16222( 3) - 15-Mar-2021 22:49:00 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16222 Version: 3 Check-in Time: 15-Mar-2021 22:49:00 STScI Edit Number: 1 Title Extinction Mapping in Leo P: Resolving the Dust Properties of the Lowest-Metallicity ISM in the Local Universe ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Christopher Clark Space Telescope Science Institute Y CoI: Dr. Julia Christine Roman-Duval Space Telescope Science Institute N CoI: Dr. Lea M. Z. Hagen Space Telescope Science Institute N CoI: Dr. Martha L. Boyer Space Telescope Science Institute N CoI: Dr. Karoline Gilbert Space Telescope Science Institute N CoI: Dr. Steven R Goldman Space Telescope Science Institute N CoI: Dr. Karl D. Gordon Space Telescope Science Institute N CoI: Dr. Kristen B W McQuinn Rutgers the State University of New Jersey N CoI: Dr. Benjamin F. Williams University of Washington N CoI: Dr. Yumi Choi Space Telescope Science Institute N ------------------------------------------------------------------------------------ Abstract Leo P is the closest extremely metal poor galaxy that is still forming stars - only 1.62 Mpc away, with a metallicity of only 0.03 Zsol. This makes it a unique object, able to provide insights onto the ISM at these extreme metallicities, and acting as a local laboratory for understanding primitive systems at high redshift. We propose using 6 orbits of HST imaging to obtain observations of Leo P in 4 UV-NIR filters. This data will enable us to perform panchromatic extinction mapping in Leo P - fitting the multiwavelength SEDs of its stars, and modelling the dust along the line-of-sight to each. We will thereby produce a resolved map of the dust extinction in Leo P - the first ever map of the cold star-forming ISM in an extremely metal poor galaxy. This dust map will tell us the amount, location, and properties, of the dust in Leo P - providing invaluable constraints on how the ISM evolves at the lowest metallicities, and supporting the calibration of metallicity corrections for primitive systems at high redshift. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our proposal is to observe the extremely metal poor nearby (1.62 Mpc) dwarf galaxy Leo P in four filters: F275W, F336W, F110W, and F160W. We will be observed the resolved stellar populations in Leo P, aiming to maximise the numbers of stars detected in all four bands. The integration times for each band are distributed accordingly. (Our observations will be used in conjunction with deep archival F475W and F814W data in our analysis.) In F275W, we plan to conduct 3 orbits of exposures. These 3 exposures will be arranged in a WFC3-UVIS 3-point dither line. These observations should allow 5-sigma detection of stars down to 25.75 vegamag. In F336W, we plan to conduct 1.6 orbits of exposure; one exposure lasting a full orbit, and a second orbit that will be partialy spent performing a further 16222( 3) - 15-Mar-2021 22:49:00 - [ 2] F336W exposure (followed by our F110W exposures). The two F336 exposures will be arranged in a WFC3-UVIS 2-point dither line. These observations should allow 5-sigma detection of stars down to 26.14 vegamag. In F110W, we plan to conduct 0.4 orbits of exposures (~16 mins), performed during the same orbit as the second F336W exposure descrirbed above. The two F110W exposures will be arranged in a WFC3-IR 2-point dither line. These observations should allow 5-sigma detection of stars down to 26.05 vegamag. In F160W, we plan to perform 1 orbit of exposures. Thsee two F160W exposures will be arranged in a WFC3-IR 2-point dither line. These observations should allow 5-sigma detection of stars down to 25.55 vegamag. ------------------------------------------------------------------------------------ 16222( 3) - 15-Mar-2021 22:49:00 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 LEO-P GALAXY, LSB RA=10H21M44.5698S, J2000 V = 260 V = 16.78 +/- 0.2 DEC=+18D05'24.53" Reference Frame: ICRS Extended: YES Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 16222( 3) - 15-Mar-2021 22:49:00 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE-3PT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.135 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 16222( 3) - 15-Mar-2021 22:49:00 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 LEO-P WFC3/UVI ACCUM UVIS2-FIX F275W FLASH=10 1 2756 S GS ACQ SCENARIO BASE1B3; S (8268 S) PATTERN 1 1 Comments: According to the HST ETC (Request ID: WFC3UVIS.im.1447512), each of the exposures in this pattern should have 10 e- pixel due to background, so the post-flash of 10 e- should bring this up to the requested 20 e-. ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ LEO-P 1 WFC3/UVI ACCUM UVIS2-FI F275W 1 none none none 1 N/A S X LEO-P 1 WFC3/UVI ACCUM UVIS2-FI F275W 2 none none none 2 N/A S X LEO-P 1 WFC3/UVI ACCUM UVIS2-FI F275W 3 none none none 3 N/A S X 16222( 3) - 15-Mar-2021 22:49:00 - [ 6] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 LEO-P WFC3/UVI ACCUM UVIS2-FIX F336W FLASH=7 1 2640 S S see below (2765 S) Comments: Becuase this exposure is long enough to exceed the old 12 e- per pixel due to background CTE threshold, the HST ETC does not give the background e- value for it. However, extrapolating from our other F336W exposure, which is a factor of 1.73 shorter and had background of 7 e-, this exposure should have 13 e- pixel due to background so the post-flash of 7 e- should bring this up to the requested 20 e-. ------------------------------------------------------------------------------------------------------------------------------------ 2 LEO-P WFC3/UVI ACCUM UVIS2-FIX F336W FLASH=13 1 1560 S POS TARG 0.1, 0.1 S see below (1597 S) Comments: According to the HST ETC (Request ID: WFC3UVIS.im.1447515 ), this exposure should have 7.1 e- pixel due to background, so the post-flash of 13 e- should bring this up to the requested 20 e-. ------------------------------------------------------------------------------------------------------------------------------------ 3 LEO-P WFC3/IR MULTIAC IR-FIX F110W NSAMP=14, SAMP-SEQ=STEP50 1 DEF CUM (449.234 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 LEO-P WFC3/IR MULTIAC IR-FIX F110W NSAMP=14, SAMP-SEQ=STEP50 1 DEF POS TARG 1.422, 1.272 CUM (449.234 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ LEO-P 1 WFC3/UVI ACCUM UVIS2-FI F336W none none none none 1 2765.0 S S X LEO-P 2 WFC3/UVI ACCUM UVIS2-FI F336W none none none none 2 1597 S S X 16222( 3) - 15-Mar-2021 22:49:00 - [ 7] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ LEO-P 3 WFC3/IR MULTIAC IR-FIX F110W none none none none 2 N/A CUM LEO-P 4 WFC3/IR MULTIAC IR-FIX F110W none none none none 2 N/A CUM 16222( 3) - 15-Mar-2021 22:49:00 - [ 8] Visit: 03 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 LEO-P WFC3/IR MULTIAC IR-FIX F160W NSAMP=15, SAMP-SEQ=STEP100 1 DEF CUM (899.233 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 LEO-P WFC3/IR MULTIAC IR-FIX F160W NSAMP=14, SAMP-SEQ=STEP100 1 DEF POS TARG 1.77, 0.24 CUM (799.233 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 LEO-P WFC3/IR MULTIAC IR-FIX F160W NSAMP=15, SAMP-SEQ=STEP100 1 DEF POS TARG 0.684, 0.849 CUM (899.233 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ LEO-P 1 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM LEO-P 2 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM LEO-P 3 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM 16222( 3) - 15-Mar-2021 22:49:00 - [ 9] Summary Form for Proposal 16222 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX, UVIS2-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=10, FLASH=13, FLASH=7, NSAMP=14, NSAMP=15, SAMP-SEQ=STEP100, SAMP-SEQ=STEP50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1B3, PATTERN 1 1, POS TARG 0.1, 0.1, POS TARG 0.684, 0.849, POS TARG 1.422, 1.272, POS TARG 1.77, 0.24 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W, F160W, F275W, F336W ------------------------------------------------------------------------------------------------------------------------------------ Target Names LEO-P ------------------------------------------------------------------------------------------------------------------------------------