evidence of asteroid satellites from 30 years of observation paul d. maley¹, d.w. dunham², d....
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EVIDENCE OF ASTEROID SATELLITES FROM 30 YEARS
OF OBSERVATION
PAUL D. MALEY¹, D.W. DUNHAM², D. HERALD³
¹UNITED SPACE ALLIANCE & INTERNATIONAL OCCULTATION TIMING ASSOCIATION (IOTA), HOUSTON, TX; ²IOTA, GREENBELT
MD; ³IOTA, CANBERRA AUSTRALIA
FIRST BINARY WORKSHOPSTEAMBOAT SPRINGS CO.
JULY 21-23, 2007
HISTORY OF SATELLITE DETECTION
• 1977 (6) HEBE OCCULTATION STARTED THE PROCESS
• >1029 PRIMARY OCCULTATIONS OBSERVED (as of December 2006)
• 42 SUSPECTED SATELLITE EVENTS
• 9 HIGH PRIORITY CANDIDATES
CONSTRAINTS
• IN SITU OBSERVATIONS
• CHASING SHADOWS
• TECHNOLOGY: SMALL TELESCOPES; COTS EQUIPMENT
• VISUAL OR VIDEO
• OBSERVATIONS ARE UNREPEATABLE
• RESOLUTION LIMITED TO HUMAN EYE OR VIDEO FRAME RATE
• NO FUNDING
(6) HEBE & γ CETI
NUMBER OF ASTEROID OCCULTATIONS OBSERVED 1961-2006
0
50
100
150
200
250
1950 1960 1970 1980 1990 2000 2010
YEAR
NUM
BER
NUMBER OF ASTEROID OCCULTATIONS WHERE POSSIBLE SATELLITES WERE REPORTED
01234567
1970 1975 1980 1985 1990 1995 2000 2005 2010
YEAR
NUM
BER
OCCULTATION CANDIDATE DEPENDENCIES
• Limiting magnitude +12.5• star and asteroid magnitudes• depth of magnitude drop during occultation• duration of occultation• path reliability• proximity of observation zone to twilight• elevation of target star above the horizon• whether available instrumentation is expected to be sensitive
enough to collect the data• angular separation from the moon• phase of the moon• overall weather in the region of proposed observation• possible hazards in observation zone including political,
civil, military
METHODS OF DETECTION
• VISUAL
• PHOTOELECTRIC
• VIDEO (STANDARD VIDEO RATE)
• DRIFT SCAN
IOTA STRATEGIES
• USE OF INTERNET
-COMMUNICATION AND COORDINATION
-DISTRIBUTION OF PREDICTIONS/CHARTS/SOFTWARE TOOLS
-LOCATING SAFE SITES
-LATEST WEATHER DATA
• USE OF MOBILE STATIONS
• PREPOINTED REMOTE STATIONS
SATELLITE DETECTION STRATEGIES
• UTILIZE VOLUNTEER OBSERVERS, KNOWN OBSERVATORIES
• MULTIPLE OBSERVERS, CLOSE SPACING
• ALTERNATION OF VIDEO & VISUAL OBSERVERS
• TWO VIDEO STATIONS 1KM APART
PREPLANNED SITE LAYOUT
ISSUES OF CREDIBILITY
• SINGLE SITE OBSERVATION
• REACTION TIME
• HARDWARE PROBLEMS
• ATMOSPHERIC SCINTILLATION
• CLOUD PASSAGE
• WRONG STAR TARGETED
• LOW ELEVATION
• INTERPRETATION OF DATA
SINGLE CHORD
ONE POLE
FRAGMENTED COVERAGE
NEAR COMPLETE MAP
TRANSATLANTIC
TRANSPACIFIC
COMPLETE SITE COVERAGE
HIGHEST RESOLUTION
FINE MAPPING
SATELLITE ANALOG: (11072) HIRAOKA
CASE STUDY 1– (532)HERCULINA (1978 June 7)
Pro: Simultaneous Photoelectric & visual observationsCon: Low star elevation (3 degrees) at Anderson Mesa
CASE STUDY 2– (216)KLEOPATRA (1980 Oct 10)Pro: 2 observations 2000 ft apart; color change reported like for main event
Con: Both observations were visual
CASE STUDY 3– (71)NIOBE (2005 Feb 10)Pro: 16-inch telescope used for secondary event; star 8th mag.
