Dark Energy Survey (DES) (Presenter: Douglas Tucker) DES is observing (Aug. 15 th – Feb. 15 th ) Year 2 Operations Collaboration Meeting in Sussex, UK, Oct darkenergydetectives.org Y1A1 tile DES (Stripe 82)

Y2 Observing Summary So far DES has had 47 scheduled observing nights, 10 half- nights and 42 full nights. 2 # Nights Total Hours Observing Lost Camera or Telescope Lost Obs. Error Lost Weather Aug.992 ¾58 ¾0034 Sept ¼122 ¼¾058 ¼ Oct ½165 ½2 ¼¼33 ½ Total47475 ½346 ½30125 ¾ 100%73%½ %½ %0%26% The first 7 half-nights were great and included seeing records in all DES filters Next 6 weeks was among the worst in 31 yrs CTIO Improved since mid-October

Y2 WF Survey Status Individual WF exposures are graded “Good” or “Bad” as part of the DESDM “1 st Cut” output. This informs the “Exposure Table” on the mountain so OBSTAC knows if the exposure needs to be redone. Right: WF tilings after night of Oct. 31 –Lt Blue: last Yr, Dk blue: this Yr, Red: last night Y1 gaps getting filled in nicely Especially in r, i-band 3 # WF Images # WF Good # WF “Bad” Aug (69%)427 Sept (59%)967 Oct (73%)890 Total (70%)2284

Y2 SN Survey Status In Y1 the SN fields had a median # days between revisits of about 6.5 days. The maximums gaps were 11 to 16 nights. Gaps so far in Y2 are 12 to 21+ nights (see right) In Y2, bad weather bracketed a 3 night stretch when DES didn’t have the telescope. Improved somewhat since 4 Oct 31 # Completed Shallow Fields # Completed Deep Fields Aug.127 Sept.3532 Oct.34

New Dome Environmental Controls: 2 large glycol-cooled air- handlers will better maintain the primary mirror at or just below the air-temperature, minimal temperature gradient within the dome, and internal and external air temperatures matched. Finished, now commissioning automatic controls. New Primary Mirror Support Pad air-pressure controls –The present system controls mirror shape depending on gravity vector with an astigmatic correction. 33 of 33 with higher resolution air-pad controls installed. Perhaps some improvement in seeing is already being attained. –New “Hexapod” (Focus ) Default –D0Nut studies indicate that primary mirror aberrations can be better zeroed-out. This new system will need commissioning to achieve the improvement. December 1-5 Engineering. A FNAL Team to –Replace LN2 pump, improve 1 of the LN2 line segments, repair a scroll pump 5 Recent Improvements for DECam/Blanco ✔ ✔ We started keeping image quality records in Y1. This year we have new records in all filters. ✔

DES Observers Y2 DES Observers so far from FNAL, Texas A&M, CTIO, U. Chicago, ANL, BNL, Brazil, SLAC, LBL, U.K., OSU, Barcelona, ETH Zurich – most of the collaboration institutions 6

Year 1 Annual Reprocessing: Calibrations 7 Year 1 Relative Calibrations Goal: 4% rms Achieved: < 2% rms -3.0% 0.0% +2.0% Credit: Eli Rykoff

Summary & Perspective Y2 started great. Then we has 6 weeks of lots of clouds. Lately the weather has improved. It should just get better as it warms up in Chile. When the dome is open we are doing well. Ahead of last year’s pace because the seeing has been better and we’ve been about 5% faster. DECam NEO from TOO: “Working for you to save the planet” (picture from Frank Valdes, NOAO) 8

Gaps 10/30/14 Better View 9