prop_v4.pdf 380734942 Assigned ID: 4139 ----- Attempting Submission 1 (Tue May 23 18:06:36 GMT 2023) ----- HST Phase I Proposal 4139 successfully submitted. Receipt: # 4139-1 ----- Attempting Submission 2 (Wed May 24 18:09:55 GMT 2023) ----- INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS We followed the same strategy as cycle 29 proposal 16698 regarding the use of FP-POS to remove the fixed pattern, etc. After consultation with the PC, the observations were split between two visits of 4 orbits each to increase the S/N. The exposure times (and corresponding buffer times) were reduced by 72 sec (exposure #2) or 22 sec (exposures #3-5) in each visit to avoid orbital visibility overruns associated with the newest version of APT. -1713027407 ----- Attempting Submission 1 (Thu Sep 07 18:38:49 GMT 2023) ----- ----- Attempting Submission 2 (Fri Feb 02 20:58:30 GMT 2024) ----- We use FP-POS = 3 and 4 only to get equal exposures on both segments A and B, following the COS2025 policies. The change from one FP-POS to the other is done between orbits so there is no overhead. The Perseus Cluster is an ideal laboratory to study the physics of radio-mode AGN feedback which prevents large-scale cooling flows and prodigious star formation at the centers of galaxy clusters. Remarkably, the engine at the heart of the Perseus Cluster, the jetted AGN NGC 1275, has never been spectroscopically observed below 1500 A with the high-resolution grating of COS. This is truly a missed opportunity. This spectral region is rich in spectroscopic diagnostics of the neutral, low-ionization, and high-ionization gas that sample a temperature range (10^4-10^7 K) largely inaccessible to the optical and X-rays. COS is an order of magnitude more sensitive than the previously used FOS and STIS. We propose to obtain a deep COS G130M spectrum of this object covering 1140-1430 A to study the central AGN, its outflow, and the multi-phase circumgalactic and intracluster media along the light of sight to the core of the Perseus Cluster. The new data will allow us to derive the ionization, total column densities, metal abundances, and locations of metal-line absorbers from the wind and circumgalactic medium. The strengths and widths of the emission lines from the cooling intracluster medium, including [Fe XXI] 1354, will be measured with unprecedented precision and compared with the Hitomi X-ray measurements as well as predictions of the ionization state and turbulent pressure support in simulations of AGN feedback in clusters. Finally, the new data will be compared with a contemporaneous (<1 week) optical spectrum and on-going monitoring in the gamma-rays, high-frequency radio, hard X-rays, and optical to test recent claims that SMBH fueling regulates jet power in this system. We requested and were allocated 8 orbits to observe NGC 1275, the central galaxy in the Perseus cluster with COS G130M. The RA and DEC coordinates of NGC 1275 are in the ICRS reference frame and taken from PID 12260 (PI Johnstone); they have been verified using the finding chart generated by the Target Confirmation tool of APT. These coordinates are those of the VLBA radio centroid and are therefore accurate to << 0.1". For each visit, we first use ACQ/IMAGE to obtain a NUV image of the field and center the aperture on the intensity peak. For this procedure, we follow the same method as in HST PID 12260, making use of MIRRORB since NGC 1275 is too bright for MIRRORA: it has a flux of 3.2E-15 erg/cm/cm/s/A at 2300 A and 3.0E-15 erg/cm/cm/s/A at 1380 A within the COS aperture (listed under "Other fluxes" in the target description). The exposure time of 60 seconds for ACQ/IMAGE is generous and results in S/N of 44 assuming NGC 1275 is approximately a point source in the NUV (S/N = 11 in the most pessimistic / unrealistic case where the source entirely fills the 1.25" aperture). For the spectroscopic observations, we request the cenwave = 1291 A setting with both segments A and B to capture redshifted Si II 1190/1193, Si III 1206, Ly-alpha, Si II 1260, O I 1302, Si II 1304, C II 1334, Si IV 1393/1402, and [Fe XXI] 1354 from the AGN and ISM/CGM/ICM of NGC 1275 / Perseus Cluster (z = 0.0176). Following the COS2025 policies, we only use FP-POS = 3 and 4 to get equal exposures for segments A and B. The observations are split into two visits of 4 orbits with a single long exposure per orbit changing the FP-POS value for each orbit to reduce the fixed pattern noise. This observing strategy minimizes the overhead and maximize the on-target exposure time, and thus S/N. All of the observations are done in TIME-TAG mode. This temporal sampling will allow us to exclude poor quality data and get improved thermal correction and background removal. For simplicity and to guard against the (unlikely) possibility that our targets are more than ~50% brighter than expected, we set buffer-time = exposure-time. According to the Bright Object Tool (BOT), there are no bright sources near our targets that could cause a problem for COS. Prof. Sylvain Veilleux (U. of Maryland) studies starburst and active galaxies, near and far, and their impact on the environment. He has extensive experience with HST in general and COS in particular. In recent years, he has led three HST programs that have focussed on the analysis of COS FUV spectra in nearby quasars, ULIRGs, and dwarf galaxies to study outflows in these systems. He is also leading a Cycle 29 COS program to probe the circumgalactic medium in nearby radio galaxy Centaurus A using background quasars. As a faculty member at Maryland, he has guaranteed access to the deVeny spectrograph on the 4.3-meter Lowell Discovery Telescope, which will be used to get an optical spectrum within a week of the planned HST/COS observation. Prof. Andy Fabian (Cambridge) studies AGN and galaxy clusters. He is an expert on the Perseus Cluster. He has also been a co-I on two of the past FUV/NUV spectroscopic programs on NGC 1275 whose data will be compared with the new COS spectra. Prof. Richard Mushotzky (U. of Maryland) studies AGN physics, including the role played by AGN in quenching star formation in galaxies and stopping cooling flows in galaxy clusters. He has an extensive multi-wavelength experience, particularly in the X-rays. Prof. Chris Reynolds (Cambridge) studies AGN physics and feedback in galaxy clusters, both observationally and theoretically. He has recently first-authored a paper on the first results from an analysis of multi-epoch high spectral resolution X-ray spectra of NGC 1275. The predictions of his simulations of AGN feedback in clusters will be compared with the new COS spectra. Supermassive Black Holes and Active Galaxies Large Scale Structure of the Universe 6 false false false false false false false false SUPPORTED GALAXY COOLING FLOW NUCLEUS QSO RADIO GALAXY NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 3.2E-15 erg/cm/cm/s/A at 2300 A and 3.0E-15 erg/cm/cm/s/A at 1380 A within COS aperture. COS/FUV Spectroscopic No No G130M 1291 1717790336931 /private/var/folders/q9/0jb3sqc10kx2dw3wnl21b_dw000702/T/OPVisit15635124812359757917.xml The scheduling data was generated by CASM 32.0. CASM was run in Phase II mode. 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