Illegal selection: 28. 'Illegal Selection: 28' is a known issues. See: https://stsci.service-now.com/hst?id=kb_article&sysparm_article=KB0012681&sys_kb_id=b348972edbf960501c70d8965e9619e8&spa=1 Had trouble with phase 1 scheduling observations. As described in the proposal, each visit is requested to be as evenly separated in time as possible (e.g. March 25, May 29, July 28, September 30). -648365202 Assigned ID: 1385 ----- Attempting Submission 1 (Sun Jan 31 04:32:57 GMT 2021) ----- HST Phase I Proposal 1385 successfully submitted. Receipt: # 1385-1 Known error, described in my submission comments. FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser Updating visit 04 exposures. 1585788719 ----- Attempting Submission 1 (Sat Mar 20 00:45:17 GMT 2021) ----- ----- Attempting Submission 2 (Thu Sep 09 17:14:39 GMT 2021) ----- Post-Flash warning, can ignore. We propose to directly measure, for the first time, the individual masses for the binary black hole candidate MOA-2019-BLG-284. Unlike some previous studies (Sahu+2009, 2019, Kains+2017), we have selected this candidate based on both its large Einstein radius crossing time of 500 days and its relatively small microlensing parallax of 0.038. The combination of these two parameters is much more effective at identifying black hole microlensing candidates than using events with large Einstein radius crossing time, but no constraint on the microlensing parallax. We also have worked with the microlensing survey groups to remove systematic photometry errors that could contaminate the microlensing parallax measurement. This target is ideal given its very long duration, clear microlensing parallax signal, relatively bright baseline magnitude and previous HST observations taken in 2020. Further, the current best-model gives a total lens mass of ~10 Msun or more, with roughly equal mass lens components. If successful, these observations will complement the groundbreaking work of LIGO, and open a new window on the population of (pre-merged) binary black holes in our Galaxy. If this observing program is successful, it will open a new window on the population of binary black holes (BHs) in our Galaxy and contribute to our understanding of the Galactic distribution of binary BHs, with which LIGO paved the way. We will avoid any potential saturation issues in these new 2021 epochs by using ground-based observations shortly before the scheduled HST observations to ensure the exposure time selected will not saturate the target. In the event that the OGLE or MOA observatories are shut down due to COVID-19 during this time frame, we can easily pivot to an observing scheme that uses primarily many short exposures that we can stack. We propose measurements in the F814W passband over four separate visits during March - September. Four visits are needed in order to maximize the probability that we are able to successfully measure the astrometric shift induced by the binary BH lens. We request 16 exposures per orbit in the WFC3/UVIS F814W passband to get good spatial sampling of the effective PSFs (Anderson and King 2000), and this means that we will be unable to do parallel, full-frame buffer dumps. However, our target is relatively bright, so we want a large enough area to ensure a sufficient number of stars with a similar color and brightness to our target that can be used to construct precise PSF models and calibrate the data. We select the UVIS2-C1K1C-SUB subarray to obtain ~ 50 stars within 0.5 in magnitude from the target, similar to the previous observing program's strategy. Due to roll-angle (U3 range) restrictions, our target cannot be observed with the same pixel orientation in two visits separated by 200 days, therefore we request a 180 degree orientation change between visit two and three (i.e. visits one and two: 269 degree, visits three and four: 89 degree). This will allow us to maintain the pixel grid alignments between all four visits. Note: Reduced gyro operations may degrade the astrometric performance and require marginally longer exposure times to achieve a comparable astrometric precision. There exist archival two-gyro astrometric data sets that we could use to estimate the impact, if needed. Again, we have a mitigation protocol ready to implement in the event that we are unable to measure the target brightness from the ground (due to COVID-19 or otherwise) and adjust the HST exposure time shortly before each epoch. This backup plan ensures we are still able to retrieve the best-possible astrometry and photometry of the magnified source star in each epoch. The PI, Sean Terry is a Postdoctoral Scholar at University of California Berkeley working on high-precision astrometry and photometry of ground-based adaptive optics (AO) observations. Terry has worked with CoI's Dr. Bennett and Bhattacharya on the development of methods to measure the brightness and separation of highly blended source and lens stars in HST WFC3 and Keck AO data. These methods have proven to be very successful (Bennett et al. 2015, Bhattacharya et al. 2018, Terry et al. 2021a, Terry et al. 2021b in prep), with the smallest separation measurement ~12 mas with HST V and I-band (Bhattacharya et al. 2017). Dr. Terry has also collaborated with CoI Jay Anderson and others on HST WFC3 UVIS/IR studies of highly