0 Assigned ID: 4723 ----- Attempting Submission 1 (Wed May 24 22:16:13 GMT 2023) ----- HST Phase I Proposal 4723 successfully submitted. Receipt: # 4723-1 Following the advice by CS Jay Anderson, we changed the sequence of filters in Visit 4 (nir) to avoid the HeI airglow in the WFC3/IR F110W images in the beginnings and ends of the orbits.. 1292179659 ----- Attempting Submission 1 (Mon Sep 11 19:38:14 GMT 2023) ----- HST Phase II Proposal 17476 successfully submitted. Receipt: # 17476-1 ----- Attempting Submission 2 (Thu Sep 21 20:45:33 GMT 2023) ----- The most puzzling UV-optical-NIR spectrum of an isolated neutron star: A disk or a magnetosphere? Unlike the commonly known rotation-powered pulsars, X-ray thermal isolated neutron stars (XTINSs) do not show radio/gamma-ray emission or other signs of magnetospheric activity but emit purely thermal soft X-ray radiation. A few HST observations of these sources have shown very puzzling results, with possible contribution from neutron star magnetospheres or fallback disks, challenging the simplistic model of a purely thermal emitter. However, because most XTINSs only have HST coverage in two spectral bands, the actual spectral shape and the origin of the XTINS UV-optical-IR emission remain unknown. RX J1243.0+0654, the most intriguing XTINS, provides the best opportunity to clarify the origin of the XTINS emission. We propose photometric measurements with high S/N in five spectral bands in the wavelength range of 0.14-1.7 microns. Fits of the five flux density points with different spectral models will help to understand the nature of this and other XTINSs. Using the same observations, we will also check for long-term variability of the target in two bands and measure its (currently unknown) proper motion with an uncertainty not exceeding 2 mas/yr, much lower than expected proper motion values. This will allow us to locate the birth place of this neutron star and estimate its kinematic age. These properties are required to constrain the neutron star cooling models and learn about evolutionary links between the diverse neutron star populations. To infer the shape of the UVOIR spectrum of the target neutron star and confront it with the available models, we will measure its fluxes in 5 bands. The far-UV emission will be observed in the ACS/SBC F140LP filter (two one-orbit visits). We choose two visits to minimize the effect of dark current (thermal glow) and simplify scheduling. In each orbit we will use a two-point dither line for better removal of detector blemishes and improving the PSF sampling. The starting points of the dither lines in the two orbits will be offset by 0.5 arcsec in the X and Y directions with POSTARG for better coverage. The near-UV observation will be carried out with the WFC3/UVIS F300X filter (one two-orbit visit). We chose the UVIS aperture UVIS2-C512C-CTE, which places our faint target near the C readout amplifier to minimize CTE losses but reads out the full detector for better astrometry. We will also mitigate CTE losses using FLASH = 13 electrons. We will use the WFC3-UVIS-DITHER-LINE-3PT in each orbit, which provides optimal 3-step sampling of the PSF and produces spacings of >1 column for removal of hot columns. The observational setup for the two-orbit visit with ACS/WFC F475W repeats that used in the program #11564. The main goals of this observation is measuring the target's proper motion and checking possible flux variabilty. This observation uses ACS-WFC-DITHER BOX in each of the two orbits. The near-IR emission of the target will be observed in two WFC3/IR filters, F110W and F160W, in one two-orbit visit. Since the F110W filter can suffer from unpredictable background variations from the He I airglow in the upper atmosphere (see WFC3/ISR 2013-03), we will sandwich the F110W exposures with F160W exposures at the beginning and end of each of the two orbits. In each orbit we will put the target in two positions, defined with POSTARG values, which provides some sampling of the PSF. We will use the readout mode SAMP-SEQ = 100, NSAMP = 12, 13 or 14 for most part of the visit, and SAMP-SEQ = 50, NSAMP = 14 for two exposures to get an optimal exposure time. We have checked the 2MASS and VLT images of this field and concluded that diffraction spikes from the sparse nearby stars would not be a problem at any ORIENT value. The HEALTH flag raised by BOT for a source at 21 43 1.5894, +06 54 26.74 (~29 arcsec from target) comes from GSC2. GALEX also lists the UV counterpart of this star (Gaia DR3 Teff=5300K) at 21 43 1.5475, +06 54 26.62 (agreement within 0.63 arcsec), but the GALEX Flag is "SAFE". Considering in addition that a similar SBC observation has already been carried out successfully, there is no BOT safety concern for any of our exposures. Dr. George Pavlov is an expert in theory and observations of neutron stars, pulsars, and