16218( 11) - 13-May-2022 19:59:19 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16218 Version: 11 Check-in Time: 13-May-2022 19:59:19 STScI Edit Number: 1 Title Confirming the first double degenerates in globular clusters ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Liliana Rivera Sandoval University of Texas Rio Grande Valley Y CoI: Prof. Thomas J. Maccarone Texas Tech University N CoI: Dr. David R. Zurek American Museum of Natural History N CoI: Dr. Craig Heinke University of Alberta N CoI: Dr. Maureen van den Berg Harvard University N CoI: Dr. Andrea Dieball Helmholtz Institut fur Strahlen- und N Kernphysik, Uni Bonn CoI: Prof. Christian Knigge University of Southampton N CoI: Dr. David A. Pooley Eureka Scientific Inc. N CoI: Dr. Knox S. Long Eureka Scientific Inc. N CoI: Dr. Michael Shara American Museum of Natural History N ------------------------------------------------------------------------------------ Abstract The first 3 good candidates to AM CVn (double degenerate binaries) binaries in a globular cluster were recently identified with HST photometry. One of them is N1851-FUV1 which was identified as a short period (18 minutes) far-ultraviolet variable near the center of the globular cluster NGC 1851 (Zurek et al 2016). The other 2 candidates have been identified in the globular cluster 47 Tuc (Rivera Sandoval et al 2018) based on a combination of the their X-ray and optical/near-ultraviolet properties. A far-ultraviolet spectrum of each of these candidates will confirm or refute these candidates as AM CVn. Their confirmation will establish globular clusters as factories of compact binaries that emit gravitational waves and which are expected to be detected with LISA. The characterization of these systems is crucial to be performed while HST is still working, as it is the only telescope capable to resolve the stars in the cores of globular clusters. If confirmed, the first comparison to AM CVns in the Galactic field will be possible, giving direct evidence of the impact of stellar interactions in their formation and evolution. This program may enable follow-up studies to set important constraints on double degenerate binary models. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will acquire a bright red giant and offset to our target. For NGC 1851 we will make a second peak up on the target before obtaining the science exposures. For NGC 104 the offset star is relatively isolated, a peak up on the target previous to science data is not feasible considering its faintness. The main observations will be with the G140L grating and the FUV-MAMA. ------------------------------------------------------------------------------------ 16218( 11) - 13-May-2022 19:59:19 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC1851-FUV1 STAR, INTERACTING RA=05H14M6.6790S, J2000 V = 16.0 +/- 0.05 F140LP = 18.7 +/- BINARY DEC=-40D02'48.71" 0.06 Reference Frame: ICRS Comments: We used the WFPC2 image (PC chip), because saturation isn't an issue, to measure the positions of this offset star and the intended source FUV1. The F555W WFPC2 frame used is U2VO0301T. We have also made calculations using a FUV image of the cluster (STIS/FUV-MAMA and the F25QTZ filter) and none of the sources exceed the bright limits. The brightest sources have about 11 cnts/ second. This corresponds (using the photflam of 1.0388894E-16) to a flux of about 1.13446722E-15. If we put this value into the ETC with our setup (using a black body model of 50, 000K to mimic a hot source) the bright limits are never in danger of being exceeded. The ETC calculation done is STIS.sp.1479536. We have also sent images to our HST program coordinator. ------------------------------------------------------------------------------------------------------------------------------------ 2 47TUC-W62 STAR, INTERACTING RA=00H23M59.3391S, J2000 V = 19.54 +/- 0.02 BINARY DEC=-72D04'48.24" Reference Frame: ICRS Comments: We used the ACS/WFC image j9l960a7q_flc.fits (exptime=3s in F606W) which is under the J9L960010 data set to select the offset star. We have also used a 3.6 sec STIS/F28X50LP image (o48c0100r0_crj.fits under o48c010r0) and the stars in the cluster did not exceed the brightness limits, we sent finding chart to our HST program coordinator. The cluster has previously been observed in FUV slitless spectroscopy with no problems, so the current configuration will not be an issue. The current coordinates are based on precise absolute astrometry performed by our group (epoch J2000), not on the above mentioned archival reference HST image. ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC1851-OFFS STAR, M III-I RA=05H14M5.7900S, J2000 V = 13.3 ET1 DEC=-40D02'46.55" Reference Frame: ICRS Comments: We used the WFPC2 image (PC chip), because saturation isn't an issue, to measure the positions of this offset star and the intended source FUV1. The F555W WFPC2 frame used is U2VO0301T. ------------------------------------------------------------------------------------------------------------------------------------ 16218( 11) - 13-May-2022 19:59:19 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 4 47TUC-OFFSET STAR, K III-I RA=00H23M56.2960S +/- 0.06", J2000 V = 14.3 F606W = 12.8, F814W=11.8 1 DEC=-72D04'41.49" +/- 0.06" Reference Frame: ICRS Comments: We used the ACS/WFC image j9l960a7q_flc.fits (exptime=3s in F606W) which is under the J9L960010 data set to identify a suitable, isolated, bright offset-star. The current coordinates are based on precise absolute astrometry performed by our group (epoch J2000), not on the above mentioned archival reference HST image. ------------------------------------------------------------------------------------------------------------------------------------ 16218( 11) - 13-May-2022 19:59:19 - [ 4] Visit: 01 (NGC1851-FUV1) Visit Requirements: On Hold Comments: Additional Comments: It would be very convenient to have visits 1 and 2 for this target scheduled very close to each other. 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 NGC1851-OFF STIS/CCD ACQ F28X50LP MIRROR 1 0.2 S (0.2 SET1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC1851-OFF STIS/CCD ACQ/PEA 52X0.1 MIRROR 1 0.2 S (0.2 SET1 K S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC1851-FUV STIS/CCD ACQ/PEA 52X0.1 MIRROR 1 1.0 S (1 1 K S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC1851-FUV STIS/FUV TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=500.0 1 1829 S 1 -MAMA G (1829 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC1851-FUV STIS/FUV TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=500.0 1 2818 S 1 -MAMA G (2818 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC1851-OFFSET1 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A NGC1851-OFFSET1 2 STIS/CCD ACQ/PEA 52X0.1 MIRROR none none none none 1 N/A K NGC1851-FUV1 3 STIS/CCD ACQ/PEA 52X0.1 MIRROR none none none none 1 N/A K NGC1851-FUV1 4 STIS/FUV TIME-TA 52X0.1 G140L 1425 none none none none 1 N/A -MAMA G NGC1851-FUV1 5 STIS/FUV TIME-TA 52X0.1 G140L 1425 none none none none 2 N/A -MAMA G 16218( 11) - 13-May-2022 19:59:19 - [ 5] Visit: 02 (NGC1851-FUV1) Visit Requirements: On Hold Comments: Additional Comments: It would be very convenient to have visits 1 and 2 for this target scheduled very close to each other. 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 NGC1851-OFF STIS/CCD ACQ F28X50LP MIRROR 1 0.2 S (0.2 SET1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC1851-OFF STIS/CCD ACQ/PEA 52X0.1 MIRROR 1 0.2 S (0.2 SET1 K S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC1851-FUV STIS/CCD ACQ/PEA 52X0.1 MIRROR 1 1.0 S (1 1 K S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC1851-FUV STIS/FUV TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=500.0 1 1829.0 S 1 -MAMA G (1829 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC1851-FUV STIS/FUV TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=500.0 1 2818.0 S 1 -MAMA G (2818 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC1851-OFFSET1 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A NGC1851-OFFSET1 2 STIS/CCD ACQ/PEA 52X0.1 MIRROR none none none none 1 N/A K NGC1851-FUV1 3 STIS/CCD ACQ/PEA 52X0.1 MIRROR none none none none 1 N/A K NGC1851-FUV1 4 STIS/FUV TIME-TA 52X0.1 G140L 1425 none none none none 1 N/A -MAMA G NGC1851-FUV1 5 STIS/FUV TIME-TA 52X0.1 G140L 1425 none none none none 2 N/A -MAMA G 16218( 11) - 13-May-2022 19:59:19 - [ 6] Visit: 03 (47TUC-W62) Visit Requirements: ORIENT 135D TO 181 D; ORIENT 315D TO 1 D On Hold Comments: Additional Comments: It would be very convenient to have visits 1 and 2 for this target scheduled very close to each other. We have given 6 orbits to the target in 47 Tuc, the faintest one, to recover some of the time lost in the visit's split. 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 47TUC-OFFSE STIS/CCD ACQ F28X50LP MIRROR 1 0.5 S (0.5 T1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 47TUC-OFFSE STIS/CCD ACQ/PEA 52X0.1D1 MIRROR 1 1 S (1 S) T1 K ------------------------------------------------------------------------------------------------------------------------------------ 3 47TUC-W62 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 BUFFER-TIME=500.0 1 2337 S -MAMA G (2337 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 47TUC-W62 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 BUFFER-TIME=500.0 1 3105 S -MAMA G (3105 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 47TUC-W62 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 BUFFER-TIME=500.0 1 3105 S -MAMA G (3105 