17781( 2) - 12-Aug-2024 17:34:27 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17781 Version: 2 Check-in Time: 12-Aug-2024 17:34:27 STScI Edit Number: 0 Title A superluminal jet in 3C264: the view at 30 ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Eileen T Meyer University of Maryland Baltimore County Y CoI: Dr. Markos Georganopoulos University of Maryland Baltimore County N CoI: Dr. William B. Sparks SETI Institute N CoI: Dr. Roeland P. van der Marel Space Telescope Science Institute N CoI: Dr. Jay Anderson Space Telescope Science Institute N CoI: Dr. Marco Chiaberge Space Telescope Science Institute - ESA - N JWST CoI: Prof. Eric S. Perlman Florida Institute of Technology N CoI: Dr. Onic I. Shuvo University of Maryland Baltimore County N CoI: Dr. Karthik Reddy Solipuram Arizona State University N CoI: Prof. Judd Bowman Arizona State University N ------------------------------------------------------------------------------------ Abstract 3C264 is a nearby radio galaxy with a prominent optical jet. Previous HST observations from the 1990s through the 2010s discovered not only the fastest-ever superluminal speed (on kpc scales) of 7c for a knot in the jet, but also captured the motion of this knot through the start of a collision with slow-moving material downstream, with concomitant brightening indicating in-situ particle acceleration. This remarkable discovery represents the first direct evidence for the "internal shock" model for particle acceleration, a mechanism proposed to explain variability and particle acceleration in sources as diverse as gamma-ray bursts, microquasars, and jetted AGN. The collision is expected to manifest in brightening and hardening of the optical spectrum and increasing polarization over the next several years to decade, and this unprecidented source gives us the unique opportunity to directly evaluate the applicability, efficiency and physical characterization of the internal shock mechanism.Following previous HST/VLA/Chandra observations in 2018/2019 showing a continued rise in flux and polarization in the shock region, we propose a new epoch of imaging to monitor the spectral evolution of the colliding knots and continue spatial proper motion measurements of the jet features, for comparison to the expectations from theoretical models. In keeping with past monitorig we request 2 orbits with WFC3/UVIS (near-UV, B, and I band), 1 orbit with the ACS/WFC polarizers in F606W, as well as K-band VLA and Chandra ACIS observations. ------------------------------------------------------------------------------------ Observations Description ------------------------ Observations are of an optical jet approximately 2" long in the northeast direction, as part of a monitoring proposal for flaring behavior (this is the follow-up of an identical set of observations in 2015/16 and 2018/19). The field of view is dominated by the host galaxy, a nearby elliptical. The observations consist of two visits: the first is WFC3/UVIS imaging in three filters (F475W, F814W splitting the first orbit, F225W in the second orbit). 17781( 2) - 12-Aug-2024 17:34:27 - [ 2] The second visit is ACS/WFC polarimetry in F606W filter. Orient constraints are specified to avoid any risk of the central nucleus from producing diffraction spikes that run over the jet. ------------------------------------------------------------------------------------ 17781( 2) - 12-Aug-2024 17:34:27 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 3C264 GALAXY, ELLIPTICAL, RA=11H45M5.0090S, J2000 V = 13.97 JET, NUCLEUS, RADIO DEC=+19D36'22.74" GALAXY Reference Frame: Other: SIMBAD Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 17781( 2) - 12-Aug-2024 17:34:27 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE-3PT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.135 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.173 Line_Spacing 0.112 Coordinate_Frame POS-TARG Pattern_Orient 23.884 Angle_Between_Sides 81.785 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 3.011 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 85.28 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 4 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 ------------------------------------------------------------------------------------------------------------------------------------ 17781( 2) - 12-Aug-2024 17:34:27 - [ 5] Visit: 01 (ACS Polariz.) Visit Requirements: ORIENT 40D TO 85 D; ORIENT 128D TO 170 D; ORIENT 215D TO 270 D; ORIENT 305D TO 345 D On Hold Comments: Additional Comments: 1 orbit of ACS polarization in F606W filter. The observations cover the three polarization angle filters, with two exposures each, using a 2-point dither pattern to improve image quality and mitigate cosmic ray artifacts. Orient constraints are specified to avoid any risk of the central nucleus from producing diffraction spikes that run over the jet. 