17891( 3) - 30-Dec-2024 18:25:36 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17891 Version: 3 Check-in Time: 30-Dec-2024 18:25:36 STScI Edit Number: 0 Title Low-mass Dwarf Galaxies: Dark Matter & Reionization at the Edge ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. David J. Sand University of Arizona Y CoI: Dr. Michael Gordon Jones University of Arizona N CoI: Dr. Ananthan Karunakaran University of Toronto N CoI: Dr. Kristine Spekkens Queen's University N CoI: Richard Donnerstein University of Arizona N CoI: Prof. Dennis Zaritsky University of Arizona N CoI: Dr. Catherine Fielder University of Arizona N CoI: Dr. Burcin Mutlu-Pakdil Dartmouth College N CoI: Dr. Denija Crnojevic University of Tampa N CoI: Dr. Paul Bennet Space Telescope Science Institute N ------------------------------------------------------------------------------------ Abstract We request 2x3.25=6.5h of VLA D-configuration time in order to detect and map HI emission in the direction of two newly discovered Local Volume dwarf galaxies which display prominent UV and/or blue stellar emission. These dwarf galaxies were identified with a convolutional neural network approach which has already yielded two of the lowest mass, isolated dwarf galaxies known to date and we will double the sample with this proposal. The VLA data will be used to measure the HI content and velocity gradients for initial kinematic modeling. We will also identify HI-optical offsets or signs of gas accretion, both of which are expected for low-mass systems which have been strongly effected by reionization or internal feedback. In addition, we request 1+1=2 orbits of HST/WFC3 (F606W+F814W) in order to measure a tip of the red giant branch distance (essential for deriving physical quantities) and star formation history of each system. Combined HI+optical data are required to understand the nearly unexplored effects of reionization and supernova/star formation feedback in the smallest dark matter halos. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will use WFC3/UVIS observations in the F606W and F814W bands to observe two nearby dwarf galaxies (one orbit per dwarf). The science goals are to measure a TRGB distance, luminosity, structural properties and potentially a star formation history for each system. Each target will be observed for one orbit. We have employed a two-point dither pattern for each filter to remove cosmic rays and hot pixels. We chose the UVIS1 aperture to center each dwarf on one of the chips. Each target is small enough that this will give full spatial coverage of each dwarf no matter what the orient is. We do not place any orient constraints on the observations. ------------------------------------------------------------------------------------ 17891( 3) - 30-Dec-2024 18:25:36 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SMDG1309 GALAXY, DWARF RA=13H09M45.9100S, J2000 V = 17 ELLIPTICAL DEC=-23D32'32.64" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 2 SMDG1333 GALAXY, DWARF RA=13H33M25.8720S, J2000 V = 17 ELLIPTICAL DEC=+56D29'59.64" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 17891( 3) - 30-Dec-2024 18:25:36 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17891( 3) - 30-Dec-2024 18:25:36 - [ 4] Visit: 01 (SMDG1309) 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 SMDG1309 WFC3/UVI ACCUM UVIS2 F606W 1 557 S PATTERN 1 1 S (1114 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SMDG1309 WFC3/UVI ACCUM UVIS2 F814W FLASH=4 1 557 S PATTERN 1 2 S (1114 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 | ------------------------------------------------------------------------------------------------------------------------------------ SMDG1309 1 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 N/A S SMDG1309 1 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 N/A S SMDG1309 2 WFC3/UVI ACCUM UVIS2 F814W 1 none none none 1 N/A S SMDG1309 2 WFC3/UVI ACCUM UVIS2 F814W 2 none none none 1 N/A S 17891( 3) - 30-Dec-2024 18:25:36 - [ 5] Visit: 02 (SMDG1333) 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 SMDG1333 WFC3/UVI ACCUM UVIS2 F606W 1 557 S PATTERN 1 1 S see below (1150 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SMDG1333 WFC3/UVI ACCUM UVIS2 F814W FLASH=4 1 557 S PATTERN 1 2 S see below (1150 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 | ------------------------------------------------------------------------------------------------------------------------------------ SMDG1333 1 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 575.0 S S SMDG1333 1 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 575.0 S S SMDG1333 2 WFC3/UVI ACCUM UVIS2 F814W 1 none none none 1 575.0 S S SMDG1333 2 WFC3/UVI ACCUM UVIS2 F814W 2 none none none 1 575.0 S S 17891( 3) - 30-Dec-2024 18:25:36 - [ 6] Summary Form for Proposal 17891 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=4 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SMDG1309, SMDG1333 ------------------------------------------------------------------------------------------------------------------------------------