17591( 5) - 09-Dec-2025 14:06:24 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17591 Version: 5 Check-in Time: 09-Dec-2025 14:06:24 STScI Edit Number: 3 Title Probing the long-term evolution of obscuring winds and their impact in NGC 5548 ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Missagh Mehdipour University of Michigan Y CoI: Dr. Gerard A. Kriss Space Telescope Science Institute N CoI: Dr. Jelle Kaastra Space Research Organization Netherlands N CoI: Dr. Elisa Costantini Space Research Organization Netherlands N CoI: Dr. Liyi Gu Space Research Organization Netherlands N CoI: Dr. Junjie Mao Tsinghua University N CoI: Dr. Hermine Landt Durham University N CoI: Dr. Daniele Rogantini University of Chicago N CoI: Dr. Jon Matthew Miller University of Michigan N ------------------------------------------------------------------------------------ Abstract The link between obscuration and outflows in AGN was first discovered in NGC 5548. This archetypal Sy-1 galaxy underwent major changes due to obscuring winds from the accretion disk. These remarkable winds, captured by joint X-ray/UV spectroscopy, have significant impact on their environment. Swift monitoring shows that over the last 10 years the obscuration in NGC 5548 has gradually declined. This presents a valuable opportunity for analyses that have not been feasible before due to too much obscuration. The lowered obscuration facilitates high-resolution RGS spectroscopy of the outflow to ascertain its evolution. We need to constrain the intrinsic continuum with NuSTAR and EPIC+OM, and the UV outflow with HST/COS. We request joint XMM (180 ks), NuSTAR (70 ks), and HST (2 orbits) spectra. ------------------------------------------------------------------------------------ Observations Description ------------------------ This HST observation (2 orbits) was approved as part of a joint XMM program to obtain the HST/COS spectrum of NGC 5548 to study the obscuring wind in this AGN. The HST observation needs to be taken simultaneously as justified in the XMM proposal (the source and the obscuring wind are variable). Therefore, please coordinate with the XMM planners. The most likely XMM visibility window is: 2024-12-21 to 2025-02-03 The HST exposure time is based on our 2021/2022 observations of NGC 5548 (Mehdipour, M. et al. 2022, ApJL, 934, L24), which required 2 orbits per visit to observe Ly-alpha, N V, and C IV with gratings G130M and G160M. We have confirmed this with the ETC tool. Two orbits yields a S/N of at least 10 per resolution element in the continuum using the G130M grating with central wavelength 1222 and 1291 (for modeling Ly-alpha and N V) and using the G160M grating with central wavelengths 1600 and 1623 (for modeling Si IV and C IV). 17591( 5) - 09-Dec-2025 14:06:24 - [ 2] This is adequate to measure the parameters of the broad UV absorption lines associated with the obscurer, as well as the narrow absorption lines (including low ionization lines) associated with the warm absorber outflows. For the BUFFER-TIME, we obtained the recommended buffer (2/3 of the buffer fill time) from the ETC for each exposure. In order to obtain the requisite S/N in the minimum number of orbits, we request the use of Lifetime Position 4 for both the G130M and G160M observations. This was requested as required in the Phase 1 proposal with XMM. This will also replicate our observations from 2021/2022 and enable a one-to-one comparison. Because we are using two different CENWAVES with each grating and two FP-POS positions in each, we already accomplish the actual objectives of switching between different FP-POS settings: (1) Better science return: the spectrum is placed at four different locations on the detector, enabling us to detect and reject detector anomalies like dead spots, hot spots, grid-wire shadows, etc. (2) Spread the flux across the detector in multiple locations, especially in bright emission lines, to decrease charge depletion and extend the lifetime of the detectors. We do not want to sacrifice S/N with unnecessary extra exposures and increased overhead during each visit by using all 4 FP-POS settings with each CENWAVE. When only one CENWAVE is used, then 4 FP-POS settings makes sense, but that's not the case for our observations. Our chosen FPPOS settings reflect our S/N requirements while still meeting the objectives of using different FP-POS settings in our program. Reduced gyro does not impact the feasibility of our program. Also, orientation limitation would not impact our program. ------------------------------------------------------------------------------------ 17591( 5) - 09-Dec-2025 14:06:24 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-5548 GALAXY, ACCRETION DISK, RA=14H17M59.5400S +/- 0.07", J2000 V = 13.73 BLR, SEYFERT, WIND DEC=+25D08'12.60" +/- 0.07" Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 -1.6053682911936426E-5 2.6700000000000004E-4 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17591( 5) - 09-Dec-2025 14:06:24 - [ 4] Visit: 01 Visit Requirements: SCHED 100%; BETWEEN 01-FEB-2025:10 AND 01-FEB-2025:19:21; BETWEEN 03-FEB-2025:11 AND 03-FEB-2025:18:27 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 NGC-5548 COS/NUV ACQ/IMA BOA MIRRORA 1 81 S (81 GE S) Comments: Using the NGC 5548 HST UV continuum (1367 A) lightcurve published by Kriss et al. (2019), we took the lowest observed flux (1.8e-14 erg/cm^2/s/A), to calculate the required exposure time to obtain S/N ratio of 30 for ACQ/IMAGE with BOA. ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-5548 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=1268, FP-POS=1 1 145 S (145 G S) Comments: Using the NGC 5548 HST UV continuum (1367 A) lightcurve published by Kriss et al. (2019) and the mean flux of the 2014 campaign (4.3e-14 erg/cm^2/s/A), the exposure time is calculated. ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-5548 COS/FUV TIME-TA PSA G130M 1222 BUFFER-TIME=1268, FP-POS=2 1 145 S (145 G S) Comments: Using the NGC 5548 HST UV continuum (1367 A) lightcurve published by Kriss et al. (2019) and the mean flux of the 2014 campaign (4.3e-14 erg/cm^2/s/A), the exposure time is calculated. ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC-5548 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=967, FP-POS=3 1 157 S (157 G S) Comments: Using the NGC 5548 HST UV continuum (1367 A) lightcurve published by Kriss et al. (2019) and the mean flux of the 2014 campaign (4.3e-14 erg/cm^2/s/A), the exposure time is calculated. ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-5548 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=967, FP-POS=4 1 157 S (157 G S) Comments: Using the NGC 5548 HST UV continuum (1367 A) lightcurve published by Kriss et al. (2019) and the mean flux of the 2014 campaign (4.3e-14 erg/cm^2/s/A), the exposure time is calculated. ------------------------------------------------------------------------------------------------------------------------------------ 17591( 5) - 09-Dec-2025 14:06:24 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-5548 COS/FUV TIME-TA PSA G160M 1600 BUFFER-TIME=2067, FP-POS=1 1 584 S (584 G S) Comments: Using the NGC 5548 HST UV continuum (1367 A) lightcurve published by Kriss et al. (2019) and the mean flux of the 2014 campaign (4.3e-14 erg/cm^2/s/A), the exposure time is calculated. ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC-5548 COS/FUV TIME-TA PSA G160M 1600 BUFFER-TIME=2067, FP-POS=2 1 488 S (488 G S) Comments: Using the NGC 5548 HST UV continuum (1367 A) lightcurve published by Kriss et al. (2019) and the mean flux of the 2014 campaign (4.3e-14 erg/cm^2/s/A), the exposure time is calculated. ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC-5548 COS/FUV TIME-TA PSA G160M 1623 BUFFER-TIME=2281, FP-POS=3 1 586 S (586 G S) Comments: Using the NGC 5548 HST UV continuum (1367 A) lightcurve published by Kriss et al. (2019) and the mean flux of the 2014 campaign (4.3e-14 erg/cm^2/s/A), the exposure time is calculated. ------------------------------------------------------------------------------------------------------------------------------------ 9 NGC-5548 COS/FUV TIME-TA PSA G160M 1623 BUFFER-TIME=2281, FP-POS=4 1 586 S (586 G S) Comments: Using the NGC 5548 HST UV continuum (1367 A) lightcurve published by Kriss et al. (2019) and the mean flux of the 2014 campaign (4.3e-14 erg/cm^2/s/A), the exposure time is calculated. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-5548 1 COS/NUV ACQ/IMA BOA MIRRORA none none none none 1 N/A GE NGC-5548 2 COS/FUV TIME-TA PSA G130M 1222 none none none none 1 N/A G NGC-5548 3 COS/FUV TIME-TA PSA G130M 1222 none none none none 1 N/A G NGC-5548 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A G 17591( 5) - 09-Dec-2025 14:06:24 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-5548 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A G NGC-5548 6 COS/FUV TIME-TA PSA G160M 1600 none none none none 1 N/A G NGC-5548 7 COS/FUV TIME-TA PSA G160M 1600 none none none none 2 N/A G NGC-5548 8 COS/FUV TIME-TA PSA G160M 1623 none none none none 2 N/A G NGC-5548 9 COS/FUV TIME-TA PSA G160M 1623 none none none none 2 N/A G 17591( 5) - 09-Dec-2025 14:06:24 - [ 7] Summary Form for Proposal 17591 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures BOA, PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1268, BUFFER-TIME=2067, BUFFER-TIME=2281, BUFFER-TIME=967, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-FEB-2025:10 AND 01-FEB-2025:19:21, BETWEEN 03-FEB-2025:11 AND 03-FEB-2025:18:27, SCHED 100% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, G160M, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC-5548 ------------------------------------------------------------------------------------------------------------------------------------