In the recent years, four white dwarfs with gaseous planetary debris disk were discovered. It is thought that they were created by tidally disrupted planetary bodies. This offers the unique possibility to determine directly the composition of exo-planetary material by spectroscopic means. However, only very few bright emission lines from the optically thin gas disk are detectable because the white dwarf's photospheric flux in the near-IR to UV spectral band is rather strong. Here we propose to perform far-UV observations of one of these WDs shortward of 115 nm where the WD flux is effectively blocked by broad and deep photospheric hydrogen Lyman lines. We expect to detect disk emission lines from carbon and silicon. Together with optical and near-UV archival spectra that exhibit lines from Ca, Mg, and Fe, this enables us for the first time to determine the relative abundances of most of the abundant elements in the disk. In particular, we may decide whether the planetary debris was formed from chondritic or bulk-Earth like material. We want to observe our single target for 4 orbits with COS/G130M with central wavelength setting 1096 A, where Segments B and A cover 940-1080 A and 1096-1236 A, respectively. Orbit 1: guide star and target acquisition; science overhead; science integration Orbits 2-4: guide star re-acquisition; science overhead; science integration FP-POS change: Each orbit is at one different position, i.e., no overhead In total, we will achieve S/N=2-4 in the 905-1050A range (when binned over 6px). Further binning to sufficient 2A resolution yields S/N=12-23. At longer wavelengths, S/N increases strongly, e.g. S/N>50 at 1110A. ISM AND CIRCUMSTELLAR MATTER 12 false false 0.0 0.0 false false false SUPPORTED STAR DA J2000 J2000 6.0E-14 erg/cm2/s/A @ 1150 A COS/FUV Spectroscopic No No G130M 1096 The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. 1364038347000 201.4733529236405 (Tic-Visit :proposal-id 12906 :visit-id "01" :proposal-version -1 :trans-version "20120604" :date "02-Jul-2012 16:06:55.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 408928 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12906 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12906 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2682 :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 3015 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12906 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2793 :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 3015 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12906 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2793 :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 3015 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12906 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2793 :al-overhead-at-end 0 :internal-dur-at-end 385 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3015 :pcs-gap 0 ) true 4 0 (Tic-Visit :proposal-id 12906 :visit-id "01" :proposal-version -1 :trans-version "20120604" :date "02-Jul-2012 16:06:55.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 408928 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12906 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12906 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2682 :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 3015 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12906 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2793 :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 3015 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12906 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2793 :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 3015 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12906 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2793 :al-overhead-at-end 0 :internal-dur-at-end 385 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3015 :pcs-gap 0 ) false 4 0