Final version. I mean it this time. Assigned ID: 265 ----- Attempting Submission 1 (Fri Feb 26 05:44:20 GMT 2010) ----- HST Phase I Proposal 265 (CHVC_phase1.apt) successfully submitted. ----- Attempting Submission 2 (Fri Feb 26 21:30:50 GMT 2010) ----- HST Phase I Proposal 265 (CHVC_phase1.apt) successfully submitted. ----- Attempting Submission 3 (Fri Feb 26 22:40:12 GMT 2010) ----- HST Phase I Proposal 265 (CHVC_phase1.apt) successfully submitted. ----- Attempting Submission 4 (Fri Feb 26 22:47:13 GMT 2010) ----- HST Phase I Proposal 265 (CHVC_phase1.apt) successfully submitted. ----- Attempting Submission 5 (Fri Feb 26 23:02:02 GMT 2010) ----- Updated V-mag for B0117-2837, as requested by CS Ghavamian. ----- Attempting Submission 1 (Tue Jun 29 16:47:41 GMT 2010) ----- HST Phase II Proposal 12204 (CHVC_phase2.apt) successfully submitted. ----- Attempting Submission 2 (Fri Jul 02 03:53:42 GMT 2010) ----- ----- Attempting Submission 3 (Fri Jul 30 21:13:05 GMT 2010) ----- Probing the Ionized Gas in the Magellanic Stream We propose a 14 orbit pilot study to investigate the ionized gas in the interface region between the cool neutral gas of the Magellanic Stream and the ambient hot gas of the Milky Way halo. We have chosen 3 bright QSOs clustered around a small (~1 sq. deg.) cloud associated with the Magellanic Stream. One of these QSOs (Ton S210) probes the neutral 21cm gas, while the other two lie just outside 21cm contours. Observations of Ton S210 will be used in conjunction with neutral and low-ionization absorption lines to set the metallicity of the gas. The outer two targets will be used to detect higher ionization states such as CIV, SiIV and NV, that typically trace warm ionized gas. The observed metallicity, gas temperature and line ratios will be used as inputs to modeling in order to determine the ionization state and physical conditions of the gas in the cool-hot interface region. Contingent on the success of this pilot program, we anticipate future observations to fully characterise the ionization state along the full length of the Magellanic Stream. These observations would be a significant advance in our understanding of the nature of Milky Way halo, the evolution of clouds in the halo, and the formation and ultimate fate of the Magellanic Stream. They will also have important implications for the inpretation of z > 0 QSO absorption-line studies.
We will employ the COS medium-resolution FUV gratings G130M and G160M to obtain medium- to high-S/N observations of our 3 targets. The medium resolution gratings (dv ~ 15km/s) are required in order separate the halo cloud absorption (v_LSR ~ -200km/s) from the strong MW disk absorption (v_LSR ~ 0km/s). Using both FUV gratings allows us to cover a host of neutral, low- and high-ionization species. Line ratios of multiple ionization states of the same element, such as SiII, SiIII, and SiIV will allow us to disentangle the ionization conditions of the gas, determining the metallicity, density and temperature of the neutral and ionized gas. We have used the COS ETCs to estimate our time requirements as follows. In all cases, the overheads were set by the recommended acquisition strategy, combined with our experience in Cycle 17. For TonS210 we perform two separate calculations. In the first, we use the measured GALEX magnitudes, with the FOS QSO template at the measured redshift (z_qso = 0.117) to estimate the time required to achieve S/N ~ 30 at all points in the G130M grating, and S/N > 25 for the majority of the G160M wavelength range. The different S/N requirement is set by our need to detect weaker features in the G130M wavelength range, in order to provide an accurate metallicity measurement. The ETCs indicate these S/N requirements are met in 4600s for G130M (COS.A244561) and 4800s for G160M (COS.A244564). Since low S/N STIS data exist for this target, we can double-check these numbers using the same parameters, but normalizing by the observed flux in the STIS spectrum, {viz 3.0x10^-14 erg/cm^2/s/A at 1310A (G130M; COS.A274426) and 2.3x10^-14 erg/cm^2/s/A at 1544A (G160M; COS.A274446). We obtain consistent estimates using both techniques. We have used 3 exposures for each grating and CENWAVE setting, but with different FP-POS settings in order to be able to remove the detector fixed pattern noise. For our other two targets we adopt the same approach as above. The GALEX magnitudes are used to normalize the FOS QSO template and the redshifts set to z_qso = 0.347 and z_qso = 0.4347. Since our primary goal is to detect the ionized gas towards these sightlines, and ionized transitions such as CIV are typically stronger, the limiting equivalent width (and hence S/N requirements) can be relaxed. We aim to obtain S/N > 10 for these sightlines at all points along the spectra. The ETC indicates the required time is 4600s for the G130M grating (COS.A244109, COS.A244129) and 7200s for G160M (COS.A245621, COS.A245623). Since these two targets are fainter, and hence will have lower S/N, we employ only 2 FP-POS settings per grating/cenwave combination. In all cases, our exposure