0 Assigned ID: 1185 ----- Attempting Submission 1 (Wed Sep 30 20:14:06 GMT 2015) ----- INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS Hi Amber, here is the Phase II for the AR Sco G140 observations. Unfortunately, as outlined at Phase I, the scientific goals need the five orbits to be consecutive. Do you think there is any chance to get this into one of the upcoming visibility windows in early 2015? We have a draft of a paper that we will submit to Nature, and the HST data will be an important ingredient (that's why we went for the mid-cycle initiative rather than waiting for Cycle 24). Best wishes, Boris 139615826 ----- Attempting Submission 1 (Wed Dec 02 01:19:40 GMT 2015) ----- We decided to have all four FP-POS positions in each single HST orbit to have a optimally wavlength sampling at five different orbital phases. AR Sco was mis-classified in 1971 as a pulsating delta-Scuti star, and has received little attention until now. In May this year, we became aware of the truly unique nature of this object: besides a two-magnitude modulation on the 3.56h orbital period, we detected a coherent 2min variability from the optical into the radio, and a spectacular infrared excess across the WISE bands. Our optical spectroscopy reveals a late-type companion star, clearly identifying AR Sco as a compact binary. While most of its observational characteristics are reminiscent of neutron star or black hole binaries, the 2min modulation is archetypical of the spin period of a strongly magnetic white dwarf. We believe that AR Sco is the first white dwarf radio pulsar, where the combination of a large field and rapid rotation results in the acceleration of relativisitic particles that blast the inner hemisphere of the M-dwarf companion, akin to the well-known milli-second pulsars. The ultimate proof of our hypothesis relies on the unambiguous identification of the white dwarf, which will be achieved through the detection of Zeeman-split Ly alpha absorption in the requested COS/G140L observations. We believe that AR Sco is the first white dwarf pulsar, and these COS FUV G140L observations are designed to detect the white dwarf photoshere, in particular Zeeman-split Ly alpha, to confirm our hypothesis. We have obtained detailed ground-based photometry (ULTRACAM u, g, i bands) as well as many SWIFT UVW1observations. The u-band and UVW1 flux have nearly identical flux levels, and the same orbital modulation amplitude, and we assume for the Phase II a flat spectrum (in Flambda). The target is acquired spectroscopically, assuming that HST hits the faintest (2e-14erg/cm2/s/AA) phase, any other phase will result in a S/N>40 in the target acq. We need to observe the target for five consecutive orbits to achieve nearly-complete orbital phase coverage (the orbital period is 3.55h), see Fig. 4 in the Phase I proposal. Because of the large orbital variability, we decided to split every single HST orbit into four FP-POS settings, so that we get an optimally wavelength-sampled spectrum at five different orbital phases. To minimise the overheads, we set the BUFFER-TIME to Texp-110sec (which is significantly shorter than the maximum buffer time given by our ETC simulation). The flux level at orbital maximum, 1.2e-14erg/cm2/s/AA (Fig. 1 in the Phase I proposal, middle panel), falls a factor ~30 below the maximum count rate of COS/G140L, so should pose no threat to the detector. We have a decade worth of optical monitoring of AR Sco (from the Catalina Real Time Survey), which shows no variability besides the orbital modulation, i.e. no flares, no outbursts. HOT STARS 3 false true false false SUPPORTED STAR DA PULSAR NO J2000 J2000 The scheduling data was generated by CASM 23.2. CASM was run in Phase I mode. COS/FUV Spectroscopic No No G140L 1105 1449018176905 /tmp/OPVisit991320834325779148.xml The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. Because of the substantial orbital phase variation, we split every single orbit into four FP-POS settings, so that we get five fully-sampled FUV spectra across the binary orbit. (Tic-Visit :proposal-id 14470 :visit-id "01" :proposal-version -1 :trans-version "20150609" :date "02-Dec-2015 01:02:56.0" :trans-errors '(:WARNINGS 4 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 1948736 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14470 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14470 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2889 :al-overhead-at-end 0 :internal-dur-at-end 57 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3222 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14470 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3000 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3222 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14470 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3000 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3222 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14470 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 3000 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3222 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14470 :visit-id "01" :orbit-number 5 :pcs-time 222 :si-vis-utilization 3000 :al-overhead-at-end 0 :internal-dur-at-end 341 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3222 :pcs-gap 0 ) true 5 0 We have good orbital phase coverage with Swift UVW1 (2600A) and SDSS u (3650A), amplitude and flux in the two bands are identical, so we adopt a flat spectrum in Flambda. At orbital minimum, the flux in Swift UVW1 is 2e-15 erg/cm2/s/AA, and we set up the target acquisition to achieve a S/N of 40 at that faintest phase. At orbital maximum, the system reaches 1.2e-14 erg/cm2/s/AA. This is a factor ~30 below the COS bright limit for the chosen setup. We have good orbital phase coverage with Swift UVW1 (2600A) and SDSS u (3650A), amplitude and flux in the two bands are identical, so we adopt a flat spectrum in Flambda. At orbital minimum, the flux in Swift UVW1 is 2e-15 erg/cm2/s/AA, at orbital maximum 1.2e-14 erg/cm2/s/AA. We adopt the max. flux for the ETC run given above. The bright phase is a factor ~30 below the COS maximum count rate. We have good orbital phase coverage with Swift UVW1 (2600A) and SDSS u (3650A), amplitude and flux in the two bands are identical, so we adopt a flat spectrum in Flambda. At orbital minimum, the flux in Swift UVW1 is 2e-15 erg/cm2/s/AA, at orbital maximum 1.2e-14 erg/cm2/s/AA. We adopt the max. flux for the ETC run given above. The bright phase is a factor ~30 below the COS maximum count rate. We have good orbital phase coverage with Swift UVW1 (2600A) and SDSS u (3650A), amplitude and flux in the two bands are identical, so we adopt a flat spectrum in Flambda. At orbital minimum, the flux in Swift UVW1 is 2e-15 erg/cm2/s/AA, at orbital maximum 1.2e-14 erg/cm2/s/AA. We adopt the max. flux for the ETC run given above. The bright phase is a factor ~30 below the COS maximum count rate. We have good orbital phase coverage with Swift UVW1 (2600A) and SDSS u (3650A), amplitude and flux in the two bands are identical, so we adopt a flat spectrum in Flambda. At orbital minimum, the flux in Swift UVW1 is 2e-15 erg/cm2/s/AA, at orbital maximum 1.2e-14 erg/cm2/s/AA. We adopt the max. flux for the ETC run given above. The bright phase is a factor ~30 below the COS maximum count rate. We have good orbital phase coverage with Swift UVW1 (2600A) and SDSS u (3650A), amplitude and flux in the two bands are identical, so we adopt a flat spectrum in Flambda. At orbital minimum, the flux in Swift UVW1 is 2e-15 erg/cm2/s/AA, at orbital maximum 1.2e-14 erg/cm2/s/AA. We adopt the max. flux for the ETC run given above. The bright phase is a factor ~30 below the COS maximum count rate.