0 Assigned ID: 16 ----- Attempting Submission 1 (Wed Mar 25 11:27:05 GMT 2015) ----- HST Phase I Proposal 16 (30Dor.apt) successfully submitted. Receipt: # 16-2 0 ----- Attempting Submission 1 (Tue Jul 14 14:16:44 GMT 2015) ----- The optical-UV extinction law in 30 Doradus We propose 1700-10 200 A STIS spectroscopy of over 30 stars in 30 Doradus to derive a detailed (~100 A resolution) family of UV-optical extinction laws. We will extend our previous optical study into the critical UV regime and we will significantly improve on past studies by increasing the wavelength resolution in the optical. Our proposed observations will provide the largest sample of UV spectra ever obtained along sightlines with large total-to-selective extinction ratios (R_5495), enabling robust analysis of such extinction laws for the first time. The coverage of a wide parameter space in R_5495 range and ISM physical conditions will shed new light on debates regarding the origins of differences in extinctions laws, such as the intensity of the 2175 A feature (e.g. the relative roles of metallicity vs. environmental conditions). In addition to the UV spectroscopy, the increased resolution in the optical region will improve the accuracy of the dereddening of stellar photometry and the analysis of the extinction in H II regions as measured by Balmer and Paschen lines. Regarding the latter, we will extract the hydrogen lines in emission in regions adjacent to the stars and compute their ratios. The variation in the strength of these hydrogen emission lines allows a direct comparison between stellar and gas extinction over a large wavelength range. This study is only possible with HST due to the spatial resolution required in the optical and the UV wavelength coverage (making it part of the UV initiative). With only 10 orbits it will produce detailed extinctions laws vital for the realistic dereddening of objects located in distant star-forming galaxies. The observations planned for this proposal follow the same strategy of a previous successful series of HST programs, the Next Generation Spectral Library or NGSL. The NGSL obtained 1700-10 200 Angstrom, R~ 1000, flux-calibrated spectroscopy of several hundred stars using a combination of G230LB+G430L+G750L exposures within a single HST orbit. Here we detail some of the characteristics of that approach and we specify some differences between our observations and those of the NGSL: - G230L cannot be used instead of G230LB because of the prohibitive cost of switching detectors within an orbit. G230LB also has the advantages of having a 52" slit instead of a 25" one (see next point) and of not having bright object issues. The G230LB disadvantage (slightly lower S/N) is relatively unimportant. - As opposed to the NGSL (which were three SNAPSHOT programs), we request ORIENTs in order to include several stars per slit and, in that way, maximize the use of STIS. - For each grating, we will split the exposures into two with a small dithering pattern in order to eliminate hot pixels and cosmic rays. - We have used the ETC and APT (phase 2 version) to calculate the exposure times and to test that all observations fit within a single orbit. Our required S/N (per spectral element) is lower than for the NGSL because our goal is not to build a detailed stellar library but to measure the extinction law i.e. we are interested in a good flux calibration (1% or better) but only after binning the data in ~100 Angstrom bins. The reason for the difference in S/N between the NGSL observations and ours is that our stars are fainter due to distance and extinction. - WAVECALs have to be turned off in order to fit all exposures within a single orbit (both for the NGSL and here). In our case, wavelength calibration can be easily done with our ground-based spectra and the overlap regions between gratings. - With the conditions above, the optimal exposure times as calculated with the ETC are 20 m, 8 m, and 8 m (in each case split into two) for G230LB, G430L, and G750L, respectively. Once the spectra are binned into 100 Angstrom bins, we obtain a S/N of 100 or better in 90% of the wavelength bins in the 1700-10 200 Angstrom range (and slightly lower values for the rest), which is our required target to derive a precise extinction law for each star. - One of the issues with the NGSL data was flux calibration due to the use of the narrow 52x0.2 slit. We will avoid that problem by using the wider 52x2 slit, which will also allow us to include more stars. Note also that we have multiband WFC3 photometry to allow us to perform an independent flux calibration. In any case, absolute UV-to-IR spectrophotometric calibrations are relatively easy to do with HST (as opposed to similar ground-based calibrations). - Another difference with the NGSL data is the stronger CTI effect due to the aging of the STIS CCD detector. To correct this, we will use an adaptation to STIS of the ACS code that yields a pixel-based CTI correction. We have successfully tested this code with the STIS CCD data we obtained in GO 12 465. In summary, this approach is a highly efficient use of STIS: we will obtain flux-calibrated 1700-10 200 Angstrom spectroscopy of over 30 stars in only 10 orbits. ISM AND CIRCUMSTELLAR MATTER 12 false true false false AVAILABLE EXT-STAR MAIN SEQUENCE O J2000 J2000 PA=39.1+180 