou1c$ befilled with junk mail as a result, Inthis way, someone selling equipmentwhich may fndeed be of interest tomany of us can send us an advertise-ment without going to a somewhatgreater expense of puttfng an ad in

Sky and TeicBcope, for example. If {duhave any strong feelings about this,let us know; we could make provisionto delete certafn addresses when rf-quests for IOTA's mailing lfst arefilled. The first request was from Dr.Mynek's Center for UFO Studies, whfchwonts to poll serious observing ama-teur astronomers. Although we won'tbend over backwards for such requests,it might be of some value for them toknow that most serious observCrs havenegative views Qn the subject, if thqtis the case. Another possibility alongthese 1fnes is to accept paid adver-using in Cjc\cUltati,Qn N~Uetter, butwe have received no requests for this,ahd have therefQre formed no policy.

Definite sections have evolved in qc-cuZtation Newsletter, such as IOTANews, Lunar Occultations of PlanetSoNew Double Stars, Grazes, PlanetaryOccultqtions, Galactic-Nebular Ob-Jects, observations of special events,and star position errors. If you sendme a letter containing information K-kting to two or more different sec-tfons, it would be helpful to havethem written on separate pieces of pa-pm", each with date and your name. Ikpw that in some such cases, I haveleft out some material which'l wantedta.inc'lude, A)S9, write the informa-tfon in a tom as ready as possiblefer publication here, sending it toMr. DaBo11, the editor, rather than tome, for items several sentences, ormore than one paragraph long. Prepara-tion of material for Occultation Newg-

lettez takes a lot of my time, whichfn part could be better spent workingon such things as the iota Graze Manu-al or minor planets computer work (seePlanetary 0ccu)tations, p. 85-86).Therefore I would like to decrease thepercentage of' o.n. written by me, andstrongly encourage others who canwrite passable English and are reason- 'ably capable of meeting dead1i"es, tovolunteer to write some of the sec-tions of o.n. If you volunteer to do asection, we would publish an announce-ment of this in the next issue, askingobservers to send reports relating toyour section directly to you. Thiswould also help the separation problemmentioned above.

I am no longer In Cincinnati. My ad-dress is now: P.0. Box 488, SIlverSprfng, Maryland 20907. My telephonenwber is 301,585-0989. ! work in theOrbit Determination Department of Com-puter Sciences Corporation's SystemScIences Division, which does contractwork for Goddard Space Flfght Center.

This does not include work on occulta-tions, which, like most of you, I mustdo during evenings and on weekends.The U.S. Naval Observatory is nearby,so that I can work closely with ThomasVan Flandern and Peter Espenschied,Khereby better coordinating IOTA acti-vities with those of U.S.N.O. But thetime I can work on occultations islimited, so help from others is neededin order to make better progress withthe various IOTA projects, such as themmiua7 and the Zodiacal double starproject. i am grateful for the extrawOrk currently done by others, such asthe other IOTA officers, the computorsfor graze predictions, Michael Rey-nolds for writing the Lunar Occulta-tions of Planets section, Robert Walk-er and Wayne Coskrey for keypunchingdata, and David Herald for determiningHint star positions and preparingmaps cf the M24 and the 1978 March 24)unar eclipse fields. I am especiallyindebted to Conrad Bardwe11 at Cincin-Mti Observatory. He gave much valua-ble assistance in my computer work inCincinnati; the significant computa-tional advances which were made duringthe past year would not have been pos-sfble without his help.

I am typing this less than a day be-fore departing for France and the IAUGeneral Assembly in Grenoble, where Iplan to garner support for the minorplanet occultation project (see p. 85-86), among other things. I will returnSeptember 7th.

STILL MORE TIMEKUBE

Our comnent that the Timekube was be-ing discontinued (o.n. i, 66) is here-by retracted. Radio Shack's latestcatalog not only lists it, at a reduc-ed price of $31.95, but adds a CHV[sic] version, also at $31.95.

James H. Van Nu1and writes: "I've beenusing my Timekube for 10 months and ampleased with it. Good reception ofColorado or Hawaii or both. I havefound all three frequencies necessaryat various times, but have always hada usable signal. No trouble with sel-ector buttons yet.

"At a recent San Jose star party, Ipunched-up ldWV for a coming occulta-tiori. A voice said, 'There goes thatsong again.' Another, "I don't knowhow that station can stay on the air,playing that one crurmy tune all thetime.' And a last, 'Well, I hear theyget a lot of requests for it."'

132

PASSAGE OF THE MOON THROUGH M24 of the field near M24, made from themeasur~nts, and can be used to de-termine approximate predictions. The

, stdrs are ninbered in order of right, ascension, and those which also haveSAD ninbers are cross-referenced in .

the table. There are six stars of 9thmagnitude or brighter which are notincluded in the SAD; their ntmbersare: 19, 32, 38, 45, 69, and 104.

Note added by David Dunham:Using Mr. Herald's measurements, ac-curate to I" or 2", I will compute anddistribute detailed occultation pre-dictions of the stars near' M24 tothose in the region of visibility whorequest them, late in September or

early October.

David Herald

The Southern Hanisphere will see a "series of M24 passages starting Sep-tember 2 (see the table on p. 77, col.I). The best will be on November 14,observable from western Australia. M24is actually composed of 15th magnitudestars, and is only about 5° in diame-ter. However, it is mbedded in a richfield of 9th to 12th magnitude stars.I have taken and measured two photo-graphs of this region. The photographscover most of the star field, and Imeasured stars down to approximatelymag. 10. The chart with this note is

A table cross-referencing Mr. Herald'sidentification numbers with the Astro-graphic Catalog and the BD, as well asdouble star information, will be pre-pared for a later issue.

g SAD # SAD # SAD

4 161200 59 )61249 94 16130415 16)208 61 161255 95 16130625 161217 62 161257 97 16130828 161227 74 161267 Ill )6132833 161229 80 161278 116 16133543 161241 83 161284 123 16135147 161245 84 16128853 161247 90 161294

FIELD NEAR M 2 4

"' 't' 't -'I'" Y" 't" 1f it? \1"

- · + m < 0 % 19¢0. O0 m «, ¶ E(0j W76·T

· m i6 t"-18° 15' — 0 in 100 qq qj

P/oi "0

,pItt

' lc |2/ m Q7 q:i "" . i 20 ' °1DC ' .ql " fez

J:C . 107 MY Y7 " j7£ m L — _ _ _ " _ _ _, i; ,C / ·C6 4C · WIQ! , · 0 0 "13 I

. , |1[ .· jib .||0 " goo · K-18° 30' _ 'Lb .10¥ ·n + ·°70 3!'7t

· Ill Cc" 5¶ 0lq I71 "·6 t " 2¶ " bO

""' "" . ';. , .'C ' '6y ·' 3C · 't ·' I

in ,,, q4" n jM "7' ' .'b · ¥g i'" iiq ·1oq - U3 . ·1¢ "Co ,u .8

5 I-18° 45' — " "l'r 4t 42 yq · Lb" " " 37 rjf . 0. :' ",, '"" 'i;;' :: ·S;" "¥3 '7 "" 7 k I

· |12 lOt tb q.CC C.C sr 3'! !3 ' " '

Jj - 27 , " 11" " " " " " " " " 7

F I, C: !:"H .41" , 0',

-19" 00' — . f7 3c 'j :' 2¢ 'B .g, I0t 6$ ·¢7 JCi .Gz Cl ·10 I

-18" 15'

-78° 30'

-18° 45'

-19" 00'

O

L

Z 3

I I Ijg1\ j}h 16!m 15" 14" 13" 12" )8h 11"

LUNAR OCCULTATIONS OF PLANETS

Mike Reynolds

The maps showing the regions of visi-bility of lunar occultations of plan-ets are reprinted by permission from

the japanese Ephemeris for 1976, pub-lished by the Hydrographic Departmentof Japan.

K4/ -"/ — :. ' ' \

C /"t.¢ ,. "t'"'"' "- ";§,, , X"°'

/""'4 2 -.r \ , I O

y Y . ^ . \I y i 7./"' ,3 I.

-1 \ ' · / \., b. ,_ , ·JU"

-"q ' :, "

t m- , "· ," "\ 1 ix 25,± R YEWS '\ , . ·L_t-,·.u± ·K'Jt""/ "/·W

7-, ,..fj'2""'"'S it?:)- . ,: ' ix4Z4, "'1',u a' 'k '~ ' ,,.

