18187( 2) - 02-Oct-2025 12:55:03 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 18187 Version: 2 Check-in Time: 02-Oct-2025 12:55:03 STScI Edit Number: 0 Title A Movie Campaign on M87: Chandra, NuSTAR, Hubble, and the EHT ------------------------------------------------------------------------------------ Type Cycle GO 33 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Joseph Neilsen Villanova University Y CoI: Prof. Daryl Haggard McGill University N CoI: Dr. Michael Nowak Washington University in St. Louis N CoI: Prof. Sera Markoff Universiteit van Amsterdam N CoI: Giacomo Principe INAF - Istituto di Radioastronomia N CoI: Dr. Michael Johnson Smithsonian Institution Astrophysical N Observatory CoI: Dr. Mislav Balokovic Yale University N CoI: Dr. Sunil Chandra North-West University Potchefstroom Campus N CoI: Dr. Shuo Zhang Michigan State University 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. Razieh Emami Smithsonian Institution Astrophysical N Observatory CoI: Monika Moscibrodzka Radboud University Nijmegen N CoI: Mr. Chris Sheridan Villanova University N CoI: Bart Ripperda Canadian Institute for Theoretical N Astrophysics CoI: Dr. Venkatessh Ramakrishnan University of Turku N ------------------------------------------------------------------------------------ Abstract With a large, well-studied jet and the second largest event horizon on the sky, the radio galaxy M87 is one of the primary targets for the Event Horizon Telescope, but the origin of its jet remains unclear. If the jet is powered by the supermassive black hole spin, there should be a direct connection between the bright shadow/ring and the subsequent evolution of the jet. An upcoming EHT movie campaign will test this connection in 2026 (priv comm) with an unprecedented study of the dynamics of the turbulent near-horizon plasma. Chandra observations (4x5 ks) coordinated with NuSTAR (priv comm) and HST (4 orbits) will be essential for tracking the high-energy variability of this plasma, diagnosing particle heating and acceleration, and interpreting models of the accretion flow. ------------------------------------------------------------------------------------ Observations Description ------------------------ The goal of our HST program is to study the optical and UV variability of M87 in conjunction with Chandra/EHT observations in Spring 2026. 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 vists pieces consisting of two orbits each. This is now standard for M87. Beyond taking place during the EHT campaign, no specific coordination is required. We 18187( 2) - 02-Oct-2025 12:55:03 - [ 2] 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. The first orbit consists of three dithered 449 s exposures in F275W and two dithered 348 s exposures in F814W in ACCUM mode, for a total of 2043 s on source; the second orbit has 2x489 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 second visit has a ~3-day window. ------------------------------------------------------------------------------------ 18187( 2) - 02-Oct-2025 12:55:03 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M-87 GALAXY, JET, RADIO RA=12H30M49.4234S, J2000 V = 8.63 GALAXY 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 ------------------------------------------------------------------------------------------------------------------------------------ 18187( 2) - 02-Oct-2025 12:55:03 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 18187( 2) - 02-Oct-2025 12:55:03 - [ 5] Visit: 01 (Visit 1) Visit Requirements: PCS MODE FINE; BETWEEN 28-FEB-2026:00:00:00 AND 01-APR-2026:00:00:00 On Hold Comments: Additional Comments: This visit is scheduled earlier in the EHT campaign. No specific coordination with the EHT, Chandra, or NuSTAR is required. 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 1 449 S PATTERN 1 1 S see below (1346 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 1 489 S (978 PATTERN 2 3 S 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 1 448.0 S S M-87 1 WFC3/UVI ACCUM UVIS2 F275W 2 none none none 1 N/A 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 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 M-87 4 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 2 N/A S 18187( 2) - 02-Oct-2025 12:55:03 - [ 6] Visit: 02 (Visit 2) Visit Requirements: PCS MODE FINE; BETWEEN 01-APR-2026:00:00:00 AND 30-APR-2026:00:00:00 On Hold Comments: Additional Comments: This visit is scheduled later in the EHT campaign. No specific coordination with the EHT, Chandra, or NuSTAR is required. 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 1 449 S PATTERN 1 1 S see below (1346 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 1 489 S (978 PATTERN 2 3 S 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 1 448.0 S S M-87 1 WFC3/UVI ACCUM UVIS2 F275W 2 none none none 1 N/A 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 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 M-87 4 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 2 N/A S 18187( 2) - 02-Oct-2025 12:55:03 - [ 7] Summary Form for Proposal 18187 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=14, FLASH=21 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-APR-2026:00:00:00 AND 30-APR-2026:00:00:00, BETWEEN 28-FEB-2026:00:00:00 AND 01-APR-2026:00:00:00, PATTERN 1 1, PATTERN 1 4, PATTERN 2 2, PATTERN 2 3, PCS MODE FINE ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F275W, F390W, F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names M-87 ------------------------------------------------------------------------------------------------------------------------------------