8196( 4) - 06/07/99 10:09 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8196 Version: 4 Check-in Date: 07-Jun-1999 10:08:16 1.Proposal Title: High Spatial Resolution UV/Optical Spectroscopy of H II Regions in the Magellanic Clouds ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Donald Garnett University of Minnesota CoI: Prof. Reginald Dufour Rice University N ------------------------------------------------------------------------------------ 5. Abstract We propose to obtain high signal/noise UV/optical spectra of several H II regions in the SMC with STIS to make definitive measurements of the abundances of C and N, and to study the temperature, density, and ionization structures of the nebulae at 10^17 cm resolution. We will measure gas-phase C/O and N/O ratios from UV emission lines of C III, N III, and O III, which can provide very reliable abundance determinations. The new C/O and N/O measurements will be used to address apparent discrepancies between C and N abundances in the H II regions and those derived in luminous stars in the Clouds. N III measurements will provide the first reliable N abundances in the Clouds, and resolve disagreements between optical and IR abundance determinations. We will look at the magnitude of spatial variations in C/O and N/O to study the efficiency of mixing of PN ejecta in the ISM. Measurements of Si III Lambda1883 will yield accurate Si/O ratios and a better understanding of grain depletions in a variety of environments. Our H II region sample overlaps that of an ISO IR spectroscopy program, which will provide complementary information on several ions not observable in the optical/UV spectrum. High spatial resolution mapping of physical conditions and ionization will enable us to develop photoionization models of greatly improved accuracy for the Magellanic Cloud regions. ------------------------------------------------------------------------------------ 8196( 4) - 06/07/99 10:09 - [ 2] Observations Description ------------------------ We will obtain long-slit spectra of three high surface brightness H II regions in the SMC using STIS/NUV plus G230L(1570-3180) and G230M(1839-1929) in the UV and STIS/CCD to cover the optical with three grating settings: G430L(2900- 5700), G750L(5236-10266), and G750M(6482-7054). The 52X0.2 slit will be used for all the spectra to optimize both spectral resolution and throughput. The low-resolution L gratings provide high sensitivity at moderate spectral resolution, while an exposure in G750M is needed to resolve the important HAlpha+ N II and S II blends. A deep exposure in G230M will resolve the C III 1907, 1909 pair, whose ratio is sensitive to electron density. We divide our observations into 3- or 4-orbit timelines of 96 minutes each, since we are proposing to take advantage of several CVZ opportunities available for the SMC. For each target, we allocate 6 min for ACQ and 6 min for offset (REACQ of guidestars); taking into account overhead time for grating changes (= 3 X 6 min for CCD and 2 X 8 min for NUV-MAMA) leaves a net 231 minutes available for actual STIS exposures during a three-orbit visit. Within such a visit, we will divide the available exposure time as follows: 20 min for G750L, 6 min for G750M, 20 min for G430L, 60 min for G230M, and 120 min for G230L. With CR- SPLITs for the longest CCD exposures, we calculated the S/N expected (with the STIS ETC) for key emission lines needed in our science objectives: S II 6717, 31 for G750L and G750M, O III 4363Angstrom\ for G430L, and O III 1660, 6 for G230L. Based on our FOS observations of SMC N88A, we present the S/N derived for a ``generic'' SMC H II region for the times listed above and given surface brightness (``S'' in units of 10^-15 ergs cm^-2 arcsec^-2). For our ``generic'' SMC H II region, S = (25, 4, & 5) for the weak, but crucial, lines of 1666Angstrom, 4363Angstrom, and 6723Angstrom, respectively. Using these surface brightnesses, an equal amount of underlying continuum at 1666 Angstrom, a throughput of 0.003 at 1666 Angstrom, and a background count rate computed with the STIS ETC, we estimate s/n per resolution element of 2.5 for 1666Angstrom\ in G230L in 120 min., or S/N ~ 5 for a 0."2*0."2 spatial element. Similarly, we estimate S/N = (23, 8, 29) for 4363Angstrom/G430L, and 6723Angstrom/G750L, M for exposure times (15, 2, & 6 min, respectively). The expected surface brightness in C III 1909Angstrom\ is a factor of 5-10 higher than O III 1666Angstrom; given