' - 976 X 23 4 4 m ,4m "':\ X m MARS - ,0

jij\, I ·wr , I ·d "'I -'0'y , -lW -i m -mer -kt, -W

- X <\,

K

, 0 'X

Q" $

%

' W%

2 , 4%

.4

' 3 ;' / I "

f ", ' /1-f ' " 6d

,, , C"· 76 XII 5IK m J IT R

-, ,-,.,',, -l / Ff-t

";" " " ¢yi:7:?°i : ': ": ! °jy"i "'7I

'1" i \_" I': 1 I' " ":", , ' ',TK' : i ,'""

m j";j-jj"jj-, . 1975 XI 2'- 4 I - ' --L - i i I t"' - t

-:!"=--4- t 1- 1- |---1---:--·. -i·--t-!- i::'!l',,' 4-;"M " I °E' °H I °W °t'[ I °1Cc' ·', T ·"0 "K 1

Region I:only R visible

Region 2:R & D visible

Region 3: ,only D visible I

PP

j

I

-,:I),""'j"";'c':' ::i "'"g:'!:,:: ::y"i ' "b ¢ <J, ( I ,·,;.t.

_ _ L. __ _ ,_.'?":""zA, ,"< JJ; ;' ""P- Y" - - « I " ""

"K,L ,r4i- Ktq- , q - k - % - n -i a' 4· 1 k E'

83

OBSERVATIONS AND ANALYSESOF SOME TOTAL OCCULTATIONS,

INCLUDING B SCORPII

Richard Nolthenius

On UT date )976 July 8, the 85% sunlitwaxing moon occulted the multiple starsystem B Scorpii as seen from North A-merica. In order to interpret the pho-tometric data obtained during the qc-cultation passage of this star systmbehfnd JUpiter's atmosphere in )971May, accurate information on magni-tudes, position angles, and separa-tions of all components is needed.This is especially important for the Bcomponent. The spacing of these compo-nents is too close to allow directvisual observation, and lunar 0cct)ta-

tion timings promise the best results.

In order to use occultation timings todetermine position angles and separa-tions for close multiple star systems,observations widely separated in oc-cultation position angle must be made.This report presents the results madeat observing sites in the San joseHills above the California PolytechnicUniversity, Pomona, California.

For the best results, at each observa-tion location, the slope of the lunar1fmb should be known over a distancecorresponding to the separation of thestars. For the July 8 event as seenfrom southern California, resolvfngthe components of the A and C systmsof 8 Scorpfi required finding the

slope over a distance of about a milealong the lunar surface. This sloperesolution was obtained by setting upa team of seven observers spaced overa mile and a half along a north-southdirection. In this way, timings of agiven star from each station corre-sponded to a height value at a differ-ent point on the lunar limb.

Given the geographic positions andtimes of occultation for two observ-ers, the point of occultation on thehmar limb can be found for one ob-server with respect to the other byusing quantities given in the U.S. Na-val Observatory Total Occultation Pre-dictions (with and without the photo-electric option) and by consideringtit: geometry involved.

Ta bl e 0 f Be to SCorpi i Dec ul ta t ion Pred Sc r. ion Pa rame te rs

Azi-Comp. PH muth Alt.

AB D 190?8 35?4C D 190.8 35.4

AB R 211 30

HourAngle P ,^ Id. A. VA_

9?352 1.!3?5 111?1 1149.352 1,!2.6 110.2 113

27.842 2·19.3 237.C 223

Lfbrations CNT T.A. t a b c _A,n .le.

1?8 -1?7 -2.1 -1.2 -0.5 ' -2.?31.8 -1.7 -2.7 -1.2 -0.5 -2'4.41.5 -1.7 -7.8 -0.1 'LO -)£1.6

R"lsec Distance Declination

-0.3500 365]55 km -19" 44' 31"-0.3524 365155 km -19 44 18"0.3670 365703 km -19 44 31

Altitude and azimuth can be found ac-curately from declination, hour angle,and the latitude of the observer usingspherical trigonometry. Given a paral-lel to the mean limb and a centralstation star path, two quantities areneeded to fix the position of the oth-er timings; the distance a betweenstar paths on the lunar limb plot, andthe height above the mean limb paral-lel. The station 3 timings were usedto establish a central station refer-ence elevation for the plots. (j can befound from S, the perpendicular dis-tance between stations.

S = -(Lac-La) sin B -(LOC-LO) m cos B

where m is the ratio of the length ofa unit of longitude to a unit of lati-tude at the observer's latitude, and Bis the bearing, or azimuth of travelof the moon's shadow. With the dfffer-ence in elevation (E is elev?tionabove sea level) considered, this be-comes:S = -(Lac-La) sin B -(LOC-LO) m cos B

" ta:iiAft) (Ec-E), where D X Az - B.

If S fs converted to miles, then

a · S X VPS.

0.864 S" =/sjn:2A¶t " COS2 D in arc seconds.

B can be found from: B =

Az +tan"l [tan (VA + CNTCT) sin (Alt)]

subtracting 180° ff B > 180°.

The height value can be found frocj thea, b, c factors. Let Tp be the pre-dicted time of occultation at the sta-tion, computed from the actual time ofoccultation at the central station Te,and let Ta be the actual time of oc-cultation. Then the hefght wf11 be:

H " "CO: " T R u [Tc " Ta " a (Loc

- Lo) - b (Lac " La) - c (Ec - i)]

FOr the B Scorpf1 occultation disap-pee ranee, these equations become:

VPS · .501? arc sec/mile

6 " - . 570 (Lac - La ) + .on (Loc - Lo)

-.(100133 (E, - E)

H · .388 (T, - Ta) " .467 (Lac -La)

" .816 (Ldc -Lo) ' .00006 (Ec -E)

for longftude and latitude in minutes,elevation in feet, and a, H in arcseconds.

Respectively, the seven station nm-bers, observers, telescopes, and rela-tive station heights (o'S) were: 41,Patti Gunther, 6" f/8 ref1., '0:'2202;R, Alan Devault, 4" f/10 ref1.,"0:'0705; 43, Richard Nolthenius, 6"f/8 ref)., ±O;OOO0; 44, Susan Beran,5" .f/5 refr. , -0!'0612; 05, Pat Harvey,6" f/8 refl., -OR417; 96, RobertFischer, 8" f/7.5 ref)., -OM923; and17, Paul Gordon, 3" f/16, -omto. Allobservers succeeded fn making timingsof A, B, and C ccmponents, wf th esthmated accuracies ranging from OSlO to0530. Roughly speaking, for each ob-server, the disappearance of C wasfo11~d, in about 11 or )2 seconds,

t,i' the disappearance of A, which, inturn, was followed by the disappear-ance of B, after another second or so.

Cements were recorded at three sta-tfons, as follows: #3, 5.7 magnitudeC component appeared to take between.05 and .10 seconds to disappear com-pletely. AB systm was suspected tohave faded by .I or .2 magnitudes 4.8seconds before the disappearance of A.C systm was expected to fade by .1mgnitude .2 second before final D.Though watched for, ft was not detect-ed. Estimated magnitude of B componentw3s 6.3, compared to 5.1 of C and 6.5of distant companion of v Scorpiinearby. No unusual color seen; #4, 5.1w'zgnitude C component appeared to take.2 seconls to disappear completely.Fade appeared more or less gradual,but conditions at this station werenot so favorable as to rule out aquick step, #6, 5.1 magnitude C compo-nent appeared to disappear instantan-eously. B component estimated to be ofmagnitude 6.5.

All observers noted that A and B bothdisappeared sharply, wfth no fadi'fi .Only Beran and I saw C fade gradua y

G)

©?t

OBSERVERt 0

%0

· =R—

C - cmpmjrr © A B 0 '1 i ·?ARC SEUMOS

~ ' '

q 'T 'g"LUNAR SURFACE SCALE:

A%" "" " ',":, ""P '

SECONDS OF TIKE

i;j"' ' .'\)s%,$m,

C A B

84

The fadings seen at stations 3 and 4may indicate a close companion to C.The limb plot suggests that such fad-ings might result if the primary dis-appeared on the mountain shown On thestation 3 and 4 star tracks, leavingthe companion visible in the valley a-bove. If this were the case, the sec-ondary would be about 0:'2 north of theprimary. The magnitude of the second-ary probably would be faint enoughthat if it disappeared first the sys-tem would fade by not more than about0.4 magnitude (an estfmate of thesmallest magnitude step observable atthe other stations, especially the ex-perienced observers at stations 5 and6, who noted a rather sharp disappear-ance). This would put the secondary atabout 7th magnitude. This is probablythe 7.6 magnitude component (discover-ed photoelectrically during the 197}occultation by Id) at PA 308 listed inthe University of Texas Special DoubleStar List. The positfon angle has mostlikely changed due to orbital motionsince 1971.

