david james (ctio) for the dark energy survey pan-starrs1: science results stsci , baltimore - 24...

David James (CTIO)for the Dark Energy Survey

Pan-STARRS1: Science ResultsSTScI, Baltimore - 24 June 2014

Dark Energy Camera – DES: YR1 of the Dark Energy Survey

The Dark Energy Survey:

Pan-STARRS1: Science Results Dark Energy Survey David James

The Dark Energy Survey:

Blanco 4-metre Telescope at CTIO

Ω Survey project to probe signatures of Dark Energy using four complementarytechniques:

Ω Cluster CountsΩ Weak LensingΩ Large-scale StructureΩ Supernovae

Ω Two multiband surveys:Ω 5000 deg2: 10σ griz(Y) to 24th (21.6th) magΩ 30 deg2: repeated SNe fields

Ω Build new 3 deg2 FoV camera and data management system:

Ω Survey 2013-2018 (525 nights)Ω Facility instrument for Blanco

http://lsst.org


The DES Collaboration

FermilabUniversity of Illinois at Urbana-Champaign/NCSAUniversity of ChicagoLawrence Berkeley National LabNOAO/CTIODES Spain ConsortiumDES United Kingdom Consortium

University of MichiganOhio State University

University of PennsylvaniaDES Brazil Consortium

Argonne National LaboratorySLAC-Stanford-Santa Cruz Consortium

Universitats-Sternwarte MunchenTexas A&M University

plus Associate members at: Brookhaven National Lab, U. North Dakota, Paris, Taiwan

Several hundred members plus students & postdocs

Funding: DOE, NSF; UK: STFC, SRIF; Spain Ministry of Science,

Brazil: FINEP, Ministry of Science, FAPERJ; Germany: Excellence Cluster; collaborating

institutions


Dark Energy Camera: A new prime focus instrument

Hexapod

Corrector Lenses

CCDReadout Filters +

Shutter

Focal plane (detector, 62+ CCDs)


Brave New World: DECam

Parameter Mosaic II DECamNo. of CCDs 8 62 + 12(F&A, guiding)

CCD Format 2Kx4K, 15μ pixels 2Kx4K, 15μ pixels

CCD Type Standard, BBAR Depleted, red optimized

Full well 60K 130K

Image size 128 MB 1040 MB

RON 6-12 e- rms 15 e- rms

Read time 100s 17s

Overheads 10s 3s

Guiding separate Focal plane

Filters many g r i z Y

ADC yes no


Controlling DECam: SISPI

Ω Data Flow: Ω Image acquisition (Panview, 6 Monsoon crates) Ω Image Builders (multiple instances)

Ω FITS formatting

Ω Image Health

Ω Telemetry

Ω Compression

Ω Submit to NCSA (DTS)

Ω Observation Control:Ω OCS (pipeline architecture)Ω OBSTAC

Ω Instrument Control:Ω Internal (shutter, hexapod, filters)Ω External (cooling, temperatures, ICC)

Ω Guider & Focus:Ω Interfaces to TCS & Cloud Camera:

SISPI is the DECam dataacquisition and control system:


The Dark Energy Camera: Detector

2k x 2kGuide

2k x 2kFocus &

Alignment

2k x 2kFocus &

Alignment

2k x 2kGuide


(original) DES Observing Strategy:

2 tilings 3 tilings

Ω Sept-Feb observing seasonsΩ 80-100 sec exposures Ω 2 filters per pointing (typically)

Ω gr in dark timeΩ izy in bright/grey time

Ω Photometric calibration: overlap tilings, standard stars, spectrophotometric calibration system, preCAM

Ω 2 survey tilings/filter/yearΩ Interleave 10 SNe fields in griz if

non-photometric or bad seeing or time gap (aim for ~5 day cadence)


(present) DES Observing Strategy:

Year 1 regionsSDSS Stripe 82

SPT

Year 1:Ω Moved footprint eastward to

reduce secZ, improve image quality

Ω Cover 2000 sq. deg. (4 tilings per filter) rather than full 5000 sq. deg. (2 tilings) to improve photometric calibration

Ω Allow g, Y observations with seeing>1.1” (not used for Weak Lensing).

Year 2:Ω Complementary 3000 sq. deg.Ω Optimize: many more half-nights

than YR1

By end of YR2, expect will have done 90% of the exposures needed to complete 4 tilings of the 5000 sq. deg. footprint.


