5827( 3) - 11/20/95 19:16 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5827 Version: 3 Check-in Date: ********** 1.Proposal Title: The Interstellar medium of Nearby Galaxies using Supernovae as Probes ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Interstellar Medium GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: David V. Bowen Space Telescope Science Institute CoI: J. Chris Blades Space Telescope Science Institute N CoI: Katherine Roth Space Telescope Science Institute N CoI: David Meyer Northwestern University N ------------------------------------------------------------------------------------ 6. Abstract We propose using ECH-B and G140L gratings of the GHRS to observe the one bright (V < 12.5) supernova which is likely to occur during Cycle 5 in order to probe the interstellar gas of the host galaxy as well as gas in the local Galactic halo. We wish to observe Mg II and Mg I absorption lines with ECH-B; the 3 kms\ echelle resolution will enable us to resolve individual components within the absorption lines, study the kinematic structure of the absorbing gas, and derive accurate column densities and Doppler parameters of absorbing clouds. We would use the G140L grating to search for C IV and Si IV absorption, as well as strong low ionization lines of O I, C II, Ni II & Si II from both the host galaxy and the Milky Way. C IV/C II & Si IV/Si II ratios will then provide details on the ionization conditions in the gas. Information on interstellar absorption from any low-redshift galaxy other than our own is sparse, and our aim is to detect lines whose strengths and structures can be compared with Galactic absorption and absorption seen at high redshift in QSO spectra. Should a SN occur with V < 11, we would add exposures of C IV with the G160M grating, Zn II, Cr II with the G190M grating, and LyAlpha absorption with the G140L grating. Such data would allow us to calculate metallicities and depletions of intervening gas clouds, values which can be compared with higher redshift abundance studies. ------------------------------------------------------------------------------------ 5827( 3) - 11/20/95 19:16 - [ 2] Observations Description ------------------------ Discoveries of SNae are announced via IAU Telegrams. We would activate our ToO based on the visual magnitude of the object or knowledge of the flux if IUE spectra are available (as they have been in the past). Another criterion is that the redshift of the host galaxy must lie at a systemic velocity such that absorption from the host would not be blended with local Milky Way gas. Fluxes of SN observed with IUE and HST at 2800 Angstrom\ show a correlation with visual magnitude, hence we are able to estimate required exposure times for SN of given magnitudes. A few SN have been observed in the far UV, and we adopt F_Lambda(1550) ~ 0.8times10^-14 \flux\ at V ~ 12.5. We propose the following set of observations, depending on the magnitude of the SN: vspace*0.5cm Case 1: for SN with magnitudes in the range 11.0 < V <= 12.5, or F_Lambda(2800) >= 1.5times10^-14 \flux we would observe Mg II and Mg I with ECH-B. This lower limit to the observed flux would give a count rate of ~eq 70 \cdh . We achieve a S/N of at least 10 pixel^-1 (assuming half-stepped data) in 4.3 hrs for each of the settings, giving 3Sigma equivalent width limits of 10 mAngstrom . We would also observe far UV absorption lines using the G140L. For F_Lambda(1550) = 0.8times10^-14 \flux\ (V ~ 12.5) count rates of 200 \cdh\ are reached, giving 3Sigma equivalent width limits of at least 0.15 Angstrom\ in 2.0 hrs. The programme is complete after 14 orbits. vspace*0.5cm Case 2: in the unlikely event that a SN with V< 11.0 occurs, we would perform the same observations described above, plus add observations of C IV with the G160M, and Zn II & Cr II with the G200M. For the same 14 orbits requested, we can achieve the same equivalent width limits for the ECH-B and G140L gratings, plus reach 3Sigma equivalent width limits of 20 mAngstrom\ with the G190M (in 4.8 hrs), and 50 mAngstrom\ with the G160M (in 1.5 hrs). Real Time Justification ----------------------- The magnitude limit which will determine whether this ToO programme would be activated is based on the frequency of V < 12.5 SNae. Fig. 3 shows the number of SNae per year within this limit frequency for the last 14 years, based on the compilation by Barbon, Capellaro & Turatto (1989) and IAU Telegrams from 1990 to June 1994. The figure shows that we can expect roughly 1 SN brighter than 12.5 during a cycle, a prediction confirmed during Cycles 2-4. As the UV flux of SNae are known to drop sharply after the explosion, we would activate our proposal immediately. Observations of SN 1993J, SN 1992A & SN1994I demonstrate that HST is well able to respond to these ToOs. We will seek to obtain ground-based optical data to complement the HST data we obtain. Calibration Justification ------------------------- The