Less likely, considering the contactangle, is the possibility that thefadings were due to a distorted Fres-nel diffraction effbct. Limb plotswere made for both possibilities. As-suming it was a diffraction effect,the times of final disappearance wereused. Assiming duplicity, the times offirst fading would correspond to thebrighter component seen by the otherobservers, and thus it was these thatwere used in the second limb plot,which is the one shown. This enhancedthe mountain - valley difference inelevation. In the plots, the hatchedareas represent the accuracy of thetimings. Error due to round-off of-thea, b, and c factors is not included.

The sharpness of the disappearances ofA and B suggests that there are nocompanions south and east of thesestars brighter than about 9th magni-tude, unless they are closer thanabout O':OS.

The B component was considerablybrighter than expected. The estimateof 6.3 is considered accurate to with-in about half a magnitude. It was con-siderably brighter than 8.1 RagnitudeSAD 159684, which was a few minutes ofarc away, but definitely much fainterthan the 5.1 magnitude C component.Considering the Rhodesian observationsfndfcatfng a magnftude of 7 or 8 lastyear, perhaps B is variable.

Most observers attmpted to time thereappearance of B Scorpii A on thebright limb. However, only two doubt-ful timings were obtained, both prob-ably a second or two late due to thedifficulty of finding the star agafnstthe brfght limb irradiation.

Not fncluding the reappearance of BScorpii A, timings of five other qc-cultations were made that night. Amongthem was that of ZC 2296, magnitude7.1. Harvey and I both made accuratetimings of the disappearance. I sawthe star fade gradually to invisibili-ty over 0.15 seconds. As this may in- "dfcate duplicity, a limb profile (notshown) was drawn. The four others wereSAD 159660, -662, -684, and -691.

THE REVISION OFthe akkrican EplmyERIs and nautical

ALMANAC AND THE ASTRCWCWICAL 8pHmKRIs

U. S. Naval Observatory

Tentative plans have been made to re-vise the contents of The American B-

pH~rts and Nautical Almanac and themtrommical 8pH~mis beginning with

the 1984 edition.

The revised a.k. will be a single,unified publication prepared by theFrench, German, British and Americanepheneris offices.

New astronomical constants and newfundamental planetary and lunar theo-ries will be introduced in the 1984editfon.

Since these revisions are planned sothat the publications might betterserve the requirements of all astrono-mers, the suggestions and comnents ofas many astronomers as possible arebeing sought. The principal modffica-'tions planned for the 1981 a.b. are asfollows:

7. Replace the hourly apparent lu-nar ephemeris by daily shortpower series which permit thedirect determination of the lu-nar position for any time.

2. Eliminate 1st differences.

3. Eliminate Independent Day Nwn-bers.

4. Eliminate fixed tables for unitconversions.

5. Give longitudes and latitudesof the moon and planets to 0?01accuracy only.

6. Organize the voltme into sec-tions which have their own pag-ination.

7. Provide times of sunrise, sun-set, moonrise, moonset forsouthern latitudes.

8. ?mvfde times of civil twilightin addition to astronomicaltwilight.

9. Expand the list of occultationsto Include lunar occu1tatfonsof radio sources and planetaryoccultations of stars.

10. Include transformation matricesfor reduction of apparent plaC-es.

11. Include an ephemeris of the ba-rycenter of the solar system.

12. Include a BIH polar motion ta-ble.

13. Include physical ephemeridesfor all planets, ccmnensuratewith current knowledge.

14. Give satellite ephemerides toobserving accuracy for all sat-ellites, generally for the en-tire year.

15. Provide mino" planet ephemeri-des to I" for as many as 20 mi-nor planets.

)6. Expand the star list to about1600 stars.

)7. Include standard lists of vari-able stars, radio sources, pul-sars and X-ray sources.

18. Give locations of observatoriesto reduced precision in the an-nual Observatories List, andperiodically publish for eachobservatory a list of accurateastronomic and geodetic loca-tions of each instrument.

19. Introduce a rewritten explana-tion with a glossary of termsused in the volume.

20. Introduce tables of new valuesof astronomical constants as

' appropriate.

21. Introduce chapters for a newversion of the Explanatory Sup-pIt as supplements to thea.e. prior to the publicationof the new voltme.

Suggestions, comnents, or requests foradditional information can be sent toDr. P. Kenneth Seidelmann, U. S. NavalObservatory, Washington, D.C. 20390.

FROM THE IOTA SECRETARY

Berton L. Stevens, Jr.

Quite a few observers have written me,to the effect that they have not re-ceived their predictions fjjr the thirdquarter. They are mainly in the A3, D,F, and XB regions.

These regions were assigned to GaryRingler, of Cleveland, Ohio, who wasready to run the predictions when anadministrative problem prevented himfrom using the computer.

A3 has been assigned to joe Sowers. D,F, and XB were reassigned to WayneGreen, of Jacksonville, Florida. Bothcomputors expect to have the predic-tions and profiles out shortly.

Predictions and profiles for thefourth quarter should be in the handsof observers soon. If you have not re-ceived your predictions, please sendme a postcard, so I can investigate.

You no longer need to request pro-files; they are generated for eachprediction, as part of the predictionprocess. If you are receiving limitdata without profiles, please let meknow.

Finally, if you are an IOTA memter,and are not getting predictions, itmay be that you did not return the Ob-server Information Form. We need theinformation on it, not only for com-puting grazes, but also for computingspecial events, such as occultationsof planets by the moon, occultationsduring lunar eclipses, etc.

4032 N. Ashland Ave.Chicago, IL 60613

85

NEW DOUBLE STARS

David Id. Dunham

The table lists additions and correc?tions to the special double star listof 1974 May 9 not listed in previousissues. The columns and general formatare the same as in previous issues,except that as none of the stars list-ed are previously known doubles ortriples, the usual columns for thirdcomponents have been omitted.

The most interesting occultation of adouble star since the last issue wasthe occultation of B Scorpii on July8. I have learned second-hand thathigh-speed photoelectric records ofthe occultation were obtained at Dav-is, CA; Mt. Hopkins Observatory, AZ;and McOonald Observatory, TX. Otherphotoelectric records were likely ob-tained at other observatories. The in-formation about the star in the spe7cial double star list will be updatedas soon as results of the photoelec-tric observations are available. Unwfortunately, the photoelectric dataprobably will not be of much help inderiving more information about thecompanion to the C component (Z.C.2303), which was occulted before thebright AB components (Z.C. 2302) diswappeared. Consequently, there was ahigh noise level since all componentswere in the observing diaphragm. Butit will be possible to detemine themagnitude, separation, and positionangle of the B component to high ac-curacy, information needed for preciseanalysis of the light curves obtainedwhen the system was occulted by jupi-ter in 1971. A letter from Graham Blowstates that the occultation of 1975September 11 was recorded photoelec-trically at Auckland, New Zealand.

Several reports of the total occu'lta-tion of B Scorpii have been receivedfrom visual observers. The consensusseems to be that the B component isabout magnitude 64, considerablybrighter than the estimates by Rhode-sian observers during the occultationlast October. Francis X. Hart led ateam of four visual observers, but themost ambitious visual project was thatorganized by Richard Nolthenius, des-cribed on pp. 83-84. His group's ob-servations indicated an A-B distanceof o:m projected in the position an-gle direction 123°.

F. K. Reed, Scottsdale, AZ, reports anunusual observation: "In observing the

0ccu)tation of B Scorpii, I noticedsane scintillation (2 or 3 brightflashes of 2 or 3 magnitudes increasein brilliance) of the C component some20 or 30 seconds before its disappear-ance. Seeing was excellent (steadyc$iffraction rings around the stars inmy lS-cm reflector). This scintilla-tion was also seen by Ed Grath, ob-serving the event with a B-cm Questar,several kilometers distant."

Michael Reynold and Thomas Campbell,Jr. made extensive preparations to ob-serve the southern-limit grazes of thecomponents of B Scorpii from severalsites across northern Florida. Therewas heavy cloudiness in the area, sothey set up at several stations separ-ated by large intervals across Floridain the predicted path, hoping thatsomeone could observe the grazethrough a break in the clouds. Unfor-tunately, there were no breaks duringthe graze. Astronomers at Kitt PeakNational Observatory, Arizona, whotried photoelectric observations, hadthe same bad luck with the weather, asdid many others. Richard Noltheniusmentions that he tried to observe twoearlier occultations of B Scorpii. OnMarch 20, he could not find the starat 8° altitude with the sun 20° up. OnKay 14, he timed the bright-limb im-mersion of AB at 9° altitude, with thesun at -2° and the moon 99% sunlit.

