16760( 3) - 29-Jul-2021 18:41:10 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16760 Version: 3 Check-in Time: 29-Jul-2021 18:41:10 STScI Edit Number: 0 Title First detection of an isolated stellar mass black hole with astrometric microlensing ------------------------------------------------------------------------------------ Type Cycle GO 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Casey Lam University of California - Berkeley Y CoI: Dr. Jessica Ryan Lu University of California - Berkeley N ------------------------------------------------------------------------------------ Abstract We propose to confirm the detection of the first isolated black hole (BH), OB110462. We analyzed archival HST data with improved astrometric techniques and demonstrate that the 3 sigma lower mass limit of OB110462 is 5 Msun, making it a solid BH detection. However, the allowed mass range of the BH is quite wide (68% CI of 9-31 Msun), due to the lack of sufficient time baseline of the archival data. We propose to obtain a new measurement of the target, now 10 years after the lensing event, in order to better constrain the baseline proper motion. This will allow the mass constraints of the BH to be improved by a factor of at least 2. This will provide the first mass measurement of an isolated BH, which will inform theoretical models of massive star death, the Milky Way BH mass distribution, and the population of BH-BH binaries discovered via gravitational waves. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will observe two additional epochs of OB110462 in order to increase our time baseline to more precisely measure its proper motion, and in turn its mass. In order to match past observations and better understand color-dependent astrometric effects, we will image using WFC3-UVIS in both F814W and F606W filters. For observations in each filter, we will dither a small amount 5-6 times to sample the pixel phase and maximize our SNR. We will also take our observations in the same ORIENT as the past observations to minimze astrometric systematics due to unmodeled camera distortion and seasonal effects. In terms of the possibility of HST going into reduced gyro mode (RGM), the astrometry technique we are using is not the spatial-scan technique, so will not be affected by RGM. In addition, our observations are more affected by systematic errors, not FWHM or SNR, and so nominal changes in these metrics due to RGM will not adversely affect the proposed observations. ------------------------------------------------------------------------------------ 16760( 3) - 29-Jul-2021 18:41:10 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 OGLE-2011-BL STAR, BULGE RA=17H51M40.1900S, J2000 V = 20.25 +/- 0.1 G-0462 DEC=-29D53'26.30" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 16760( 3) - 29-Jul-2021 18:41:10 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type SPIRAL Pattern_Purpose DITHER Number_Of_Points 6 Point_Spacing 0.13 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 45 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type SPIRAL Pattern_Purpose DITHER Number_Of_Points 5 Point_Spacing 0.13 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 45 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 16760( 3) - 29-Jul-2021 18:41:10 - [ 4] Visit: 01 Visit Requirements: ORIENT 88D TO 96 D; ORIENT 278D TO 282 D On Hold Comments: Additional Comments: It would be strongly preferred that this visit be scheduled in October 2021 if possible, when ORIENT is between 88 and 96 degrees. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 OGLE-2011-B WFC3/UVI ACCUM UVIS2-2K2 F814W FLASH=15 1 307 S POS TARG 0, 0; PATTERN 1 LG-0462 S C-SUB (1842 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 OGLE-2011-B WFC3/UVI ACCUM UVIS2-2K2 F606W FLASH=5 1 407 S POS TARG 0, 0; PATTERN 2 LG-0462 S C-SUB (2035 S) 2 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 1 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 2 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 3 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 4 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 5 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 6 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 2 WFC3/UVI ACCUM UVIS2-2K F606W 1 none none none 2 N/A S 2C-SUB OGLE-2011-BLG-0462 2 WFC3/UVI ACCUM UVIS2-2K F606W 2 none none none 2 N/A S 2C-SUB OGLE-2011-BLG-0462 2 WFC3/UVI ACCUM UVIS2-2K F606W 3 none none none 2 N/A S 2C-SUB OGLE-2011-BLG-0462 2 WFC3/UVI ACCUM UVIS2-2K F606W 4 none none none 2 N/A S 2C-SUB OGLE-2011-BLG-0462 2 WFC3/UVI ACCUM UVIS2-2K F606W 5 none none none 2 N/A S 2C-SUB 16760( 3) - 29-Jul-2021 18:41:10 - [ 5] Visit: 02 Visit Requirements: ORIENT 88D TO 96 D; ORIENT 278D TO 282 D; AFTER 01 BY 180 D TO 360 D On Hold Comments: Additional Comments: It would be strongly preferred that this visit be scheduled August 2022 or after, if possible, when ORIENT is between 88 to 96 degrees. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 OGLE-2011-B WFC3/UVI ACCUM UVIS2-2K2 F814W FLASH=15 1 307 S POS TARG 0, 0; PATTERN 1 LG-0462 S C-SUB (1842 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 OGLE-2011-B WFC3/UVI ACCUM UVIS2-2K2 F606W FLASH=5 1 407 S POS TARG 0, 0; PATTERN 2 LG-0462 S C-SUB (2035 S) 2 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 1 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 2 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 3 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 4 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 5 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 1 WFC3/UVI ACCUM UVIS2-2K F814W 6 none none none 1 N/A S 2C-SUB OGLE-2011-BLG-0462 2 WFC3/UVI ACCUM UVIS2-2K F606W 1 none none none 2 N/A S 2C-SUB OGLE-2011-BLG-0462 2 WFC3/UVI ACCUM UVIS2-2K F606W 2 none none none 2 N/A S 2C-SUB OGLE-2011-BLG-0462 2 WFC3/UVI ACCUM UVIS2-2K F606W 3 none none none 2 N/A S 2C-SUB OGLE-2011-BLG-0462 2 WFC3/UVI ACCUM UVIS2-2K F606W 4 none none none 2 N/A S 2C-SUB OGLE-2011-BLG-0462 2 WFC3/UVI ACCUM UVIS2-2K F606W 5 none none none 2 N/A S 2C-SUB 16760( 3) - 29-Jul-2021 18:41:10 - [ 6] Summary Form for Proposal 16760 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2-2K2C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=15, FLASH=5 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 180 D TO 360 D, ORIENT 278D TO 282 D, ORIENT 88D TO 96 D, PATTERN 1 1, PATTERN 2 2, POS TARG 0, 0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names OGLE-2011-BLG-0462 ------------------------------------------------------------------------------------------------------------------------------------