Con: Visual (but accurately timed with WWV)
CASE STUDY 4– (98)IANTHE (2004 May 16)Pro: Video
Con: Event was 0.2 seconds long
REJECTION (2004 Jun 24)
OPPORTUNITIES for STUDY
• VESTA OCCULTATION JAN 07 (CHILE) + 1991 OBSERVATIONS + HST IMAGES3D MODEL
• CHECKS ON POSITIONS OF KNOWN SATELLITES USING MOBILE IOTA OBSERVERS
CHALLENGES - 1• AGING EXPERIENCED OBSERVER CADRE• LACK OF FUNDING PREVENTS EXPANSION
OF EFFORTS• SIFT THROUGH THE FACTS TO ISOLATE
THE TRUTH• LIMITED TO EARTHBOUND OBSERVATION• NEA’S HAVE POOR ASTROMETRY• EDUCATING NEW OBSERVERS
CHALLENGES - 2
SAGAN DANGERFIELD GALILEO
PROMISE FOR THE FUTURE
•MIGRATION AWAY FROM VISUAL OBSERVATION
•ESTABLISH VIDEO AS A STANDARD
•ADOPT SOFTWARE VIDEO REDUCTION TOOLS
•ADOPT STANDARD METHODOLOGY:
-OBSERVATION WINDOW
-MULTIPLE FIELD STARS
-AUTOMATED OBSERVATION STATIONS
•IMPROVE NEA ASTROMETRY
PROMISE -2•DEMONSTRATIONS IN OTHER COUNTRIES
•ESTABLISH FUNDING SOURCES
-CLAY CENTER MOBILE OBSERVATORY DEVELOPMENT
•DEVELOP BETTER STRATEGIES FOR INTERCEPTION
•EXPAND OBSERVER CORPS THROUGH PUBLICATION
•BETTER PREDICTIONS FROM TMO AND FASTT
•INTERACTIVE GOOGLE MAPS FOR SITE DETERMINATION
•NEW SOFTWARE FOR OBSERVER COORDINATION
•DEVELOP WAYS TO USE ROBOTIC OBSERVATORIES
•COLLABORATION WITH PROFESSIONAL COMMUNITY (E.G. BERTHIER—KNOWN MINOR SATELLITES, SICARDY—PLUTO)
•EXPANSION OF ONE OBSERVER ESTABLISHING MULTIPLE UNTENDED STATIONS
CONCLUSIONEVIDENCE SHOWS:
• DETECTION OF A KNOWN SATELLITE HAS BEEN PROVEN
• NO SATELLITES HAVE BEEN CONFIRMED VIA METHODS DESCRIBED
SATELLITE SIGNIFICANCE:
• ORION MISSION TO A NEA
BACKUP SLIDES
CASE STUDY 5– (2)PALLAS (1978 May 29)Pro: Photoelectric; secondary event reached level of primary event
Con: 0.1 second duration
CASE STUDY 6– (146)LUCINA (1982 Apr 18)Pro: Image intensified video; bottom level expected for Lucina alone
Con: No other field stars
CASE STUDY 7 – (18)MELPOMENE (1978 Dec 11)Pro: Photoelectric obs of primary/secondary
Photoelectric Record at Monticello, UT; tracking errors, frozen drive
Photoelectric recording at Flower & Cook Obs., Ambler, PA
CASE STUDY8 = (772)TANETE (2004 Apr 18)Con: Visual, seen 2 minutes before primary
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