0 Assigned ID: 5248 ----- Attempting Submission 1 (Mon Mar 25 21:17:36 GMT 2024) ----- HST Phase I Proposal 5248 successfully submitted. Receipt: # 5248-1 The number of orbits used exceeds the number allocated last 6 exposures in visit 2 orbit 2, made into visit 52 (HOPR) 1829868471 ----- Attempting Submission 1 (Wed Aug 14 13:54:58 GMT 2024) ----- ----- Attempting Submission 2 (Thu May 08 10:22:01 GMT 2025) ----- Confirming Serendipitous Microlens Host Detections with New and Archival HST Imaging We propose a GO-Archival program to study seven planetary microlensing events for which we identify serendipitous HST archival data that have observed these targets between 8 - 25 years prior to the gravitational microlensing events. We will couple this archival data with new HST observations in order to definitively confirm the candidate lens objects via their proper motions. Three of the seven targets likely represent very exotic lenses; two of the targets are candidate white dwarf (WD) hosts and one target is a free-floating planet (FFP) candidate. Successful confirmation of any of the proposed targets requires a second-epoch HST observation, and would represent a first of its kind precursor detection of a lens object prior to the microlensing event. Further, confirmation of either of the WD or FFP candidates will help inform planet formation and evolution theory for unbound FFPs as well as bound planets in stellar remnant systems. We will conduct ten (10) total orbits, five in each of the WFC3/UVIS F814W and F606W passbands to get good spatial sampling of the effective PSFs (Anderson & King 2004). Each of the five targets are relatively bright, we expect a sufficient number of stars with a similar color and brightness to our target(s) which 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 and V - I color from the targets. The visits for each target will consist of one orbit that includes 16 x 60 sec exposures in the F814W passband, and one orbit that includes approximately 16 x 80 sec exposures in the F606W passband. We will use a custom sub-pixel dither pattern designed to optimally map the PSF in the 16 total exposures. Using the WFC3 exposure time calculator (ETC), we estimate our observations will yield a S/N > 80 in both passbands for all five targets. The PI, Sean Terry is a Postdoctoral Associate at University of Maryland College Park working on high-precision astrometry and photometry of space-based (HST) and ground-based (AO) observations. For many years, Terry has worked on the development of methods to measure the brightness and separation of highly blended microlensing 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. 2021, 2022, 2023), with the smallest separation measurement ~12 mas with HST V and I-band (Bhattacharya et al. 2017). Dr. Terry is also a member of the Roman Galactic Exoplanet Survey Project Infrastructure Team (RGES PIT), where he primarily works on the development of Roman's photometry and astrometry pipeline for the microlensing survey as well as high-precision lens flux methods that Roman will utilize to obtain exoplanet mass measurements for microlensing events that are discovered by the survey. Co-I Przemek Mroz is an Assistant Professor at the University of Warsaw, where he analyzes gravitational microlensing events through light curve modeling as well as high resolution imaging of free-floating planet (FFP) candidates discovered through microlensing. Mroz is a co-leader of the OGLE microlensing survey, which detects over 1,000 gravitational microlensing events per year, and is a leading expert in microlensing FFP populations. Both Terry and Mroz have proven over time that they have strong expertise in all the necessary skills needed to analyze and interpret the data from this proposal. Exoplanets and Exoplanet Formation Stellar Physics and Stellar Types 6 false false false false true false false false false false SUPPORTED STAR BULGE GRAVITATIONAL LENS J2000 J2000 I-Magnitude = 19.99 +/- 0.04 STAR BULGE GRAVITATIONAL LENS J2000 J2000 I-Magnitude = 19.80 +/- 0.02 STAR BULGE GRAVITATIONAL LENS J2000 J2000 I-Magnitude = 20.32 +/- 0.07 STAR BULGE GRAVITATIONAL LENS J2000 J2000 I-Magnitude = 20.84 +/- 0.03 STAR BULGE GRAVITATIONAL LENS J2000 J2000 I-Magnitude = 18.90 +/- 0.02 WFC3/UVIS Imaging No No F606W WFC3/UVIS 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 WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W The scheduling data was generated by CASM 32.1.1. CASM was run in Phase II mode. 1745340615000 269.0 (Tic-Visit :proposal-id 17834 :visit-id "01" :proposal-version -1 :trans-version "20240604" :date "11-Aug-2024 18:28:02.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 570384 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17834 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17834 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2643 :al-overhead-at-end 87 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17834 :visit-id "01" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2648 :al-overhead-at-end 87 :internal-dur-at-end 660 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 32.1.1. CASM was run in Phase II mode. 1745691609000 269.0 (Tic-Visit :proposal-id 17834 :visit-id "02" :proposal-version -1 :trans-version "20240604" :date "11-Aug-2024 18:28:04.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 570384 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17834 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17834 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2643 :al-overhead-at-end 87 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17834 :visit-id "02" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2648 :al-overhead-at-end 87 :internal-dur-at-end 660 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) true 2 0 /private/var/folders/q9/0jb3sqc10kx2dw3wnl21b_dw000702/T/OPVisit8291221852457611075.xml HOPR copy of the last 6 exposures of orbit 2, visit 2, exposure 27-32 (Tic-Visit :proposal-id 17834 :visit-id "52" :proposal-version -1 :trans-version "20241217" :date "08-May-2025 06:20:47.0" :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 106960 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17834 :visit-id "52" :obset-id "52" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17834 :visit-id "52" :orbit-number 1 :pcs-time 380 :si-vis-utilization 927 :al-overhead-at-end 87 :internal-dur-at-end 153 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 32.1.1. CASM was run in Phase II mode. 1745408616000 269.0 (Tic-Visit :proposal-id 17834 :visit-id "03" :proposal-version -1 :trans-version "20240604" :date "11-Aug-2024 18:28:06.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 570384 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17834 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17834 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2643 :al-overhead-at-end 87 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17834 :visit-id "03" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2648 :al-overhead-at-end 87 :internal-dur-at-end 660 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 32.1.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17834 :visit-id "04" :proposal-version -1 :trans-version "20240604" :date "11-Aug-2024 18:28:09.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 570384 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17834 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17834 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2643 :al-overhead-at-end 87 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17834 :visit-id "04" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2648 :al-overhead-at-end 87 :internal-dur-at-end 660 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 32.1.1. CASM was run in Phase II mode. 1745680288000 269.0 (Tic-Visit :proposal-id 17834 :visit-id "06" :proposal-version -1 :trans-version "20240604" :date "11-Aug-2024 18:28:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 570384 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17834 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17834 :visit-id "06" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2643 :al-overhead-at-end 87 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17834 :visit-id "06" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2648 :al-overhead-at-end 87 :internal-dur-at-end 660 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3032 :pcs-gap 0 ) true 2 0