Version 2596863690Assigned ID: 3975
----- Attempting Submission 1 (Fri May 19 19:45:23 GMT 2023) -----
HST Phase I Proposal 3975 successfully submitted.
Receipt: # 3975-1
----- Attempting Submission 2 (Wed May 24 21:23:20 GMT 2023) -----No Parallel Exposures Specified in Parallel Exposure Group
No Parallel Exposures Specified in Parallel Exposure Group
FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser
FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser
FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser
FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browserThis is to update Visit 1 for one gyro mode.
Note that I remove the parallels to make this visit work, and then after that simply adjusted the exposure time to even out the F606W, F814W exposures.
Scientifically, it is acceptable to remove the parallels from this visit, as we will still achieve our primary scientific aims of the program: to measure the distance, luminosity, and structure of the dwarfs associated with NGC300.
Recent Gemini imaging backs this up, suggesting that the dwarf will fit nicely on one chip as requested, and we can use the other ACS chip as a 'background' field in much the same way as we would have used the WFC3 data.-345953635----- Attempting Submission 1 (Tue Sep 05 21:16:00 GMT 2023) -----
----- Attempting Submission 2 (Thu Nov 09 16:22:57 GMT 2023) -----
----- Attempting Submission 3 (Fri Jun 28 16:31:57 GMT 2024) -----Most problems have to do with visits 2 and 3 being executed already. The other warning may have to do with the fact that I stripped the parallel observations out. I do not think this is a real problem.The Ultra-faint Dwarf Galaxy System of NGC300 -- A New Frontier and Analog to the Large Magellanic CloudWe request three orbits of HST/ACS imaging (F606W+F814W) of three new ultra-faint dwarf galaxy candidates around NGC300 (D=2 Mpc), a nearby analog to the Large Magellanic Cloud (LMC). The faint end of the galaxy luminosity function is a strong probe of dark matter physics and galaxy formation models, but can only be studied in the most constraining "ultra-faint" regime in the nearby universe. Of particular interest are the dwarf satellite properties of lower mass LMC-like galaxies because these systems will experience weaker tidal fields and ram pressure environments in comparison to those of the Local Group, possibly leading to dwarfs with different physical properties.
A search for dwarf satellites around the isolated LMC-analog NGC300 has uncovered three strong ultra-faint dwarf galaxy candidates, ranging in luminosity between M_V=-5.8 to -7 mag (log(M_star)~4.5--5). Two out of three of these discoveries are observed near the viral radius of NGC300, potentially probing its ram pressure environment. These candidate dwarf galaxy satellites represent the faintest population ever found outside the Local Group. HST imaging will allow us to measure the distance, luminosity, structure and approximate star formation history/metallicity of these dwarf candidates, and place them in context with similar ultra-faint dwarf galaxies near the Milky Way and LMC that have been discovered in the last ~20 years.The observations will be performed with ACS/WFC (primary) and WFC3/UVIS (parallel). We request imaging in the F606W and F814W filters (broad V and I) for both instruments in order to compute accurate color-magnitude diagram based distances for our targets while characterizing their stellar content (e.g. star formation histories and metallicities) and structural parameters. The parallel pointings will allow us to observe a field region next to our targets. We will thus be able to estimate more precisely the number of background/foreground contaminants present in our ACS fields.
Our main target dwarf galaxies will be placed in the center of a chip -- we will use the WFC1 aperture. For each band we will use a two point ditherline pattern to mitigate hot pixels, cosmic rays, etc. We will not try to cover the chip gap as each dwarf fits well on a single chip.
This program is resilient to two-gyro mode. Our visits are 1-orbit, and we have no ORIENT requirements. Nor does this program have time constraints (other than the baseline excitement of the science!). We can also achieve our science goals with a longer acquisition time, if necessary.Dr. David Sand has led (and participated in) several previous HST campaigns related to resolved stellar populations of dwarf galaxies that have led to published results. Some we highlight below. He is an expert in near field cosmology and has expertise in HST data reduction for ACS and WFC3 which are the primary and parallel instruments used in this proposal.
Dr. Denija Crnojevic is an expert in near field cosmology and has led several previous HST observing campaigns leading to 5 papers published over the past decade based on HST data (e.g., Crnojevic et al. 2010, 2013, 2014, 2016, 2019).
Dr. Burcin Mutlu-Pakdil is also an expert in near field cosmology. She has recently completed an HST study of five faint and ultra-faint dwarf galaxies around NGC253 (Mutlu-Pakdil et al. 2022).
Dr. Jones, Dr. Spekkens and Dr. Karunakaran are experts in low surface brightness galaxies in both visible light as well as in their gas content. They will pursue further HI observations of the NGC300 dwarfs, and have already set limits with existing data.
Recently Dr. Jones published an HST study of two nearby ultra-diffuse galaxies, measuring their globular cluster content, and comparing that with models describing the formation of these unusual galaxies (Jones et al. 2021). He also led an HST study of two dwarf-like objects in the direction of the Virgo cluster (Jones et al. 2022).
Dr. Paul Bennet is a postdoctoral researcher who has led two previous M101-focused HST dwarf galaxy campaigns leading to two papers (Bennet et al. 2019, 2020), along with a recently completed study of two isolated dwarf galaxies in the Local Volume (Bennet et al. 2021).
Dr. Alex Drlica-Wagner is a world expert in near field cosmology, finding dwarf galaxies in the Local Group, and survey leader of the DELVE program (among other DECam projects). It was data from this program that led to the discovery of the NGC300 dwarfs which are the subject of this program.
Dr. Jeff Carlin is another dwarf galaxy and nearby universe expert. He is one of the leaders of the MADCASH program, which is searching for faint dwarf galaxies around Magellanic Cloud analogs in the Local Universe.
He recently completed an HST paper on two of the faint dwarf discoveries from that program (Carlin et al. 2021).
Mr. Guiseppe Donatiello helped with the discovery of the dwarf galaxies found in program, and has discovered other dwarf galaxies in the Local Universe.
Dr. David Martinez-Delgado is an expert in the low surface brightness universe, and has led a long-standing program to identify nearby dwarf galaxies and stellar streams from deep imaging data.
Dr. Catherine Fielder is an expert in HST observations, recently finishing a paper on the globular cluster system of an exceptional ultra-diffuse galaxy.Galaxies6falsefalsefalsefalsefalsefalsefalsefalseSUPPORTEDGALAXYDWARF SPHEROIDALYESJ2000J2000GALAXYDWARF SPHEROIDALYESJ2000J2000GALAXYDWARF SPHEROIDALYESJ2000J2000ACS/WFCImagingNoNoF606WACS/WFCImagingNoNoF814WWFC3/UVISImagingNoNoF606WWFC3/UVISImagingNoNoF814WACS/WFCImagingNoNoF606WACS/WFCImagingNoNoF814WWFC3/UVISImagingNoNoF606WWFC3/UVISImagingNoNoF814WACS/WFCImagingNoNoF606WACS/WFCImagingNoNoF814WWFC3/UVISImagingNoNoF606WWFC3/UVISImagingNoNoF814WPOS-TARGDITHER0.364Two point dither. No need to fill chip gap.LINEfalsefalse247.23ACS-WFC-DITHER-LINE1false/private/var/folders/8t/mg1bkfyj20xf2vfc_9vyhfs80006z1/T/OPVisit17930675651210002997.xmlThe scheduling data was generated by CASM 32.1.1.CASM was run in Phase II mode.(Tic-Visit
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