most accurate wavelength calibration possible is required so that the HST data can be compared with optical data obtained at echelle resolutions from the ground. Hence WAVE exposures are requested. Additional Comments ------------------- ------------------------------------------------------------------------------------ 5827( 3) - 11/20/95 19:16 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: stsci Ship Via: Internal Email: , ------------------------------------------------------------------------------------ 5827( 3) - 11/20/95 19:16 - [ 4] TARGET LIST c)Generic Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Selection Criteria | Flux data No | Name | Description | | ------------------------------------------------------------------------------------------------------------------------------------ SN1995X ext-star,supernova;ext- SN must be brighter than one of V=12.5 medium,absorption line the quoted fluxes to execute F(2800)=1.5e-14 system ------------------------------------------------------------------------------------------------------------------------------------ 5827( 3) - 11/20/95 19:16 - [ 5] Visit: 10 Visit Requirements: ON HOLD;GROUP 10-11 WITHIN 12H On Hold Comments: Visits 10-11 conditional on SN fainter than V=11, brighter than V=12.5 Additional Comments: First visit for MgII and far UV ions. Visit 11 should follow visit 10 ASAP Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 100 SN1995X HRS ACQ 2.0 MIRROR-N2 bright=return,s 1 18S ONBOARD ACQUISITION FOR 200-400 earch-size=3 Comments: STEP-TIME=2s ------------------------------------------------------------------------------------------------------------------------------------ 200 wave HRS accum SC2 ECH-B 2800.5 1 def Comments: Wave calib for 300. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity ------------------------------------------------------------------------------------------------------------------------------------ 300 SN1995X HRS ACCUM 2.0 ECH-B 2800.5 fp- 30 217.6S split=two,step- patt=7,doppler= def,spybal=no Comments: Observing MgII. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. 1st set of exposures. ------------------------------------------------------------------------------------------------------------------------------------ 350 wave HRS accum SC2 ECH-B 2800.5 1 def Comments: Wave calib for 370, really to set SPYBAL again. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. When orbit length known, WAVE should not cross occultation. ------------------------------------------------------------------------------------------------------------------------------------ 370 SN1995X HRS ACCUM 2.0 ECH-B 2800.5 fp- 35 217.6S split=two,step- patt=7,doppler= def,spybal=no Comments: Observing MgII. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. 2nd set of exposures. Total req=4.3hrs ------------------------------------------------------------------------------------------------------------------------------------ 400 SN1995X HRS ACCUM 2.0 G140L 1421 fp-split=two 23 217.6S Comments: Observing high ions in far UV. Total req=2.0 hrs. ------------------------------------------------------------------------------------------------------------------------------------ 5827( 3) - 11/20/95 19:16 - [ 6] Visit: 11 Visit Requirements: ON HOLD;GROUP 10-11 WITHIN 12H On Hold Comments: Conditional on SN fainter than V=11, brighter than V=12.5 Additional Comments: Second set of orbits, observing MgI Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 500 SN1995X HRS ACQ 2.0 MIRROR-N2 bright=return,s 1 18S ONBOARD ACQuisition FOR 600-700 earch-size=3 Comments: STEP-TIME=2s ------------------------------------------------------------------------------------------------------------------------------------ 600 wave HRS accum SC2 ECH-B 2852.0 1 def Comments: Wave calib for 700. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. ------------------------------------------------------------------------------------------------------------------------------------ 700 SN1995X HRS ACCUM 2.0 ECH-B 2852.0 fp- 30 217.6S split=two,step- patt=7,doppler= def,spybal=no Comments: Observing MgI. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. 1st set of exposures. ------------------------------------------------------------------------------------------------------------------------------------ 750 wave HRS accum SC2 ECH-B 2852.0 1 def Comments: Wave calib for 790, really for setting SPYBAL. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. When orbit length known, WAVE should not cross occultation. ------------------------------------------------------------------------------------------------------------------------------------ 790 SN1995X HRS ACCUM 2.0 ECH-B 2852.0 fp- 35 217.6S split=two,step- patt=7,doppler= def,spybal=no Comments: Observing MgI. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. 