Guillemo MallCn recorded the June 8occultation of Spica photoelectricallyusing the 102-an reflector at Tonant-zintla, Mexico. The disappearance wasat the dark 'limb of the 80% sunlitmoon. He writes that the light curve"shows a strong diffraction pattern,typical of point sources. The observa-tion was made through a thin cloud inthe middle of a hole in thick clouds."This casts some doubts on the observa-tions of other components noted duringthe graze of Spica in Australia lastNovember, but a detailed analysis ofl'la11Cn's data will be needed beforeredching firm conclusions. Hopefully,more photoelectric data will be ob-tained during the occultation of Aug-

List 28 in Canada and the U.S.A., orperhaps during the few remaining fav-orable occultations in the currentseries, none (except Aug. 28) visiblein North America and ending with anArctic event on December 16. The pho-tometer used by MallCn was made byMauricio Tapia, and is simple enoughthat amateurs might be able to use it.MallCn writes: "An op amp picks up avoltage from the load resistor of thephotomultiplier. A vco converts thissignal into a square wave modulated infrequency. The frequency is adjustedto about 3 KHZ for the sky and 9 or 10KHZ for the star, so it is in the aud-io range, and is recorded in a stereotape recorder, with hlhlV on the othertrack. After the observation, we ob-tain a punched tape which is loaded toa computer. we simply count the numberof pulses in ofooi, using an xtalclock and standard anos chips. Ithink, in the future, many amateursmay have the photometer, and they maysend the recording to centers with thesecond device, and a computer." A de-tailed description of the equipmentwill be published in English in Revis-ta Mexicana dc Astroncmfa y Astrofls-lea.

Paul Couteau, Nice Observatory, Francewrites, saying that he observed SAD78778 to be single on 1972 January 31,using a SO-an refractor visually. Aphotoelectric observation of an occu1-tation at Hamburg, Germany, on 1971April 4, showed the star to be double,with a separation of 0!'25. It is prob-able that the separation decreased dueto orbital motion, so that Couteaucould not see the companion in 1972.The Hamburg observation was in thelist on p. 73 of the last issue.

During the graze of Z.C. 2079 observednear Vi11iers, South Africa, on 1975September 9, M. D. Overbeek timed someevents of a companion at least onemagnitude fainter (so that it would beabout 9th mag.) and at least 30" away.It is certainly a wide double; thecompanion is likely listed separatelyfn the B.D. or Astrographic Catalog.

NEW ZODIACAL SPECIAL DOUBLE STARS, 1976 AUGUST 14

SAD ZC M N MG1 MG2 SEP PA DATE, DISCOVERER, NOTES

95127 G K8.4 8.40!'02 0°146412 3370 G X 6.5 7.8 0.02 157158992 2147 T V 7.2 9.0 0.32 163159540 2264 T V 7.4 7.9 0.30 80159655 2296 T X 7.6 8.3 0.03 160163460 T X 9.4 10.3 0.06 125

1976 July 24, H.1976 june 18, R.1976 July 7, R.1976 Aug. 4, R.1976 july 8, R.1976 Apr. 21 , R.

Povenmire, FLNolthenius, Eden Springs, CANolthenius, Long Beach, CANolthenius, Long Beach, CANolthenius, Pomona, CANolthenius, Tucson, AZ

PLANETARY OCCULTATIONS

Davfd Id. Dunham

The occultation of SAD 80046 by Sat-urn's satellite Iapetus was observedby F. M. Strauss in Porto Alegre, RioGrande do Sui, Brazil, according toI.A.U. Circular No. 296h9. The disap-pearance occurred at 21 32m 24S U.T,of 1976 june 16. The duration was atleast 15S, after which clouds began tointerfere. I have heard of no otherobservations of this, or other eventslisted on p. 79 of the last issue.

Observers in western North America arerminded of the occultation of 8.9-magnitude SAD 153844 at about 13h 0QPof October 10, by Pa11as. Improvedpredictions for the path will be dis-tributed to affected IOTA members assoon as they are supplied by GordonTaylor, H.M.N.A.O. Hopefully, theevent will be recorded photoelectric-ally from one or more of the large ob-servatories in western North America,In any case, observations by largenumbers of visual observers stationedat intervals across the possible areaof vislbi11ty would be valuable fordetermining the asteroid's exact sizeand shape. Coordination of plans among

various groups of observers would beuseful to ensure good coverage, as wasattempted for the occultation of Meb-suta by Phobos last April.

Working at U.S.N.O. during eveningsduring the past few weeks, using pro-grams and help from Paul Janiczek andothers, I have developed a capabilityfor routinely calculating accurate as-trometric ephemerides of minor plan-ets, given accurate orbital elementsfor some epoch. These can be comparedwith star catalog data on magnetictape to find possible occultations.This work should eliminate the needfor H.M.N.A.O. to laboriously keypunch

86

astrometric ephemerides supplied bythe Institute of Theoretical Astronomyin Leningrad, U.S.S.R., so that itshould be possible to hunt for occul-tations by many more minor planetsthan are being considered in currentsearches. Hopefully, a few hundredminor planets can be involved. Sinceeach minor planet occults about oneSAD star each year as seen from some-where on the earth's surface, thisShould result in many more predictionsend observations. Accurate diametersof a few asteroids detemined fromsuch observations would be valuablefor calibrating the relative diameterswhich have been determined fQr manyminor planets from polarimetric andinfrared observations.

Precise photographic observations willbe needed in order to refine the rela-the positions of minor planets andStars to be occulted by them, oftentaken only a week or two before the e-vent (so that both objects appear onone plate). Coordination with observa-to"ies to obtain such observations isin the planning stages. Of course, co-ordination with observers in the pre-dicted regions of visibility will alsobe needed, to disseminate last-minuteimprovements in the prediction and toset up observing fences to ensure goodcoverage.

Maiy occultations by minor planets arevery short, lasting only 1 or 2 sec-OMS, so that visua7 observations be-cone marginal for deteminfng diame-te:"s. For this reason, an inexpensive,easy-to-use photoelectric system whichamateurs could build and use becomesimperative. A nimber of people areworking on such systems, some of themmentioned in previous Issues, such asSeville Chapman°s photodfode-loud-speaker-taperecorder combination stim-ulated by the occultatfon Gf k Gemfn-orin by Eros; see p. 19 of the 1975January issue (#3). Apparently, thephotodiodes are sensitive enough to beused only for the brightest stars. Ob-servers in Montreal who built copiesof Chapman's equiµnent were going totest it on lunar occultations, but Ihave heard of no successful attempts.Astronomers at Cornell University areworking on what probably will be amore useful scNne, fnvolving a beamsplitter, fiber Qptics, photoenu)tip1i-er, and electronics for a cassettetaperecording system. Guillermo Mal-'lCn's systen is described on p. 85.Mark Trueblood, Wshfngton, DC, hasplans for a systm utilizing the in-creasingly widespread and relativelyinexpensivC Altair 8800 microcomputerto control data acquisition. RichardGomer's equipment was used to recordthe occultation of Mebsuta by Mars, asbriefly mentioned on p. 79 of the lastissue. Any of these systems duplicatedon a large scale would not only beuseful for planetary occultations, butwould also be a boon for lunar occul-tations, including grazes.

Only about a minute before Y,ebsutadisappeared behind Mars in April,Thomas Campbell, Jr. saw an artificialsate11fte cross his field of' view. Heobserved from a site in northernFlorida to avoid clouds which foiledother observers In the Tampa area.

GRAZES REPORTED TO IOTA

David id. Dunham

Graze reports should be sent to mycurrent address, P.0. Box 488, SilverSpring, Maryland 20907, U.S.A. As usu-al, if possible, a copy should also besent to H.M.N.A.O.

Few graze reports have been receivedsince the list for the last issue wasprepared, partly due to the moon's lowaltitude during sumer evenings fornorthern observers, partly due to theshort time since the last list wasmade, and partly due to mail forward-ing delays. Recent letters mentioned agraze of a 9.2-mag. star observed byRichard Nolthenius on June 20 and asuspected double (see the New DoubleStars secticjn) whose graze was seen byHarotd Povemnire on July 24, but notenough details were given to includethem in the graze list.

Due to my move to Maryland and otherwork mentioned elsewhere in this is-sue, I have not had a chance to pre-pare the new graze report foms men-tioned in the last issue. The newfoms will have high priority when Ireturn in September. '

Star %Mo Dj Number MaA Sn.1. LA Location

}9764 10 )397 5.5 75+ BN Theriot, LA

Wayne Coskrey, Starkville, MS, hasdone a good lob keypunching graze re-ports during the last couple ofmonths. Progress with the overall pro-ject, however, is slow, and more vol-unteers to help with some of the key-punching would certainly be welcome.Whenever possigie, observers are en-couraged to keypunch their own obser-vations.

If skies are clear, the graze of Spicaon August 28 seems destined to set anew record; see pp, 113 and 122 of theAugust issue of Sky and Telescope. Inaddition to the Florida effort, I knowof daytime expeditions planned by Wal-ter Morgan in Nevada, Richard Nolthen-ius in Arizona, and Paul Maley in Tex-as.

