0 Assigned ID: 1006 ----- Attempting Submission 1 (Fri Apr 07 22:35:45 GMT 2017) ----- For the best data quality, it is strongly recommended that the maximum number of allowed FP-POS positions is used when observing at a given COS CENWAVE setting. See full description for details. For the best data quality, it is strongly recommended that all four FP-POS positions are used when observing at all COS CENWAVE settings, with the exception of the G130M/1291 configuration with SEGMENT=B,BOTH at LP4. For this setting, only FP-POS=3 and FP-POS=4 are allowed and this is the setting we are using in this program. -825219863 ----- Attempting Submission 1 (Thu Jul 20 13:43:16 GMT 2017) ----- For the best data quality, it is strongly recommended that all four FP-POS positions are used when observing at all COS CENWAVE settings, with the exception of the G130M/1291 configuration with SEGMENT=B,BOTH at LP4. For this setting, only FP-POS=3 and FP-POS=4 are allowed and this is the setting we are using in this program. Unveiling the mysterious nature of the cataclysmic variable SDSS J153817.35+5123238.0 Evolution of cataclysmic variables (CVs) is driven by angular momentum loss, which keeps mass loss from the donor star continually going, replenishing the disc with new higher-momentum material and maintaining, in this way, the accretion process. The angular momentum loss rate can be accurately constrained by measuring the white dwarf (WD) effective temperature (Teff), and provides one of the best available tests for the present model of the CV evolution. We conducted an HST/COS survey (ID 12870, PI Gaensicke) in which we measured Teff for 31 CV WDs. Our results are in good agreement with the theoretical prediction with one exception: SDSS J153817.35+5123238.0, a short period (93.1 min) CV which contains an anomalously hot WD. We argue that the system is either a very young CV (~20Myr), or has been recently re-heated to ~35000K. While the former hypothesis is statistically unlikely, the latter is most likely related to a nova eruption within the past few 1000 years or to additional mechanisms of angular momentum losses that are not account for by the present theory of CV evolution. To distinguish between these three scenarios, we need higher resolution UV observation to accurately measure the white dwarf mass, its effective temperature and photospheric abundances, along with a search for absorption features due to an ejected shell and their velocity. In this way we will constrain the WD age (from an improved mass measurement), its cooling rate (from this second temperature measurement) and we will also identify possible ashes and the expanding circumstellar gas shell expected in case of a recent nova explosion, shedding light on the mysterious nature of this system. The aim of this program is to obtain high-resolution far-ultraviolet COS G130M spectroscopy of the cataclysmic variable white dwarf SDSS J1538. Our previous observations of this object on Cycle 20 with COS/G140L (dataset LC1V30010) demonstrated that the white dwarf is the dominant source of emission in the ultraviolet, with an effective temperature ~30 000 K. Given the white dwarf temperature, it is quite unlikely that SDSS J1538 can experience a dwarf nova outburst. Nonetheless, in order to insure the safety of the COS detectors, we will carry out an intense ground-based monitoring leading up to the HST observations. We will perform the target acquisition in dispersed light using the G130M grating. The coordinates and proper motions are drawn from the PPMXL catalogue, which has proven to be reliable and accurate to fractions of an arcsec, hence we do not precede the observations with a search pattern. We will make use of the 2 FP-POS positions available for G130M at the central wavelength 1291 A. Stellar Physics 6 false true false false false false AVAILABLE STAR DWARF NOVA NO J2000 UNIDENTIFIED BLANK FIELD NO This target is a blank piece of sky which is the bright object safe pointing and is 9.043 arcseconds away at PA (U3) 230.3 degrees from SDSSJ1538+5123. COS/FUV Spectroscopic No No G130M 1291 Timing link suitability includes constraints ([01 After 02 by 3.0 to 5.0 days] [01 After 02 by at least 3.0 days]) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. This visit should be scheduled in the day or evening-local time. Flags need to be cleared during the work day. (Tic-Visit :proposal-id 15316 :visit-id "01" :proposal-version -1 :trans-version "20171009" :date "01-Mar-2018 19:41:21.0" :trans-errors '(:WARNINGS 1 :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 487152 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15316 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15316 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2669 :al-overhead-at-end 0 :internal-dur-at-end 105 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3002 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15316 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2780 :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 3002 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15316 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2780 :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 3002 :pcs-gap 0 ) false 3 1 Timing link suitability includes constraints ([01 After 02 by 3.0 to 5.0 days] [01 After 02 by at least 3.0 days]) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. 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. This 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 15316 :visit-id "02" :proposal-version -1 :trans-version "20171009" :date "01-Mar-2018 19:41:21.0" :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 15316 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15316 :visit-id "02" :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 3393 :pcs-gap 0 ) false 1 0 This visit allocates and sets up the safe position offset slot for visit 1531601, which will use that slot. This S/C visit, 1531602, should go earlier in the week while 1531601 will be at least 3 days later. Note: weekends are to be avoided since the CS must clear the target 24 hours before HST execution. The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. This visit is for BOP checking the safe target pointing only and should not execute onboard HST. (Tic-Visit :proposal-id 15316 :visit-id "03" :proposal-version -1 :trans-version "20171009" :date "01-Mar-2018 19:41:23.0" :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 487152 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15316 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15316 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2669 :al-overhead-at-end 0 :internal-dur-at-end 105 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3002 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15316 :visit-id "03" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2780 :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 3002 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15316 :visit-id "03" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2780 :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 3002 :pcs-gap 0 ) true 3 0