0 Assigned ID: 535 ----- Attempting Submission 1 (Fri Mar 06 16:27:31 GMT 2020) ----- HST Phase I Proposal 535 successfully submitted. Receipt: # 535-1 ----- Attempting Submission 2 (Fri Mar 06 18:31:00 GMT 2020) ----- HST Phase I Proposal 535 successfully submitted. Receipt: # 535-2 ----- Attempting Submission 3 (Fri Mar 06 19:48:23 GMT 2020) ----- HST Phase I Proposal 535 successfully submitted. Receipt: # 535-3 This target is not used in this proposal. FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser Oct 2020: We have relaxed the ORIENT constraints following the recommendation from the STScI/TTRB to allow for better schedulability. Exposure times can be slightly shortened to accommodate more flexibility in the scheduling (if necessary), same for a slight relaxation of the roll angle constraints. With our WFC3/UVIS exposure times we expect about 2 electrons background level per pixel. We add 19 electrons of post flash to mitigate CTI problems (following new recommendation to have a total level of 20 electrons). Target is shifted slightly towards the UVIS readout amplifier to further reduce CTI problems (POS TARGET shifted in Y direction). Also a shift in ACS/WFC pointing to maximise spatial overlap between the ACS and WFC3 data sets (even though the chips are not aligned anymore). -1280436012 ----- Attempting Submission 1 (Wed Jun 10 13:55:02 GMT 2020) ----- HST Phase II Proposal 16186 successfully submitted. Receipt: # 16186-1 ----- Attempting Submission 2 (Fri Jun 12 14:40:38 GMT 2020) ----- ----- Attempting Submission 3 (Mon Oct 19 07:40:41 GMT 2020) ----- Target coordinate is slighly revised by ~1 arcsec. To avoid confusion, we added an extra target in PH2, to not have the same target name with two different coordinates. FLASH level recommendation is updated, so second error should be waved. Recent observations of Ultra-Diffuse Galaxies (UDGs, which have the luminosities of dwarfs but sizes of giant galaxies) have picked up a lot of attention by the community. Two nagging problems that are being discussed in the context of UDGs, are 1) the apparent lack of dark matter of some UDGs, and 2) their anomalously abundant-and-bright globular cluster systems. The former is difficult to reconcile with a LCDM model of structure formation, while the latter is contrary to what we observe in essentially any other galaxy system. We have recently discovered a UDG candidate, that may provide valuable insight towards solving both problems. This object has very similar properties to typical UDGs, apart from a widely spread population of compact star-forming regions. Our ground-based photometry indicates that these regions have stellar masses similar to globular clusters (GCs), and at least three have radial profiles that are unresolved by our ground based imaging - in line with expectations for young massive clusters. The HST brings the high spatial resolution, and imaging capability in the near-UV, that are required to better constrain the physical sizes and formation ages of these compact regions. Interestingly and coincidentally, some properties of this galaxy are strikingly similar to those hypothesised by Silk 2019, who predicts the simultaneous formation of massive GCs, and links this to the formation of UDGs that lack dark matter and exhibit extreme GC systems. This UDG may just provide us a very rare local view on such processes in action. This is an HST imaging program of a single ultra-diffuse galaxy in three filters: ACS/WFC F606W and F814W, and WFC3/UVIS F275W. Data will be combined to measure fluxes and sizes of candidate globular clusters (expected to be borderline resolved at HST spatial resolution) in this galaxy. One orbit is allocated to each of three filters. Each orbit is split in 4 exposures with offset positions of half-pixel plus several pixels (i.e. the standard DITHER BOX option for both instruments) so that the individual frames can be interlaced and combined in the reduction. This is to improve the spatial sampling of the PSF and to facilitate CR and hot pixel removal. The chip gap does not have to be filled, so those small dithers suffice. ORIENT constraints: The galaxy will fall on WFC3/UVIS chip 2 and ACS/WFC chip 1 (aperture UVIS2 and WFC1). The galaxy is strongly elliptical (PA ~35 degrees from North Eastwards) and we intend to align the major axis with the x-axes of both chips, to be able to probe all star clusters in this galaxy. We allow a tolerance of 20 degrees between the major axis and the x-axis of UVIS chip1, and the whole configuration can be flipped by 180 degrees. To ensure a maximum overlap between the WFC3 and ACS imaging, also for the second chips, we impose a 10 degrees tolerance between the x-axes of UVIS2 and WFC1. Given how the detectors are placed in the HST FoV, we split the orbits over two HST visits. We believe these ORIENT constraints strike a good balance between maximising science return and schedulability. NOTE Oct 2020: To increase schedulability, we had to relax the ORIENT constraints listed above. TARGET POSITION: The galaxy is off-set towards the readout amplifier on the UVIS chip 2 to reduce CTI problems (-20'' in Y direction). Accordingly, we shift the target on the ACS/WFC chip 1 (-50'' in X direction and -20'' in Y direction) to maximise spatial overlap between the WFC3 and ACS data sets. We will apply a post-flash level of 19 electrons to the UVIS chips. Including the ~2 electrons of background per pixel we expect with our exposure times, this meets the updated recommended total background level of at least 20 electrons to reduce CTI problems. In the event of Reduced Gyro mode, our program would need a minor reduction of exposure times to accommodate a longer initial target acquisition. There are no bright sources in the field of view and there are no limitations for using WFC3/UVIS and ACS/WFC. The team consists of expertise in the following key areas: Dwarf galaxies (Hilker, Prole, McDermid) Star clusters (Beccari, Hilker) PSF modeling and Photometry (Prole, van der Burg) HST specific imaging and data handling (Beccari) The team has a proven publication track record with impactful publications in the area of dwarf galaxies (Hilker, McDermid), star-forming regions studied with HST/UVIS (Beccari et al. 2019), ultra-diffuse galaxies: van der Burg et al. 2016, 2017, Prole et al. 2018, 2019a, 2019b. Prole and van der Burg have a proven track record with the science goals, the technical aspects of the analysis, and are committed to lead the analysis and publication of this work. Galaxies 6 false false false false false false false SUPPORTED GALAXY DWARF ELLIPTICAL LSB STAR FORMING REGION This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 GALAXY DWARF ELLIPTICAL LSB STAR FORMING REGION Elliptical UDG/LSB galaxy with major axis ~1 arcmin. Contains at least 10-20 bright clusters/star-forming regions. GAMA-526784-CENTER J2000 WFC3/UVIS Imaging No No F275W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 1 false POS-TARG DITHER 0.262 LINE 0.192 false false 68.14 4 18.39 ACS-WFC-DITHER-BOX 2 false /private/var/folders/mr/3fjsvbcs0sj8wq5fwh7j4_ch0007l8/T/OPVisit4299849941977814991.xml 1603093142962 The scheduling data was generated by CASM 28.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16186 :visit-id "01" :proposal-version -1 :trans-version "20200518" :date "19-Oct-2020 09:39:02.0" :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 16186 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16186 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2758 :al-overhead-at-end 126 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0 /Users/rvanderb/Documents/proposals/HST/GAMAUDG/APT_files/OP-cache/16186_altconstraints-v02.xml 1603092811981 The scheduling data was generated by CASM 28.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16186 :visit-id "02" :proposal-version -1 :trans-version "20200518" :date "19-Oct-2020 09:33:31.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 2273792 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16186 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16186 :visit-id "02" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2758 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16186 :visit-id "02" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2747 :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 2 0