Paul Maley has plans to observe threegrazes in one night in September. Ifhe can do it, it will be a first, asfar as 1 know. Robert Sandy's expedi-tion'for the graze of Z.C. 495 on Nr.7 was listed in the last issue. Mr.Sandy notes that it was the 6th grazewhich he has been able to observe fromhis back yard.

[Ed: Bert Stevens successfully observ-ed grazes on three consecutive morn-

0 g C ApSU.N!£ £m. Organizer ,S.t. BA §

1 5 7 20 Robert Schiffer 0

5 5 1106 3.6 28+ -7S St. Augustine, FL 4 6 25 Harold Povenmfre5 9 )611 5.7 74+ Canberra, Austrl. 6 22 9 15 David Herald5 )9 Z22248 9.3 65- IS Pontiac, IL I 4 2 25 Berton Stevens, Jr. 179-605 20 223262 8.7 55- 3N Kankakee, IL .1 4 5 25 Berton Stevens, Jr. 3555 21 3290 7.3 45- IN Id. Kankakee, IL 2 2 7 25 john Phelps, Jr. 5N 0-55

6 1 ion 6.2 9+ N Ehren, FL . 4 26 9 20 Thomas Campbell, jr.6 18 3370 6.2 61- ON Eden Springs, CA 2 6 9 IS Richard Nolthenius 6N 0-49

8 2 Z13041 8.3 40' 6S Johnston City, IL 1 8 7 20 Homer DaBo11 ON173 38 5 2394 6.5 74+ S La Porte, TX 2 4 20 Paul Maley ION8 19 0726 6.8 36- -IS New Lebanon, IL 3 6 7 20 Fkner DaBo11 2N179 438 20 Z04575 7.4 28- -iS Wing, IL 2 5 6 20 Homer DaBoll 55178 54

LUNAR OCCULTATION OF (89) JULIAON 1976 OCTOBER I

Davfd Id. Dunham

Dona7d Davis, Planetary Science Insti-tute, Tucson, Arizona, noints out thata lunar occultation of this minorplanet will be visible under fair con-ditions from western Europe on 1976October 1. Donald wells, Kitt PeakNational Observatory, supplied thepredictions using a copy of my predic-tion computer program and data sup-plied by me. julia's magnitude (V)will be 10.3 and her diameter is as-swed to be 137 km, based on recentpolar1metric results. julia's eppar-CAt position at the time of the occul-tation will be R.A. jgh 51m 35% Decl.

Location UT

Grenoble, France 22h 52¶7Herstmonceux, United Kingdom 22 32.4Saint Michel, France 22 57.7Meudon, France 22 38.5Pie ¢u Midi, France ?2 51.2Strasbourg, France 22 45.2Zurlch, Switzerland 22 48,5jungfraujoch, Swftzerland 22 51,3

-16° 29:3. The moon will be 65% sun-lit waxing, so that disappearance willbe at the dark limb. The southernlimit of the occuitation apparentlycrosses Iberia and northern Italy; de-tailed predictions of its locationwill be computed soon. The predictedquantities in the list below are theUT of disappearance, the duration of'be fade at disappearance"due to thesize of julia, the POsition angle ofdi$appearance{ the Cusp angle measuredaround the moon's 1Tmb from the south-ern cusp, the altitude of julia abovethe horizon whCn it is occulted, andher Azimuth measured clockwise fromnorth, High-speed photoelectric ob-servat'lons of julia's disappearancewould be valuable for accurately meas-uring her d1ameter· (1976 August I4)

d P C a A

Os49 13]° 40"S ?" 238°0:30 103 68 S 9 229

0.63 139 32 S 7 2390.33 111 60 S 9 2320.53 131 39 S 12 2340.36 119 52 S 5 238DAD 124 47 S 5 2390,44 128 43 S 5 240

87

ings (1976 Aug. 19, 20, and 21). Thissurely must be a record for Illinois.Has it been topped elsewhere? With themoon only 16° up in the western sky,Bob Sandy observed the Z.C. 830 grazeon May 3 (see o.n. i, 74) from a point25 feet east of railroad tracks. Thefreight train did not arrive until 2m23s after his final timing, Murphy'sLaw notwithstanding. For other good)uck enjoyed by that expedition, seeSky and Telescope, 52, 225-226 (Sep-tenber 1976).]

ANOTHER WAY OF LOOKING AT EMERSIONS

James H. Van Nuland

The larger circles are scaled to 16:8and 14:7, the maximum and minimum ra-dii of the moon; the small circle isactually a hole, scaled to 2' radiusand centered on the mean radius of themoon, 15:8. Thehole exposes 15°

ig')s),:satern is scribedon the back of a frame of unexposedprocessed Kodachrome, which passesjust enough light to see the moon. Thefilm is glued to the end of a shorttube, which is padded to a snug fit inthe skirt of my 20-m eyepiece. Indexmarks on the tube and skirt allowready re-a)igrment and proper focus onthe reticle. A 360° scale made of astrip of paper divided into 36 equalparts is taped to the outside of theeyepiece to complete the construction.

In use, I set the eyepiece to the pre-dicted P.A. by using the scale and anindex mark on the focyser, then pre-focus on a star. Next, I cente'r themoon within the large circles, thensit back and waft for the reappear-ance, guiding as needed to center themoon. The drawing shows the reticle ata P.A. of 240°.

The r~vable tube allows normal useof the Erfle at 61x in my 8-fnch New-tonian. In an earlier versioni 1 hadscribed the markings on the film gnu1-sion, but this allowed far too muchlight to come through. H~ver, withthe marks on the film backing, thisproblm is solved.

Now if I could design away the mornihghaze, I'd be able to hunt down lots ofR's, if I "could get up in the mornfng.

MP PRICES INCREASE

We note with regret that the Geologi-cal Survey has had to increase priceson several classes of maps, effective1976 July 15. Inter alia, standard to-pographic 7.5- and lS-minute maps wentfrom 75¢ to $1.25, and 1:250,000 mapswent from $1.00 to $2.00.

A cheerful thought: Formerly, the 30%discount applied to orders of 400 ormore topographic quadrangles; now youcan get It on an order of only 240.

OBSERVATIONS OF OCCULTATIONS timings is the same. If the total andDURING THE 1975 NOVEMBER g of R°s is the same, the ranking is

LUNAR ECLIPSE then baSed on the # of non-SAO starstimed. If necessary, the number of

David Id. Dunham non-BD star timings is considered. Fi-nally, if all these numbers are equal,

General cements about observations of the observers are listed in alphabeti-occultations during the lunar eclipse cal order of last name. Under Tele-of 1975 November 18-19 are given on p. scope, L, R, and C indicate reflector,80 of the last issue. The tally of e- refractor, and catadioptric, respec-clipse occultation timings given here tively. I am indebted to H. M. Nauti-is in the same fom as the one for the cal Almanac Office for supplying me1975 Kay 24-25 eclipse in issue #5, p. with copies of reports from which most38. The lower rank ntnber is given to of this tally was prepared. I alsothe observer who timed the most reap- thank the many observers who sent mepearances, if their total number of reports directly. (Cont. on p. 88)

1975 NOVEMBER 18-)9 ECLIPSE OCCULTATION TALLY

Rank

I23456789

1011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162

Observer

G. Appleby, Herstmonceux, EnglandK. Blackwell, Pevensey, EnglandR. Rutten, Eindhoven, Netherland6L. Pazzi, Nigel, TVL, S. AfricaL. Morrison, Herstmonceux, EnglandA. Hilton, Salisbury, RhodesiaS. Pattinson, S. Croydon, EnglandJ. Van Zyl, Johannesburg, S. AfricaJ. OsOrio, Vila Nova dc Gala, PortugalL. Quijano, San Fernando, SpainL. Brundle, Haywards Heath, Sus., EnglandI. Pablos Quiros, Madrid, SpainM. Overbeek, Johannesburg, S. AfricaM'. Abdul-Ahad, Bradhiya Basra, IraqD. ScNnidt, Huizen, NetherlandsD. Gibbon, lkntali, Rhodesia$. Rayner, ldeymouth, EnglandA. Jones, Gi11ingham, EnglandJ. Ripero, Madrid, SpainG. Marshall, Johannesburg, S. AfricaI. Broadbank, Weymouth, EnglandP. Ellis, Herstmonceux, EnglandG. Taylor, Cowbeech, EnglandQ. Dunham, Lebanon, OhioF. Bateman, Johannesburg, S. AfricaB. Fraser, " "J. Hers, " "G. Papadopoulos, '° "G. Paxton, " "A. Voorvelt, " "S. Sack, Highland Park, New Jerseyd. Barata Araujo, Recife, BrazilR. Laureys, Diepenbeek, BelgitnT. Vinvent, Salisbury, RhodesiaJ. Azcona Crespo, Madrid, SpainR. Blissett, London, SpainG. Buss, Arundel, EnglandG. Kirby, ldeymouth, EnglandA. Morrisby, Causeway, RhodesiaC. Pither, ldeymuth, EnglandC. Reid, Arunde1, EnglandR. Stebbage, Mafdstone, EnglandId. Verhaegen, Wetteren, BelgiumR. Clyde, Streetsboro, OhioR. Durette, Suncook, New HampshireR. Hays, Chicago, IllinoisV. Slabinski, Washfngton, D. C.j. Rodriguez Bravo, Madrid, SpainN. Bryniidsen, Horten, NorwayI. Cohen, K. Yavne, IsraelL. Felipe Hurtado, San Fernando, SpainD. Hall, Leicester, EnglandB. Innerny, Weymouth, EnglandR. Kalleberg, Tromso, NorwayM. Knitsch, Hannover, DBRj. Mason, Arundel, EnglandC. Morse, Maidenhead, EnglandC. Ost, Hannover, DBRM. Pascua1 Martinez, Madrid, SpainN. Wright, London, EnglandF. Van Loo, Itigem, BelgiumA. Salazar, San Fernando, Spain

