18186( 2) - 03-Oct-2025 14:23:26 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 18186 Version: 2 Check-in Time: 03-Oct-2025 14:23:26 STScI Edit Number: 0 Title The First Serendipitous Dual [Ne V] AGN: Probing Obscured Black Hole Growth with Chandra ------------------------------------------------------------------------------------ Type Cycle GO 33 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Michael J Koss Eureka Scientific Inc. Y CoI: Dr. Connor Auge Eureka Scientific Inc. N CoI: Dr. Alessandro Peca Eureka Scientific Inc. N ------------------------------------------------------------------------------------ Abstract We propose a 50 ks Chandra ACIS observation to resolve X-ray emission in the merging Seyfert 2 galaxy 2MASX J22373491-1925343, which exhibits dual narrow-line [Ne V] 3426 A emission, a hallmark of AGN activity. Keck/KCWI data reveal two distinct [Ne V] regions, suggesting either a dual AGN or a single AGN illuminating multiple gas structures. Chandra's subarcsecond resolution will determine whether both nuclei are X-ray bright and assess their obscuration, providing the first X-ray-confirmed dual AGN detected in [Ne V]. We also request 2 HST orbits (F814W/F160W) to map stellar structures and extinction. This study will refine [Ne V] as an AGN tracer and inform JWST high-z AGN searches. T ------------------------------------------------------------------------------------ Observations Description ------------------------ The goal of this program is to search for two sources of extended emission potentially associated with dual [Ne V] emission from black holes, using the i-band and H-band with WFC3. The WFC3/UVIS detector with F814W provides the highest spatial resolution, with a fine plate scale of 0.04'' for optimal PSF sampling. The complementary F160W observations are critical because the NIR traces the bulk of the stellar mass, dominated by cooler stars in older populations, and is far less affected by dust extinction. Our exposure strategy is designed to maximize sensitivity to faint host galaxy features while avoiding saturation and limiting overheads. For F814W, the nucleus has an i-band PSF magnitude of ~17.0 (from gaia), but it's a Sy 2 so should be extended. To ensure an unsaturated measurement, we begin with a short 20 s exposure, followed by a 4-point dither pattern with 550 s exposures at each pointing. We employ the 40x 40'' UVIS2-C1K1C subarray to reduce readout and buffer-dump overheads, while the dither pattern improves PSF reconstruction and cosmic-ray rejection. For the F160W observations, the nucleus has a 2MASS H magnitude of 14.9 mag. To balance field of view and efficiency, we adopt the IRSUB512 aperture, providing a 60''x60'' FOV. We use the 4-point BOX dither pattern with long MULTIACCUM exposures (SPARS25 and STEP25 sequences, 14 or15 reads each) to achieve both deep sensitivity to faint extended emission and unsaturated short reads for the nucleus. ------------------------------------------------------------------------------------ 18186( 2) - 03-Oct-2025 14:23:26 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 LEDA-855412 GALAXY, INTERACTING RA=22H37M34.9145S +/- 0.3", J2000 Z = V = 18. GALAXY, NLR, QUASAR, DEC=-19D25'34.40" +/- 0.3" 0.1252 SEYFERT Reference Frame: ICRS Extended: YES Comments: Position based on WISE/Simbad. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0 ------------------------------------------------------------------------------------------------------------------------------------ 18186( 2) - 03-Oct-2025 14:23:26 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 1.716 Line_Spacing 1.095 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 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 ------------------------------------------------------------------------------------------------------------------------------------ 18186( 2) - 03-Oct-2025 14:23:26 - [ 4] Visit: 01 Visit Requirements: 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 LEDA-855412 WFC3/UVI ACCUM UVIS2-C1K F814W 1 20 S (20 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 2 LEDA-855412 WFC3/UVI ACCUM UVIS2-C1K F814W FLASH=10 1 550 S PATTERN 3 2 S 1C-SUB (2200 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 LEDA-855412 WFC3/IR MULTIAC IRSUB512 F160W NSAMP=15, SAMP-SEQ=SPARS25 1 DEF PATTERN 2 3-4 CUM (1287.002 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 LEDA-855412 WFC3/IR MULTIAC IRSUB512 F160W NSAMP=14, SAMP-SEQ=STEP25 1 DEF CUM (880.499 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 | ------------------------------------------------------------------------------------------------------------------------------------ LEDA-855412 1 WFC3/UVI ACCUM UVIS2-C1 F814W none none none none 1 N/A S K1C-SUB LEDA-855412 2 WFC3/UVI ACCUM UVIS2-C1 F814W 1 none none none 1 N/A S K1C-SUB LEDA-855412 2 WFC3/UVI ACCUM UVIS2-C1 F814W 2 none none none 1 N/A S K1C-SUB LEDA-855412 2 WFC3/UVI ACCUM UVIS2-C1 F814W 3 none none none 1 N/A S K1C-SUB LEDA-855412 2 WFC3/UVI ACCUM UVIS2-C1 F814W 4 none none none 1 N/A S K1C-SUB LEDA-855412 3 WFC3/IR MULTIAC IRSUB512 F160W 1 none none none 2 N/A CUM LEDA-855412 3 WFC3/IR MULTIAC IRSUB512 F160W 2 none none none 2 N/A CUM LEDA-855412 3 WFC3/IR MULTIAC IRSUB512 F160W 3 none none none 2 N/A CUM LEDA-855412 3 WFC3/IR MULTIAC IRSUB512 F160W 4 none none none 2 N/A CUM LEDA-855412 4 WFC3/IR MULTIAC IRSUB512 F160W 1 none none none 2 N/A CUM LEDA-855412 4 WFC3/IR MULTIAC IRSUB512 F160W 2 none none none 2 N/A CUM 18186( 2) - 03-Oct-2025 14:23:26 - [ 5] 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 | ------------------------------------------------------------------------------------------------------------------------------------ LEDA-855412 4 WFC3/IR MULTIAC IRSUB512 F160W 3 none none none 2 N/A CUM LEDA-855412 4 WFC3/IR MULTIAC IRSUB512 F160W 4 none none none 2 N/A CUM 18186( 2) - 03-Oct-2025 14:23:26 - [ 6] Summary Form for Proposal 18186 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IRSUB512, UVIS2-C1K1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=10, NSAMP=14, NSAMP=15, SAMP-SEQ=SPARS25, SAMP-SEQ=STEP25 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 2 3-4, PATTERN 3 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names LEDA-855412 ------------------------------------------------------------------------------------------------------------------------------------