the higher throughput of STIS at 1909 Angstrom, adequate S/N for C III at sub-arcsecond resolution will not be a problem. C III is the brightest feature in the UV spectrum, and the surface brightnesses we expect do not approach the MAMA bright limits. Other UV lines, such as the N III 1747- 54Angstrom\ multiplet, are 5-10 times weaker than O III 1666Angstrom\ in LMC H II regions, so we will expose for 3 orbits with G230L for N160A in order to ensure adequate S/N for detection of these faint lines. Following target acquisition, we will expose with the CCD for about 50 min, then switch to the MAMA for the remainder of the orbits, which will have low overhead due to the CVZ. We will do at least one CR-split on the CCD integrations to eliminate cosmic-rays. We will also schedule a short (3-5 minute) fringing flat exposure in G750L for each target. Parallel images are proposed with the F656N, F502N, F372N, F487N, and F673N filters (in roughly the fractions 10\ for a given visit) in order to map the distribution and ionization of the ionized gas in the vicinity of our STIS targets. Short (~ 5 min.) exposures will also be obtained in F675W, F336W, F814W, and F547M WFPC2 filters to highlight the continuum sources and to distinguish compact ionized knots from stars. The H II region targets all have O-type stars associated with them, with brightnesses of 14th-15th magnitude, based on ground-based imaging. We will set on the H II region targets by peaking up on one of these nearby stars and then offsetting a short distance to the desired position. Real Time Justification ----------------------- The relatively long exposures in the UV required for this program would take 4- 6 normal orbits to be completed. By scheduling the observations for the CVZ, we save approximately 2 orbits per target in exposure time. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8196( 4) - 06/07/99 10:09 - [ 3] Data Distribution Paper Products: NO Media: DAT Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8196( 4) - 06/07/99 10:09 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SMC-N81- EXT-STAR RA=1H 9M 13.05S +/-0.1S, DEC=- J2000 V=+160 V = 14.4+/-0.1 OFFSET 73D 11' 38.3" +/-0.3", PLATE- U = 12.6+/-0.1 ID=06B1 Comments: TARG ACQ for target 2; V=14.9 star 0.27" to NW 2 SMC-N81 EXT-MEDIUM, HII REGION RA=1H 9M 12.50S +/-0.01S, DEC=- J2000 V=+160 SURF(1909)=3.5e-14 73D 11' 38.0" +/- 0.2"PLATE- SURF(5007)=1.2e-12 ID=06B1 SURF(6563)=5.7e-13 V = 15.4 Comments: 2.4"W, 0.3"N of target 1 3 SMC-N12A- EXT-STAR RA=0H 46M 32.71S +/-0.04S, DEC=- J2000 V=+160 V = 13.8+/-0.1 OFFSET 73D 06' 04.5" +/-0.1", PLATE- B-V = -0.17+/-0.02 ID=06B1 Comments: TARG ACQ for target 4 4 SMC-N12A EXT-MEDIUM, HII REGION RA=0H 46M 34.26S +/-0.04S, DEC=- J2000 V=+160 SURF(1909)=2.0e-14 73D 05' 53.2" +/- 0.1", PLATE- SURF(5007)=5.9e-13 ID=06B1 SURF(6563)=3.3e-13 V = 16.2 Comments: offset 6.8"E, 11.3" N of target 3 5 SMC-N66NW- EXT-STAR RA=0H 58M 57.30S +/-0.1S, DEC=- J2000 V=+160 V = 14.02+/-0.02 OFFSET 72D 10' 33.5" +/-0.2", PLATE- B-V = -0.24+/-0.05 ID=06B1 Comments: TARG ACQ for target 6 6 SMC-N66NW EXT-MEDIUM, HII REGION RA=0H 58M 55.94S +/-0.1S, DEC=- J2000 V=+160 SURF(1909)=1.2e-13 72D 10' 22.3" +/- 0.2", PLATE- SURF(5007)=4.2e-12 ID=06B1 SURF(6563)=2.0e-12 V = 14.0 Comments: 6.3"W, 11.2"N of target 5 8196( 4) - 06/07/99 10:09 - [ 5] Visit: 01 Visit Priority: Visit Requirements: CVZ On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 100 SMC-N81-OFF STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 S ONBOARD ACQ for 101-103, SET CD P 106 ------------------------------------------------------------------------------------------------------------------------------------ 101 SMC-N81 STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=2 1 1500 S PAR 104 WITH 101-103 CD ------------------------------------------------------------------------------------------------------------------------------------ 102 SMC-N81 STIS/C ACCUM 52X0.2 G750M 6768 1 660 S CD ------------------------------------------------------------------------------------------------------------------------------------ 103 SMC-N81 STIS/C ACCUM 52X0.2 G750L 7751 CR-SPLIT=2 1 1500 S CD ------------------------------------------------------------------------------------------------------------------------------------ 104 ANY WFPC2 IMAGE WFALL F656N 6564 CR-SPLIT=NO 3 1000 S ------------------------------------------------------------------------------------------------------------------------------------ 