Non NonTelescope Total .RX SAD. §D_

30-cm R 9 4 3 2lS-cm R 9 3 3 240-cm L 8 1 4 2lO-cm L 7 4 4 033-cm R 7 3 0 0lS-cm L 7 2 4 221 -cm L 7 2 I 025-cm L 6 3 6 0lS-cm R 6 I I 118-cm L 5 2 I 0U-cm L 5 2 0 0lS-cm R 5 0 3 231-cm L 4 2 4 030-cm L 4 2 0 0R-cm R 4 0 0 0lS-cm 3 1 I 076-cm L 3 1 1 025-cm L 3 1 0 0IS-an C 3 0 1 IIS-cm L 3 0 I 0U-an L 3 0 0 0lS-cm R 3 0 0 0SO-cm L 3 0 0 025-cm L 2 2 1 1lS-cm L 2 1 2 0lS-cm L 2 7 2 020-cm L 2 I 2 020-cm L 2 1 2 0lS-cm L 2 1 2 030-an L 2 1 2 020-an 2 1 1 0lS-cm L 2 1 0 025-cm L 2 1 0 013-cm R 2 i 0 027-cm R 2 0 1 0

2 0 0 0IS-cm L 2 0 0 022-an L 2 0 0 022-cm L 2 0 0 030-cm L 2 0 0 021-cm L 2 0 0 0lS-cm R 2 0 0 0

2lS-cm L I 1 0 0lS-cm L 1 1 0 0lS-cm L I 1 0 0lS-cm L 1 I 0 027-cm R I 0 I 1ll-cm L I 0 0 0lO-cm L 1 0 0 0lS-cm R 1 0 0 025-cm L I 0 0 0I6-cm R I 0 0 0R-cm R I 0 0 0lS-cm R I 0 0 021-cm L 1 0 0 0lS-cm L 1 0 0 0IO-cm R I 0 0 027-cm R 1 0 0 013-cm R I 0 0 0lS-cm L I 0 0 018-cm L 1 0 0 0

T76 50 54 ITT

88

The only possible double star discov- - 554A, seen during a graze observed by +ered during the eclipse was BD "19° -' L. Paul in Nigel, South Africa, as -+

1976 JUNE 2-3 1467 our sympathy; that's all we saw tOO!OCCULTATION TALLY

Joan Bixby Dunham

Poor weather clouded-out most of usfor the M67 passage of June 3. Manyobservers were hampered by haze orcirrus clouds which prevented timingsof at least the non-SAO stars. Aweather satellite photo for June 2shows clouds over most of the area forwhich observations were possible. ChetPatton actually reported an astoundingtotal of 56 timings, but his timingson most of them were uncertain, andmay well be events beyond the capabil-ity of a lS-cm scope. Observers withclear skies found many of the non-SAOstars difficult to observe against theearthshine of the 24% sunlit moon.Many people have written complainingof observing only clouds, and you have

The next passage of the moon throughi%7 will occur on September 20 in theU.S. and Canada (see table in the lastissue, p. 77). lde do not plan to dis-tribute special predictions for thisbecause the earthshine wi)1 be sobright with the 15% sunlit waning moonthat most of the reappearances on non-SAD stars will be extremely difficultto time. Observers who have the USNOtotal predictions who want to try canplot the path of the moon for theirstations on the chart of M67 in thelast issue and determine approximatepredictions.

T:ie next good passages will be onO:tober 17, observable in japan, andon November 14 for the U.K. and Eu-rope. We will prepare predictions forthose events.

Rank Observer

I Chet Patton, Buchanan, Michigan2 Robert H. Hays, Jr., Chicago, Illinois3 Paul Murn, Milwaukee, Wisconsin4 Edward Halbach, Milwaukee, Wisconsin5 joe Horvath, Buchanan, Michigan6 Ben Hudgens, Clinton, Mississippi7 Frank Olsen, Cedar Rapids, Iowa8 Robert Sandy, Kansas City, Missouri9 Wade Eichhorn, San Angelo, Texas

10 Ronald Henderson, Farmington, Illinofs

Ncn NonTelescope To.ta.l, 29 BD_

lS-cm L 14 9· 6lS-cm L 12 6 232-cm L 12 ? 2R-cm L 9 4 06-cm R 8 2 0

25-cm L 7 4 320-cm C 4 0 - 0IS-an L 2 0 020-cm L 1 0 0lS-cm L I 0 0

7(1 TU 13

ERRONEOUS TOTALOCCULTATION PREDICTIONS

David Id. Dunham

Reports of timings where the star wasocculted well outside the predictedrange (predicted U.T. ± the accuracyvalue given in the USNO predictions)are listed below. All events were dfs-appearances. Ace. is the predicted ac-curacy from the 1jsno predictions andDfff. is the difference between thepredicted and observed times, a nega-tive value indicatfng that the inner-sion was earlier than predicted and apositive value showing that it waslater than predicted.

The source position for Z08240 was theold General Catalog, whose star posi-tfons are often more than I" in errorat the current epoch due to accumula-tion of the error in the proper motiOnand the early epoch (late 1800's) ofthe observations used for the catalog,On May 6, the star position errorprobably combined with a large errorin the limb correction, since theevent occurred at an extreme 1ongftude1ibration of -7?8, over 1° outside thecoverage of Watts' data.

Z06958 is a wide double, A.D.S. 5816,

with component magnitudes of 8.3 and8.4 separated by 6!'9 in P.A. 355°;watch the double star code column ofthe USNO predictions. Again, the posi-tion source is the G.C. Both compo-nents are listed in the AGK3 (AGK3ntnbers are +16° 731 and 732), whosepositions are 9" and 24" north of thecurrent GC position used for the pre¶diction. If the AGK3 had been used,the prediction would have agreed withthe observed time in each case. VanNuland notes that the star will be oc-culted again knersion) for his sta-tion on 1976 Septenber 18.

The GC and ZC positions of ZC 2591 areIn agreanent to better than 4'. Theobservation of ZC 2591 was comunicat-ed by Robert Sandy, who was observingwith Mr. Yoksh. Although the moon was97% sunlit, and the sun only 1° belowthe horizon, the 6.5-mag. star was nottoo difficult to see in the lS-cm re-flector. Yoksh claims that the eventwas a definite disappearance not caus-ed by poor atmospherics.

David Herald has taken plates of thestars he observed, pIus SAD ]38528(see p. 78 of the last issue), andfound no signfficant discrepancy athis approximately 2" measurement-ac-curacy level.

1976Date

Kay 6June Ijune IJuly 8July 9July 10

Observer Star Ace. Diff. Notes

5' JO' PA. 56°

4 -R PA. 166°4 -378 "15 C.A. 8°N3 +17 C.A. 83'N2 --60 C.A. 68°N

·+ noted at the bottom of the list on p.73 of the last issue. The only knowngrazes observed during the eclipse in-volved this star and its relativelydistant B component, also observed inSouth Africa as recorded in the liston p. 74 of the last issue. All tim-ings made by observers in Johannesburginvolved the graze stars; variablecloudiness prevented other timingsthere. Most of the observers had mydetailed predictions of all Astro-graphic Catalog stars, but even so, I.Pablos QuirOs of Madrid, Spain timedthe unpredicted disappearance of astar that was not even in the Astro-graphic Catalog. Similarly, RichardNolthenius and I were able to time acouple of unpredicted occultations ofstars indicated as 13th mag. on the XSc·jrpii variable star chart during the1'375 May 25 eclipse.

