15351( 2) - 20-Jul-2017 20:17:37 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15351 Version: 2 Check-in Time: 20-Jul-2017 20:17:37 STScI Edit Number: 0 Title Continued Long-Term Ultraviolet Spectroscopy of a Tidal Disruption Event at only 90 Mpc ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Walter Peter Maksym III Smithsonian Institution Astrophysical Y Observatory CoI: Dr. James Francis Guillochon Harvard University N CoI: Dr. William Clifford Keel University of Alabama N ------------------------------------------------------------------------------------ Abstract We propose continued long-term multi-epoch ultraviolet spectroscopy of ASASSN-14li, a stellar tidal disruption event (TDE) at ~90 Mpc. Such a bright, nearby stellar TDEs provides an exceptional opportunity to study broad emission lines which describe the abundances and accretion flow of the stellar debris in one of the most important physical regimes for understanding basic TDE behavior. We also request brief XMM observations to constrain the high-energy spectral evolution on similar timescales. These observations will build upon surprising new results, and will provide an important foundation for follow-up of more ambiguous TDE candidates subsequently identified by LSST and WFIRST at higher redshifts. ------------------------------------------------------------------------------------ Observations Description ------------------------ We are observing the UV-bright tidal disruption event (TDE) on extended baselines to study the spectroscopic evolution of this transient and how it relates to its accretion history. Complementary joint XMM-Newton observations have been granted to constrain the bolometric luminosity and relate high-energy emission to the UV. We will discuss XMM-Newton scheduling with the XMM-Newton team given the visibility windows available. <2 weeks separation is preferred, and the closer the better. Current predictions for XMM-Newton visibility look favorable for this strategy in June and July of 2018. This program is essentially an extension of programs 14272 and 14812, so the instrumental requirements are similar. The TDE is fainter, so we have requested (and been granted) an additional orbit per grating per epoch, but only one epoch per year is necessary since the TDE is evolving slowly. For the purposes of this program, LEDA-43234, PGC-043234 and ASASSN-14LI are effectively the same target. We kept the name "LEDA-43234" to agree with the Phase I proposal data in APT, but changing it to "ASASSN-14LI" would be more consistent with previous programs. As before, we are taking spectroscopy in FUV (STIS-MAMA/G140L) and NUV (STIS-MAMA/G230L). TIME-TAG mode should still be practical. All visits are grouped within 6 days to measure broadly representative properties within that time. We have broken observations into 4 groups of 2 orbits each to allow more 15351( 2) - 20-Jul-2017 20:17:37 - [ 2] flexible scheduling than 2 groups of 4 orbits would allow. Under this configuration, the optimal monitoring strategy is to keep each FUV visit tightly grouped with a NUV visit (<2 days) to allow full-spectrum variability comparisons with timescales of ~days if the signal-to-noise ratio warrants it. We have increased the acquisition times modestly per visit, but we expect most of the acquisition photons to come from the host galaxy at this point and not the transient. Since the transient is at the nucleus, identification of the nuclear peak is fine for acquisition and has been effective in the previous cycle. ------------------------------------------------------------------------------------ 15351( 2) - 20-Jul-2017 20:17:37 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 LEDA-43234 GALAXY, ACCRETION DISK, RA=12H48M15.2300S, J2000 Z = V = 16.1 Currently AB mag ~16.4 at 1500 BLR, NUCLEUS, DEC=+17D46'26.56" 0.0206 AA. Host GALEX baseline is (21.7, 19.0) UNDESIGNATED for (FUV, NUV). Reference Frame: ICRS Extended: NO Comments: Phase I coordinates in Cycle 25 were taken using SIMBAD. Phase II coordinates are adjusted to match those of Cycle 24 observations. ------------------------------------------------------------------------------------------------------------------------------------ 15351( 2) - 20-Jul-2017 20:17:37 - [ 4] Visit: 01 (ASASSN-14li Epoch 5 NUV-1) Visit Requirements: BETWEEN 10-APR-2018:00:00:00 AND 10-SEP-2018:00:00:00; GROUP 01, 02 WITHIN 2D; GROUP 01, 02, 03, 04 WITHIN 6D On Hold Comments: Additional Comments: Joint XMM observations have been awarded to complement the HST STIS observations. Although the transient is currently evolving slowly over years, coordination with XMM is preferred if possible, to minimize discrepencies due to short-timescale variability. A gap of <2 weeks between XMM and HST would be representative, but ideally the shorter the better. 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 LEDA-43234 STIS/CCD ACQ 50CCD MIRROR ACQTYPE=DIFFUSE, CHECKBOX=5, 1 50 S (50 DIFFUSE-CENTER=FLUX-CENTROID S) ------------------------------------------------------------------------------------------------------------------------------------ 2 LEDA-43234 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=1000 1 1000 S -MAMA G see below (2131 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 LEDA-43234 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=1000 1 1000 S -MAMA G see below (2966 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 | ------------------------------------------------------------------------------------------------------------------------------------ LEDA-43234 1 STIS/CCD ACQ 50CCD MIRROR none none none none 1 N/A LEDA-43234 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 2131.0 S -MAMA G LEDA-43234 3 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 2 2966.0 S -MAMA G 15351( 2) - 20-Jul-2017 20:17:37 - [ 5] Visit: 02 (ASASSN-14li Epoch 5 FUV-1) Visit Requirements: BETWEEN 10-APR-2018:00:00:00 AND 10-SEP-2018:00:00:00; GROUP 02, 01 WITHIN 2D; GROUP 02, 01, 03, 04 WITHIN 6D On Hold Comments: Additional Comments: Joint XMM observations have been awarded to complement the HST STIS observations. Although the transient is currently evolving slowly over years, coordination with XMM is preferred if possible, to minimize discrepencies due to short-timescale variability. A gap of <2 weeks between XMM and HST would be representative, but ideally the shorter the better. 