17209( 6) - 21-Jan-2025 14:17:43 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17209 Version: 6 Check-in Time: 21-Jan-2025 14:17:43 STScI Edit Number: 2 Title Circumgalactic Gas on the Outskirts of the Local Group: the Halo of Sextans B ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Andrew J. Fox Space Telescope Science Institute - ESA Y CoI: Dr. Jason Tumlinson Space Telescope Science Institute N CoI: Prof. Philipp Richter Universitat Potsdam N CoI: Dr. Rongmon Bordoloi North Carolina State University N CoI: Dr. Sanchayeeta Borthakur Arizona State University N CoI: Ms. Jacqueline Monkiewicz Arizona State University N CoI: Dr. Trisha Ashley Space Telescope Science Institute N CoI: Dr. Frances H. Cashman Presbyterian College N CoI: Dr. Nicolas Lehner University of Notre Dame N CoI: Dr. David M. French Space Telescope Science Institute N ------------------------------------------------------------------------------------ Abstract Irregular galaxies are gas-rich, star-forming, and abundant. Around 40 exist in the Local Group (LG) where their gaseous halos cover large angular sizes on the sky, yet only a handful have published CGM detections. Furthermore, we have little knowledge of the CGM at the outer frontier of the Local Group at distances above 1 Mpc, where the intragroup medium is expected to be very low density so the influence of ram-pressure stripping should be small. Using archival COS observations, we have found tentative evidence for a detection of the CGM of Sextans B using a QSO sightline at low impact parameter (8 kpc or ~0.09 r_virial). We propose to confirm the CGM detection using high-S/N COS observations of a second QSO sightline at very low impact parameter from the Galaxy (4 kpc or ~0.04 r_virial). The relative strength of metal-line absorption in the two sightlines will allow us to determine the CGM mass, kinematics, and metal budget. This important experiment will allow us to place constraints on a gaseous halo in a quiescent low-density environment and explore gas flows in a previously uncharted region of the Local Group. ------------------------------------------------------------------------------------ Observations Description ------------------------ This COS program contains two 4-orbit visits on a single QSO (J1000+0524) behind the halo of Sextans B, an irregular galaxy on the edge of the Local Group. The two visits are identical, each with an ACQ/IMAGE with PSA/MIRRORA followed by four G130M/1291 science exposures (two with FP-POS=3 and two with FP-POS=4). Only 2 FP-POS are used because this is the default for G130M/1291 with both detector segments on. ------------------------------------------------------------------------------------ 17209( 6) - 21-Jan-2025 14:17:43 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ100035. EXT-MEDIUM, ABSORPTION RA=10H00M35.4827S +/- 0.1", J2000 V = 18.32 GALEX FUV=19.13 NUV=19.04 48+052428.5 LINE SYSTEM, ABSORPTION DEC=+05D24'28.48" +/- 0.1" LINE SYSTEM - EXTRAGALACTIC, HIGH VELOCITY CLOUD, IGM Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 17209( 6) - 21-Jan-2025 14:17:43 - [ 3] Visit: 01 (J1000+0524-Visit1) 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 SDSSJ100035 COS/NUV ACQ/IMA PSA MIRRORA 1 21 S (21 .48+052428. GE S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=5000 1 2397 S .48+052428. G (2397 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=5000 1 2689 S .48+052428. G (2689 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=5000 1 2689 S .48+052428. G (2689 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=5000 1 2689 S .48+052428. G (2689 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ100035.48+0524 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 28.5 GE SDSSJ100035.48+0524 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 28.5 G SDSSJ100035.48+0524 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A 28.5 G SDSSJ100035.48+0524 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A 28.5 G SDSSJ100035.48+0524 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A 28.5 G 17209( 6) - 21-Jan-2025 14:17:43 - [ 4] Visit: 02 (J1000+0524-Visit2) 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 SDSSJ100035 COS/NUV ACQ/IMA PSA MIRRORA 1 21 S (21 .48+052428. GE S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=5000 1 2397 S .48+052428. G (2397 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=5000 1 2689 S .48+052428. G (2689 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=5000 1 2689 S .48+052428. G (2689 S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=5000 1 2689 S .48+052428. G (2689 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ100035.48+0524 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 28.5 GE SDSSJ100035.48+0524 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A 28.5 G SDSSJ100035.48+0524 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A 28.5 G SDSSJ100035.48+0524 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A 28.5 G SDSSJ100035.48+0524 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A 28.5 G 17209( 6) - 21-Jan-2025 14:17:43 - [ 5] Visit: 11 (J1000+0524-Visit11) Visit Requirements: On Hold Comments: Additional Comments: Repeat of Visit 01 under HOPR 92824 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 SDSSJ100035 COS/NUV ACQ/IMA PSA MIRRORA 1 21 S (21 .48+052428. GE S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=5000 1 2397 S .48+052428. G see below 5 (2275 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=5000 1 2689 S .48+052428. G see below 5 (2566 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=5000 1 2689 S .48+052428. G see below 5 (2566 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=5000 1 2689 S .48+052428. G see below 5 (2566 S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ100035.48+0524 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 28.5 GE SDSSJ100035.48+0524 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2275.0 S 28.5 G SDSSJ100035.48+0524 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 2566.0 S 28.5 G SDSSJ100035.48+0524 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 2566.0 S 28.5 G SDSSJ100035.48+0524 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 2566.0 S 28.5 G 17209( 6) - 21-Jan-2025 14:17:43 - [ 6] Visit: 12 (J1000+0524-Visit12) Visit Requirements: On Hold Comments: Additional Comments: Repeat of Visit 02 under HOPR 92824 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 SDSSJ100035 COS/NUV ACQ/IMA PSA MIRRORA 1 21 S (21 .48+052428. GE S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=5000 1 2397 S .48+052428. G see below 5 (2275 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=5000 1 2689 S .48+052428. G see below 5 (2566 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=5000 1 2689 S .48+052428. G see below 5 (2566 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=4, BUFFER-TIME=5000 1 2689 S .48+052428. G see below 5 (2566 S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ100035.48+0524 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 28.5 GE SDSSJ100035.48+0524 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2275.0 S 28.5 G SDSSJ100035.48+0524 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 2566.0 S 28.5 G SDSSJ100035.48+0524 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 2566.0 S 28.5 G SDSSJ100035.48+0524 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 2566.0 S 28.5 G 17209( 6) - 21-Jan-2025 14:17:43 - [ 7] Visit: 21 (J1000+0524-Visit21) Visit Requirements: On Hold Comments: Additional Comments: Repeat of Visit 11 under HOPR 93038 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 SDSSJ100035 COS/NUV ACQ/IMA PSA MIRRORA 1 21 S (21 .48+052428. GE S) 5 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=5000 1 2397 S .48+052428. G see below 5 (2275 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ100035 COS/FUV TIME-TA PSA G130M 1291 FP-POS=3, BUFFER-TIME=5000 1 2689 S .48+052428. G see below 5 (2566 S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ100035.48+0524 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A 28.5 GE SDSSJ100035.48+0524 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 2275.0 S 28.5 G SDSSJ100035.48+0524 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 2566.0 S 28.5 G 17209( 6) - 21-Jan-2025 14:17:43 - [ 8] Summary Form for Proposal 17209 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=5000, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names SDSSJ100035.48+052428.5 ------------------------------------------------------------------------------------------------------------------------------------