If there are problems with the submission, please cc "ben@astro.washington.edu" in addition to the PI (jd@astro.washington.edu) use FGS3 on visits 5-6 This resubmission is added a single, small, integer-pixel dither to visits 5 and 6 to allow for better rejection of ACS hot pixels. This resubmission fixed the small dither to be exactly 3 pixels in X and 3 pixels in Y. ----- Attempting Submission 1 (Sat Jun 28 01:14:30 GMT 2008) ----- ----- Attempting Submission 2 (Mon Jun 30 15:25:22 GMT 2008) ----- ----- Attempting Submission 3 (Mon Jul 28 18:59:37 GMT 2008) ----- ----- Attempting Submission 4 (Thu Jul 31 20:46:10 GMT 2008) ----- Assigned ID: 93 ----- Attempting Submission 1 (Wed Mar 05 20:38:46 GMT 2008) ----- Phase I Proposal 93 (dwarfhalo.apt) successfully submitted. ----- Attempting Submission 2 (Thu Mar 06 20:31:42 GMT 2008) ----- Phase I Proposal 93 (dwarfhalo.apt) successfully submitted. ----- Attempting Submission 3 (Fri Mar 07 18:27:56 GMT 2008) ----- Phase I Proposal 93 (dwarfhalo.apt) successfully submitted. ----- Attempting Submission 4 (Fri Mar 07 22:59:49 GMT 2008) ----- The Stellar Halos of Dwarf Galaxies The metal-poor stellar halo is the oldest extended structure in the Galaxy. Such halos are thought to form through hierarchical merging, and contain stars pulled from accreted subhalos. The diffuse stellar halo therefore stores information about the prop reties of the accreted galaxies (i.e., their orbits, stellar masses, and metallicities). It is therefore unsurprising that stellar halos have become a popular probe of the early epoch of galaxy formation. Almost all current work on stellar halos has focused on massive galaxies, however. We propose to extend the work on stellar halos to much lower mass scales, by studying the halos of faint dwarf galaxies. By taking halo studies into the dwarf galaxy regime, we can probe exceptionally small mass scales for the accreted halos. At these mass scales the effects of reionization and supernova feedback have the largest impact on the galaxy population. Stellar halos of dwarf galaxies are therefore a sensitive probe of the key processes needed to resolve the lack of substructure observed at low masses. We are requesting two far-field ACS pointings for the three closest isolated nearby dwarf irregular galaxies whose inner halos have already been mapped with the ACS Nearby Galaxy Survey Treasury. These outer fields will allow us to trace the halo out to roughly half the virial radius, further than any previous study. We will use the resulting distribution of halo stars (1) to unambiguously measure the structure of the stellar halo, with minimal contamination from the main galaxy; (2) to constrain the flattening of the stellar halo; (3) to measure the metallicity of halo stars as a function of radius; (4) to correlate any changes in halo profile with changes in metallicity. The resulting data will constrain models of halo accretion and the epoch of reionization.
We are taking ACS images in F475W+F814W at two pointings along the major and minor axes of three nearby dwarfs, targeting the outer regions where we expect to find halo stars. Parallel images will be taken with WFC3/UVIS in the same filter set. Images are CR split for DDO 190 and UGC 8508, with one filter per orbit (2 orbits total). For GR8 we have 1 orbit per pointing, and take two single dithered exposures in each filter. Exposure times for GR8 are split unevenly between the two filters to allow for maximum depth at the color of red clump stars. COSMOLOGY 12 false 0.0 0.0 false false false false false SUPPORTED GALAXY DWARF ELLIPTICAL DWARF COMPACT This object was generated by the targetselector and retrieved from the NED database. J2000 14 25 1.0742 +44 32 39.57 J2000 GALAXY DWARF COMPACT DWARF ELLIPTICAL This object was generated by the targetselector and retrieved from the NED database. J2000 14 24 40.3004 +44 33 53.62 J2000 GALAXY MAGELLANIC IRREGULAR LSB This object was generated by the targetselector and retrieved from the NED database. J2000 13 30 59.5348 +54 56 58.24 J2000 GALAXY LSB MAGELLANIC IRREGULAR This object was generated by the targetselector and retrieved from the NED database. J2000 13 31 5.6961 +54 52 38.43 J2000 GALAXY DWARF COMPACT This object was generated by the targetselector and retrieved from the NED database. J2000 12 58 37.2753 +14 10 6.50 J2000 GALAXY DWARF COMPACT This object was generated by the targetselector and retrieved from the NED database. J2000 12 58 54.3342 +14 11 19.87 J2000 ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F475W ACS/WFC Imaging No No F814W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F814W POS-TARG DITHER 3.011 LINE false false 3 85.28 ACS-WFC-DITHER-LINE 1 false The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. /tmp/OPVisit13697.xml 1 orbit per filter, ANGST style (Tic-Visit :proposal-id 11718 :visit-id "01" :proposal-version -1 :trans-version "20080624" :date "31-Jul-2008 13:43:32.0" :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 3437840 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11718 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11718 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3018 :al-overhead-at-end 26 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3351 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11718 :visit-id "01" :orbit-number 2 :pcs-time 195 :si-vis-utilization 3153 :al-overhead-at-end 21 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3351 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. /tmp/OPVisit13698.xml 1 orbit per filter, ANGST style (Tic-Visit :proposal-id 11718 :visit-id "02" :proposal-version -1 :trans-version "20080624" :date "31-Jul-2008 13:43:38.0" :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 3437840 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11718 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11718 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3018 :al-overhead-at-end 26 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3351 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11718 :visit-id "02" :orbit-number 2 :pcs-time 195 :si-vis-utilization 3140 :al-overhead-at-end 26 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3351 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. /tmp/OPVisit13699.xml 1 orbit per filter, ANGST style (Tic-Visit :proposal-id 11718 :visit-id "03" :proposal-version -1 :trans-version "20080624" :date "31-Jul-2008 13:43:46.0" :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 3437840 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11718 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11718 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3120 :al-overhead-at-end 35 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3453 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11718 :visit-id "03" :orbit-number 2 :pcs-time 195 :si-vis-utilization 3258 :al-overhead-at-end 36 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3453 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. /tmp/OPVisit13700.xml 1 orbit per filter, ANGST style (Tic-Visit :proposal-id 11718 :visit-id "04" :proposal-version -1 :trans-version "20080624" :date "31-Jul-2008 13:43:51.0" :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 3437840 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11718 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11718 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3120 :al-overhead-at-end 35 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3453 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11718 :visit-id "04" :orbit-number 2 :pcs-time 195 :si-vis-utilization 3258 :al-overhead-at-end 36 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3453 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. /tmp/OPVisit13701.xml 1 orbit for the whole target. (Tic-Visit :proposal-id 11718 :visit-id "05" :proposal-version -1 :trans-version "20080624" :date "31-Jul-2008 13:43:55.0" :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 11718 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11718 :visit-id "05" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2913 :al-overhead-at-end 46 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3251 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. /tmp/OPVisit13702.xml 1 orbit for the whole target. (Tic-Visit :proposal-id 11718 :visit-id "06" :proposal-version -1 :trans-version "20080624" :date "31-Jul-2008 13:43:58.0" :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 11718 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11718 :visit-id "06" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2913 :al-overhead-at-end 46 :internal-dur-at-end 1019 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3251 :pcs-gap 0 ) true 1 0