0 Assigned ID: 4191 ----- Attempting Submission 1 (Tue May 23 22:00:45 GMT 2023) ----- HST Phase I Proposal 4191 successfully submitted. Receipt: # 4191-1 ----- Attempting Submission 2 (Wed May 24 14:17:24 GMT 2023) ----- This submission is identical to the previous submission, except for added orient range constraints for CANDIDATE-1. 743626796 ----- Attempting Submission 1 (Thu Sep 14 20:07:39 GMT 2023) ----- HST Phase II Proposal 17484 successfully submitted. Receipt: # 17484-1 ----- Attempting Submission 2 (Tue Sep 19 02:04:11 GMT 2023) ----- M33 is predicted to host more than ten satellites galaxies, but only two potential companions (And XXII, Pisces VII) have been discovered to date. Is this a failure of galaxy formation models, or simply a by-product of how difficult it is to find low surface brightness galaxies in the nearby Universe? In this proposal, we request deep HST observations of two candidate dwarf satellite galaxies identified around M33 using the Dragonfly Telephoto Array. We have undertaken ground-based follow-up which strongly suggests these candidates are dwarf galaxies in the Local Group, but definitive confirmation requires high-resolution space-based imaging. With high-quality HST data, we will (1) confirm the nature of these candidates as galaxies by detecting an adequate number of red giants associated with these galaxies; (2) measure the precise distance to these dwarf candidates to confirm whether they are indeed M33 satellites; (3) measure their physical properties -- geometry and structural parameters, total luminosities, stellar masses, and preliminary star formation histories. If these candidates are indeed dwarfs around M33, this small HST program would quickly double the known population of M33 satellite galaxies and provide a new avenue for carrying out a rigorous search for all potential M33 satellites. This data set will also enable follow-up studies of the dynamics of the M33-M31 system, including new constraints on the orbit of M33, and a direct test for the hierarchical nature of the LCDM paradigm in the regime of low mass galaxies. This proposal aims to obtain two-band photometry for two candidate dwarf satellite galaxies identified around M33, identified using ground-based data. This HST/ACS data will be used to constract deep color-magnitude diagrams with ACS and parallel WFC3 pointings. Each target will be observed with a asingle orbit split between two F606W and two F814W sub-exposures, to effectively eliminate hot pixels and cosmic rays. A single parallel exposure per filter will be obtained with WFC3 and will be used to estimate the background contamination from the MW and M31 stellar halos. The Co-Is on this proposal have been assembled to provide the greatest scientific gains from these observations. PI Patel is an expert on the dynamics of M31-M33 system and authored the paper on the predicted population of satellites around M33. PI Patel will provide theoretical context for the results of this program, both from large-scale cosmological simulations and modeling. PI Danieli is an expert in observational near-field cosmology, with a focus on the evolution and dynamics of low-mass galaxies and studies of the low surface brightness universe. Together, both PIs are leading the search for finding the remainining population of M33 satellites with the Dragonfly Telephoto Array. Our team, including Co-Is Carlin, Beaton, McQuinn, van Dokkum, Danieli, Abraham, is very familiar with HST-image processing and photometry packages, including the generation of final images, photometry catalogs, generation of artificial stars, and detection of any substructure. Thus, we do not anticipate data processing to be a substantive hurdle for this program. Co-I Liu led the analysis of our Candidates with Gemini and DECaLS. They will continue to help run the stellar photometry analysis with HST data. Co-I McQuinn is an expert in measuring SFHs of dwarf galaxies and will lead the SFH measurements for Candidates 1 and 2. Co-Is Abraham and van Dokkum are the PIs of the Dragonfly Telephoto Array and are experts in galaxy evolution in the low mass regime. Co-I Dolphin is the author of multiple stellar photometry packages ( i.e., MATCH, DOLPHOT) that will be utilized in this program. Co-I Ceppas de Castro is familiar with stellar photometry analysis in the low surface brightness regime. Stellar Populations and the Interstellar Medium Galaxies 6 false false false false false false false false SUPPORTED GALAXY DWARF SPHEROIDAL LSB J2000 J2000 GALAXY DWARF SPHEROIDAL LSB J2000 J2000 ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W 1695088793630 /private/var/folders/th/b12l1n2x2y38cfq6b3vcqxz00000gn/T/OPVisit6424863305357681639.xml The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17484 :visit-id "01" :proposal-version -1 :trans-version "20230627" :date "18-Sep-2023 21:59:53.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1714384 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17484 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17484 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2756 :al-overhead-at-end 28 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3139 :pcs-gap 0 ) true 1 0 1694721371188 /Users/shanydanieli/projects/m33/hst_proposal/phase2/OP-cache/phase2_17484_final_orient-v02.xml The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17484 :visit-id "02" :proposal-version -1 :trans-version "20230627" :date "14-Sep-2023 15:56:10.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1714384 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17484 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17484 :visit-id "02" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2760 :al-overhead-at-end 24 :internal-dur-at-end 1015 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3144 :pcs-gap 0 ) true 1 0