0 Assigned ID: 943 ----- Attempting Submission 1 (Fri Apr 08 22:46:21 GMT 2016) ----- HST Phase I Proposal 943 (ret2_actual.apt) successfully submitted. Receipt: # 943-1 ----- Attempting Submission 2 (Fri Apr 08 23:28:51 GMT 2016) ----- HST Phase I Proposal 943 (ret2_actual.apt) successfully submitted. Receipt: # 943-2 FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser 0 ----- Attempting Submission 1 (Thu Jul 21 15:17:31 GMT 2016) ----- We believe that the low FLASH levels should be ok for these observations, but would welcome feedback from the PC. ACS Imaging of the Ultra-Faint Dwarf Galaxy Reticulum II: Age-Dating a Unique Nucleosynthetic Event Recent chemical abundance measurements show that ~80% of the stars in the ultra-faint Milky Way satellite Reticulum II contain >100 times more r-process elements than stars in any other ultra-faint dwarf. These heavy elements must have been synthesized early in the formation history of Ret II in a single event that produced ~0.003 solar masses of r-process nuclei. The best explanation for these results is that a rare neutron star merger occurred in Ret II 12-13 Gyr ago. We propose HST/ACS imaging of Ret II to derive its star formation history, which will place new constraints on the origin of r-process elements in the galaxy. These measurements will be on the same photometric system as previous studies, enabling a careful comparison of the mean age and duration of star formation of Ret II and other ultra-faint dwarfs. We will determine whether the timing of the r-process enrichment is consistent with a neutron star merger, model the chemical evolution of Ret II, and set the stage for a comparison of the star formation and radioactive decay timescales of the system. This program will obtain a 12 tile ACS/WFC mosaic of a nearby dwarf galaxy. Each tile will receive a single 1-orbit visit with imaging in the F606W and F814W filters. Each visit will consist of four exposures, two in each filter, in the sequence F606W, F814W, F606W, F814W, with a dither separating the first two exposures from the last two to fill in the chip gap and reject hot pixels. For the mosaic, we want to maximize the total area covered, so we would like minimal overlap between tiles. The arrangement of the tiles will be on a rectangular grid, but given the elongated shape of the galaxy and the limited amount of observing time the full grid will not be populated with observations. We are also obtaining WFC3/UVIS parallel imaging, again with two F606W and two F814W exposures per orbit. Stellar Populations 12 false false false false false false SUPPORTED GALAXY DWARF SPHEROIDAL J2000 J2000 ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W POS-TARG DITHER 3.034 LINE false false 2 85.29 LINE 2 false Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "05" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:36.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "05" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "08" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:37.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "08" :obset-id "08" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "08" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "09" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:38.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "09" :obset-id "09" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "09" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "10" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:39.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "10" :obset-id "10" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "10" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "11" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:39.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "11" :obset-id "11" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "11" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "12" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:40.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "12" :obset-id "12" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "12" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "13" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:41.0" :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "13" :obset-id "13" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "13" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "14" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:42.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "14" :obset-id "14" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "14" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "15" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:43.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "15" :obset-id "15" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "15" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "16" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:44.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "16" :obset-id "16" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "16" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "17" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:45.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "17" :obset-id "17" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "17" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0 Hst Same orient constraint links visits (05 08 09 10 11 12 13 14 15 16 17 18) The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14766 :visit-id "18" :proposal-version -1 :trans-version "20160601" :date "16-Jul-2016 22:25:46.0" :trans-errors '(:WARNINGS 1 :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 2291888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14766 :visit-id "18" :obset-id "18" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14766 :visit-id "18" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2943 :al-overhead-at-end 101 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3403 :pcs-gap 0 ) true 1 0