17746( 5) - 07-Apr-2026 16:11:45 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17746 Version: 5 Check-in Time: 07-Apr-2026 16:11:45 STScI Edit Number: 0 Title Locating Clouds in the Milky Way's Nuclear Outflow ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Andrew J. Fox Space Telescope Science Institute - ESA Y CoI: Dr. Rongmon Bordoloi North Carolina State University N CoI: Dr. Frances H. Cashman Presbyterian College N CoI: Dr. Alexander W. Fullerton Space Telescope Science Institute N CoI: Dr. Edward B. Jenkins Princeton University N CoI: Dr. Tanveer Karim University of Toronto N CoI: Dr. Felix J. Lockman Associated Universities, Inc. N CoI: Dr. Jessica Kay Werk University of Washington N CoI: Dr. Sara Cazzoli Instituto de Astrofisica de Andalucia N (IAA) ------------------------------------------------------------------------------------ Abstract Recent HST/COS observations have discovered outflowing cool gas clouds in the Milky Way's nuclear wind. While their chemical compostion, covering fraction, and kinematics have been characterized, their distance is largely unconstrained, so we do not know where along each line of sight the cool gas clouds are located. Without the distance to the clouds, we cannot definitively associate them with the Fermi or eROSITA Bubbles (the giant gamma-ray and X-ray structures created by a nuclear outburst) or reconstruct the history of the nuclear outflow. We have designed a novel experiment to determine the distance to the cool clouds using HST/COS observations of a sample of six blue horizontal branch (BHB) stars projected onto the Fermi and eROSITA Bubbles. The targets are chosen to lie at a range of distances from 4.7 to 9.5 kpc, with two targets inside the Bubbles and four in the foreground. By bracketing the location of high-velocity clouds (HVCs) seen in UV metal absorption lines (Si II, Si IV, C IV, Fe II) in the BHB spectra, we will determine whether the clouds arise inside or in front of the Bubbles. A detection of HVCs in both the foreground and background sightlines would place the clouds in front of the Bubbles. A detection in the background but not the foreground sightlines would place the clouds within the Bubbles or at their boundaries. We also request deep H I 21 cm spectra of each direction from the Green Bank Telescope to constrain the velocities and locations of the neutral gas in the HVCs, which directly aids our science goals. This experiment provides a method for mapping the spatial distribution of high-velocity gas in the Galactic halo. ------------------------------------------------------------------------------------ Observations Description ------------------------ This is a COS FUV program to observe six blue horizontal branch (BHB) stars toward the Galactic Center, with the science goal of detecting foregound gas in absorption in several UV metal lines (particularly Si IV 1393, 1402 and C IV 1548, 1550). 17746( 5) - 07-Apr-2026 16:11:45 - [ 2] Each target will be acquired with a NUV ACQ/IMAGE with the PSA and MIRRORB, followed by science observations with the G160M/1577 setting. For each target, the four FP-POS positions will be obtained either in one visit or spread across two visits. All visits are either 2 or 3 orbits in length, following the guidance from the PC. ------------------------------------------------------------------------------------ 17746( 5) - 07-Apr-2026 16:11:45 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ160553. ISM, ABSORPTION LINE RA=16H05M53.3780S +/- 0.1", J2000 V = 14.8 FUV=17.74 NUV=16.77 38+045820.4 SYSTEM - GALACTIC, HIGH DEC=+04D58'20.30" +/- 0.1" VELOCITY CLOUD, INTERMEDIATE VELOCITY CLOUD Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 -2.8380133612298586E-4 -0.014809000003879191 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ155747. ISM, ABSORPTION LINE RA=15H57M47.6814S +/- 0.1", J2000 V = 15.0 FUV=17.17 NUV=16.79 67+043815.6 SYSTEM - GALACTIC, HIGH DEC=+04D38'15.61" +/- 0.1" VELOCITY CLOUD, INTERMEDIATE VELOCITY CLOUD Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 -2.1884985410363134E-4 -0.005894000014450285 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ155943. ISM, ABSORPTION LINE RA=15H59M43.1227S +/- 0.1", J2000 V = 15.2 FUV=18.08 NUV=17.43 11+050908.5 SYSTEM - GALACTIC, HIGH DEC=+05D09'8.56" +/- 0.1" VELOCITY CLOUD, INTERMEDIATE VELOCITY CLOUD Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 -3.630669828076738E-4 -0.01251499998033978 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ154825. ISM, ABSORPTION LINE RA=15H48M25.8015S +/- 0.1", J2000 V = 15.9 FUV=18.19 NUV=17.72 80+052038.8 SYSTEM - GALACTIC, HIGH DEC=+05D20'38.87" +/- 0.1" VELOCITY CLOUD, INTERMEDIATE VELOCITY CLOUD Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 -1.0967673105207091E-4 -0.0072169999384641415 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17746( 5) - 07-Apr-2026 16:11:45 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ152022. ISM, ABSORPTION LINE RA=15H20M22.6863S +/- 0.1", J2000 V = 14.9 FUV=17.80 NUV=16.93 68+060059.7 SYSTEM - GALACTIC, HIGH DEC=+06D00'59.61" +/- 0.1" VELOCITY CLOUD, INTERMEDIATE VELOCITY