16004( 2) - 21-Aug-2019 12:07:17 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16004 Version: 2 Check-in Time: 21-Aug-2019 12:07:17 STScI Edit Number: 0 Title Monitoring the Unprecendented Near-Infrared Variability of Sgr A* ------------------------------------------------------------------------------------ Type Cycle GO/DD 26 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Tuan Do University of California - Los Angeles Y CoI: Dr. Eric E. Becklin University of California - Los Angeles N CoI: Dr. Mark R. Morris University of California - Los Angeles N CoI: Dr. Gunther Witzel University of California - Los Angeles N CoI: Dr. Jessica Ryan Lu University of California - Berkeley N CoI: Matthew Hosek Jr. University of Hawaii N CoI: Dr. Andrea M. Ghez University of California - Los Angeles N ------------------------------------------------------------------------------------ Abstract Sgr A*, the electromagnetic counterpart to the supermassive black hole at the Galactic center offers us a unique view into the physics black hole accretion and the growth of black holes. This summer, near-infrared observations of Sgr A* show unprecedented brightness and variability. This is increased activity is compared to over 20 years of historical near-infrared observations, which have until 2019 shown consistent variability characteristics. Unusual activity has also been reported by X-ray observatories with large outbursts. The current activity may be indicating a change Sgr A*'s accretion state or a change in the accretion flow. However, a physical explanation is lacking because basic questions about this activity is unknown, including: is this elevated activity a brief change, or is it a precursor to even larger events? With ground-based near-infrared observations soon unable to observe Sgr A*, we propose a monitoring program to observe Sgr A* during the remaining observable HST period in 2019 for Sgr A* (Sept. & Oct.) with WFC3-IR. This will provide us critical data on the nature of the current Sgr A* activity and a unique opportunity to study supermassive black hole accretion. ------------------------------------------------------------------------------------ Observations Description ------------------------ The main science goal of this proposal is to monitor the supermassive black hole, Sgr A*, at the Galactic center to assess whether it is increasing in activity and characterize its variability. The most important part of this program is cadence of the monitoring. We request monitoring of the source from early-September to late-October, when the HST observing window for the Galactic center closes. To measure Sgr A* variability, we request observations using WFC3-IR and the F153M filter. We request observations using SAMP-SEQ=STEP50, NSAMP=12 for individual exposure times of 349.233 s. This exposure time is a balance between observing short time-scale variations in Sgr A* and minimizing the overhead from reading out the detector. We request an ORIENT=90 deg to maximize the available number of dates for 16004( 2) - 21-Aug-2019 12:07:17 - [ 2] scheduling. This ORIENT will also match WCF3-IR Galactic center data from 2010, 2011, and 2012. This will increase the legacy value of this data for astrometry and variability studies. ------------------------------------------------------------------------------------ 16004( 2) - 21-Aug-2019 12:07:17 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SGR-A STELLAR CLUSTER, RA=17H45M40.0360S, J2000 V = 14 NUCLEUS DEC=-29D00'28.17" Reference Frame: Other: SIMBAD Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 16004( 2) - 21-Aug-2019 12:07:17 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type SPIRAL Pattern_Purpose DITHER Number_Of_Points 27 Point_Spacing 0.42 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 11.0 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 16004( 2) - 21-Aug-2019 12:07:17 - [ 5] Visit: 01 Visit Requirements: ORIENT 90D TO 90 D; BETWEEN 01-SEP-2019:00:00:00 AND 07-SEP-2019:00:00:00 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 SGR-A WFC3/IR MULTIAC IR-FIX F153M SAMP-SEQ=STEP50, NSAMP=12 1 DEF PATTERN 2 1 CUM (9429.289 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 1 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 2 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 3 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 4 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 5 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 6 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 7 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 8 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 9 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 10 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 11 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 12 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 13 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 14 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 15 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 16 none none none 3 N/A CUM 16004( 2) - 21-Aug-2019 12:07:17 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 17 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 18 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 19 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 20 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 21 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 22 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 23 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 24 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 25 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 26 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 27 none none none 4 N/A CUM 16004( 2) - 21-Aug-2019 12:07:17 - [ 7] Visit: 02 Visit Requirements: ORIENT 90D TO 90 D 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 SGR-A WFC3/IR MULTIAC IR-FIX F153M SAMP-SEQ=STEP50, NSAMP=12 1 DEF PATTERN 2 1 CUM (9429.289 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 1 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 2 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 3 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 4 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 5 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 6 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 7 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 8 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 9 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 10 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 11 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 12 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 13 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 14 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 15 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 16 none none none 3 N/A CUM 16004( 2) - 21-Aug-2019 12:07:17 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 17 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 18 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 19 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 20 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 21 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 22 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 23 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 24 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 25 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 26 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 27 none none none 4 N/A CUM 16004( 2) - 21-Aug-2019 12:07:17 - [ 9] Visit: 03 Visit Requirements: ORIENT 90D TO 90 D 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 SGR-A WFC3/IR MULTIAC IR-FIX F153M SAMP-SEQ=STEP50, NSAMP=12 1 DEF PATTERN 2 1 CUM (9429.289 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 1 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 2 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 3 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 4 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 5 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 6 none none none 1 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 7 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 8 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 9 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 10 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 11 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 12 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 13 none none none 2 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 14 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 15 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 16 none none none 3 N/A CUM 16004( 2) - 21-Aug-2019 12:07:17 - [ 10] 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 | ------------------------------------------------------------------------------------------------------------------------------------ SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 17 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 18 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 19 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 20 none none none 3 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 21 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 22 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 23 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 24 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 25 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 26 none none none 4 N/A CUM SGR-A 1 WFC3/IR MULTIAC IR-FIX F153M 27 none none none 4 N/A CUM 16004( 2) - 21-Aug-2019 12:07:17 - [ 11] Summary Form for Proposal 16004 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=12, SAMP-SEQ=STEP50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-SEP-2019:00:00:00 AND 07-SEP-2019:00:00:00, ORIENT 90D TO 90 D, PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F153M ------------------------------------------------------------------------------------------------------------------------------------ Target Names SGR-A ------------------------------------------------------------------------------------------------------------------------------------