This public DECam Deep Drilling Program is being run at the Blanco 4m telescope at Cerro Tololo-Inter-American Observatory as part of the DECam Alliance for Transients (DECAT), a consortium of time-domain DECam programs that have pooled their time and are scheduled for every ~3rd night from March 18 through June 10 (with pending partnership extensions through July). The DDF observational sequences described below will (weather permitting) occur every DECAT night, and will have flexible start times to enable co-scheduling with other DECAT programs.
The images have no proprietary period, and are available through the NOIRLab Astro Data Archive under proposal ID 2021A-0113. Difference image analysis will be done in real time at NERSC, on both the single exposures and the nightly deep stacks. Public alerts will be streamed to all alert brokers that receive public ZTF alerts, including ANTARES, Lasair, and ALeRCE. All are welcomed and encouraged to do science with these data products.
Extragalactic -- Three pointings in the COSMOS deep fields: COSMOS-1 (150.0,+3.1), COSMOS-2 (149.22,+1.75), and COSMOS-3 (150.78,+1.75). Every DECAT night, three ~0.5 hour sequences will be done; some nights these will be back-to-back, and some nights they will be separated in time by up to a couple of hours. Each sequence cycles through the fields, obtaining a series of images in the g, r, and i filters with exposure times of 60, 86, and 130 seconds, respectively. In total, each field will be imaged five times in each filter, for a total of 15 photometric observations per night (45 for sources in the ~5% overlap region; no dithering). The 5-sigma limiting magnitudes will be r~23.5 mag (single exposure) and r~24.5 mag (nightly stack).
Galactic -- One pointing in the Galactic bulge which we are calling “DECaPS East” (18:03:34 -29:32:02; l=1.462 b=-3.681). Every DECAT night, two ~0.3 hour sequences will be done; some nights these will be back-to-back, and some nights they will be separated in time by up to a couple of hours. Each sequence will cycle through the g, r, i, and z filters three times with exposure times of 96, 50, 30, and 30 seconds, respectively. In total, the field will be imaged six times in each filter, for a total of 24 photometric observations per night. The 5-sigma limiting magnitudes will be, at most, r~23.5 mag (single exposure) and r~24.5 mag (nightly stack) -- but potentially shallower in such a crowded field.