17902( 3) - 03-Nov-2025 19:31:54 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17902 Version: 3 Check-in Time: 03-Nov-2025 19:31:54 STScI Edit Number: 0 Title The Variable Optical-X-ray SED of M87 ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Joseph Neilsen Villanova University Y CoI: Prof. Daryl Haggard McGill University N CoI: Dr. Venkatessh Ramakrishnan University of Turku N CoI: Dr. Mislav Balokovic Yale University N CoI: Dr. Kazuhiro Hada National Astronomical Observatory of Japan N (NAOJ) CoI: Dr. Michael Johnson Smithsonian Institution Astrophysical N Observatory CoI: Dr. Stefanie Komossa Max Planck Institut fur Radioastronomie N CoI: Dr. Thomas Krichbaum Max Planck Institut fur Radioastronomie N CoI: Dr. Geoffrey Bower Academia Sinica, Institute of Astronomy N and Astrophysics CoI: Dr. Jaeyeong Kim Korea Astronomy and Space Science N Institute (KASI) CoI: Prof. Sera Markoff Universiteit van Amsterdam N CoI: Dr. Michael Nowak Washington University in St. Louis N CoI: Mr. George Wong University of Illinois at Urbana - N Champaign CoI: Monika Moscibrodzka Radboud University Nijmegen N CoI: Dr. Marcos Santander University of Alabama N CoI: Dr. Svetlana G. Jorstad Boston University N CoI: Dr. Alan P. Marscher Boston University N CoI: Dr. Mark Reynolds The Ohio State University N CoI: Mr. Chris Sheridan Villanova University N ------------------------------------------------------------------------------------ Abstract On behalf of the EHT's Multiwavelength (MWL) Working Group, we propose a joint campaign on M87* coordinated in part with EHT: 50 ks XMM-Newton, 4 orbits Hubble, & 50 ks NuSTAR. These observations will improve constraints on (1) the SED of M87* and its particle acceleration processes, as well as (2) the variability of the famous jet across the electromagnetic spectrum. ------------------------------------------------------------------------------------ Observations Description ------------------------ The goal of our HST program is to study the optical and UV variability of M87 in conjunction with NuSTAR and XMM-Newton observations. We are particularly interested in tracking the relative flux and SED changes of the core and the knot HST-1 over time. Our observations will occur in two pieces separated by roughly six months and consisting of two orbits each. The first piece should be 17902( 3) - 03-Nov-2025 19:31:54 - [ 2] coordinated with XMM and NuSTAR in June/July 2025; the second will be coordinated with XMM and NuSTAR in December 25/Jan 26. We adopt a modified version of the WFC3/UVIS observing strategy used for historical Hubble M87 monitoring (e.g. PI:Shara). In our analysis, comparable exposures produced to 3-10% uncertainties on the core and HST-1 fluxes after subtracting the host galaxy contribution. Generally each visit consists of two orbits to acquire observations in F275W and F814W (orbit 1) and F390W and F606W (orbit 2) in ACCUM mode. For the summer visit ~contemporaneous with XMM-Newton/NuSTAR, the first orbit consists of three dithered 462 s exposures in F275W and two dithered 348 s exposures in F814W in ACCUM mode, for a total of 2084 s on source; the second orbit has 2x509 s in F390W and 3x348 s in F606W. ETC calculations are given for the nucleus and are approximate as they neglect the host galaxy. The remaining ~1 ks per orbit is covered by overhead (setup, readouts, filter changes, and dithering). We mitigate CTE with a flash to increase the background; sub-exposures reduce cosmic rays. The winter visit ismuch the same, though roll angle constraints make it possible to arrange simultaneous observations with XMM/NuSTAR. ------------------------------------------------------------------------------------ 17902( 3) - 03-Nov-2025 19:31:54 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M-87 GALAXY, ELLIPTICAL, RA=12H30M49.4234S, J2000 V = 8.63 JET, KNOT, NUCLEUS DEC=+12D23'28.04" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. SIMBAD listed proper motion for this target. When retrieving targets with PM from SIMBAD, APT requests the coordinates be calculated with an epoch of the year 2000. Do not modify this epoch. Always review coordinates using the Target Confirmation tool, which graphically displays the PM. