0Assigned ID: 5097
----- Attempting Submission 1 (Sat Mar 23 20:38:07 GMT 2024) -----I have adjusted the exposure times to accomodate the buffer dumps and visibilities.
Please let me know if Visit 5 is now scheduable!
Thank you!
Kristen McQuinn-1363799186----- Attempting Submission 1 (Wed Aug 07 19:18:37 GMT 2024) -----
----- Attempting Submission 2 (Wed Sep 25 18:09:56 GMT 2024) -----
----- Attempting Submission 3 (Fri Sep 27 13:30:24 GMT 2024) -----
----- Attempting Submission 4 (Fri Feb 28 20:06:59 GMT 2025) -----
HST Phase II Proposal 17759 successfully submitted.
Receipt: # 17759-4
----- Attempting Submission 5 (Fri Feb 28 20:12:25 GMT 2025) -----
HST Phase II Proposal 17759 successfully submitted.
Receipt: # 17759-5
----- Attempting Submission 6 (Thu Mar 27 18:50:34 GMT 2025) -----
----- Attempting Submission 7 (Fri Sep 12 20:36:00 GMT 2025) -----already run.Discovery of Extremely Faint Galaxy Candidates out to the Edge of the Local GroupThe smallest galaxies in the universe play an important role in understanding structure formation at all scales. They inform us about the the build-up of more massive galaxies, test our understanding of the coupling of baryon and dark matter physics, and can place critical constraints on our understanding of the epoch of reionization. Yet, because of their paltry stellar content, these systems are incredibly faint and difficult to find. To date, nearly all ultra-faint dwarfs that have been detected are in close proximity to the Milky Way (making them easier to find) or are satellites of another massive galaxy (where searches can be targeted). This has limited our understanding of ultra-faint dwarfs to a single type of environment, which rarely turns out to be representative.
We have discovered 6 ultra-faint dwarf candidates within the Local Group that appear to lie at distances from the MW and M31 that are beyond the virial radius, the traditional definition of "satellite" (i.e., > 400 kpc). If confirmed, these systems will provide unique insights into the growth and evolution of ultra-faint dwarfs that reside in relatively isolated environments and that are not satellites. We request 1-orbit of HST imaging per candidate to confirm and characterize these systems. The data will enable robust measurements of distances, structural parameters, integrated magnitudes, and star formation histories.The observations included ACS/WFC and WFC3/UVIS imaging in the F606W and F814W filters. The data will be used to confirm that the targets are galaxies, measure the distances to the systems from resolved stars (TRGB and/or Horizontal Branch methods), characterize the stellar properites (star formation histories and metallicities), and measure the structural parameters of the galaxies. 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.
Each of the 6 targets will be observed for 1 orbit. We use a 5x5 pixel dither implemented using pos-targ (equivalent to the ACS WFC DITHER LINE pattern #14) to reject cosmic rays and handle hot pixels. The first pointing is executed with both filters in ACS and with both filters in WFC3 parallel fields. After the dither, the observations are then repeated. The exposure time per orbit is split roughly equally between the F606W and F814W filters.
In order to obtain 4 exposures in both ACS and WFC3 in one orbit and accomodate buffer dumps during exposures, we have added a special requirement to the visibility intervals, which was requested as part of the Phase I proposal.
Each visit is 1-orbit. We have place ORIENT constraints to ensure we maximum coverage of the stellar disk and prevent the galaxy centers from falling in the ACS chip gap, while avoiding nearby bright stars.Our team is comprised of scientists responsible for the discovery and characterization of the ultra-faint dwarf galaxy Pegasus W. PI McQuinn and Co-I Cohen are experts on resolved stellar populations, measuring distances to galaxies reconstructing star formation histories, and measuring the structural parameters to galaxies. Co-I Hai is a graduate student working with PI Dr. McQuinn, with experience working with HST imaging of low-mass galaxies and resolved stellar populations. They all have significant expertise with HST images and will be primarily responsible for the data handling. Co-I Tollerud is a SAGA team member and an expert in HST data analysis and will aid in measuring the structural parameters of the galaxies. Dr. Mao brings expertise in the formation of low-mass galaxies in the context of CDM and hierarchical structure formation and has experience studying low-mass satellites around Milky Way analog galaxies in the SAGA survey. Drs. Mao, Shih, and Buckley are all experts on dark matter and built the basis of the search algorithm used to find the galaxy candidates. Dr. Mao's students, Co-Is Anderson and Leishman, aided in the development of the algorithm and the discovery of the targets. Dr. Dolphin, author of the photometry software DOLPHOT and the CMD-fitting code MATCH that we will use on the data, brings significant technical expertise and knowledge of stellar populations.Stellar Populations and the Interstellar Medium6falsefalsefalsefalsefalsefalseSUPPORTEDGALAXYDWARF SPHEROIDALJ2000J2000GALAXYDWARF SPHEROIDALJ2000J2000GALAXYDWARF SPHEROIDALJ2000J2000GALAXYDWARF SPHEROIDALJ2000J2000GALAXYDWARF SPHEROIDALJ2000J2000GALAXYDWARF SPHEROIDALJ2000J2000ACS/WFCImagingNoNoF606WACS/WFCImagingNoNoF814WWFC3/UVISImagingNoNoF606WWFC3/UVISImagingNoNoF814WACS/WFCImagingNoNoF606WACS/WFCImagingNoNoF814WWFC3/UVISImagingNoNoF606WWFC3/UVISImagingNoNoF814WACS/WFCImagingNoNoF606WACS/WFCImagingNoNoF814WWFC3/UVISImagingNoNoF606WWFC3/UVISImagingNoNoF814WACS/WFCImagingNoNoF606WACS/WFCImagingNoNoF814WWFC3/UVISImagingNoNoF606WWFC3/UVISImagingNoNoF814WACS/WFCImagingNoNoF606WACS/WFCImagingNoNoF814WWFC3/UVISImagingNoNoF606WWFC3/UVISImagingNoNoF814WACS/WFCImagingNoNoF606WACS/WFCImagingNoNoF814WWFC3/UVISImagingNoNoF606WWFC3/UVISImagingNoNoF814W3128The scheduling data was generated by CASM 32.1.3.CASM was run in Phase II mode.1749927706000253.2416198922644(Tic-Visit
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