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 | ------------------------------------------------------------------------------------------------------------------------------------ 47TUC-OFFSET1 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A 47TUC-OFFSET1 2 STIS/CCD ACQ/PEA 52X0.1D1 MIRROR none none none none 1 N/A K 47TUC-W62 3 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 none none none none 1 N/A -MAMA G 47TUC-W62 4 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 none none none none 2 N/A -MAMA G 47TUC-W62 5 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 none none none none 3 N/A -MAMA G 16218( 11) - 13-May-2022 19:59:19 - [ 7] Visit: 04 (47TUC-W62) Visit Requirements: ORIENT 135D TO 181 D; ORIENT 315D TO 1 D On Hold Comments: Additional Comments: It would be very convenient to have visits 1 and 2 for this target scheduled very close to each other. We have given 6 orbits to the target in 47 Tuc, the faintest one, to recover some of the time lost in the visit's split. 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 47TUC-OFFSE STIS/CCD ACQ F28X50LP MIRROR 1 0.5 S (0.5 T1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 47TUC-OFFSE STIS/CCD ACQ/PEA 52X0.1D1 MIRROR 1 1 S (1 S) T1 K ------------------------------------------------------------------------------------------------------------------------------------ 3 47TUC-W62 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 BUFFER-TIME=500.0 1 2337 S -MAMA G (2337 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 47TUC-W62 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 BUFFER-TIME=500.0 1 3105 S -MAMA G (3105 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 47TUC-W62 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 BUFFER-TIME=500.0 1 3105 S -MAMA G (3105 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 | ------------------------------------------------------------------------------------------------------------------------------------ 47TUC-OFFSET1 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A 47TUC-OFFSET1 2 STIS/CCD ACQ/PEA 52X0.1D1 MIRROR none none none none 1 N/A K 47TUC-W62 3 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 none none none none 1 N/A -MAMA G 47TUC-W62 4 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 none none none none 2 N/A -MAMA G 47TUC-W62 5 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 none none none none 3 N/A -MAMA G 16218( 11) - 13-May-2022 19:59:19 - [ 8] Visit: 53 (47TUC-W62) Visit Requirements: ORIENT 135D TO 181 D; ORIENT 315D TO 1 D On Hold Comments: Additional Comments: It would be very convenient to have visits 1 and 2 for this target scheduled very close to each other. We have given 6 orbits to the target in 47 Tuc, the faintest one, to recover some of the time lost in the visit's split. Repeat of failed visit 03. 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 47TUC-OFFSE STIS/CCD ACQ F28X50LP MIRROR 1 0.5 S (0.5 T1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 47TUC-OFFSE STIS/CCD ACQ/PEA 52X0.1D1 MIRROR 1 1 S (1 S) T1 K ------------------------------------------------------------------------------------------------------------------------------------ 3 47TUC-W62 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=500.0 1 2294 S -MAMA G (2294 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 47TUC-W62 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=500.0 1 3105 S -MAMA G (3105 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 47TUC-W62 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=500.0 1 3063 S -MAMA G (3063 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 | ------------------------------------------------------------------------------------------------------------------------------------ 47TUC-OFFSET1 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A 47TUC-OFFSET1 2 STIS/CCD ACQ/PEA 52X0.1D1 MIRROR none none none none 1 N/A K 47TUC-W62 3 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 1 N/A -MAMA G 47TUC-W62 4 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 2 N/A -MAMA G 47TUC-W62 5 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 3 N/A -MAMA G 16218( 11) - 13-May-2022 19:59:19 - [ 9] Summary Form for Proposal 16218 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.1, 52X0.1D1, 52X0.2D1, 52X0.5D1, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ, ACQ/PEAK, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=500.0 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 135D TO 181 D, ORIENT 315D TO 1 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names 47TUC-OFFSET1, 47TUC-W62, NGC1851-FUV1, NGC1851-OFFSET1 ------------------------------------------------------------------------------------------------------------------------------------