mid-Cycle HST proposal. -77554714 Assigned ID: 1255 ----- Attempting Submission 1 (Fri Jan 29 22:35:03 GMT 2016) ----- HST Phase I Proposal 1255 (pristine.apt) successfully submitted. Receipt: # 1255-1 For the best data quality, it is strongly recommended that all four FP-POS positions be used when observing at a given COS CENWAVE setting. For the best data quality, it is strongly recommended that all four FP-POS positions be used when observing at a given COS CENWAVE setting. 0 ----- Attempting Submission 1 (Mon Mar 21 19:54:07 GMT 2016) ----- We have used all 4 FP-POS positions in our program, but they are split across 2 visits in order to make the visits <=3 orbits. The explosions of Population III stars provided the first metal pollution of the Universe. These stars eventually polluted their own and other nearby halos with sufficient metals to allow the formation of a more normal, less top-heavy population of stars. The subsequent Pop II stars produced the majority of the metals seen in the Universe today. However, is that pollution complete? While some ultra-metal poor stars in the Galactic halo may be fossils of the Pop III epoch, are there regions of the Universe that remain untouched by Pop II metal pollution at low redshift? We have identified a z~0.9 Lyman limit system - a dense stream of gas likely associated with a galaxy halo - with [Mg/H] < -2.4 on the basis of a low-resolution COS snapshot observation. We propose a 5 orbit COS NUV program to attempt to determine the metallicity of this gas through the very strong C III 977 Ang transition, pushing our sensitivity to [C/H] < -3.3, i.e., into the regime of Pop III-only enrichment at metallicities comparable to the z~4 IGM. We will also use these data to confirm our H I column density and study the temperature and kinematics of the gas using Lyman series absorption. With our statistical sample of metallicities in 60 LLSs, these observations will allow us to determine the fraction of high over-density gas at z<1 that remains relatively pristine, perhaps unenriched since the Pop III epoch. We have recently identified a Lyman limit system (LLS) - a dense stream of gas with H I column density log N(HI) ~ 17.2 - at z<1 that may have been unenriched since the epoch of Population III stars. This system was chosen from a sample of LLSs identified in a Cycle 18 snapshot survey and is H I selected. Our proposed observations will target the z=0.89759 LLS toward J1500+4836 using the COS G185M grating with central wavelength setting 1850. This setting fortuitously provides coverage of most of the Lyman series lines for this absorber (spanning strengths from Ly -betathrough Ly-20) plus metal lines C II 1036, C III 977, and O VI 1031. Given the metallicity limits for this absorber, we do not expect to detect C II, but it provides a consistency check on our models. In 5 orbits we will obtain S/N~8 per resolution element for the metal transitions and S/N~6 for the higher-order Lyman series lines Intergalactic Medium and Cosmology 3 false true false false false false SUPPORTED GALAXY QSO NO SDSSJ150031.79+483646.9 RXJ1500.5+4836 J2000 J2000 COS/NUV Spectroscopic No No G185M 1835 /private/var/folders/4m/4kt1pgtw8xj7rr006s6dgwv80000gp/T/OPVisit7032476130789652724.xml 1458589982326 The scheduling data was generated by CASM 24.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14490 :visit-id "01" :proposal-version -1 :trans-version "20160129" :date "21-Mar-2016 15:53:02.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "32" :si-bright-earth-limb-angle 20.0 :data-volume 461024 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14490 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14490 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3018 :al-overhead-at-end 0 :internal-dur-at-end 86 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3352 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14490 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3127 :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 3352 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14490 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3127 :al-overhead-at-end 0 :internal-dur-at-end 407 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3352 :pcs-gap 0 ) true 3 0 Used as input for the ETC a model of the observed spectrum. This uses a Telfer composite continuum absorbed by the Lyman limit systems we have fit along this sight line. The use of the model allows us to extend the flux to longer wavelengths as needed for the imaging. 1458589977631 /private/var/folders/4m/4kt1pgtw8xj7rr006s6dgwv80000gp/T/OPVisit3369657352429879041.xml The scheduling data was generated by CASM 24.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14490 :visit-id "02" :proposal-version -1 :trans-version "20160129" :date "21-Mar-2016 15:52:57.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "32" :si-bright-earth-limb-angle 20.0 :data-volume 304480 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14490 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14490 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3018 :al-overhead-at-end 0 :internal-dur-at-end 86 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3352 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14490 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3127 :al-overhead-at-end 0 :internal-dur-at-end 407 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3352 :pcs-gap 0 ) true 2 0 Used as input for the ETC a model of the observed spectrum. This uses a Telfer composite continuum absorbed by the Lyman limit systems we have fit along this sight line. The use of the model allows us to extend the flux to longer wavelengths as needed for the imaging.