0 ----- Attempting Submission 1 (Wed Jan 15 16:03:27 GMT 2020) ----- HST Phase II Proposal 16061 (Phase2_J1023.apt) successfully submitted. Receipt: # 16061-1 ----- Attempting Submission 2 (Fri Feb 07 08:40:01 GMT 2020) ----- PSR J1023+0038 is a binary system that hosts a neutron star and a low-mass, main sequence companion star. It has been observed to switch on timescales of years between a radio millisecond pulsar state and a disc-dominated state, of uncertain origin. After its last switch to a disc-dominated state in 2013, the source has been the object of extensive multiwavelength monitoring campaigns, during which the continuous switch between three X-ray modes (high, low and flare) on timescales of 10 s has been observed. Here we propose the ultimate, strictly simultaneous, multi-wavelength campaign to study in detail this unique mode-switching phenomenon. We will involve NuSTAR, XMM-EPIC, Swift-UVOT, XMM-OM, VLT/HAWK-I, and VLA observations to probe models using correlations and lags (a profitable tool to study the emission mechanisms), as well as establish differences among the power spectra of the multi-band light curves. We will also track the elusive pulsations along the spectral energy distribution. This visit will consist in two HST orbits during which we will carry out time-resolved NUV TIME-TAG spectroscopy with the STIS/NUV-MAMA/G230L instrument/grating combination. We will use the 2376 \AA setting for this observation to achieve continuous wavelength coverage between 1570 \AA and 3180 \AA, with the 52X0.2 slit. The TIME-TAG mode of STIS will provide a maximum time resolution of 125 $\mu$s, fast enough to resolve pulsations at the 1.6 ms (the neutron star spin period) in the Near-UV band. Our observations require strict simultaneity between HST and XMM-Newton observatories. It is essential to have simultaneous observations in the X-ray band so as to evaluate the system ephemerides at the epoch of the HST observations and restrict the parameter space for a sensitive search for UV pulsations. 6 false false false false false false false SUPPORTED STAR ACCRETION DISK LMXB PULSAR This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 1586357631237 /private/var/folders/8t/mg1bkfyj20xf2vfc_9vyhfs80006z1/T/OPVisit3522857284070234277.xml The scheduling data was generated by CASM 28.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16061 :visit-id "01" :proposal-version -1 :trans-version "20191203" :date "08-Apr-2020 10:53:51.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 591840 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16061 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16061 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2624 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16061 :visit-id "01" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2718 :al-overhead-at-end 0 :internal-dur-at-end 582 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 2 0