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 3C264 ACS/WFC ACCUM WFC1 F606W, 1 260 S (520 POS TARG 0, 0; PATTERN 3 POL0V S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 3C264 ACS/WFC ACCUM WFC1 F606W, 1 260 S (520 POS TARG 0, 0; PATTERN 3 POL120V S) 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 3C264 ACS/WFC ACCUM WFC1 F606W, 1 260 S (520 POS TARG 0, 0; PATTERN 3 POL60V S) 3 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 3C264 1 ACS/WFC ACCUM WFC1 F606W, 1 none none none 1 N/A POL0V 3C264 1 ACS/WFC ACCUM WFC1 F606W, 2 none none none 1 N/A POL0V 3C264 2 ACS/WFC ACCUM WFC1 F606W, 1 none none none 1 N/A POL120V 3C264 2 ACS/WFC ACCUM WFC1 F606W, 2 none none none 1 N/A POL120V 3C264 3 ACS/WFC ACCUM WFC1 F606W, 1 none none none 1 N/A POL60V 3C264 3 ACS/WFC ACCUM WFC1 F606W, 2 none none none 1 N/A POL60V 17781( 2) - 12-Aug-2024 17:34:27 - [ 6] Visit: 02 (UVIS imaging) Visit Requirements: ORIENT 25D TO 55 D; ORIENT 110D TO 145 D; ORIENT 290D TO 325 D On Hold Comments: Additional Comments: We used a 3-point dithering pattern for the sets of F475W (3 exp) and F814W (2 exp) observations in the first orbit, with an additional shorter exposure in the latter filter to fill the orbit (the third exposure is particularly useful to minimize impacts of CR). We used a 4-point dithering pattern for the 4 F225W exposures in the second orbit. Orient constraints are specified to avoid any risk of the central nucleus from producing diffraction spikes that run over the jet. POS TARGS are also used to put the target somewhat closer to the readout corner to minimize CTE. 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 3C264 WFC3/UVI ACCUM UVIS1 F475W FLASH=15 1 350 S POS TARG 30, 10; PATTERN S (1050 S) 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 3C264 WFC3/UVI ACCUM UVIS1 F814W FLASH=12 1 350 S (700 POS TARG 30, 10; PATTERN S S) 4 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 3C264 WFC3/UVI ACCUM UVIS1 F814W FLASH=18 1 180 S (180 POS TARG 30, 10 S S) ------------------------------------------------------------------------------------------------------------------------------------ 4 3C264 WFC3/UVI ACCUM UVIS1 F225W FLASH=19 1 550 S POS TARG 30, 10; PATTERN S (2200 S) 2 4 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 3C264 1 WFC3/UVI ACCUM UVIS1 F475W 1 none none none 1 N/A S 3C264 1 WFC3/UVI ACCUM UVIS1 F475W 2 none none none 1 N/A S 3C264 1 WFC3/UVI ACCUM UVIS1 F475W 3 none none none 1 N/A S 3C264 2 WFC3/UVI ACCUM UVIS1 F814W 1 none none none 1 N/A S 3C264 2 WFC3/UVI ACCUM UVIS1 F814W 2 none none none 1 N/A S 3C264 3 WFC3/UVI ACCUM UVIS1 F814W none none none none 1 N/A S 3C264 4 WFC3/UVI ACCUM UVIS1 F225W 1 none none none 2 N/A S 3C264 4 WFC3/UVI ACCUM UVIS1 F225W 2 none none none 2 N/A S 3C264 4 WFC3/UVI ACCUM UVIS1 F225W 3 none none none 2 N/A S 17781( 2) - 12-Aug-2024 17:34:27 - [ 7] 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 | ------------------------------------------------------------------------------------------------------------------------------------ 3C264 4 WFC3/UVI ACCUM UVIS1 F225W 4 none none none 2 N/A S 17781( 2) - 12-Aug-2024 17:34:27 - [ 8] Summary Form for Proposal 17781 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS1, WFC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=12, FLASH=15, FLASH=18, FLASH=19 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 110D TO 145 D, ORIENT 128D TO 170 D, ORIENT 215D TO 270 D, ORIENT 25D TO 55 D, ORIENT 290D TO 325 D, ORIENT 305D TO 345 D, ORIENT 40D TO 85 D, PATTERN 1 1, PATTERN 2 4, PATTERN 3 1, PATTERN 3 2, PATTERN 3 3, PATTERN 4 2, POS TARG 0, 0, POS TARG 30, 10 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F225W, F475W, F606W, F814W, POL0V, POL120V, POL60V ------------------------------------------------------------------------------------------------------------------------------------ Target Names 3C264 ------------------------------------------------------------------------------------------------------------------------------------