17607( 7) - 13-Nov-2024 11:24:48 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17607 Version: 7 Check-in Time: 13-Nov-2024 11:24:48 STScI Edit Number: 1 Title A new gas-rich local dwarf galaxy identified with machine learning ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Michael Gordon Jones University of Arizona Y CoI: Dr. Ananthan Karunakaran University of Toronto N CoI: Prof. David J. Sand University of Arizona N CoI: Richard Donnerstein University of Arizona N CoI: Prof. Dennis Zaritsky University of Arizona N CoI: Dr. Kristine Spekkens Queen's University N CoI: Dr. Paul Bennet Space Telescope Science Institute N CoI: Dr. Denija Crnojevic University of Tampa N CoI: Dr. Burcin Mutlu-Pakdil Dartmouth College N CoI: Dr. Catherine Fielder University of Arizona N ------------------------------------------------------------------------------------ Abstract We request 3.5h of VLA C-configuration time in order to confirm that a recent HI detection at 500km/s (from GBT) in the direction of a newly identified dwarf galaxy, is localized to that object. In addition, we request 1 orbit of HST in order to measure an accurate tip-of-the-red-giant-branch distance to this galaxy, laying the foundation for a robust study of its nature. This object was detected in public DECaLS images using a combination of an automated search algorithm, a convolutional neural network classifier, and finally, human inspection. Its appearance is reminiscent of Leo P and low-mass dwarfs in the SHIELD sample. It is also semi-resolved in the DECaLS images, suggesting that it is within several Mpc. The nearest large galaxy is NGC5253 (407km/s) and we suspect that this object may be a Leo P analog in another nearby (3.55 Mpc) Milky Way-like system. This object is one of the first we are following up from our novel search and we hope this will act as a proof of concept, demonstrating the viability of this approach for identifying undiscovered Local Volume dwarfs, and will result in further follow-up of additional candidates. ------------------------------------------------------------------------------------ Observations Description ------------------------ These observations target a newly identified candidate extremely low mass, star-forming galaxy. Our primary goal is to resolve its stellar population, to understand its recent star formation history and measure a tip of the red giant branch distance estimate. We follow a standard strategy of approximately 1000 s integrations in F606W and F814W with ACS/WFC and parallel observations in the same filters in WFC3/UVIS. The target is less than 30 arcsec across and has therefore been centered in a single ACS chip and we use only a 2-point line dither and do not fill the chip gap. We have attempted to pack the orbit, making the exposures as long as possible, while permitting all the required buffer dumps. We do not require any orient constraints. ------------------------------------------------------------------------------------ 17607( 7) - 13-Nov-2024 11:24:48 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SMDG1339-320 GALAXY, AMORPHOUS RA=13H38M57.6000S, J2000 V = 18.5 1 IRREGULAR DEC=-32D01'4.44" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 17607( 7) - 13-Nov-2024 11:24:48 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.364 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 47.23 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17607( 7) - 13-Nov-2024 11:24:48 - [ 4] Visit: 01 Visit Requirements: ORIENT 333.5D TO 353 D 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 SMDG1339-32 ACS/WFC ACCUM WFC1 F606W 1 450 S POS TARG 01 see below -65.2328008652219, (916 S) -120.5275435281317; PATTERN 1 1-2 ------------------------------------------------------------------------------------------------------------------------------------ 2 SMDG1339-32 ACS/WFC ACCUM WFC1 F814W 1 450 S POS TARG 01 see below -65.2328008652219, (916 S) -120.5275435281317 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SMDG1339-3201 1 ACS/WFC ACCUM WFC1 F606W 1 none none none 1 458.0 S SMDG1339-3201 1 ACS/WFC ACCUM WFC1 F606W 2 none none none 1 458.0 S SMDG1339-3201 2 ACS/WFC ACCUM WFC1 F814W 1 none none none 1 458.0 S SMDG1339-3201 2 ACS/WFC ACCUM WFC1 F814W 2 none none none 1 458.0 S 17607( 7) - 13-Nov-2024 11:24:48 - [ 5] Summary Form for Proposal 17607 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 333.5D TO 353 D, PATTERN 1 1-2, POS TARG -65.2328008652219, -120.5275435281317 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SMDG1339-3201 ------------------------------------------------------------------------------------------------------------------------------------