CLOUD Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 -6.652644539079872E-4 -0.01106499989873555 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 6 SDSSJ152011. ISM, ABSORPTION LINE RA=15H20M11.6252S +/- 0.1", J2000 V = 15.2 FUV=17.54 NUV=16.97 62+081911.1 SYSTEM - GALACTIC, HIGH DEC=+08D19'11.11" +/- 0.1" VELOCITY CLOUD, INTERMEDIATE VELOCITY CLOUD Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 -1.8110594671411762E-4 -0.009797999928196077 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17746( 5) - 07-Apr-2026 16:11:45 - [ 5] Visit: 01 (J1605-1) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ160553 COS/NUV ACQ/IMA PSA MIRRORB 1 9 S (9 S) .38+045820. GE 4 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ160553 COS/FUV TIME-TA PSA G160M 1577 FP-POS=1, BUFFER-TIME=4000 1 2132 S .38+045820. G (2132 S) 4 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ160553 COS/FUV TIME-TA PSA G160M 1577 FP-POS=2, BUFFER-TIME=4000 1 2565 S .38+045820. G (2565 S) 4 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ160553.38+0458 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 20.4 GE SDSSJ160553.38+0458 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 20.4 G SDSSJ160553.38+0458 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 20.4 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 6] Visit: 02 (J1605-2) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ160553 COS/NUV ACQ/IMA PSA MIRRORB 1 9 S (9 S) .38+045820. GE 4 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ160553 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 2132 S .38+045820. G (2132 S) 4 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ160553 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 2565 S .38+045820. G (2565 S) 4 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ160553.38+0458 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 20.4 GE SDSSJ160553.38+0458 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 20.4 G SDSSJ160553.38+0458 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 20.4 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 7] Visit: 03 (J1557-1) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ155747 COS/NUV ACQ/IMA PSA MIRRORB 1 9 S (9 S) .67+043815. GE 6 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ155747 COS/FUV TIME-TA PSA G160M 1577 FP-POS=1, BUFFER-TIME=4000 1 2132 S .67+043815. G (2132 S) 6 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ155747 COS/FUV TIME-TA PSA G160M 1577 FP-POS=2, BUFFER-TIME=4000 1 2565 S .67+043815. G (2565 S) 6 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ155747 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 1102 S .67+043815. G (1102 S) 6 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ155747 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 1102 S .67+043815. G (1102 S) 6 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ155747.67+0438 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 15.6 GE SDSSJ155747.67+0438 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 15.6 G SDSSJ155747.67+0438 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 15.6 G SDSSJ155747.67+0438 4 COS/FUV TIME-TA PSA G160M 1577 none none none none 3 N/A 15.6 G SDSSJ155747.67+0438 5 COS/FUV TIME-TA PSA G160M 1577 none none none none 3 N/A 15.6 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 8] Visit: 04 (J1559-1) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ155943 COS/NUV ACQ/IMA PSA MIRRORB 1 16 S (16 .11+050908. GE S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=1, BUFFER-TIME=4000 1 2123 S .11+050908. G (2123 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=2, BUFFER-TIME=4000 1 2570 S .11+050908. G (2570 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 1105 S .11+050908. G (1105 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 1104 S .11+050908. G (1104 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ155943.11+0509 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 08.5 GE SDSSJ155943.11+0509 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 08.5 G SDSSJ155943.11+0509 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 08.5 G SDSSJ155943.11+0509 4 COS/FUV TIME-TA PSA G160M 1577 none none none none 3 N/A 08.5 G SDSSJ155943.11+0509 5 COS/FUV TIME-TA PSA G160M 1577 none none none none 3 N/A 08.5 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 9] Visit: 05 (J1559-2) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ155943 COS/NUV ACQ/IMA PSA MIRRORB 1 16 S (16 .11+050908. GE S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=1, BUFFER-TIME=4000 1 885 S (885 .11+050908. G S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=2, BUFFER-TIME=4000 1 885 S (885 .11+050908. G S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 1105 S .11+050908. G (1105 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 1104 S .11+050908. G (1104 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ155943.11+0509 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 08.5 GE SDSSJ155943.11+0509 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 08.5 G SDSSJ155943.11+0509 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 