Joint NRAO-HST proposal 1732870990 Assigned ID: 6012 ----- Attempting Submission 1 (Wed Nov 13 20:25:38 GMT 2024) ----- New version submitted after email exchange with contact scientist. 1051434344 ----- Attempting Submission 1 (Sun Dec 08 23:20:28 GMT 2024) ----- ----- Attempting Submission 2 (Mon Dec 23 17:15:38 GMT 2024) ----- no issues Low-mass Dwarf Galaxies: Dark Matter & Reionization at the Edge 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. 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. Already accepted proposal. Stellar Populations and the Interstellar Medium 6 false false false false false false false true SECONDARY NRAO VLA/25A-287 false SUPPORTED GALAXY DWARF ELLIPTICAL J2000 J2000 GALAXY DWARF ELLIPTICAL J2000 J2000 WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W POS-TARG DITHER 0.145 LINE false false 2 46.84 WFC3-UVIS-DITHER-LINE 1 false /private/var/folders/lk/kgyb23rx78z9r8t653drxmfw0000gn/T/OPVisit4745570991894138041.xml The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17891 :visit-id "01" :proposal-version -1 :trans-version "20240627" :date "23-Dec-2024 10:14:39.0" :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 1154992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17891 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17891 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2647 :al-overhead-at-end 120 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3028 :pcs-gap 0 ) true 1 0 /private/var/folders/lk/kgyb23rx78z9r8t653drxmfw0000gn/T/OPVisit3500860383407199713.xml The scheduling data was generated by CASM 32.1.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17891 :visit-id "02" :proposal-version -1 :trans-version "20240627" :date "23-Dec-2024 10:14:40.0" :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 1154992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17891 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17891 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2719 :al-overhead-at-end 120 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3099 :pcs-gap 0 ) true 1 0