Initial submission 1446151624 Assigned ID: 3887 ----- Attempting Submission 1 (Thu Feb 16 13:25:02 GMT 2023) ----- ----- Attempting Submission 2 (Wed Feb 22 10:23:32 GMT 2023) ----- For the best data quality, it is generally required to use all four FP-POS positions when observing at a given COS cenwave. See the COS Instrument Handbook for exceptions that may apply to observations with G130M/1291 or G160M. We note that the target itself is a point source, although it is embedded within an extended H II region. Since the target is a point source, I have set EXTENDED=False. Given the uncertainty of the FUV and NUV magnitudes, should I be setting the buffer time to a lower value to be "safe"? The current buffer time is based on measured U-band magnitudes (U=12.5), spectral type (B0V) and reddening E(B-V)=0.95. As per the manual recommendation, we use FP-POS=3,4 due to our chosen setup (G130M/1291). -1910210177 ----- Attempting Submission 1 (Tue Apr 04 12:45:29 GMT 2023) ----- HST Phase II Proposal 17303 successfully submitted. Receipt: # 17303-1 ----- Attempting Submission 2 (Fri Apr 07 17:18:50 GMT 2023) ----- HST Phase II Proposal 17303 successfully submitted. Receipt: # 17303-2 ----- Attempting Submission 3 (Tue Apr 25 19:57:21 GMT 2023) ----- We are using G130M/1291, so we only use FP-POS=3,4. The cosmic abundance of helium-3 (3He) is a key probe of cosmology and galactic chemical evolution. However, 3He is extremely difficult to measure. Recently, metastable 3He (3He I*) was detected for the first time in absorption against the light of an O star in the Orion Nebula. Motivated by their discovery, we searched the world's optical and near-infrared data archives for new examples of He I* absorbers. With this 1 orbit mid-cycle application, we propose to record HST/COS FUV data of the highest value target that we have only just identified - a young O star in the outer Milky Way (at a galactocentric radius of ~12.5 kpc) that intersects previously unidentified strong He I* absorption. Galactic chemical evolution models predict that the helium isotope ratio (3He/4He) in this distance regime is enhanced by just ~10 percent relative to a primordial composition. The key goal of these HST data is to measure the gas-phase metallicity of the cloud that gives rise to the near-infrared He I* absorption. Combining our new result with literature measurements, we will fit a linear relationship between metallicity and the 3He/4He ratio, and extrapolate this relationship to zero-metallicity; such an extrapolation will deliver our current best opportunity to deduce - for the first time - the primordial 3He/4He value. As an added bonus, with the same data we will: (1) compare absorption and emission line abundances of this outer Milky Way H II region; (2) search for evidence of a radial abundance gradient in the Milky Way using absorption line techniques; and (3) assess the prospects of measuring D/H with a future application. Our aim is to measure the metallicity of the H II region PDS 241, which intersects strong metastable He I* absorption. The star that we will target is the brightest in the H II region. We will use COS/FUV (G130M with CENWAVE=1291) to measure the H I column density from Lya (1215A) and a column density of a volatile metal (N I, O I, or S II). We note that the H I column density of this sightline has never been measured, and it's FUV flux is not known. Based on the U band magnitude (U=12.5) and the extinction (E(B-V)=0.6) we have estimated that with one orbit, we will achieve a S/N=20 per resolution element. We will also use these data to assess the feasibility of measuring D I with future observations. The expertise of our team completely covers the full aims and goals of this program. The main goals of this program extend the work described in a recent paper by the Co-Is on this proposal. R. Cooke, P. Noterdaeme, M. Pettini, L. Welsh, and C. Peroux have significant experience with absorption line fitting, isotopic abundances, primordial nucleosynthesis, and UV/optical/near-infrared echelle spectroscopy. J. Johnson and D. Weinberg are experts at developing Galactic Chemical Evolution models, and are responsible for developing the models that we will use to interpret our observations in the context of our Galaxy. Stellar Populations and the Interstellar Medium Large Scale Structure of the Universe 3 false true true false false true false false SUPPORTED STAR B0-B2 V-IV BE EMISSION LINE NEBULA STAR FORMING REGION NO This object was generated by the targetselector and retrieved from the SIMBAD database. The PI confirms the coordinates. Note that the target is a point source, but it resides in an H II region that is extended. The FUV and NUV magnitudes of the target are not known, so the buffer time is estimated based on a B0V star with E(B-V)=0.95, and U=12.5. PDS-241 J2000 J2000 U=12.48, B=12.71 COS/FUV Spectroscopic No No G130M 1291 1682452545924 /private/var/folders/4l/h7gyzvc929l47zxcdb5tz7v00000gp/T/OPVisit2100197453434223981.xml The scheduling data was generated by CASM 31.0. CASM was run in Phase II mode. We only use FP-POS=3, as per the guidelines for G130M/1291. (Tic-Visit :proposal-id 17303 :visit-id "01" :proposal-version -1 :trans-version "20220630" :date "25-Apr-2023 20:55:45.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 87104 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17303 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17303 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2749 :al-overhead-at-end 0 :internal-dur-at-end 379 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0