08.5 G SDSSJ155943.11+0509 4 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 08.5 G SDSSJ155943.11+0509 5 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 08.5 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 10] Visit: 06 (J1548-1) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ154825 COS/NUV ACQ/IMA PSA MIRRORB 1 21 S (21 .80+052038. GE S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=1, BUFFER-TIME=4000 1 2113 S .80+052038. G (2113 S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=2, BUFFER-TIME=4000 1 2570 S .80+052038. G (2570 S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 1105 S .80+052038. G (1105 S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 1104 S .80+052038. G (1104 S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ154825.80+0520 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 38.8 GE SDSSJ154825.80+0520 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 38.8 G SDSSJ154825.80+0520 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 38.8 G SDSSJ154825.80+0520 4 COS/FUV TIME-TA PSA G160M 1577 none none none none 3 N/A 38.8 G SDSSJ154825.80+0520 5 COS/FUV TIME-TA PSA G160M 1577 none none none none 3 N/A 38.8 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 11] Visit: 07 (J1548-2) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ154825 COS/NUV ACQ/IMA PSA MIRRORB 1 21 S (21 .80+052038. GE S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=1, BUFFER-TIME=4000 1 880 S (880 .80+052038. G S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=2, BUFFER-TIME=4000 1 881 S (881 .80+052038. G S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 1105 S .80+052038. G (1105 S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 1104 S .80+052038. G (1104 S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ154825.80+0520 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 38.8 GE SDSSJ154825.80+0520 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 38.8 G SDSSJ154825.80+0520 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 38.8 G SDSSJ154825.80+0520 4 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 38.8 G SDSSJ154825.80+0520 5 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 38.8 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 12] Visit: 08 (J152022-1) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ152022 COS/NUV ACQ/IMA PSA MIRRORB 1 10 S (10 .68+060059. GE S) 7 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ152022 COS/FUV TIME-TA PSA G160M 1577 FP-POS=1, BUFFER-TIME=4000 1 2135 S .68+060059. G (2135 S) 7 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ152022 COS/FUV TIME-TA PSA G160M 1577 FP-POS=2, BUFFER-TIME=4000 1 2570 S .68+060059. G (2570 S) 7 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ152022.68+0600 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 59.7 GE SDSSJ152022.68+0600 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 59.7 G SDSSJ152022.68+0600 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 59.7 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 13] Visit: 09 (J152022-2) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ152022 COS/NUV ACQ/IMA PSA MIRRORB 1 10 S (10 .68+060059. GE S) 7 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ152022 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 2135 S .68+060059. G (2135 S) 7 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ152022 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 2570 S .68+060059. G (2570 S) 7 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ152022.68+0600 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 59.7 GE SDSSJ152022.68+0600 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 59.7 G SDSSJ152022.68+0600 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 59.7 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 14] Visit: 10 (J152011-1) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ152011 COS/NUV ACQ/IMA PSA MIRRORB 1 10 S (10 .62+081911. GE S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ152011 COS/FUV TIME-TA PSA G160M 1577 FP-POS=1, BUFFER-TIME=4000 1 2135 S .62+081911. G (2135 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ152011 COS/FUV TIME-TA PSA G160M 1577 FP-POS=2, BUFFER-TIME=4000 1 2570 S .62+081911. G (2570 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ152011.62+0819 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 11.1 GE SDSSJ152011.62+0819 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 11.1 G SDSSJ152011.62+0819 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 11.1 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 15] Visit: 11 (J152011-2) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ152011 COS/NUV ACQ/IMA PSA MIRRORB 1 10 S (10 .62+081911. GE S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ152011 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 2135 S .62+081911. G (2135 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ152011 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 2570 S .62+081911. G (2570 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ152011.62+0819 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 