We have obtained the deepest optical dataset ever taken or planned towards the bulge, allowing bulge/disk decomposition down to F606W=23 and variability monitoring over seven days, diagnostics not available for any bulge field observed by Chandra. We propose ACIS-I imaging to identify X-ray point sources in this field. This will directly trace a number of fundamental yet poorly-constrained parameters of the inner Milky Way, for example the spin-down timescale of stars along the disk and bulge; the formation history of the bulge and, for the first time, direct constraints on the gravitational potential of the inner milky way through AGN-enabled absolute proper motions. Our proposed survey will be an essential calibrator for other X-ray/optical surveys of the bulge both past and planned.

Fall 2010 - visit 08 failed and visit 09 is now not schedulable. Field WFPC2-3 has therefore been discarded from the strategy. Instead, Visit 09 has been changed in target and orientation to match the pointing of visit 58 (i.e. 1 before). The fields SWEEPS and WFPC2-1 will now be visited with three orbits, WFPC2-1 entirely with WFC3/UVIS. Filter and pointing strategy ================= We place our fields to maximize the number of visits that are repeats to previous epochs, to maximize proper motion coverage. Three of four fields with previous coverage are imaged with ACS/WFC, the third with WFC3. All orients picked have schedulability according to APT. The following table gives the previous coverage within the ACIS-I footprint: Name archive Coverage Visit PM? Notes ===== ======= ==== === === ==== SWEEPS J9EV01010 ACS: R,Ha 1 Y ACS/WFC previous pointing WFPC2-1 U8W8F903 ACS: R, Ha 2 Y NW of SWEEPS WFC3: R,V 1 (R in both camera) WFPC2-2 U2KL0306 ACS: R, Ha, V 3 Y N of SWEEPS WFPC2-3 U3ZV9505 WFC: R, Ha, V 3 Y NNW of SWEEPS; just within ACIS-I WFPC2-4 n/a WFC: Ha, R 2 N Between WFPC2-2 and SWEEPS The previous WFPC2 observations at WFPC2-1 and WFPC2-2 only have significant depth in a single filter (F606W and F555W respectively), so we obtain V, R colors for these fields. The visits ("coverage" above) divide as follows: Vis1 (2 orbits) -- 1 orbit each with ACS/WFC in F658N and F625W to obtain H-alpha excesses from sources for which proper motion data already exists. Parallel field - WFPC2-1, F658N and F625W with WFC3. Vis2 (2 orbits) -- 1 orbit each with ACS/WFC in F658N and F606W to overlap WFPC2-1. Visit oriented to place WFC3 footprint between WFPC2-2 and WFPC2-3 fields. Paralllel field with WFC3: F625W and F658N in order to measure H-alpha excess for the intermediate field WFPC2-4. Vis3 (3 orbits) -- 1 orbit each with ACS/WFC in F658N, F625W and F606W to overlap WFPC2-2. Visit oriented to catch WFPC2-3 with WFC. Dithering ====== Want four corners of 1pix box for subpixel sampling. Want ~few pix to mitigate badpix. Also want pointing maneuver to be as short as possible (so start at POS TARG = 0,0). Input manually because exposure time varies throughout each orbit. Resulting POS TARGS: X - 0.0, 0.0, 0.425, 0.425 arcsec Y - 0.0, 0.425, 0.425, 0.0 arcsec Note Feb 2010 - in practice the dithers are slightly different, but still achieve the same goals Exposure times and buffer dumps ====================== Five requirements, somewhat in conflict: 1. Want as many samples per orbit as possible (characterize propmotion error) 2. Want 1 or more short (25s max) exposure to measure motions at and above main sequence turn-off, without saturating the red clump 3. Want depth for faint astrometry BUT want deep to saturate AT MOST 3.5 mags fainter than the short exposures (ACS/WFC position measurement hits 0.01pix rms per coord at about 3.8 mags fainter than saturation). Max exp time alllowed thus ~500s for the F606W and F625W exposures (no such restriction for F658N). 4. Want to achieve depth in stacks to look for very faint companions 5. Both ACS/WFC and WFC3 in parallel, each at full aperture. The exposure strategies used in each visit meets these requirements to the best of our abilities.This affords at least 3 exposures each in ACS/WFC and WFC3 at >339s, in every orbit. The exposure times had to be somewhat finessed to achieve this efficiency, so the dithers are entered manually as POS TARGs. H-alpha orbits are the ones requiring the greatest depth - use the second orbit per visit for H-alpha to take advantage of the shorter guide star acquisition time (compared to first orbit). (This additional available time is not long enough to fit another astrometry exposure.) Contiguous exposures =============== Uninterruptable sequences within each orbit are required. Also required