0 Assigned ID: 1122 ----- Attempting Submission 1 (Thu Sep 26 21:23:35 GMT 2019) ----- The visits for the safe position offset will need to be set up by the support scientist. This resubmission adds 50 sec unused time for each orbit to account for new times for acquisiton not included in APT. 641059535 ----- Attempting Submission 1 (Wed Nov 13 19:39:32 GMT 2019) ----- HST Phase II Proposal 16046 (16046ph2.apt) successfully submitted. Receipt: # 16046-1 ----- Attempting Submission 2 (Mon Dec 02 23:20:36 GMT 2019) ----- Understanding the Instability Strip of Accreting Pulsating White Dwarfs: Followup to a Recent COS Result Analysis of August, 2019 COS time-tag ultraviolet spectra shows great promise for confirmation of the physical properties defining the observed wide instability strip for pulsating white dwarfs in close binaries accreting material from their companions. The dwarf nova V386 Ser containing a pulsating white dwarf underwent its first rare large amplitude outburst in January 2019. The August UV spectra 7 months after this outburst implies a large He abundance from a white dwarf ~5000K hotter than at quiescence, with a pulsation period 6 times shorter than its quiescent one. Both the temperature and period fit with a mode driven by a He enriched composition, exactly what is predicted as the cause of the wide instability strip. For the first time, the observations match theoretical predictions! We propose to monitor the cooling during the next 6 months to further constrain the HeII and H/HeI convection zones in pulsating white dwarfs. This information is unique to the few white dwarf pulsators that undergo dwarf nova outbursts, as their heating and cooling only takes months-few years (versus millions of years in single white dwarf pulsators), presenting a rare opportunity to track how a deepening convection zone begins to drive pulsation modes with longer periods. Unfortunately, the January outburst missed the normal Cycle 26 deadline and the August observation (a Cycle 26 mid proposal) took place too late for results to provide a strong case for the Cycle 27 deadline. Due to the decades long recurrence time between outbursts in dwarf novae with pulsating white dwarfs, this is likely the last object HST can follow from outburst to quiescence. We will use COS with the G140L grating (setting 800) in time-tag mode for 3 consecutive HST orbits. This same configuration was used for the 2 orbits in our August 2019 observation which provided a useful spectrum with coverage between 900-1900A and detection of 3% amplitude pulsations. The AAVSO shows the system is currently at 18.5 magnitude, about one-half magnitude above quiescence and a half-magnitude fainter than the previous Aug observation. The 3 orbits will provide an adequate spectrum for determining the temperature which is expected to be somewhat cooler than the 20,000K determined in August. To maximize the determination of pulsations, the orbits should be consecutive. To maximize the cooling rate, the observations should be conducted as soon as possible within the window when the object is observable from the ground (Feb-March). Target acquisition will be done using the ACQ/IMAGE in the NUV. This is the first outburst since the discovery 19 years ago, meaning the outburst recurrence time is several decades. However, we will determine the precise quiescent magnitude within 24 hrs of the HST observation as done in the past. While the science is optimized if the observations take place as soon as possible (before the object cools to its quiescent temperature), if reduced gyros impact the observation windows, the observations can be made up to August 2020 when it will no longer be visible from the ground. All our team members have past experience with HST UV spectroscopy. The PI Szkody obtained the SBC spectrum of V386 Ser in 2005 and has had HST programs from Cycles 8 to 24 as PI or Co-I and was the PI of the mid-cycle 26 program that obtained COS G140L time-tag data in August 2019 that is shown in Figs 1 and 2. Co-I Gaensicke has had large COS UV programs in 2013 and 2017 with data analyzed with help from Co-I Toloza. Sion and Godon have also had numerous HST proposals and have done modeling of the white dwarfs. Kafka is the head of the AAVSO and coordinates ground-based coverage. Keaton Bell is an expert on pulsations of white dwarfs. Stellar Physics 3 false false true false false false false AVAILABLE STAR DWARF NOVA INTERACTING BINARY PULSATING VARIABLE NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 UNIDENTIFIED BLANK FIELD NO This object was generated by the targetselector and retrieved from the SIMBAD database. Ths target is a blank piece of sky which is the bright object safe pointing and is 9.794 arcseconds away at a PA 279.9 degrees from V-V386-SER. J2000 COS/FUV Spectroscopic No No G140L 800 Timing link suitability includes constraints ([01 After 1A by 3.0 to 5.0 days] [01 After 1A by at least 3.0 days]) The scheduling data was generated by CASM 28.0. CASM was run in Phase II mode. /private/var/folders/8k/sxlgy5ts2xdbykzf_vw6jrfw0001c5/T/OPVisit3119542052099372474.xml This should be scheduled in evening-local time. Flags need to be cleared during the work day. (Tic-Visit :proposal-id 16046 :visit-id "01" :proposal-version -1 :trans-version "20191203" :date "11-Feb-2020 15:58:09.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 591664 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16046 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16046 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2699 :al-overhead-at-end 0 :internal-dur-at-end 76 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16046 :visit-id "01" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2790 :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 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16046 :visit-id "01" :orbit-number 3 :pcs-time 302 :si-vis-utilization 2790 :al-overhead-at-end 0 :internal-dur-at-end 331 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 3 0 The scheduling data was generated by CASM 28.0. CASM was run in Phase II mode. /private/var/folders/8k/sxlgy5ts2xdbykzf_vw6jrfw0001c5/T/OPVisit17026359802002797791.xml This visit is for BOP checking the safetarget only and should not execute onboard HST. (Tic-Visit :proposal-id 16046 :visit-id "1B" :proposal-version -1 :trans-version "20191203" :date "11-Feb-2020 15:58:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 591664 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16046 :visit-id "1B" :obset-id "1B" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16046 :visit-id "1B" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2699 :al-overhead-at-end 0 :internal-dur-at-end 76 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16046 :visit-id "1B" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2790 :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 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16046 :visit-id "1B" :orbit-number 3 :pcs-time 302 :si-vis-utilization 2790 :al-overhead-at-end 0 :internal-dur-at-end 331 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 3 0 /private/var/folders/8k/sxlgy5ts2xdbykzf_vw6jrfw0001c5/T/OPVisit14873090582057765582.xml Timing link suitability includes constraints ([01 After 1A by 3.0 to 5.0 days] [01 After 1A by at least 3.0 days]) The scheduling data was generated by CASM 28.0. CASM was run in Phase II mode. This visit allocates and set up the safe position offset slot for visit 01 which will use that slot. This S/C visit should go earlier in the week while Visit 01 will be atleast 3 days later. The S/C visit will contain only 1 exposure. Note: weekends are to be avoided since the CS must clear the target within 24 hours of HST execution. (Tic-Visit :proposal-id 16046 :visit-id "1A" :proposal-version -1 :trans-version "20191203" :date "11-Feb-2020 15:58:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "11" :si-bright-earth-limb-angle 20.0 :data-volume 0 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16046 :visit-id "1A" :obset-id "1A" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16046 :visit-id "1A" :orbit-number 1 :pcs-time 333 :si-vis-utilization 5 :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 3142 :pcs-gap 0 ) true 1 0