2nd set of exposures. Total Time Needed=4.3hrs. ------------------------------------------------------------------------------------------------------------------------------------ 5827( 3) - 11/20/95 19:16 - [ 7] Visit: 20 Visit Requirements: ON HOLD; GROUP 20-21 WITHIN 12H On Hold Comments: Visits 20-21 conditional on SN brighter than V=11 Additional Comments: Visit 21 should follow 20 asap. First group to observe far UV and MgII Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 100 SN1995X HRS ACQ 2.0 MIRROR-N2 bright=return,s 1 18S ONBOARD ACQuisition FOR 200-700 earch-size=3 Comments: STEP-TIME=2s ------------------------------------------------------------------------------------------------------------------------------------ 200 wave HRS accum SC2 G160M 1550.0 1 def Comments: Wave calib for 300. Searching for CIV. Since UV flux of SN dies rapidly, far UV observations should be made first ------------------------------------------------------------------------------------------------------------------------------------ 300 SN1995X HRS ACCUM 2.0 G160M 1550.0 fp- 30 217.6S split=two,spyba l=no Comments: Observing CIV. Total Time Needed=1.5 hrs ------------------------------------------------------------------------------------------------------------------------------------ 500 wave HRS accum SC2 ECH-B 2800.5 1 def Comments: Wave calib for 600. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. When orbit length known, WAVE should not cross occultation. ------------------------------------------------------------------------------------------------------------------------------------ 600 SN1995X HRS ACCUM 2.0 ECH-B 2800.5 fp- 22 217.6S split=two,step- patt=7,doppler= def, spybal=no Comments: Observing MgII. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. Total Time Needed=1.3 hrs ------------------------------------------------------------------------------------------------------------------------------------ 700 SN1995X HRS ACCUM 2.0 G140L 1310 fp-split=two 11 217.6S Comments: Observing high ions in far UV, including Lyman-a. Total T req=0.5 hrs ------------------------------------------------------------------------------------------------------------------------------------ 5827( 3) - 11/20/95 19:16 - [ 8] Visit: 21 Visit Requirements: ON HOLD; GROUP 20-21 WITHIN 12H On Hold Comments: Visits 20-21 conditional on SN brighter than V=11 Additional Comments: Visit 21 should follow 20 asap. Second group to observe MgI and Zn, Cr Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 700 SN1995X HRS ACQ 2.0 MIRROR-N2 bright=return,s 1 18S ONBOARD ACQuisition FOR 800-950 earch-size=3 Comments: STEP-TIME=2s ------------------------------------------------------------------------------------------------------------------------------------ 800 SN1995X HRS ACCUM 2.0 G200M 2060.0 fp- 29 217.6S split=two,spyba l=yes Comments: Observing Zn & Cr. Correct wavelength setting for G200M is unknown, and depends critically on host galaxy velocity. 1st set. ------------------------------------------------------------------------------------------------------------------------------------ 850 SN1995X HRS ACCUM 2.0 G200M 2060.0 fp- 38 217.6S split=two,spyba l=yes Comments: Observing Zn & Cr. Correct wavelength setting for G200M is unknown, and depends critically on host galaxy velocity. 2nd set. Total Time Needed=5.0 hrs ------------------------------------------------------------------------------------------------------------------------------------ 900 wave HRS accum SC2 ECH-B 2852.0 1 def Comments: Wave calib for 950. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. When orbit length known, WAVE should not cross occultation. ------------------------------------------------------------------------------------------------------------------------------------ 950 SN1995X HRS ACCUM 2.0 ECH-B 2852.0 fp- 22 217.6S split=two,step- patt=7,doppler= def, spybal=no Comments: Observing MgI. Correct wavelength setting for ECH-B is unknown, and depends on host galaxy velocity. Total Time Needed=1.3 hrs ------------------------------------------------------------------------------------------------------------------------------------ 5827( 3) - 11/20/95 19:16 - [ 9] Summary Form for Proposal 5827 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ accum ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters bright=return search-size=3 spybal=no doppler=def fp-split=two step-patt=7 spybal=yes ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Interstellar Medium ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ON HOLD;GROUP 10-11 WITHIN 12H ONBOARD ACQUISITION FOR 200-400 ONBOARD ACQuisition FOR 600-700 ON HOLD; GROUP 20-21 WITHIN 12H ONBOARD ACQuisition FOR 200-700 ONBOARD ACQuisition FOR 800-950 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 ECH-B G140L G160M G200M ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN1995X wave ------------------------------------------------------------------------------------------------------------------------------------