I have received no observations of qc-cu)tations made during the small par-tial' lunar eclipse of 1976 May 13, butD,wid Herald, Woden, Australia, madeanother interesting occultation obser-jation that night several hours beforethe eclipse. He was waiting for an oc-cultation of 6.6-magnitude Z.C. 2160,p"edicted to disappear at jjh 46m 02SU.T. He followed the star in, but itdidn't disappear until jjh 50m 0651!By checking his USNO total occultationpredictions for other months, he cor-rectly guessed that the star he ob-served was 5.3-mag. Z.C. 2159. It dis-appeared very close to the terminatorof the nearly full moon, but apparent-1\' with a hairline of darkness separ-ating the star from the sunlit fea-tures. The moon was 100% sunlit, elon-gation 175° from the sun, at a cuspangle of 18°N, so the occultation ofZ.C. 2159 was rejected from the USNOpredictions with a zero observabilitycode. Consulting the chart on p. 26 ofissue #3 shows that the theoreticalterminator was only 0:'4 from the darklimb, which would almost certainly beextended to the dark limb by irradia-tion, and the "worst" teminator wouldbe beyond the limb. A detailed analy-sis of Herald's timing gave a veryreasonable residual of -m, indicat-ing that foreground mountains musthave shaded the area which would nor-mally bC sunlit. It appears that ourcusp angle rejection criteria shouldbe loosened slightly near full moon. Imade a somewhat similar observation ofan occultation of µ Geminorum a fewhours before the total lunar eclipseof 1963 December.

The next total lunar eclipse will oc-cur on 1978 March 24, just beforeEaster, when Australian amateurs willbe holding a convention in Canberra.David Herald has taken photographs ofthe eclipse star field, noting overISO stars down to about 1)th magni-tude, and plans to measure their posi-tions for occu1tation predictions.

MORE PUBLISHED PAPERSABOUT OCCULTATIONS

D. Scott, Panama City, FloridaJ. Van Nuland, San jose, Calif.j. Van Nuiand, San Jose, Calif,D. Herald, ldoden, AustraliaD. Herald, Woden, AustraliaL. Yoksh, Kansas City, M1ssourl

Z08240Z06958AZ06958BZC 2346

SAD 160504ZC 259]

David K. Dunham

G. Id. Amery, "Report of Lunar SectionMeeting, j. Brit. Astr. Ass. 86,241-243 (April 1976). This meetingwas held on )975 November I at Read-

89

frig, Berkshire, now regarded as theSectfon's occultation centre, so itwas appropriate that the afternoonpapers were all concerned with thistopic, as follows: L. V. Morrison,"Lunar Occultations: The Motion ofthe Moon and the Rotation of theEarth," mainly about the utility ofoccultation timings for studyingtidal friction. E. G. Moore, "Starswhich Appear to Fade at Occulta-tions," durfng which, among othertopics, the use of a portable cas-sette tape recorder was discussed.He noted that the recorder should bekept upright to prevent variation inspeed of the flywheel drive mechan-ism. I feel that this is not crucipiif time sfgnals are clearly recordedsimultaneously; during cold weather,the upright condition is not as im-portant as keeping the recorderwarm, such as by hanging it inside ajacket with a cord arond the neckattached to the recorder's handle.The advantage of a portable stereotape recorder, for recording timesignals on a separate channel, wasnoted. j. C. D. I'larsh, "Fringe Bene-fits," a discussion of the informa-tion which can be obtained fromstudy of the fringes in the diffrac-tion pattern recorded during occul-tations with high-speed photoejec.-tric equipnent.

Chr. dc Vegt, "Angular Diameters ofStars from Lunar Occultations," ab-tron. & Astrphys. 47, 457-459 (NrCh1976). The angular diameters of thefollowing stars have been determinedfrom photoelectric occultation ob-servations with the 60-cm refractorof Hamburg Observatory; uniformlyilltninated disks were assumed: ZC105 (6 Piscitm, m 4.4, sp K5III),diameter !'0042 ± Y0010; ZC 1486 (3]Leonis, 4.4 K4IIIj, ':0028 ± :'OOO6;

ZC 1030 (e Geminortn, Mebsuta, 3.0,G8lb), :'OOS6 ± !'0006; and of inferi-or quality, ZC 885 (m 5.5, gG7j,:'0024 ± !'0012; ZC 1193 (I Cancri,

5.8, gk3), :'OO21 ± !'0006; and ZC3017 (u Capricorni, 5.1, M2III),':0086 ± :'OO20. dc Vegt notes thatthe :'OO18 diameter for Mebsuta de-termined by Beavers and Utter wouldlead to an unrealistically high ef-fective twperature. An oCcultatfonof u Capricorni was also obServedwith the 107-inch reflector at Mc-Donald Observatory, yielding a diam-eter half of that obtained by dcVegt (Dunham .e.t. a!., Astron. j. 78,199).

Chr. dc Vegt and U. K. Gehlich, "Re-sults of Photoelectric Lunar Occul-tation Observations Obtained at theHamburg Observatory during 1969-1973," Astron. & Astrophym 48, 245-252 (April 1976). 195 observations,fncluding four Pleiades occultationsand 49 reappearances, were recordedphotoelectrfca11y. Duplicity is in-dicated for 11 stars, 4 of whichwere not previously known and are inthe list of new doubles (d. n. i,73). The results for the triple starZC 399 (µ Arietis) are especiallyInteresting. A useful discussion oflocal lunar slopes Is given.

j. L. Elliot, E. Dunham, and C.Church, "A Unique Airborne Observa-

tion," Sky and Telescope, 52, 23-25(July 1976). Most readers undoubted-ly already have read this interest-ing article about these Cornell Uni-versity astronomers' observations ofthe 0ccu)tation of Mebsuta by Marsfrom the Kuiper Airborne Observato-ry. The curious record of the cen-tral flash is shown and discussed.

R. G. French and P. J. Gierasch,"Diffraction Calculation of Occulta-tion Light Curves in the Presence ofan Isothermal Atmosphere," Astron.j. 81, 445-451 (June 1976). Thecharacter of the resulting curves isdetermined by the scale height H,the Fresnel zone size i, the suFfaceatmospheric refractivity, and theplanetary radius. An exact generalsolution and two approximations val-Id when H>>1 are presented. It turnsOUt that the diffraction effects ofth? pu¶?etary limb are unimportantfer planets with significant abnos-pheres, including Mars, but thistheory may be needed for some of thesatellites of the outer planets*.ich may have thin atmospheres. Theor.ly non-lunar photoelectric occiiktztion record showing diffractionfringes is the one obtained by Bar-tholdi and (Men during the occulta-tion of B Scorpii C by Id in 1971,and even there, the identificationfs not certain. A range of stellarNgnitudes for detecting diffractionfringes for different solar systemobjects is given in a table; if thestar is too bright, its diameterwill be so large that the diffrac-tion fringes will be washed out, butsuch events are rare. ConsiderationQf diffraction effects of atmspher-ic inhomogeneities, turbulence,scint111ation, and other complexi-ties will ultimately be hportant,but seens prenature at this stage.The authors note that surface irreg-ularities significantly distort lun-ar occultatfon diffraction patterns,but the extensive results of theUniversity of Texas program showthat this is very rarely the case;the moon's limb s~s to be quitesmooth, in general, to the ,1 scaleof a few meters.

I. S. Glass and L. V. Morrison, "Angu-lar diameter of 31 Leonis from a lu-nar occultation," Njn. Not. r. A8tl'.Soc. 175, 57P-60P (May 1976). Ahigh-speed photoelectric record wasobtained with the 70-an refractor atthe Royal Greenwich Observatory,Herstmonceux, on 1971 May 3. The dcsignal from the photomultiplier wasamplified and recorded on a high-speed ultraviolet photographic re-corder. The tracing was digitizedusing a O-Mac pencil follower andthe data analyzed by A. Walker atthe University of Cape Town using acopy of the University of Texas pho-toelectric occultatfon analysis pro-gram. The dfameter of the spectral-type K4 III star was found to be0!'0031 ± O:'OOO6 assuming a uniform-ly i1lumfnated stellar disk.

R. F. Griffin and H. A. Abt, "Radial-Velocity Measurements of the Lunar-Occultation Binary HR 2013," The ob-gervatory 96, 54-56 (April 1976). Afairly noisy photoelectric record of

an occultation of this star obtainedat Flagstaff Observatory on 1970March 15 indicated a possible com-panion O:'Oi away; a record obtainedat McOonald Observatory the samenight showed no evidence of duplic-ity. The authors show that, with0.99975 confidence, the star is sin-gle based on ntnerous spectroscopicobservations. This emphasizes thecare with which photoelectric occul-tation data must be analyzed.