crowded stellar fields toward the Galactic Center as precursor science for the Nancy Grace Roman Space Telescope mission (Terry et al. 2020). Co-PI Prof. J. Lu has expertise in high-precision astrometry both from ground-based adaptive optics and HST observations. Prof. Lu has used high-precision astrometry to study resolved stellar populations throughout the Milky Way, including showing evidence for a top-heavy IMF in the massive, young clusters in the Galactic Center and disk and conducting the first search for astrometric microlensing signals by black holes from the ground. Lu and her group also develop microlens modeling codes. Her student (and CoI), Casey Lam, built the microlens population synthesis code, PopSyCLE (Lam et al. 2020). David Bennett is a Senior Research Scientist at University of Maryland and NASA Goddard Space flight Center, and he has led the development of the methods for measuring small separations between micolens source and lens star with the first such measurement for a planetary system (Bennett et al. 2006) and the first theoretical paper discussing the methods to be used for these measurements. Starting from the HST analysis methods developed by CoI Jay Anderson for HST astrometry, Bennett has continued to lead in these high-precision astrometry and photometry efforts that will be essential to the Roman Galactic Exoplanet Survey (RGES). These methods are the state-of-the-art in the field, with no other group able to duplicate this work. Our team includes Jean-Phillpe Beaulieu, a senior researcher in CNRS, IAP. Beaulieu has led the Keck AO observing effort that is done in close cooperation with past HST programs. He has published numerous papers on microlensing follow-up observations including mass measurements of the first two planets found by microlensing to orbit a solar type star (Beaulieu et al. 2016). Finally, our team also includes leaders from both the MOA and OGLE ground-based microlensing survey groups: Bennett, and Ian Bond Of Massey University In New Zealand lead the MOA group along with Takahiro Sumi, and CoI Andrzej Udalski leads OGLE. Stellar Populations and the Interstellar Medium 0 false false false false false false false false SUPPORTED STAR BULGE GRAVITATIONAL LENS J2000 J2000 I = 15.38 +/- 0.10 WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F814W 1616200708555 The scheduling data was generated by CASM 29.0. CASM was run in Phase II mode. 1617601509000 269.0 (Tic-Visit :proposal-id 16509 :visit-id "01" :proposal-version -1 :trans-version "20200619" :date "19-Mar-2021 17:38:28.0" :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 320848 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16509 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16509 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2791 :al-overhead-at-end 83 :internal-dur-at-end 387 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3180 :pcs-gap 0 ) true 1 0 1616200858767 The scheduling data was generated by CASM 29.0. CASM was run in Phase II mode. Target is variable, prior to visit the exposure times should be updated via communication with science team who have access to real-time ground-based photometry. 1622033660000 269.0 (Tic-Visit :proposal-id 16509 :visit-id "02" :proposal-version -1 :trans-version "20200619" :date "19-Mar-2021 17:40:58.0" :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 320848 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16509 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16509 :visit-id "02" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2791 :al-overhead-at-end 83 :internal-dur-at-end 387 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3180 :pcs-gap 0 ) true 1 0 1616200868707 The scheduling data was generated by CASM 29.0. CASM was run in Phase II mode. Target is variable, prior to visit the exposure times should be updated via communication with science team who have access to real-time ground-based photometry. 1628056199000 89.0 (Tic-Visit :proposal-id 16509 :visit-id "03" :proposal-version -1 :trans-version "20200619" :date "19-Mar-2021 17:41:08.0" :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 320848 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16509 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16509 :visit-id "03" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2791 :al-overhead-at-end 83 :internal-dur-at-end 387 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3180 :pcs-gap 0 ) true 1 0 /private/var/folders/vz/xvz4kw6x52g989vsrhghzjdr0000gn/T/OPVisit17279005115888684934.xml 1631207562587 The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. Target is variable, prior to visit the exposure times should be updated via communication with science team who have access to real-time ground-based photometry. (Tic-Visit :proposal-id 16509 :visit-id "04" :proposal-version -1 :trans-version "20210514" :date "09-Sep-2021 10:12:42.0" :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 374320 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16509 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16509 :visit-id "04" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2788 :al-overhead-at-end 83 :internal-dur-at-end 446 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3180 :pcs-gap 0 ) true 1 0