0 Assigned ID: 1212 ----- Attempting Submission 1 (Fri Jan 17 16:25:24 GMT 2020) ----- HST Phase I Proposal 1212 (MATLAS-2019_midcycle.apt) successfully submitted. Receipt: # 1212-1 ----- Attempting Submission 2 (Fri Jan 17 20:56:40 GMT 2020) ----- HST Phase I Proposal 1212 (MATLAS-2019_midcycle.apt) successfully submitted. Receipt: # 1212-2 Adopted custom 2 line dither pattern of 7.5x6.5 pixels (=spacing of 0.504", orient=42.11), per CS, to help with CR, hot pixels -- this should be large enough to account for bad columns, but small enough to avoid large affects of geometric distortion when combining both images/filter. Three pairs of possible ORIENT values to avoid stars with V<17.0 -- can relax this a bit if needed to make a small increase in schedulability, but program as is appears to be schedulable over 6+ months. WFC1 aperure has been used to keep the primary galaxy centered on that chip, and not be affected by chiop gap. We want to thank the phase II support Porterfield and the CS Lucas for their quick, helpful assistance! -298751647 ----- Attempting Submission 1 (Wed Mar 11 19:37:17 GMT 2020) ----- As part of a systematic survey with MegaCam/CFHT, we have identified an ultra-diffuse galaxy (UDG) with an excess of globular cluster (GC) candidates in the galaxy grop NGC 5846, dubbed MATLAS-2019. A large fraction of the GCs have been confirmed with follow-up MUSE spectroscopy, all of which are over-luminous with a luminosity one magnitude brighter than what is expected from the GC luminosity function. Many of the properties of MATLAS-2019 - e.g., the number of GCs, the brightness of the GC population, and an apparent lack of dark matter - are similar to the heavily discussed UDGs NGC1052-DF2 and NGC1052-DF4. The controversial nature of these two galaxies is due, in part, to uncertainties in their distances and the fact that they reside in the same field; the confirmation of a similar object in an independent group with an unambiguous distance will bring much desired and needed additional data to the discussion. We propose follow-up of MATLAS-2019 with HST, employing two-band ACS imaging to trace the full population of GCs three magnitudes below the peak of the GC luminosity function. The HST observation, combining depth, color-information, and its superior image quality, will give us an accurate estimate of the total number of GCs. With that we can test whether the UDG hosts an exceptionally large number of GCs, but with a regular GC function, or it contains a population consisting of only over-luminous GCs. Both cases pose a conundrum for our understanding of GC and galaxy formation. F606W/F814W imaging of a single ultra-diffuse galaxy. Limited to 4 exposures of equal length for the single orbit requested/allocated. Use of small DITHER LINE as we do not require filling in the chip gap, but we do need two exposures in each filter to facilitate CR and hot pixel removal. We have created a dither of 7.5 pixels x 6.5 pixels, or spacing 0.504" at an angle of 42.11 degrees. Data to be used to obtain magnitudes and colors of most (marginally-resolved) globular cluster candidates in this galaxy. We have cntered the galaxy on aperture WFC1 in order to avoid chip gap running through galaxy. We have a wide range of possible ORIENT values, chosen only to to avoid a very brgiht (V=13) star to the NE of the target galaxy, and also to avoid a pair of V=15-16 stars SE and SW of the target galaxy. All are far from the galaxy, but we are maximizing the amount of the FOV available for background corrections. Relaxing the roll angles to allow the V=15-16 stars will not change the schedulability very much. Reduced Gyro mode: We do not expect large complication if less than 3 gyros are available for the observations, reducing the effective time available for observations. Our program allows for manyu possible roll angles, which means there are many months of schedulability available. The team consist of several junior and senior members of the MATLAS collaboration who have ample experience with: - HST data (e.g. Francine Marleau, Sungsoon Lim), - dwarf galaxies (e.g. Pierre-Alain Duc, Rebecca Habas), - PSF and aperture photometry (e.g. Oliver Mueller, Sungsoon Lim), - globular clusters (e.g. Patrick Durrell, Ruben Sanchez-Janssen) and have proven to have an excellent publication track on the topic of dwarf/ultra-diffuse galaxies (e.g. van der Burg et al. 2015, 2016, Mueller et al. 2018, Lim et al. 2018, Emsellem et al. 2019, Fensch et al. 2019, Habas et al. 2019). The project will be lead by the postdoctoral researcher Oliver Mueller who is based at the University of Strasbourg (France) and has funding secured for another two years (SNF Postdoc Fellowship). The data can be reduced timely and the results be published in a renowned journal like APJ. Galaxies and the IGM 6 false false false false false false false SUPPORTED GALAXY DWARF ELLIPTICAL J2000 J2000 ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F606W POS-TARG DITHER 0.504 LINE false false 2 42.11 ACS-WFC-DITHER-LINE 1 false 1583954596811 /private/var/folders/1b/yx3zlx911zl6np_bzjrqc4245gvmgy/T/OPVisit3041529207037651782.xml The scheduling data was generated by CASM 28.0. CASM was run in Phase II mode. 2xF606W + 2xF814W images of target galaxy. Center galaxy on WFC1 to be sure no GC candidates fall outside FOV, or on chip gap. (Tic-Visit :proposal-id 16082 :visit-id "01" :proposal-version -1 :trans-version "20191203" :date "11-Mar-2020 15:23:16.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1136896 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16082 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16082 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2809 :al-overhead-at-end 0 :internal-dur-at-end 347 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0