D. Herald, "Observations of Baily'sBeads from near the Northern Limitof the Total Solar Eclipse of June20, 1974," The MOon 15, 91-107(1976). These visual timings of 72Baily bead events were made with a6-cm refractor using eyepiece pro-jection at a location near Quininup,N'stern Australia, about 6 km southof the predicted northern limit. Lu-Mr features based on Watts' limbccrrection data were identified byF.lculating the solar and mean lunar

Imb intersection points for eachevent tfme. Nearly all features wereurdquely identified this way. Aleast-squares analysis showed thatthe corrections to the solar eclip-tic longitude and latitude, and ra-dius (asscning the lunar values askmwn), were -0:'19 ± om, -om ±0!'10, and -0!'05 ± 0:'17, respective-ly. The observations show a highlyTbable 0!'6 discontinuity in Watts'

imb correction reference datin at95° Watts angle, and a deep valleyin a plateau 2" above the mean limba': Watts angle 169?2 not present inldii.tts' data. The topocentric lunarltbrations were -3?05 in longitudeand +0?23 in latitude.

D. A. Howe, "The Feasibility of Apply-ing the Active TvTime System to Au-tomatic Vehicle Location," Naviga-tion 21, 9-15 (1974). The NationalBureau of Standards, Boulder, CO,has worked with the three major A-merican television networks to pro-vide a source of accurate time andfrequency in television transmis-sions. These can be used, with suit-able equiµnent, in areas with threeor more suitably placed transmit-ters, to detemine locations using atechnique similar to that used inLORAN navigation. Tests in the Den-ver area showed that automobileswith the equipment could be locatedto about 40 m accUracy, but thatthis could be improved to about 15 min rural areas, beginning to makethe system useful for graze work,which is usually done in rural are-as. Multipath effects degrade theaccuracy in cities, but these can becalibrated with some work to achieverural accuracies. Hopefully, inter-est in this field will increase, andthe price of the equipment will de-crease as it is manufactured in com-mercial quantities for potential us-ers, such as police departments andtaxi fleets. But it probably will beseveral years before something is a-vailable for the average occultationobserver. Planned precision artifi-cial satellite navigation systemsalso show some promise.

S. L. Howe, Editor, "Of Special Inter-est," nbs Time and Frequency Sert

90

ices Bulletin NO. 223, 8-17 (June

1976). This is an extensive list ofpublications, with abstracts, abouttime and frequency dissemination.

S. L. Howe, Editor, "How to use theLine-lO Television Time TransferMeasurements," nbs Time and Frequen-cy Services Bulletin No. 224, 7-11(July 1976). This tells how to ob-tain or build equiµnent for obtain-ing precise time and frequency fromABC, CBS or NBC network transmis-sions. Prices are not unreasonable,and a diagram of the electronics isgiven.

D. Wallentfne, "Asteroidal Occulta-tions", Minor Planet Bulletin 3, 41-44 (1976 January). This mentions thevalue of occuitatlons of or by minorplanets for determining the diame-ters of these objects, and mentionssome recent predictions. He des-cribes observational problems andhow events might be recorded. Dr.Clark R. Chapman (Planetary ScienceInstitute, Tucson, AZ) points outthat hundreds of occultations ofnon-SAO stars by faint minor planetsoccur each year and are not beingpredicted. There is a need to try topredict these events; watching minorplanets move through rich starfields waiting for an occultation tohappen, without predictions, is awaste of time. I have some cements,mostly about observing procedures,in the April issue of Minor PlanetBulletin, p. 56.

A GRAZE OF THE SUN

David Id. Dunham

Observers are reminded of the total e-clipse of the sun visible from partsof eastern Africa and southeasternAustralia on 1976 October 23. If oneobserves near the northern or southernlimit of the zone of totality, butwithin the zone, prolonged multipleBaily bead phenomena can be observed,analogous to the multiple contacts ob-served during grazing occultations ofstars by the moon. Timings of these e-vents are valuable for determining therelative declinations of the sun andthe moon to high accuracy, and'forstudies of Watts' lunar limb correc-tion data. See the abstract of DavidHerald's article, "Observations ofBaily's Beads from near the NorthernLimit of the Total Solar Eclipse ofJune 20, 1974" on p. 89. The visibili-ty of the chromosphere is also greatlyprolonged near the path edge, oftenduring the'fu11 length of totality(which typically would be a fourth toa third that as seen from the centralline). Mr. Herald also plans observa-tions near the path edge during thisOctober's eclipse. He is coordinatingthe efforts of many Australian observ-ers to establish several stations atvarying distances from both the north-ern and southern limits. Observerstraveling to Australia interested inthis worthwhile project should writeto Mr. Herald at Box 254, kloden, A.C.T. 2606, Australia in order to coor-dinate plans. [Ed: A note from Mr.Herald adds; "It is my desire to ob-tain as many timings as possible fromas many different places as possible.

I would be most appreciative if anyobserver who makes successful timingsCit Baily bead events would write tome."] Dr. A. M. Sinzi, Director, Astt"onomica1 Division, Hydrographic Dc-pirtment, japan, writes saying thatPis office is planning expeditions touo sites in South Australia, one.nearthe central line and one near the.mrthern limit, to obtain high time-resolution photography of Baily'sbeads and the flash spectnn for as-t"ophysica1 and accurate positionalstudies, while a team from the Mizusa-hi Observatory plans to make similarooservations from Portland, Victoria,ni!ar the southern limit.

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HZATHKIT DIGITAL ELECTRONIC STOPWATCH

Wayne R. Coskrey

Several months ago I bought and assem-bled a Heathkit GB-1201 ProgramabieDigital Stopwatch (latest catalogprice $84.95 plus postage, from theHeath Company, Benton Harbor, MI49022). Its main attraction to me wasits great versatility, with sevenfunctions, although only two are use-f'j] in occultation work, the "TotalActivity Time" and the "Split Time."

In both of these functions, the stop-batch is started by pressing the"Start/Stop" (SIS) button, or alter-rttely, by using the remote Start/Stoprelay input jack, possibly by means ofe hlWV synch circuit. In the "Total Ac-tivity Time" mode, the stopwatch meyt.e stopped at the first timing ever,tvith the SIS switch and at the secund('tent with the separate "Final Stop""Is) switch. Both timings are then

contained in two internal counters andcan each be displayed by alternatelypressing the SIS switch. In the "SplitTime" mode, any number of consecutiveevents may be timed by stopping thestopwatch with the SIS switch. Howev-er, the counters are inoperative inthis mode, and only the last timingcan be displayed.

The main disadvantage of this stop-watch is that Heath sells it only as akit. However, assembly is not particu-larly difficult if you've used a sol-ckring iron before, and it should bepossible for a novice kitbuilder toconstruct it in IO-lS hours (hopefullyspaced out in three or four sessions).

The only assembly procedure that re-ciires extreme care is the installa-1.01) of three very static electricity-smitive IC'S. In assembling my stop-¥Itch, I accidentally dropped one oft me IC'S on my pants leg and blew(.it one whole function; and since two(pf these IC's are $18 apiece, and thec'.her is $4.80, it becomes an expen-ENC proposition to replace the wholeiC if part is damaged. The main thing1 ' remember in installing these IC'Sis to be sure to gently squeeze the[ ns against the body of the IC tot'ace the pins the correct distancedort, so that the IC can be pushedi ito its socket with minimum effort.

T':e only other problem I've encounter-ed after extensive UsC of the stop-k tch is a slight malfunction of thep"'ogrann1ng function of the F/S switch( new one would cost $5.10). This dc-cirred just after the 90-day guaranteer n out, too. If you need any replace-m"nt of parts near the end of thegiarantee period, be sure to requestan extension of the guarantee.

The stated accuracy of the stopwatchis ± 0.006%, typically better thanC ®3%, obtained by simple adjustmentof a trimer capacitor. In my firsttests, I detennined that the accuracyof my stopwatch was about ± 0.002%.However, after several months of use,I re-tested the stopwatch, and it hadfallen to an abysmal ± 0.18%. After apainstaking day of trial-and-error ad-justments, I was able to return thestopwatch to ± 0.005%, which is quiteworkable. I would suspect that all e-lectronic stopwatches would need suchperiodic readjustment, due to quartzcrystal aging, shocks, etc. My testsalso indicate that the stated tempera-ture ?ffects of +0.0% to -0.003% from2'5° F. to 120° F. when calibrated at80° F. are probably correct.

Both light and moderate pressureswitch springs are provided. Use themoderate springs if you want to fore-stall premature tripping.

If you want a stopwatch that you canuse for almost any conceivable timingpurpose, this one comes pretty close. .As this article only scratches thesurface of this stopwatch's features,w"ite to Heath (Dept. 322-17) fortheir free catalog. Also, I would bet'ppy to answer any questions.

206 Bridle PathStarkville, MS 39759