times have been rounded up to the nearest whole orbit, to compensate for QSO fading and the COS time-dependent sensitivity drop. ACQUISITIONS: We have used the COS ETC to estimate the exposure times for ACQ/IMAGE acquisition (recommended for Cycle 18), using the measured GALEX NUV fluxes, which match closely to the COS NUV imaging bandpass. Since these acquisition times are typically short (~30s or less), and to allow a "safety margin" in the case that the QSO fades, we calculate acquisition times half a magnitude fainter than the observed magnitude. This typical adds ~15-20s to the acquistion time. As above, these calculations were done assuming an FOS QSO template, with the measured QSO redshift. ISM AND CIRCUMSTELLAR MATTER 0 false 0.0 0.0 false false false false false false SUPPORTED ISM ABSORPTION LINE SYSTEM - GALACTIC HIGH VELOCITY CLOUD This object was generated by the targetselector and retrieved from the SIMBAD database. The co-ordinates are taken from the 2MASS point-source catalogue. N.B. This object has been previously observed with STIS. The difference between the 2MASS ICRS co-ordinates, and those listed in the archive for the STIS observations are ~0.1arcsec. GALEX MAGS: m_FUV = 15.366 +/- 0.024; m_NUV = 15.241 +/- 0.013 J2000 01 21 51.5100 -28 20 57.80 J2000 ISM HIGH VELOCITY CLOUD This object was generated by the targetselector and retrieved from the 2MASS database. GALEX MAGS: m_FUV = 16.815 +/- 0.042; m_NUV = 16.590 +/- 0.024 J2000 01 19 35.6966 -28 21 31.43 J2000 ISM ABSORPTION LINE SYSTEM - GALACTIC HIGH VELOCITY CLOUD This object was generated by the targetselector and retrieved from the 2MASS database. GALEX MAGS: m_FUV = 17.151 +/- 0.051; m_NUV = 16.925 +/- 0.028 J2000 01 22 36.7678 -28 43 21.37 J2000 COS/FUV Spectroscopic No No G130M 1291 COS/FUV Spectroscopic No No G130M 1309 COS/FUV Spectroscopic No No G160M 1600 COS/FUV Spectroscopic No No G160M 1623 COS/FUV Spectroscopic No No G130M 1291 COS/FUV Spectroscopic No No G130M 1309 COS/FUV Spectroscopic No No G160M 1600 COS/FUV Spectroscopic No No G160M 1623 COS/FUV Spectroscopic No No G130M 1291 COS/FUV Spectroscopic No No G130M 1309 COS/FUV Spectroscopic No No G160M 1600 COS/FUV Spectroscopic No No G160M 1623 /Users/cthom/work/Proposals/HST/Cycle18/CHVC/APT/OP-cache/CHVC_phase2-v01.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12204 :visit-id "01" :proposal-version -1 :trans-version "20100505" :date "30-Jul-2010 17:10:01.0" :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 1165824 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12204 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12204 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2885 :al-overhead-at-end 0 :internal-dur-at-end 50 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 50 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 50 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 362 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) true 4 0 /private/var/folders/5v/5vr0bsBnF7e0GDFNs6V6MU++1l+/-Tmp-/OPVisit4494062581282339702.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12204 :visit-id "02" :proposal-version -1 :trans-version "20100505" :date "30-Jul-2010 17:12:02.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 887552 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12204 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12204 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2885 :al-overhead-at-end 0 :internal-dur-at-end 40 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 40 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "02" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 40 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "02" :orbit-number 4 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 40 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "02" :orbit-number 5 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 352 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) true 5 0 /private/var/folders/5v/5vr0bsBnF7e0GDFNs6V6MU++1l+/-Tmp-/OPVisit2444556185787172526.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12204 :visit-id "03" :proposal-version -1 :trans-version "20100505" :date "30-Jul-2010 17:12:06.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 887552 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12204 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12204 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2885 :al-overhead-at-end 0 :internal-dur-at-end 40 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "03" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 40 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "03" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 40 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "03" :orbit-number 4 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 40 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12204 :visit-id "03" :orbit-number 5 :pcs-time 222 :si-vis-utilization 3035 :al-overhead-at-end 0 :internal-dur-at-end 352 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3257 :pcs-gap 0 ) true 5 0