15604( 7) - 17-Aug-2018 13:12:48 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15604 Version: 7 Check-in Time: 17-Aug-2018 13:12:48 STScI Edit Number: 0 Title Catching an AGN in the Act: A New Accretion Regime for 1ES 1927+654 ------------------------------------------------------------------------------------ Type Cycle GO/DD 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Chelsea L. MacLeod Smithsonian Institution Astrophysical Y Observatory CoI: Dr. Benny Trakhtenbrot ETH Zurich N CoI: Dr. Iair Arcavi University of California - Santa Barbara N CoI: Dr. Erin Amira Kara University of Maryland N CoI: Dr. Claudio Ricci Pontificia Universidad Catolica de Chile N ------------------------------------------------------------------------------------ Abstract We are currently observing an AGN caught in the act of changing its accretion state. The AGN 1ES 1927+654, formerly a "true" Type-2, has recently experienced a strong and sudden brightening accompanied by the emergence of broad Balmer lines in the optical spectrum. Observing these changes in real time offers a great opportunity to address open questions in AGN accretion. Our optical spectroscopic sequence shows, for the first time, a time-resolved increase of the blue continuum flux preceding the formation of the broad lines, allowing us to constrain the size of the broad-line region. HST UV spectra taken now will reveal the presence of outflows suggested to be associated with such a transition, and will test competing models proposed to explain the perplexing rapid time scales associated with changing look AGN. 1ES 1927+654 is rapidly fading back to its quiescent state, making the proposed observations a unique but highly time critical opportunity. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose for one orbit of DD time to follow-up with NUV/FUV spectroscopy a recent optical transient in the nucleus of the AGN 1ES 1927+654. In the FUV, COS is preferred to STIS for its higher throughout. We request both FUV and NUV to cover the emission lines CIV 1549, HeII 1640, OIII] 1664, NIII] 1750, CIII] 1909, and MgII 2800 and any blue-shifted BALs associated with the carbon lines or MgII. To obtain adequate wavelength coverage, we request the COSG140L and STISG230L gratings, centered at 1280A and 2950A, respectively. From the ETC, we expect to achieve excellent S/N will within one orbit per observation. The minimum time needed to achieve decent S/N (20 per resol. elem.) at 1450A and 2800A is 850s and 180s respectively for COSG140L and STISG230L. This assumes the target will be one magnitude fainter by the time of observation. We aim for more conservative values of S/N because the target may fade by the time the observations are taken, making the true signal weaker. One orbit each, with 2220s (2340s) for the COS FUV (STIS NUV) total science exposure, will deliver S/N=30 at 1450A, and S/N=70 at 2800A, including overhead, so we ask for 2 15604( 7) - 17-Aug-2018 13:12:48 - [ 2] orbits. The source is highly variable, so it is important to our interpretaion of the observations that the orbits be taken back-to-back. ------------------------------------------------------------------------------------ 15604( 7) - 17-Aug-2018 13:12:48 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AT2018ZF GALAXY, ACCRETION DISK, RA=19H27M19.4900S +/- 0.1", J2000 V = 15.5 +/- 0.05 4.7e-14 erg/s/cm^2/A BLR, NUCLEUS, QUASAR, DEC=+65D33'54.40" +/- 0.1" at rest-frame 1450A SEYFERT Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 15604( 7) - 17-Aug-2018 13:12:48 - [ 4] Visit: 01 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 AT2018ZF COS/NUV ACQ/IMA BOA MIRRORA 1 16.2 S GE (16.2 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2018ZF COS/FUV TIME-TA PSA G140L 1280 BUFFER-TIME=1850, FP-POS=ALL 1 555 S G see below (2464 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 AT2018ZF STIS/CCD ACQ F28X50LP MIRROR 1 1 S (1 S) Comments: Exposure time was not supported by the BOT, but the ETC run above gives a SNR = 314.7439 and an electron count rate below the saturation limit of 144, 000 electrons. ------------------------------------------------------------------------------------------------------------------------------------ 4 AT2018ZF STIS/NUV ACCUM 52X0.2 G230L 2376 3 780 S -MAMA see below (2583 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2018ZF 1 COS/NUV ACQ/IMA BOA MIRRORA none none none none 1 N/A GE AT2018ZF 2 COS/FUV TIME-TA PSA G140L 1280 none none none 1 1 616.0 S G AT2018ZF 2 COS/FUV TIME-TA PSA G140L 1280 none none none 2 1 616.0 S G AT2018ZF 2 COS/FUV TIME-TA PSA G140L 1280 none none none 3 1 616.0 S G AT2018ZF 2 COS/FUV TIME-TA PSA G140L 1280 none none none 4 1 616.0 S G AT2018ZF 3 STIS/CCD ACQ F28X50LP MIRROR none none none none 2 N/A AT2018ZF 4 STIS/NUV ACCUM 52X0.2 G230L 2376 none none 1 none 2 861.0 S -MAMA AT2018ZF 4 STIS/NUV ACCUM 52X0.2 G230L 2376 none none 2 none 2 861.0 S -MAMA AT2018ZF 4 STIS/NUV ACCUM 52X0.2 G230L 2376 none none 3 none 2 861.0 S -MAMA 15604( 7) - 17-Aug-2018 13:12:48 - [ 5] Summary Form for Proposal 15604 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.2, BOA, F28X50LP, PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV, STIS/CCD, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ, ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1850, FP-POS=ALL ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, G230L, MIRROR, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names AT2018ZF ------------------------------------------------------------------------------------------------------------------------------------