0 Assigned ID: 5652 ----- Attempting Submission 1 (Tue Mar 26 21:05:07 GMT 2024) ----- 0 ----- Attempting Submission 1 (Mon Aug 05 17:32:42 GMT 2024) ----- The UVOIR portrait of PSR J0030+0451, the key millisecond pulsar PSR J0030+0451 is a nearby single radio, X-ray and gamma-ray millisecond pulsar, which has never been studied in the UV-optical-IR (UVOIR). This pulsar turned out to be the best target for measuring neutron star mass and radius with the X-ray NICER mission, using the effects of bending of photon trajectories in a strong gravitational field. Such measurements are very important for understanding the equation of state of the superdense matter in neutron star interiors, determined by strong interactions of hadrons. The mass and radius are obtained from the analysis of the pulsations of thermal soft X-ray emission coming from ``hot spots'' on the neutron star surface, heated by relativistic particles precipitating from the pulsar's magnetosphere along the magnetic field lines. The pulse shape (hence the inferred mass and radius) critically depend on the positions of the heated regions and the temperature distribution over the neutron star surface. To understand this distribution, one should analyze not only soft X-ray but also far-UV (FUV) pulsations. Such pulsations could be detected with HST, but one should know the average thermal FUV flux to determine the needed exposure. We propose a short exploratory program to estimate the average neutron star surface temperature from measuring UVOIR fluxes in three bands. The estimated temperature will be compared with the predictions of neutron star cooling/heating models, which will give us independent constraints on properties of the superdense matter. To measure the FUV flux and estimate the neutron star temperature in PSR J0030+0451, we will employ ACS/SBC, the most sensitive detector in the FUV range. To eliminate the contribution of the geocoronal emission and maximize the FUV sensitivity, we will use the F125LP filter (cuts off geocoronal Ly-alpha) in the SHADOW parts of the orbit (1820 s for J0030), and the F140LP filter (cuts off all the geocoronal lines) in the rest of the orbit (500 s). We choose the ACS/SBC exposure time from the requirement that a temperature of T = 0.5E+5 K, which corresponds to the flux density of 10 nJy at 1438 A, to be detectable at >3 sigma level. From an analysis of archived ACS/SBC F125LP observations we found that two SHADOW orbits (shadow exposure of 3640 s) would be required. A similar estimate is obtained with the ACS ETC: S/N = 3.0 for an aperture circle radius of 0.2 arcsec; (S/N)_optimal = 5.3 (ETC Request ID: ACS.im.1930247). In the shorter non-shadow parts of the orbits (1000 s exposure) we will firmly detect the pulsar with the F140LP filter if its flux density exceeds 60 nJy (ACS.im.1930268). To minimize the effects of the SBC "thermal glow", we request the SBC observations to be taken in two one-orbit visits. We have checked that there are no bright objects in the SBC field of view that could violate the Bright Object Protection limit. As some old pulsars show a nonthermal power-law component in the optical, it is important to subtract its contribution into the FUV range from the detected FUV flux in order to measure the temperature. To do this, we need observations in two additional bands covering a broad wavelength range. Optimal filters for this goal are FWC3/UVIS F475X (3800 - 6000 A) and FWC3/IR F110W (0.9 - 1.4 microns). Thanks to the high sensitivity of these detector/filter combinations, 1 orbit in each band would detect very faint sources (or provide very low upper limits). In UVIS/ F475X we put the target in the UVIS2-C512C-CTE subarray near the chip readout to maximize the CTE. According to ETC (WFC3UVIS.im.1930279), we would detect 13 nJy (at 4850 A) for a flat f_nu continuum in 2232 s science exposure, using the WFC3-UVIS-DITHER-BOX , with S/N = 3.0 at r = 0.1 arcsec, (S/N)_optimal = 4.4. In WFC3/IR/F110W (lambda = 1.15 micron; exposure 2397 s) we will use the WFC3-IR-DITHER-BOX and readout parameters SAMP-SEQ = STEP100, NSAMP = 12. According to ETC (WFC3IR.im.1930295), we will detect a 22 nJy target with S/N = 3.0 at r = 0.15 arcsec, (S/N)_optimal = 3.5. We will use the optical image for astrometry based on the Gaia catalog, and then co-align the FUV and optical images for the FUV astrometry. Dr. George Pavlov is an expert in theory and observations of neutron stars, pulsars, and related objects. He has led several HST campaigns and published 11 papers in the past decade on HST observations. He has expertise in HST data reduction for ACS and WFC3, the instruments used in the proposed observations. Dr. Oleg Kargaltsev is an expert in multiwavelength observations of neutron stars and pulsar wind nebulae. He has led several HST campaigns and published a number of papers on the results. Dr. Bettina Posselt is an expert in HST data reduction and photometric measurements with varius HST instruments , as well as in multi-wavelength observations of neutron stars. Dr. Andreas Reisenegger is an expert in models of neutron star structure and neutrion star cooling that will be used to interpret the data. Dr. Denis Gonzalez-Caniulef works on cooling and atmosphere models of neutron stars. Mr. Luis Rodriguez is the student of Dr. Reisenegger. He will work on interpretation of observational results. Stellar Physics and Stellar Types 6 false true false false false false SUPPORTED STAR NEUTRON STAR PULSAR NO J2000 J2000 ACS/SBC Imaging No No F125LP ACS/SBC Imaging No No F140LP WFC3/UVIS Imaging No No F475X WFC3/IR Imaging No No F110W POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 1 false POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 2 false The scheduling data was generated by CASM 32.1.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17769 :visit-id "01" :proposal-version -1 :trans-version "20240627" :date "05-Aug-2024 13:04:28.0" :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 17769 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17769 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2463 :al-overhead-at-end 0 :internal-dur-at-end 77 :dark-offset 0 :dark-utilization 1901 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 32.1.1. CASM was run in Phase II mode. 1752825271000 246.3413028822784 (Tic-Visit :proposal-id 17769 :visit-id "02" :proposal-version -1 :trans-version "20240627" :date "05-Aug-2024 11:07:53.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1154992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17769 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17769 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2624 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 32.1.1. CASM was run in Phase II mode. 1752615812000 246.40409888011243 (Tic-Visit :proposal-id 17769 :visit-id "03" :proposal-version -1 :trans-version "20240627" :date "05-Aug-2024 12:54:43.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 905248 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17769 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17769 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2624 :al-overhead-at-end 0 :internal-dur-at-end 671 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) true 1 0 (Tic-Visit :proposal-id 17769 :visit-id "03" :proposal-version -1 :trans-version "20240627" :date "05-Aug-2024 12:54:43.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 905248 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17769 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17769 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2624 :al-overhead-at-end 0 :internal-dur-at-end 671 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 32.1.1. CASM was run in Phase II mode. We request this visit to be separated in time from the identical visit fuv1 (01) to minimize the "thermal glow" of the detector. (Tic-Visit :proposal-id 17769 :visit-id "04" :proposal-version -1 :trans-version "20240627" :date "05-Aug-2024 11:07:58.0" :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 17769 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17769 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2463 :al-overhead-at-end 0 :internal-dur-at-end 77 :dark-offset 0 :dark-utilization 1901 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3005 :pcs-gap 0 ) false 1 0