0 Assigned ID: 309 ----- Attempting Submission 1 (Fri Apr 11 00:38:09 GMT 2014) ----- This is basically a duplicate of the target done for Proposal 12870, altho the exposure times had to be shortened a bit so there would be no visibility overrun. 2141793259 ----- Attempting Submission 1 (Tue Jul 08 22:06:05 GMT 2014) ----- The unique dwarf nova GW Lib, the prototype of cataclysmic variables containing white dwarfs that exhibit non-radial pulsations at quiescence, underwent the largest known amplitude outburst from an accretion disk instability (9 mag) in 2007. This huge outburst provided an unprecedented opportunity to probe how the interior white dwarf structure reacts to the accretion of mass and angular momentum by using its pulsation spectrum. As the outer envelope cools, the pulsation spectrum evolves, and we obtain the first opportunity to track how a white dwarf evolves through the instability strip on a timescale of just years.We have monitored GW Lib since its outburst with ground and COS observations. For the first 4 years after outburst, GW Lib followed a normal cooling pattern, with a different pulsation period than at quiescence becoming visible by year 3. However, rather than continuing to cool to its quiescent temperature, our latest 2013 COS observation showed a hotter temperature than in 2011, as well as a variable flux, temperature and pulsation amplitude during the HST orbits. As no previous dwarf nova has been followed for more than 3 years after outburst, and it is now obvious that the white dwarf in GW Lib does not cool monotonically, we propose to continue the cooling curve with a COS measurement in 2015. The cooling can only be constrained by an UV spectrum with HST (the optical spectrum is too contaminated by the accretion disk to determine a valid temperature) and the ratio of the UV to optical pulsation amplitude is needed to provide the mode index, essential for modeling the structure of the underlying white dwarf. We have 2 goals in mind for these observations. One is to obtain a summed UV spectrum with sufficient S/N (>10) to allow a temperature determination of the underlying white dwarf by fitting the spectrum to white dwarf models. The second is to obtain time-resolved light curves by summing the background-subtracted TIME-TAG fluxes over several wavelength bands in 3sec intervals to detect and constrain the UV pulsations. From our past observations, we know that both goals can be accomplished by using the COS FUV with the G140 L grating which provides good coverage from 1100-2000A. The orbital period of GW Lib is very short (77 min) and the inclination is low (11 deg) so there is a good view of the white dwarf throughout the GW Lib orbit. Three HST orbits will provide a good spectrum as well as a light curve that will reveal pulsations down to a few percent, and allow further study of the relation between temperature and pulsation changes as observed in 2013. We will continue our ground observing programs on GW Lib to: 1) monitor the pulsation spectrum changes prior to the HST observations, 2) provide confirmation that the objects are close to quiescence at the time of the HST observation (the outburst recurrence time for GW Lib is about 25 yrs and 3) determine the amplitude of the optical pulse for comparison with that from the UV (the UV/optical amplitude ratio allows the mode determination). While the outburst timescale for GW Lib is on the order of 25 years, with the last outburst in 2007, HST still requires ground monitoring prior to the HST observations to ensure that it remains at quiescence. To accomplish this (using the AAVSO worldwide network as we have done for our past observations), as well as obtaining near-simultaneous data to compute our UV/opt pulsation amplitude ratio, we need the HST observation scheduled during months when GW Lib can be observed from the ground (Mar to June 2015). The best months would be April or May. HOT STARS Default false true false false false AVAILABLE STAR DWARF NOVA PULSATING VARIABLE J2000 J2000 UNIDENTIFIED BLANK FIELD This target is a blank piece of sky which is the bright object safe offset for GW-LIB. J2000 COS/FUV Spectroscopic No No G140L 1105 1404855053305 The scheduling data was generated by CASM 22.2. CASM was run in Phase II mode. This should be scheduled in during the evening - Baltimore time. Flags need to be cleared during the work day. The PHASE requirement will enforce this. (Tic-Visit :proposal-id 13807 :visit-id "01" :proposal-version -1 :trans-version "20140605" :date "08-Jul-2014 14:30:53.0" :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 391424 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13807 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13807 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2666 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2999 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13807 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2777 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2999 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13807 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2777 :al-overhead-at-end 0 :internal-dur-at-end 442 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2999 :pcs-gap 0 ) false 3 0 This visit allocates and sets 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 at least 3 days later. The PHASE requirement will ensure that the visit is sheduled on a Sunday. false -1 -1 1404855053305 This visit is for BOP checking the safe target only and should not execute onboard HST. (Tic-Visit :proposal-id 13807 :visit-id "01" :proposal-version -1 :trans-version "20140605" :date "08-Jul-2014 14:30:53.0" :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 391424 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13807 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13807 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2666 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2999 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13807 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2777 :al-overhead-at-end 0 :internal-dur-at-end 114 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2999 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13807 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2777 :al-overhead-at-end 0 :internal-dur-at-end 442 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2999 :pcs-gap 0 ) false 3 0