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 LEDA-43234 STIS/CCD ACQ 50CCD MIRROR ACQTYPE=DIFFUSE, CHECKBOX=5, 1 50 S (50 DIFFUSE-CENTER=FLUX-CENTROID S) ------------------------------------------------------------------------------------------------------------------------------------ 2 LEDA-43234 STIS/FUV TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=1500 1 1000 S -MAMA G see below (2131 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 LEDA-43234 STIS/FUV TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=1500 1 1000 S -MAMA G see below (2966 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 | ------------------------------------------------------------------------------------------------------------------------------------ LEDA-43234 1 STIS/CCD ACQ 50CCD MIRROR none none none none 1 N/A LEDA-43234 2 STIS/FUV TIME-TA 52X0.2 G140L 1425 none none none none 1 2131.0 S -MAMA G LEDA-43234 3 STIS/FUV TIME-TA 52X0.2 G140L 1425 none none none none 2 2966.0 S -MAMA G 15351( 2) - 20-Jul-2017 20:17:37 - [ 6] Visit: 03 (ASASSN-14li Epoch 5 NUV-2) Visit Requirements: BETWEEN 10-APR-2018:00:00:00 AND 10-SEP-2018:00:00:00; GROUP 03, 04 WITHIN 2D; GROUP 03, 01, 02, 04 WITHIN 6D On Hold Comments: Additional Comments: Joint XMM observations have been awarded to complement the HST STIS observations. Although the transient is currently evolving slowly over years, coordination with XMM is preferred if possible, to minimize discrepencies due to short-timescale variability. A gap of <2 weeks between XMM and HST would be representative, but ideally the shorter the better. 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 LEDA-43234 STIS/CCD ACQ 50CCD MIRROR ACQTYPE=DIFFUSE, CHECKBOX=5, 1 50 S (50 DIFFUSE-CENTER=FLUX-CENTROID S) ------------------------------------------------------------------------------------------------------------------------------------ 2 LEDA-43234 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=1000 1 1000 S -MAMA G see below (2131 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 LEDA-43234 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=1000 1 1000 S -MAMA G see below (2966 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 | ------------------------------------------------------------------------------------------------------------------------------------ LEDA-43234 1 STIS/CCD ACQ 50CCD MIRROR none none none none 1 N/A LEDA-43234 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 2131.0 S -MAMA G LEDA-43234 3 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 2 2966.0 S -MAMA G 15351( 2) - 20-Jul-2017 20:17:37 - [ 7] Visit: 04 (ASASSN-14li Epoch 5 FUV-2) Visit Requirements: BETWEEN 10-APR-2018:00:00:00 AND 10-SEP-2018:00:00:00; GROUP 04, 03 WITHIN 2D; GROUP 04, 01, 02, 03 WITHIN 6D On Hold Comments: Additional Comments: Joint XMM observations have been awarded to complement the HST STIS observations. Although the transient is currently evolving slowly over years, coordination with XMM is preferred if possible, to minimize discrepencies due to short-timescale variability. A gap of <2 weeks between XMM and HST would be representative, but ideally the shorter the better. 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 LEDA-43234 STIS/CCD ACQ 50CCD MIRROR ACQTYPE=DIFFUSE, CHECKBOX=5, 1 50 S (50 DIFFUSE-CENTER=FLUX-CENTROID S) ------------------------------------------------------------------------------------------------------------------------------------ 2 LEDA-43234 STIS/FUV TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=1500 1 1000 S -MAMA G see below (2131 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 LEDA-43234 STIS/FUV TIME-TA 52X0.2 G140L 1425 BUFFER-TIME=1500 1 1000 S -MAMA G see below (2966 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 | ------------------------------------------------------------------------------------------------------------------------------------ LEDA-43234 1 STIS/CCD ACQ 50CCD MIRROR none none none none 1 N/A LEDA-43234 2 STIS/FUV TIME-TA 52X0.2 G140L 1425 none none none none 1 2131.0 S -MAMA G LEDA-43234 3 STIS/FUV TIME-TA 52X0.2 G140L 1425 none none none none 2 2966.0 S -MAMA G 15351( 2) - 20-Jul-2017 20:17:37 - [ 8] Summary Form for Proposal 15351 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 50CCD, 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=DIFFUSE, BUFFER-TIME=1000, BUFFER-TIME=1500, CHECKBOX=5, DIFFUSE-CENTER=FLUX-CENTROID ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 10-APR-2018:00:00:00 AND 10-SEP-2018:00:00:00, GROUP 01, 02 WITHIN 2D, GROUP 01, 02, 03, 04 WITHIN 6D, GROUP 02, 01 WITHIN 2D, GROUP 02, 01, 03, 04 WITHIN 6D, GROUP 03, 01, 02, 04 WITHIN 6D, GROUP 03, 04 WITHIN 2D, GROUP 04, 01, 02, 03 WITHIN 6D, GROUP 04, 03 WITHIN 2D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names LEDA-43234 ------------------------------------------------------------------------------------------------------------------------------------