EXT-STAR MAIN SEQUENCE O J2000 J2000 PA=43.4+180 EXT-STAR MAIN SEQUENCE O J2000 J2000 PA=5.5 EXT-STAR MAIN SEQUENCE O J2000 J2000 PA=143.4+180 EXT-STAR MAIN SEQUENCE O J2000 J2000 PA=143.9 EXT-STAR MAIN SEQUENCE O J2000 J2000 PA=109.7 EXT-STAR MAIN SEQUENCE O J2000 J2000 PA=100.0+180 EXT-STAR MAIN SEQUENCE O J2000 J2000 PA=150.3 EXT-STAR MAIN SEQUENCE O J2000 J2000 PA=97.8 EXT-STAR MAIN SEQUENCE O J2000 J2000 PA=107.5 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G230LB 2375 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G230LB 2375 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G230LB 2375 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G230LB 2375 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G230LB 2375 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G230LB 2375 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G230LB 2375 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G230LB 2375 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G230LB 2375 STIS/CCD Spectroscopic No No G750L 7751 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G230LB 2375 POS-TARG DITHER 0.25 LINE false false 2 90.0 STIS-ALONG-SLIT 1 false The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14104 :visit-id "01" :proposal-version -1 :trans-version "20150609" :date "14-Jul-2015 09:05:07.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 147648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14104 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14104 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 629 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14104 :visit-id "02" :proposal-version -1 :trans-version "20150609" :date "14-Jul-2015 09:07:44.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 147648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14104 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14104 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 629 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14104 :visit-id "03" :proposal-version -1 :trans-version "20150609" :date "14-Jul-2015 09:07:56.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 147648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14104 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14104 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 629 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14104 :visit-id "04" :proposal-version -1 :trans-version "20150609" :date "14-Jul-2015 09:08:18.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 147648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14104 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14104 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 629 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14104 :visit-id "05" :proposal-version -1 :trans-version "20150609" :date "14-Jul-2015 09:08:42.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 147648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14104 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14104 :visit-id "05" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 629 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14104 :visit-id "06" :proposal-version -1 :trans-version "20150609" :date "14-Jul-2015 09:09:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 147648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14104 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14104 :visit-id "06" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 629 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14104 :visit-id "07" :proposal-version -1 :trans-version "20150609" :date "14-Jul-2015 09:09:17.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 147648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14104 :visit-id "07" :obset-id "07" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14104 :visit-id "07" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 629 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14104 :visit-id "08" :proposal-version -1 :trans-version "20150609" :date "14-Jul-2015 09:10:08.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 147648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14104 :visit-id "08" :obset-id "08" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14104 :visit-id "08" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 629 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14104 :visit-id "09" :proposal-version -1 :trans-version "20150609" :date "14-Jul-2015 09:10:31.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 147648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14104 :visit-id "09" :obset-id "09" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14104 :visit-id "09" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3214 :al-overhead-at-end 0 :internal-dur-at-end 629 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14104 :visit-id "10" :proposal-version -1 :trans-version "20150609" :date "14-Jul-2015 09:10:47.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 147648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14104 :visit-id "10" :obset-id "10" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14104 :visit-id "10" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 629 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3556 :pcs-gap 0 ) false 1 0