Dark Energy Survey: Year 1

Month # Full Nights # 1st Half Nights

# 2nd Half Nights

August 1 0 0

September 24 0 0

October 14 0 0

November 18 0 0

December 27 0 0

January 4 19 0

February 0 9 0

Ω DES started taking YR1 data on Aug. 31st 2013Ω In January, we switched to 1st half nightsΩ Finished YR1 in mid-February 2014


DES: Observing Sequences


Year 1 (vs. SVA1): Exposure Breakdown

SVA1 YEAR1

Time period 11/01/12 − 02/15/13 08/31/13 − 02/15/14

# exposures % accepted # exposures % accepted

All bands 10929* 60% 17605* 82%

g 1998 58% 4203 73%

r 2086 53% 2782 90%

i 2281 57% 2916 93%

z 2375 65% 2965 96%

Y 1608 88% 4738 70%

First DES YR1 Image

First DES YR1 image is #229250

Ω Image DECam_00229250 was transferred to NCSA in Urbana where; Ω DES “Data Management” processed

it and made a catalog of the stars and roughly 100,000 galaxies that can be identified in it.

• 31st Aug. 2013 23:55 Local Chilean Time


Ω Only 2 problems lasted as long as 4 consecutive hours: In Oct. we lost a night from a TCS software bug. In Nov. we lost 1½ nights due to problems w/ electronics: noise and missing backplanes, then CCD S30 failed.

Ω The other problems are computer interfaces issues, … mostly, shutter resetsΩ Shutter was open 63% of “Observing Time” during YR1. Dome control improvements gave us

~4% better efficiency starting in late December 2013.

DES Operations EfficiencyMeasurements

Operation DES Yr. 1 Accumulated Hrs. (%)

DES Extended SV Hrs. (%)

Observing Time Available 888.25 (100) 321.0 (100)Observing Time 751.50 (84.6) 226.7 (70.6)Engineering Observations NA 23.2 (7.2)Bad Weather 90.25 (10.2) 24.5 (7.6)Telescope or Infrastructure Failure => can’t observe

18 (2.0) 45.1 (14.1)

Camera Systems Failure => can’t observe

25.75 (2.9) 1.5 (0.5)

Observer Error 2.75 (0.3) 0 (0.0)


DES WFSurvey

Ω Goal was to observe 4 “tiles” of ~672 images per tile in each of 5 filters

Ω 13435 images totalΩ Plots here show what we

obtained:

Ω Gaps in Stripe 82 (North)Ω Gaps in Sept. to Nov. survey area

(West)Ω Images in YR2 fields because

nothing “available” from YR1 particularly in late Jan. to Feb. ~3k images (17%) of YR2


DES SN Survey: YR1 Observations

Ω 10 SN fields. 2 of those are “deep fields”

Ω Our plot shows day-by-day SNe cadence

Ω 2565/2699 SNe exposures “good” (95%)

Ω After 7-days, even when the weather is good, SNe team gets their data on “deadman” condition of OBSTAC.



DES Observing: YR2


First DES (SV) Science Paper:

2014arXiv1405.4285M


Community Use of DECam:

Ω DECam-NEOO: Ω Lori Allen (NOAO – PI)Ω 3-yr survey time awardedΩ 1st 10-night block executed April

2014Ω Early results are very

encouraging

Ω Light-echoes of SNe remnants:Ω Armin Rest (STSci – PI)Ω many nights per semesterΩ étendue of DECam criticalΩ latest results are now available:

Prieto et al. 2014, ApJL, 787, L8

DECam Current Status

Ω Sensor array is OK exceptΩ Two CCDs are no longer

functioning correctly: Ω N30 11/07/2012Ω S30 11/28/2013

Ω 8 CCDs ~12e- RO noise (7e- is typical), spec is 15 e-. Problem comes and goes since late Nov.

Ω S7 (½ CCD) non-linearity unstable at very low light levels (<1000e-).

Ω Two focus chips have 1 “weak” amplifier.

S30

N30

S7




Thank you !

DECam Community Workshop, Tucson, August 201124

NOAONCSAFor details, ask Brian Yanny, DES Data Coordinator,

or Robert Gruendl, UIUC

DECam Community Workshop, Tucson, August 201125

david james (ctio) for the dark energy survey pan-starrs1: science results stsci , baltimore - 24...

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