David James (CTIO) for the Dark Energy Survey Pan-STARRS1: Science Results STScI , Baltimore - 24...
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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:
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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
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Pan-STARRS1: Science Results Dark Energy Survey David James
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
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Pan-STARRS1: Science Results Dark Energy Survey David James
Dark Energy Camera: A new prime focus instrument
Hexapod
Corrector Lenses
CCDReadout Filters +
Shutter
Focal plane (detector, 62+ CCDs)
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Pan-STARRS1: Science Results Dark Energy Survey David James
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
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Pan-STARRS1: Science Results Dark Energy Survey David James
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:
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Pan-STARRS1: Science Results Dark Energy Survey David James
The Dark Energy Camera: Detector
2k x 2kGuide
2k x 2kFocus &
Alignment
2k x 2kFocus &
Alignment
2k x 2kGuide
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Pan-STARRS1: Science Results Dark Energy Survey David James
(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)
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Pan-STARRS1: Science Results Dark Energy Survey David James
(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.
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Pan-STARRS1: Science Results Dark Energy Survey David James
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
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Pan-STARRS1: Science Results Dark Energy Survey David James
DES: Observing Sequences
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Pan-STARRS1: Science Results Dark Energy Survey David James
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%
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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
Pan-STARRS1: Science Results Dark Energy Survey David James
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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)
Pan-STARRS1: Science Results Dark Energy Survey David James
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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
Pan-STARRS1: Science Results Dark Energy Survey David James
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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.
Pan-STARRS1: Science Results Dark Energy Survey David James
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Pan-STARRS1: Science Results Dark Energy Survey David James
DES Observing: YR2
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Pan-STARRS1: Science Results Dark Energy Survey David James
First DES (SV) Science Paper:
2014arXiv1405.4285M
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Pan-STARRS1: Science Results Dark Energy Survey David James
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
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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
Pan-STARRS1: Science Results Dark Energy Survey David James
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Pan-STARRS1: Science Results Dark Energy Survey David James
The DES Collaboration
Thank you !
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Pan-STARRS1: Science Results Dark Energy Survey David James
The DES Collaboration
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Pan-STARRS1: Science Results Dark Energy Survey David James
The DES Collaboration
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DECam Community Workshop, Tucson, August 201124
NOAONCSAFor details, ask Brian Yanny, DES Data Coordinator,
or Robert Gruendl, UIUC
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DECam Community Workshop, Tucson, August 201125