that the orbits within each visit be observed contiguously. RESOLVED STELLAR POPULATIONS 12 false 1000.0 0.0 false false false false false false SUPPORTED STAR BULGE Overlap field with GO-10466 field BULGE-4. J2000 17 59 8.0000 -29 14 5.00 J2000 STAR BULGE ACS/WFC overlap with WFPC2 F555W field for proper motions. If oriented right, can overlap WFC3 field with previous WFPC2 field at the N end of the Chandra coverage. J2000 17 59 8.0000 -29 14 5.00 J2000 STAR BULGE ACS/WFC overlap with WFPC2 coverage. J2000 17 59 8.0000 -29 14 5.00 J2000 ACS/WFC Imaging No No F658N ACS/WFC Imaging No No F625W ACS/WFC Imaging No No F435W ACS/WFC Imaging No No F625W WFC3/UVIS Imaging No No F438W WFC3/UVIS Imaging No No F438W WFC3/UVIS Imaging No No F625W The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. Visit 1 Prime: SWEEPS overlap field. R (orbit 1), Ha (orbit 2). ORIENT, target, aperture all identical with GO-10466 to re-image the field as closely as possible with the primary camera. WFC3 points at WFPC2-1 (GO-10084). Filters: R, V to measure motions. 1268533487000 270.0 (Tic-Visit :proposal-id 12020 :visit-id "08" :proposal-version -1 :trans-version "20100902" :date "14-Nov-2010 17:09:46.0" :trans-errors '(:WARNINGS 2 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 4867968 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12020 :visit-id "08" :obset-id "08" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12020 :visit-id "08" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2929 :al-overhead-at-end 118 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12020 :visit-id "08" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3043 :al-overhead-at-end 0 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) true 2 2 Short exposure for bright object motions. Also minimizes the gap between ACS and WFC3 buffer dumps. The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. Visit02 FALL 2010 - orient chosen to match visit 58 WFPC2-1 overlap field. Ha, R ORIENT chosen to point WFC3 at the field between SWEEPS and WFPC2-2 (see proposal description for strategy). (Tic-Visit :proposal-id 12020 :visit-id "09" :proposal-version -1 :trans-version "20100902" :date "14-Nov-2010 18:04:47.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 4867968 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12020 :visit-id "09" :obset-id "09" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12020 :visit-id "09" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2923 :al-overhead-at-end 118 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12020 :visit-id "09" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3031 :al-overhead-at-end 0 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) false 2 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. Visit 3 Primary: WFPC2-2 overlap field. Ha, R, V. Secondary: WFPC2-3 overlap field, Ha, R, V. 1272969811000 278.0 (Tic-Visit :proposal-id 12020 :visit-id "11" :proposal-version -1 :trans-version "20090702" :date "17-Feb-2010 10:49:25.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 7444064 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12020 :visit-id "11" :obset-id "11" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12020 :visit-id "11" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2927 :al-overhead-at-end 118 :internal-dur-at-end 670 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12020 :visit-id "11" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3043 :al-overhead-at-end 0 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12020 :visit-id "11" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3039 :al-overhead-at-end 117 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3267 :pcs-gap 0 ) true 3 0 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. Visit 1 Prime: SWEEPS overlap field. H-alpha. ORIENT, target, aperture all identical with GO-10466 to re-image the field as closely as possible with the primary camera. WFC3 points at WFPC2-1 (GO-10084). Filters: R, V to measure motions. (Tic-Visit :proposal-id 12020 :visit-id "58" :proposal-version -1 :trans-version "20100902" :date "14-Nov-2010 17:01:20.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 2291872 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12020 :visit-id "58" :obset-id "58" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12020 :visit-id "58" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2924 :al-overhead-at-end 0 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) false 1 0 Short exposure for bright object motions. Also minimizes the gap between ACS and WFC3 buffer dumps.