15517( 4) - 18-Jun-2019 16:05:03 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15517 Version: 4 Check-in Time: 18-Jun-2019 16:05:03 STScI Edit Number: 1 Title Continued Long-Term Ultraviolet Spectroscopy of a Tidal Disruption Event at only 90 Mpc ------------------------------------------------------------------------------------ Type Cycle GO 26 ------------------------------------------------------------------------------------ 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 2019. This program is essentially an extension of programs 14272, 14812 and 15351, so the instrumental requirements are similar. The TDE is fainter, so we have requested (and been granted) a total of four orbits 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 15517( 4) - 18-Jun-2019 16:05:03 - [ 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 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. The expected modest decline in UV flux (to ~75% of the previous cycle) should not have a significant effect. Thus far we have satisfactorally used clear filter to add statistical weight to the UV source at the nucleus. ------------------------------------------------------------------------------------ 15517( 4) - 18-Jun-2019 16:05:03 - [ 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. ------------------------------------------------------------------------------------------------------------------------------------ 15517( 4) - 18-Jun-2019 16:05:03 - [ 4] Visit: 01 (ASASSN-14li Epoch 6 NUV-1) Visit Requirements: BETWEEN 29-MAY-2019:00:00:00 AND 22-JUL-2019:00:00:00; 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 15517( 4) - 18-Jun-2019 16:05:03 - [ 5] Visit: 02 (ASASSN-14li Epoch 6 FUV-1) Visit Requirements: BETWEEN 29-MAY-2019:00:00:00 AND 22-JUL-2019:00:00:00; 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 15517( 4) - 18-Jun-2019 16:05:03 - [ 6] Visit: 03 (ASASSN-14li Epoch 6 NUV-2) Visit Requirements: BETWEEN 29-MAY-2019:00:00:00 AND 22-JUL-2019:00:00:00; 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 15517( 4) - 18-Jun-2019 16:05:03 - [ 7] Visit: 04 (ASASSN-14li Epoch 6 FUV-2) Visit Requirements: BETWEEN 29-MAY-2019:00:00:00 AND 22-JUL-2019:00:00:00; 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 15517( 4) - 18-Jun-2019 16:05:03 - [ 8] Visit: A1 (ASASSN-14li Epoch 6 NUV-1) Visit Requirements: BETWEEN 29-MAY-2019:00:00:00 AND 28-JUL-2019:00:00:00; GROUP A1, A4 WITHIN 3D 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. This is a repeat of visit 01 which failed. 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 15517( 4) - 18-Jun-2019 16:05:03 - [ 9] Visit: A4 (ASASSN-14li Epoch 6 FUV-2) Visit Requirements: BETWEEN 29-MAY-2019:00:00:00 AND 28-JUL-2019:00:00:00 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. This is a repeat of visit 04 which failed. 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 15517( 4) - 18-Jun-2019 16:05:03 - [ 10] Summary Form for Proposal 15517 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 29-MAY-2019:00:00:00 AND 22-JUL-2019:00:00:00, BETWEEN 29-MAY-2019:00:00:00 AND 28-JUL-2019:00:00:00, 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, GROUP A1, A4 WITHIN 3D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names LEDA-43234 ------------------------------------------------------------------------------------------------------------------------------------