0 Assigned ID: 258 ----- Attempting Submission 1 (Thu Apr 06 17:35:35 GMT 2017) ----- HST Phase I Proposal 258 (McQ_HST25_Leoncino_v2.apt) successfully submitted. Receipt: # 258-1 ----- Attempting Submission 2 (Thu Apr 06 22:04:16 GMT 2017) ----- HST Phase I Proposal 258 (McQ_HST25_Leoncino_v2.apt) successfully submitted. Receipt: # 258-2 ----- Attempting Submission 3 (Fri Apr 07 14:42:51 GMT 2017) ----- HST Phase I Proposal 258 (McQ_HST25_Leoncino_v2.apt) successfully submitted. Receipt: # 258-3 0 0 ----- Attempting Submission 1 (Wed Jul 19 20:16:04 GMT 2017) ----- HST Phase II Proposal 15243 (McQ_HST25_Leoncino_PII_v1.apt) successfully submitted. Receipt: # 15243-1 ----- Attempting Submission 2 (Thu Aug 03 13:36:41 GMT 2017) ----- HST Phase II Proposal 15243 (McQ_HST25_Leoncino_PII_v1.apt) successfully submitted. Receipt: # 15243-2 ----- Attempting Submission 3 (Tue Sep 19 21:44:23 GMT 2017) ----- The Leoncino Dwarf: The Lowest Metallicity Star-Forming Galaxy in the Nearby Universe Extremely metal-poor (XMP) galaxies are dwarf irregular galaxies with very low metallicities, traced by their gas-phase oxygen abundance. Galaxy evolution scenarios suggest three pathways to form an XMP: (1) secular evolution at low galaxy masses, (2) slow evolution in voids, or (3) dilution of measured abundances from infall of pristine gas. These scenarios have proven challenging to test because, despite concerted efforts, XMP galaxies in the nearby universe have proven hard to find. A notable exception is the recently discovered dwarf galaxy Leoncino. Leoncino has the lowest gas-phase oxygen abundance ever measured in a galaxy in the local Universe. From optical spectroscopy, the oxygen abundance is 12+log(O/H)=7.02+/-0.03, more than 40% lower than the iconic low-metallicity galaxy I Zw 18 and less than 2% Z_sun. Despite a precision oxygen abundance measurement, the evolutionary context of Leoncino remains uncertain without a secure distance. We propose HST WFC3 high-resolution optical imaging of Leoncino to accurately measure the distance to the galaxy using the tip of the red giant branch (TRGB) method. The distance will determine whether Leoncino is located in a typical field environment or in a void, and whether the galaxy is consistent with the luminosity-metallicity relation at low galaxy masses. The detailed study of Leoncino will provide benchmark results for future XMP discoveries in the nearby Universe, and an exceptionally timely comparison for studies of chemically primitive, high-redshift galaxies that will be observable in the JWST era. The goal of this proposal is to measure the TRGB distance to the newly discovered, extemely metal-poor galaxy, Leoncino, reconstruct the overall star formation history (SFH), and explore the environment and evolutionary pathways of such a metal-poor system. The planned data consist of WFC3 imaging in the F606W and F814W filters. Orbit allocation = 12 orbits. All visits span 2-orbits with the WFC3; each orbit is split between one F606W and one F814W exposure (with no CR-splits). We use the WFC3-UVIS-DITHER-LINE small dither pattern of 2.5 pixel shifts in x and y between orbits in order to remove hot pixels and to smooth the detector response. We have also added a small 2-4 pixel shift using POS-TARG between visits to minimize the impact of hot pixels affecting any individual star. We don't intend to cover the interchip gap. There will be 6 visits total and the observations will complete 6 dither patterns. Since the exposure times per orbit are ~1200s in F606W and ~1500s in F814W, we have not used the post-flash option. We have placed the target on the UVIS2 chip in quadrant C which minimizes geometric distortions, increases quantum efficiency, and has the absence of figure 8 shots relative to the other quadrants. The first visit is requested with a range of orientation that keeps the galaxy near the center of the quadrant and avoids getting too near the edge of the chip. Subsequent visits are requested to be obtained with the same ORIENT at visit 1 for consistent execution of our dither pattern. Stellar Populations 6 false false false false false false SUPPORTED GALAXY AMORPHOUS IRREGULAR J2000 J2000 WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W POS-TARG DITHER 0.145 LINE false false 2 46.84 WFC3-UVIS-DITHER-LINE 1 false /Users/kmcquinn/astro/proposals/hst/cycle25_26/leoncino/phaseii/OP-cache/McQ_HST25_Leoncino_PII_v1-v01.xml Hst Same orient constraint links visits (01 02 03 04 05 06) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. Based on the visibility windows in the Visit Planner, the target is visible in early 2018 and early 2019. Given that these data will help inform on extremely metal-poor systems at high redshift that will be observed by JWST, including providing tests of stellar evolution models, the observing dates in 2018 would optimize the timing of the results for future JWST studies. This is not a hard constraint, but, if at all possible, the 2018 dates would be highly preferred. Thank you. (Tic-Visit :proposal-id 15243 :visit-id "01" :proposal-version -1 :trans-version "20170613" :date "19-Jul-2017 08:57:57.0" :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 1154976 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15243 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15243 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2907 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15243 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3017 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) true 2 0 /private/var/folders/w9/_kgg3fvs0nl_09tsfqpvhw_80000gq/T/OPVisit7102946651652782507.xml Hst Same orient constraint links visits (01 02 03 04 05 06) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15243 :visit-id "02" :proposal-version -1 :trans-version "20170613" :date "19-Sep-2017 15:22:42.0" :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 1154976 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15243 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15243 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2907 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15243 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3017 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) true 2 0 /private/var/folders/w9/_kgg3fvs0nl_09tsfqpvhw_80000gq/T/OPVisit8649393875743593898.xml Hst Same orient constraint links visits (01 02 03 04 05 06) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15243 :visit-id "03" :proposal-version -1 :trans-version "20170613" :date "19-Sep-2017 15:22:55.0" :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 1154976 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15243 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15243 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2907 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15243 :visit-id "03" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3017 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) true 2 0 /private/var/folders/w9/_kgg3fvs0nl_09tsfqpvhw_80000gq/T/OPVisit1589432919493526806.xml Hst Same orient constraint links visits (01 02 03 04 05 06) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15243 :visit-id "04" :proposal-version -1 :trans-version "20170613" :date "19-Sep-2017 15:22:55.0" :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 1154976 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15243 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15243 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2907 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15243 :visit-id "04" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3017 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) true 2 0 /private/var/folders/w9/_kgg3fvs0nl_09tsfqpvhw_80000gq/T/OPVisit5957699579440924348.xml Hst Same orient constraint links visits (01 02 03 04 05 06) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15243 :visit-id "05" :proposal-version -1 :trans-version "20170613" :date "19-Sep-2017 15:22:56.0" :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 1154976 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15243 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15243 :visit-id "05" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2907 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15243 :visit-id "05" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3017 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) true 2 0 /private/var/folders/w9/_kgg3fvs0nl_09tsfqpvhw_80000gq/T/OPVisit570724096173727034.xml Hst Same orient constraint links visits (01 02 03 04 05 06) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15243 :visit-id "06" :proposal-version -1 :trans-version "20170613" :date "19-Sep-2017 15:22:57.0" :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 1154976 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15243 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15243 :visit-id "06" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2907 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15243 :visit-id "06" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3017 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) true 2 0