106 CCDFLAT STIS/C ACCUM 52X0.2 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8196( 4) - 06/07/99 10:09 - [ 6] Visit: 02 Visit Priority: Visit Requirements: CVZ; SAME ORIENT AS 1 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 200 SMC-N81-OFF STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 S ONBOARD ACQ for 201, 205 SET CD P ------------------------------------------------------------------------------------------------------------------------------------ 201 SMC-N81 STIS/N ACCUM 52X0.2 G230L 2376 2 3180 S PAR 202-204 WITH 201 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 202 ANY WFPC2 IMAGE WFALL F547M ATD-GAIN=15 3 300 S ------------------------------------------------------------------------------------------------------------------------------------ 203 ANY WFPC2 IMAGE WFALL F336W ATD-GAIN=15 3 500 S ------------------------------------------------------------------------------------------------------------------------------------ 204 ANY WFPC2 IMAGE WFALL F502N 5012 CR-SPLIT=NO 3 900 S ------------------------------------------------------------------------------------------------------------------------------------ 205 SMC-N81 STIS/N ACCUM 52X0.2 G230M 1884 1 2850 S PAR 206-207 WITH 205 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 206 ANY WFPC2 IMAGE WFALL F675W ATD-GAIN=15 3 200 S ------------------------------------------------------------------------------------------------------------------------------------ 207 ANY WFPC2 IMAGE WFALL F814W CR-SPLIT=NO,ATD-GAIN=15 3 400 S ------------------------------------------------------------------------------------------------------------------------------------ 8196( 4) - 06/07/99 10:09 - [ 7] Visit: 03 Visit Priority: Visit Requirements: CVZ On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 300 SMC-N12A-OF STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 S ONBOARD ACQ for 301-303, FSET CD P 306 ------------------------------------------------------------------------------------------------------------------------------------ 301 SMC-N12A STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=2 1 1500 S PAR 304-305 WITH 301-303 CD ------------------------------------------------------------------------------------------------------------------------------------ 302 SMC-N12A STIS/C ACCUM 52X0.2 G750M 6768 1 660 S CD ------------------------------------------------------------------------------------------------------------------------------------ 303 SMC-N12A STIS/C ACCUM 52X0.2 G750L 7751 CR-SPLIT=2 1 1500 S CD ------------------------------------------------------------------------------------------------------------------------------------ 304 ANY WFPC2 IMAGE WFALL F656N 6564 CR-SPLIT=NO 3 800 S ------------------------------------------------------------------------------------------------------------------------------------ 305 ANY WFPC2 IMAGE WFALL F814W ATD-GAIN=15 3 260 S ------------------------------------------------------------------------------------------------------------------------------------ 306 CCDFLAT STIS/C ACCUM 52X0.2 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8196( 4) - 06/07/99 10:09 - [ 8] Visit: 04 Visit Priority: Visit Requirements: CVZ; SAME ORIENT AS 3 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 400 SMC-N12A-OF STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 S ONBOARD ACQ for 401, 405 FSET CD P ------------------------------------------------------------------------------------------------------------------------------------ 401 SMC-N12A STIS/N ACCUM 52X0.2 G230L 2376 2 3240 S PAR 402-404 WITH 401 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 402 ANY WFPC2 IMAGE WFALL F547M ATD-GAIN=15 3 230 S ------------------------------------------------------------------------------------------------------------------------------------ 403 ANY WFPC2 IMAGE WFALL F502N 5012 CR-SPLIT=NO 3 600 S ------------------------------------------------------------------------------------------------------------------------------------ 404 ANY WFPC2 IMAGE WFALL F375N 3738 CR-SPLIT=NO 3 800 S ------------------------------------------------------------------------------------------------------------------------------------ 405 SMC-N12A STIS/N ACCUM 52X0.2 G230M 1884 1 2940 S PAR 406-407 WITH 405 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 406 ANY WFPC2 IMAGE WFALL F487N 4865 CR-SPLIT=NO 3 700 S ------------------------------------------------------------------------------------------------------------------------------------ 407 ANY WFPC2 IMAGE WFALL F675W ATD-GAIN=15 2 160 S ------------------------------------------------------------------------------------------------------------------------------------ 8196( 4) - 06/07/99 10:09 - [ 9] Visit: 05 Visit Priority: Visit Requirements: CVZ On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 500 SMC-N66NW-O STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 S ONBOARD ACQ for 501-503, FFSET CD P 506 ------------------------------------------------------------------------------------------------------------------------------------ 501 SMC-N66NW STIS/C ACCUM 52X0.2 G430L 4300 CR-SPLIT=2 1 1500 S PAR 504-505 WITH 501-503 CD ------------------------------------------------------------------------------------------------------------------------------------ 502 SMC-N66NW STIS/C ACCUM 52X0.2 G750M 6768 1 660 S CD ------------------------------------------------------------------------------------------------------------------------------------ 503 SMC-N66NW STIS/C ACCUM 52X0.2 G750L 7751 CR-SPLIT=2 1 1500 S CD ------------------------------------------------------------------------------------------------------------------------------------ 504 ANY WFPC2 IMAGE WFALL F656N 6564 CR-SPLIT=NO 3 800 S ------------------------------------------------------------------------------------------------------------------------------------ 505 ANY WFPC2 IMAGE WFALL F547M ATD-GAIN=15 3 260 S ------------------------------------------------------------------------------------------------------------------------------------ 506 CCDFLAT STIS/C ACCUM 52X0.2 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8196( 4) - 06/07/99 10:09 - [ 10] Visit: 06 Visit Priority: Visit Requirements: CVZ; SAME ORIENT AS 5 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 600 SMC-N66NW-O STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 S ONBOARD ACQ for 601, 605 FFSET CD P ------------------------------------------------------------------------------------------------------------------------------------ 601 SMC-N66NW STIS/N ACCUM 52X0.2 G230L 2376 2 3240 S PAR 602-604 WITH 601 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 602 ANY WFPC2 IMAGE WFALL F675W ATD-GAIN=15 3 180 S ------------------------------------------------------------------------------------------------------------------------------------ 603 ANY WFPC2 IMAGE WFALL F502N 5012 CR-SPLIT=NO 3 1200 S ------------------------------------------------------------------------------------------------------------------------------------ 604 ANY WFPC2 IMAGE WFALL F814W ATD-GAIN=15 3 230 S ------------------------------------------------------------------------------------------------------------------------------------ 605 SMC-N66NW STIS/N ACCUM 52X0.2 G230M 1884 1 2940 S PAR 606 WITH 605 UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 606 ANY WFPC2 IMAGE WFALL F673N 6732 CR-SPLIT=NO 3 800 S ------------------------------------------------------------------------------------------------------------------------------------ 8196( 4) - 06/07/99 10:09 - [ 11] Summary Form for Proposal 8196 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.2 WFALL ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD WFPC2 STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT CR-SPLIT=2 CR-SPLIT=NO ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CVZ ONBOARD ACQ for 101-103, 106 PAR 104 WITH 101-103 CVZ; SAME ORIENT AS 1 ONBOARD ACQ for 201, 205 PAR 202-204 WITH 201 PAR 206-207 WITH 205 ONBOARD ACQ for 301-303, 306 PAR 304-305 WITH 301-303 CVZ; SAME ORIENT AS 3 ONBOARD ACQ for 401, 405 PAR 402-404 WITH 401 PAR 406-407 WITH 405 ONBOARD ACQ for 501-503, 506 PAR 504-505 WITH 501-503 CVZ; SAME ORIENT AS 5 ONBOARD ACQ for 601, 605 PAR 602-604 WITH 601 PAR 606 WITH 605 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G430L G750M G750L F656N G230L F547M F336W F502N G230M F675W F814W F375N F487N F673N ------------------------------------------------------------------------------------------------------------------------------------ Target Names SMC-N81-OFFSET SMC-N81 ANY CCDFLAT SMC-N12A-OFFSET SMC-N12A SMC-N66NW-OFFSET SMC-N66NW ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 4300 6768 7751 6564 2376 5012 1884 3738 4865 6732 ------------------------------------------------------------------------------------------------------------------------------------