0 Assigned ID: 880 ----- Attempting Submission 1 (Fri Apr 11 21:38:42 GMT 2014) ----- HST Phase I Proposal 880 (HVC_HST.apt) successfully submitted. ----- Attempting Submission 2 (Fri Apr 11 23:24:52 GMT 2014) ----- This pattern is not used in this proposal. This pattern is not used in this proposal. I have updated the dither patter to 'BOX' for both visits and the observations in them 1404377707 ----- Attempting Submission 1 (Wed Jul 23 17:24:22 GMT 2014) ----- ----- Attempting Submission 2 (Fri Aug 22 02:20:16 GMT 2014) ----- HST Phase II Proposal 13735 (HVC_HST_phaseII.apt) successfully submitted. ----- Attempting Submission 3 (Mon Aug 25 16:48:54 GMT 2014) ----- HST Phase II Proposal 13735 (HVC_HST_phaseII.apt) successfully submitted. ----- Attempting Submission 4 (Mon Aug 25 17:27:10 GMT 2014) ----- These warning are simply unused patterns. A New Dwarf Galaxy Associated with an Ultra-Compact High Velocity Cloud We request three filter HST imaging to study the properties of what may be the faintest gas-rich dwarf galaxy known (M_V ~ -5). This galaxy will provide crucial information on how the very lowest mass galaxies form in isolation, unaffected by local environment. It will provide a useful reference object for interpreting the ultrafaint dwarfs in the Local Group, and help to populate the poorly known luminosity function of faint galaxies in the Local Volume. The galaxy was found through deep ground based imaging of a ultracompact high velocity HI cloud, however with current data we can only constrain that it likely lies within the local volume at a distance of < 4.5 Mpc. We propose to combine optical and UV imaging to determine the galaxy's distance, extent, current metallicity, and star formation history. Our primary science goal is to determine the basic physical properties -- distance, luminosity, metallicity and star formation history -- of the newly discovered dwarf associated with HI gas from Adams et al. (2013), HVC274pt68 (Fig. 1 & 2 from phase I). This goal requires excellent UV-optical colors for determining the extinction and stellar metallicity of the young stellar population (Fig 3; phase I). Optical magnitudes and colors (F606W, F814W) will let us measure the distance to HVC274pt68 via the tip of the red giant branch method, as well as a robust star formation history as we will image down to the red clump if the dwarf is at D<3.5 Mpc. Required Depth: We are confident that HVC274pt68 is between 2--4.5 Mpc away. Assuming the most distant estimated value, we need a S/N>20 at F814W=24.5 mag and F606W=26.0 mag (assuming M_I=-4.0 and M_V=-2.5 for the TRGB; Da Costa & Armandroff 1990) to measure a TRGB distance to ~10% (e.g. Karachentsev et al. 2007). If within D<3.5 Mpc, we can also obtain a robust star formation history of the dwarf in an economical amount of time; for instance, the red clump (M_I~-0.5 and M_V~0) at that distance is at F814W=27.2 mag and F606W=27.7 mag, and we will set our exposure limits to get a S/N=5 at that magnitude. The star formation histories will be measured with a color magnitude diagram fitting technique (e.g. MATCH; Dolphin 2002; Weisz et al. 2011). The UV/F275W observations are critical for determining the metallicity of the young stars in HVC274pt68. Once the distance to HVC274pt68 is determined via the TRGB distance, we can correct for any residual extinction via a UV/optical color-color plot, which is insensitive to the metallicity of the young stellar population but shifts strongly in the face of extinction (see Figure 3 phase I; right panel). Once corrected for extinction, the F275W-F606W colors will be a clean indicator of the metallicity of the young star population, where a ~0.5 dex metallicity difference will typically have a color difference of >0.15 mag (Figure 3 phase I; left panel). We illustrate and outline our thought process for measuring both the extinction and young population metallicity in Figure 3 in the Phase I document. To make these measurements, given the expected color differences, we will need a S/N=20 for our brightest main sequence star candidates, which will have a F275W~22.5 mag (assuming the largest distance estimate). Exposure Times and Final Orbit Count: With our desired S/N=5 at F814W, F606W=27.2, 27.7, we require 2300s in exposure time for each band, according to the ACS Exposure Time Calculator. A standard dither sequence will be incorporated. Each filter's observation can be accomplished in a single orbit. Similarly, we require a S/N=20 (with errors of 0.05 mag; see Phase I Figure 3 and the discussion above for justification) for our brightest main sequence stars in the WFC3/F275W band at F275W~22.5 mag, which requires 2000s of integration time. A two-exposure dithering strategy will be adopted and a single orbit is necessary to achieve our scientific goal. In all, we require 2 orbits of ACS imaging (one for each F606W and F814W) and 1 orbit of WFC3 UVIS imaging (F275W), for a total of three orbits for this proposal. Note added for phase II: We have put in a loose ORIENT constraint for the ACS imaging only. This is so that we can cover more of the HI radio observation's positional error circle. RESOLVED STELLAR POPULATIONS 12 Regular false true false false false SUPPORTED GALAXY AMORPHOUS IRREGULAR DWARF SPHEROIDAL J2000 J2000 ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W WFC3/UVIS Imaging No No F275W POS-TARG DITHER 3.011 LINE false false 2 85.28 ACS-WFC-DITHER-LINE 1 false POS-TARG DITHER 0.145 LINE false false 2 46.84 WFC3-UVIS-DITHER-LINE 2 false POS-TARG DITHER 0.265 LINE 0.187 false false 69.05 4 20.67 ACS-WFC-DITHER-BOX 3 false POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 4 false The scheduling data was generated by CASM 22.2. CASM was run in Phase II mode. 1430073702000 132.78442012471533 (Tic-Visit :proposal-id 13735 :visit-id "01" :proposal-version -1 :trans-version "20140605" :date "25-Aug-2014 12:21:24.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 2273792 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13735 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13735 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2890 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3226 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13735 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3003 :al-overhead-at-end 0 :internal-dur-at-end 347 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3226 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 22.2. CASM was run in Phase II mode. 1433380258000 115.0 (Tic-Visit :proposal-id 13735 :visit-id "02" :proposal-version -1 :trans-version "20140605" :date "25-Aug-2014 12:23:21.0" :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 1154992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13735 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13735 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2893 :al-overhead-at-end 123 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3226 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 23.0. CASM was run in Phase II mode. /private/var/folders/8k/sxlgy5ts2xdbykzf_vw6jrfw0001c5/T/OPVisit5815284195182447665.xml (Tic-Visit :proposal-id 13735 :visit-id "52" :proposal-version -1 :trans-version "20150417" :date "19-Jun-2015 16:18:29.0" :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 1154992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13735 :visit-id "52" :obset-id "52" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13735 :visit-id "52" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2893 :al-overhead-at-end 123 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3226 :pcs-gap 0 ) true 1 0