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -5.480327951933226E-4 0.010734 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17902( 3) - 03-Nov-2025 19:31:54 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-GAP-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 2.414 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 85.759 Angle_Between_Sides Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17902( 3) - 03-Nov-2025 19:31:54 - [ 5] Visit: 01 (Summer) Visit Requirements: PCS MODE FINE; BETWEEN 01-MAY-2025:00:00:00 AND 31-MAY-2025:00:00:00 On Hold Comments: Additional Comments: This observation should be scheduled to overlap with XMM-Newton observations; the "between" requirement represents the window where XMM observations can occur. 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 M-87 WFC3/UVI ACCUM UVIS2 F275W FLASH=21 1 462 S PATTERN 1 1 S (1387 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 M-87 WFC3/UVI ACCUM UVIS2 F814W FLASH=14 1 348 S (696 PATTERN 2 2 S S) ------------------------------------------------------------------------------------------------------------------------------------ 3 M-87 WFC3/UVI ACCUM UVIS2 F390W FLASH=21 1 509 S PATTERN 2 3 S (1019 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 M-87 WFC3/UVI ACCUM UVIS2 F606W FLASH=14 1 348 S PATTERN 1 4 S (1044 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 | ------------------------------------------------------------------------------------------------------------------------------------ M-87 1 WFC3/UVI ACCUM UVIS2 F275W 1 none none none 1 N/A S M-87 1 WFC3/UVI ACCUM UVIS2 F275W 2 none none none 1 463.0 S S M-87 1 WFC3/UVI ACCUM UVIS2 F275W 3 none none none 1 N/A S M-87 2 WFC3/UVI ACCUM UVIS2 F814W 1 none none none 1 N/A S M-87 2 WFC3/UVI ACCUM UVIS2 F814W 2 none none none 1 N/A S M-87 3 WFC3/UVI ACCUM UVIS2 F390W 1 none none none 2 N/A S M-87 3 WFC3/UVI ACCUM UVIS2 F390W 2 none none none 2 510.0 S S M-87 4 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 2 N/A S M-87 4 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 2 N/A S M-87 4 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 2 N/A S 17902( 3) - 03-Nov-2025 19:31:54 - [ 6] Visit: 02 (Winter) Visit Requirements: PCS MODE FINE; BETWEEN 05-DEC-2025:16:54:00 AND 12-JAN-2026:01:28:00 On Hold Comments: Additional Comments: This observation should be scheduled to overlap with XMM-Newton observations; the "between" requirement represents the window where XMM observations can occur. 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 M-87 WFC3/UVI ACCUM UVIS2 F275W FLASH=21 1 695 S PATTERN 2 1 S (1390 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 M-87 WFC3/UVI ACCUM UVIS2 F814W FLASH=14 1 391 S (782 PATTERN 2 2 S S) ------------------------------------------------------------------------------------------------------------------------------------ 3 M-87 WFC3/UVI ACCUM UVIS2 F390W FLASH=21 1 529 S PATTERN 2 3 S (1058 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 M-87 WFC3/UVI ACCUM UVIS2 F606W FLASH=14 1 547 S PATTERN 2 4 S (1094 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 | ------------------------------------------------------------------------------------------------------------------------------------ M-87 1 WFC3/UVI ACCUM UVIS2 F275W 1 none none none 1 N/A S M-87 1 WFC3/UVI ACCUM UVIS2 F275W 2 none none none 1 N/A S M-87 2 WFC3/UVI ACCUM UVIS2 F814W 1 none none none 1 N/A S M-87 2 WFC3/UVI ACCUM UVIS2 F814W 2 none none none 1 N/A S M-87 3 WFC3/UVI ACCUM UVIS2 F390W 1 none none none 2 N/A S M-87 3 WFC3/UVI ACCUM UVIS2 F390W 2 none none none 2 N/A S M-87 4 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 2 N/A S M-87 4 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 2 N/A S 17902( 3) - 03-Nov-2025 19:31:54 - [ 7] Summary Form for Proposal 17902 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=14, FLASH=21 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-MAY-2025:00:00:00 AND 31-MAY-2025:00:00:00, BETWEEN 05-DEC-2025:16:54:00 AND 12-JAN-2026:01:28:00, PATTERN 1 1, PATTERN 1 4, PATTERN 2 1, PATTERN 2 2, PATTERN 2 3, PATTERN 2 4, PCS MODE FINE ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F275W, F390W, F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names M-87 ------------------------------------------------------------------------------------------------------------------------------------