related objects. He has led several past HST campaigns, with 12 papers published in the past decade based on data obtained from HST observations, and he is a PI of a JWST Cycle 1 observation. He has expertise in HST data reduction for WFC3 and ACS, used in the proposed observations. He has also participated in many X-ray observations. Dr. Bettina Posselt is an expert in HST data reduction for various instruments and photometric measurements. In particular, she used HST to discover NIR emission from a neutron star similar to our target. She also has extensive experience in Spitzer, VLT and JWST data analysis, as well as in X-ray and radio observations. Dr. Oleg Kargaltsev is an expert in neutron stars and pulsar wind nebulae as well as in multiwavelength observations and data analysis. He has led several HST campaigns and authored a number of papers using HST data. Stellar Physics and Stellar Types 6 false false false false false false false false SUPPORTED STAR NEUTRON STAR NO J2000 J2000 WFC3/UVIS Imaging No No F300X WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W ACS/WFC Imaging No No F475W ACS/SBC Imaging No No F140LP POS-TARG DITHER 0.2637 LINE 0.1856 false false 69.02 4 20.7 ACS-WFC-DITHER-BOX 5 false POS-TARG DITHER 0.472 LINE false false 2 44.4 ACS-SBC-DITHER-LINE 9 false POS-TARG DITHER 0.135 LINE false false 3 46.84 WFC3-UVIS-DITHER-LINE-3PT 10 false The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. 1715928233000 250.91749985978583 (Tic-Visit :proposal-id 17476 :visit-id "01" :proposal-version -1 :trans-version "20230626" :date "21-Sep-2023 13:17:04.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 37040 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17476 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17476 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2751 :al-overhead-at-end 0 :internal-dur-at-end 77 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3135 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. 1715888428000 251.06225674710356 (Tic-Visit :proposal-id 17476 :visit-id "02" :proposal-version -1 :trans-version "20230626" :date "21-Sep-2023 16:30:34.0" :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 1732464 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17476 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17476 :visit-id "02" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2743 :al-overhead-at-end 124 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3135 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17476 :visit-id "02" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2743 :al-overhead-at-end 124 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3135 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. 1716064782000 250.4094094152868 (Tic-Visit :proposal-id 17476 :visit-id "03" :proposal-version -1 :trans-version "20230626" :date "21-Sep-2023 16:30:45.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 2273792 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17476 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17476 :visit-id "03" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2750 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3135 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17476 :visit-id "03" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2740 :al-overhead-at-end 0 :internal-dur-at-end 347 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3135 :pcs-gap 0 ) true 2 0 The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17476 :visit-id "05" :proposal-version -1 :trans-version "20240604" :date "12-Jun-2024 12:32:15.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "28" :si-bright-earth-limb-angle 20.0 :data-volume 37040 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17476 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17476 :visit-id "05" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2629 :al-overhead-at-end 0 :internal-dur-at-end 77 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3010 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 32.1. CASM was run in Phase II mode. /private/var/folders/46/4jpf0wpx40jbz16h87362w240001d2/T/OPVisit1570798805273414272.xml (Tic-Visit :proposal-id 17476 :visit-id "04" :proposal-version -1 :trans-version "20240604" :date "13-Jun-2024 17:16:47.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1932352 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17476 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17476 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2612 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3010 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17476 :visit-id "04" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2582 :al-overhead-at-end 0 :internal-dur-at-end 728 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3010 :pcs-gap 0 ) true 2 0