0 Assigned ID: 6715 ----- Attempting Submission 1 (Thu Apr 10 21:18:32 GMT 2025) ----- HST Phase I Proposal 6715 successfully submitted. Receipt: # 6715-1 This submission includes a new 2-orbit visit which approved under TTRBHST-93552 to repeat observations affected by a loss of guiding during orbit 1 of visit 2. 619622428 ----- Attempting Submission 1 (Mon Aug 04 01:29:52 GMT 2025) ----- ----- Attempting Submission 2 (Thu May 07 21:40:24 GMT 2026) ----- Visit planner was run for Visit 3 with planning windows being available in the near future (summer 2026). We propose HST/WFC3 observations of the interacting Symbiotic binary HM Sge to study the evolution of the jet we discovered using the archival April 2021 observations, which was likely ejected during a powerful outburst during 1975-1980. Since 1975, HM Sge has been slowly getting fainter, that is until recently, when a dramatic dimming of the light curve began in late 2021/early 2022, indicating a new powerful mass ejection and dust formation, similar to the outburst and jet producing events in two nearby Symbiotics CH Cyg and R Aqr. Our goal is to carry out a timely high-angular resolution (0.025") multi-wavelength (UV-Optical) line-emission study of the newly discovered jet and the recent ejecta by zooming in on the central 3" radius (3000 AU) circumbinary region, reaching as close as 25 AU to the central binary. This will allow us to determine the spatial/spectral evolution of the distribution and the characteristics of the new jet and more recent ejecta, and to gain a unique insight into jet formation and early propagation in symbiotic and other accretion-powered systems. We will take multi-wavelength observations of HM Sge to study the newly discovered jet and to measure the line ratios in the region powering the new jet and the recent dimming event. The HST observations are critical because of the required high-angular resolution, and especially the access to UV and optical lines - which are a key to this study. The UV component of this proposal is essential to the science investigation, and is in accordance with the HST UV initiative. We request a total of 5 orbits, in 1 visit. The target visibility is very good. We plan to carry out HST WFC3/UVIS imaging of HM Sge, using the 4-point dither mode in several filters (see table). Combining the dithered images will result in improvement of the sampling of the PSF and will allow us to further enhance the (nominal 0.04"/pixel) resolution using deconvolution techniques such as Richardson-Lucy reaching 0.025"/pixel (~25 AU). We also plan several long exposures to image the fainter outer structures and determine their morphology and evolution when compared to the archival HST observations. We plan to use the following filters (UV-Optical) centered on emission lines and nearby continua. F275W UV cont. set of 4x180s exp F280N Mg II set of 4x120s exp + 4x200s exp F336W U Band cont. set of 4x30s exp F373N [OII] set of 4x85s + 2x500s exp F343N [NeV] set of 4x90s exp F487N H-beta set of 4x30s exp F502N [O III] set of 4x40s + 2x660s exp F547M cont. set of 4x8s exp F656N H-alpha set of 4x10s + 2x600s exp F658N [N II] set of 4x20s exp F673N [S II] set of 4x15s exp F763M cont. set of 4x5s exp The exposure times are based on the online WFC3 ETC calculations as verified by the 2024 WFC3 observations. We will optimize the efficiency of the observing time by using 1024x1024 subarray readouts with a ~40"x40" field of view to minimize the overheads. This field of view also includes a suitable PSF candidate for subsequent deconvolution of the image. The expertise of our team is complementary (multiwavelength observations and analysis) which will allow us to achieve the goals of our proposal. Warren Hack: Expertise in HST observations of symbiotic systems and image software and data processing expertise (e.g., primary developer of the Drizzlepac package). He has been applying novel dithered-images combination techniques and PSF simulations, allowing to reach the finest resolution achievable with the HST (e.g., previous HST studies of symbiotics R Aqr, CH Cyg, Mira, HM Sge). Dr. Margarita Karovska: Scientific expertise in multiwavelength observational studies and modeling of interacting binaries including symbiotic systems. High-resolution imaging expertise (including deconvolution techniques) allowing to achieve maximum resolution (e.g., previous HST, Chandra and VLA observations) including of symbiotics R Aqr, CH Cyg, Mira, and other interacting systems). Stellar Physics and Stellar Types 6 false true false false false false false SUPPORTED STAR JET SYMBIOTIC STAR 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.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. J2000 J2000 WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F275W WFC3/UVIS Imaging No No F280N WFC3/UVIS Imaging No No F343N WFC3/UVIS Imaging No No F373N WFC3/UVIS Imaging No No F487N WFC3/UVIS Imaging No No F502N WFC3/UVIS Imaging No No F547M WFC3/UVIS Imaging No No F656N WFC3/UVIS Imaging No No F658N WFC3/UVIS Imaging No No F673N WFC3/UVIS Imaging No No F763M POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 1 false POS-TARG DITHER 0.15 LINE false false 2 23.884 LINE 2 false 1778189253287 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. 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CASM was run in Phase II mode. 1775333274000 267.80933960152464 (Tic-Visit :proposal-id 18051 :visit-id "02" :proposal-version -1 :trans-version "20250624" :date "03-Aug-2025 17:38:30.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 463440 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18051 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18051 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2588 :al-overhead-at-end 87 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2976 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18051 :visit-id "02" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2573 :al-overhead-at-end 85 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2976 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18051 :visit-id "02" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2507 :al-overhead-at-end 85 :internal-dur-at-end 543 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2976 :pcs-gap 0 ) true 3 0 1778189257790 The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. E:\data\SCI\hm_sge\proposing\cycle33_2025\OP-cache\hm_sge_2025_phase2_repeat_v1-v03.xml (Tic-Visit :proposal-id 18051 :visit-id "03" :proposal-version -1 :trans-version "20250929" :date "07-May-2026 14:27:37.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 320848 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18051 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18051 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2592 :al-overhead-at-end 87 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2976 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18051 :visit-id "03" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2568 :al-overhead-at-end 85 :internal-dur-at-end 387 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2976 :pcs-gap 0 ) true 2 0