11.1 GE SDSSJ152011.62+0819 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 11.1 G SDSSJ152011.62+0819 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 11.1 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 16] Visit: 14 (J1559-1-repeat) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ155943 COS/NUV ACQ/IMA PSA MIRRORB 1 16 S (16 .11+050908. GE S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 2123 S .11+050908. G (2123 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 2570 S .11+050908. G (2570 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ155943.11+0509 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 08.5 GE SDSSJ155943.11+0509 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 08.5 G SDSSJ155943.11+0509 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 08.5 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 17] Visit: 16 (J1548-1-repeat) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ154825 COS/NUV ACQ/IMA PSA MIRRORB 1 21 S (21 .80+052038. GE S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 2113 S .80+052038. G (2113 S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 2570 S .80+052038. G (2570 S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ154825.80+0520 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 38.8 GE SDSSJ154825.80+0520 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 38.8 G SDSSJ154825.80+0520 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 38.8 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 18] Visit: 21 (J1605-1-repeat) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ160553 COS/NUV ACQ/IMA PSA MIRRORB 1 9 S (9 S) .38+045820. GE 4 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ160553 COS/FUV TIME-TA PSA G160M 1577 FP-POS=1, BUFFER-TIME=4000 1 2133 S .38+045820. G (2133 S) 4 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ160553.38+0458 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 20.4 GE SDSSJ160553.38+0458 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 20.4 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 19] Visit: 22 (J1605-2-repeat) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ160553 COS/NUV ACQ/IMA PSA MIRRORB 1 9 S (9 S) .38+045820. GE 4 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ160553 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 2133 S .38+045820. G (2133 S) 4 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ160553.38+0458 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 20.4 GE SDSSJ160553.38+0458 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 20.4 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 20] Visit: 24 (J1559-1-repeat2) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ155943 COS/NUV ACQ/IMA PSA MIRRORB 1 16 S (16 .11+050908. GE S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 2092 S .11+050908. G (2092 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ155943 COS/FUV TIME-TA PSA G160M 1577 FP-POS=4, BUFFER-TIME=4000 1 2537 S .11+050908. G (2537 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ155943.11+0509 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 08.5 GE SDSSJ155943.11+0509 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 08.5 G SDSSJ155943.11+0509 3 COS/FUV TIME-TA PSA G160M 1577 none none none none 2 N/A 08.5 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 21] Visit: 26 (J1548-1-repeat2) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ154825 COS/NUV ACQ/IMA PSA MIRRORB 1 21 S (21 .80+052038. GE S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ154825 COS/FUV TIME-TA PSA G160M 1577 FP-POS=3, BUFFER-TIME=4000 1 2082 S .80+052038. G (2082 S) 8 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ154825.80+0520 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 38.8 GE SDSSJ154825.80+0520 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 38.8 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 22] Visit: 30 (J152011-1-repeat) Visit Requirements: On Hold Comments: Additional Comments: 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 SDSSJ152011 COS/NUV ACQ/IMA PSA MIRRORB 1 10 S (10 .62+081911. GE S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ152011 COS/FUV TIME-TA PSA G160M 1577 FP-POS=1, BUFFER-TIME=4000 1 2136 S .62+081911. G (2136 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ152011.62+0819 1 COS/NUV ACQ/IMA PSA MIRRORB none none none none 1 N/A 11.1 GE SDSSJ152011.62+0819 2 COS/FUV TIME-TA PSA G160M 1577 none none none none 1 N/A 11.1 G 17746( 5) - 07-Apr-2026 16:11:45 - [ 23] Summary Form for Proposal 17746 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=4000, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G160M, MIRRORB ------------------------------------------------------------------------------------------------------------------------------------ Target Names SDSSJ152011.62+081911.1, SDSSJ152022.68+060059.7, SDSSJ154825.80+052038.8, SDSSJ155747.67+043815.6, SDSSJ155943.11+050908.5, SDSSJ160553.38+045820.4 ------------------------------------------------------------------------------------------------------------------------------------