Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5503 Report Date: 18-Jul-95:17:32 Version: ********** Check-in Date: ********** 1.Proposal Title: ABSORPTION LINE STUDIES TOWARD BD+38 2182 AND HD 93521: AN IDEAL LABORATORY FOR HALO GAS STUDIES ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID INTERSTELLAR MEDIUM GO Sub Category ABSORPTION LINES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Laura Danly SPACE TELESCOPE SCIENCE INST USA 410-338-4422 ------------------------------------------------------------------------------------ 7. Abstract The extremely fortuitous alignment of HD 93521 and BD +38 2182 (~25 arcmin separation, z=1.5, 4.1 respectively) provides a rare opportunity to study the distribution and physical nature of gas in the milky way halo. Located at z-heights of 1.5 and 4.4 kpc respectively, the two stars are only 25 arcmin apart on the sky, corresponding to a 13 pc separation at the distance of the nearer HD93521. Data that have been accumulated previously with HST, IUE,Copernicus and other observatories show many interesting features in this direction, including (1) the first High Velocity Cloud for which the distance has been determined (Complex M); (2) a N V-bearing cloud, (3) small scale variations, and (4) absorption from the IV Arch. We will use the G160M and Echelle- B of the GHRS to study these phenomena. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.00 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5503 PI: Dr. Laura Danly Proposal Title: ABSORPTION LINE STUDIES TOWARD BD+38 2182 AND HD 93521: AN IDEAL LABORATORY FOR HALO GAS STUDIES ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Dr. Laura Danly SPACE TELESCOPE SCIENCE USA INSTITUTE Mr. Kip Kuntz SPACE TELESCOPE SCIENCE USA INSTITUTE ------------------------------------------------------------------------------------ 3. Description of proposed observations. We propose to observe BD +38 2182 with five grating setting and two Echelle-B settings. The central wavelenths and species to be studied are listed after each setting. The set of observations is designed to complement the observations taken by L. Spitzer toward HD 93521 during his GTO program. \noindent BD +38 2182 (l=182.2, b=62.2, MK=B2V, V=11.2, d=4.6 kpc, z=4.1 kpc) \noindent G160M grating, SSA: \medskip $\lambda_c$=1312.0 \hskip 0.5cm t(exp)=12$^m$ \hskip 0.5cm Si I, O I, C I, Si II $\lambda_c$=1343.0 \hskip 0.5cm t(exp)=12$^m$ \hskip 0.5cm O I, C II, C II*, Cu II $\lambda_c$=1205.0 \hskip 0.5cm t(exp)=37$^m$ \hskip 0.5cm H I, C I, N I, Si II, Mn II, S III $\lambda_c$=1249.0 \hskip 0.5cm t(exp)=15$^m$ \hskip 0.5cm S II, Si II, N V $\lambda_c$=1860.0 \hskip 0.5cm t(exp)=43$^m$ \hskip 0.5cm Al III Echelle-B, SSA: $\lambda_c$=2370.0 \hskip 0.5cm t(exp)=42$^m$ \hskip 0.5cm Fe II $\lambda_c$=2602.0 \hskip 0.5cm t(exp)=57$^m$ \hskip 0.5cm Fe II Mn II The first five settings toward BD +38 2182 are designed to achieve a S/N=30 for the grating settings and S/N=20 for the Echelle-B settings. \bigskip These lines of sight will be combined with the data on BD +38 2182 that is obtained during our current Cycle 2 program (ID no. 3706). The Cycle two setups will cover the wavelength region around the high ions of C IV, Si IV, and N V. We will also get numerous other species with a range of ionization potential. In addition to studying the ionization and kinematic structure, we will have sufficient data for a detailed analysis of the depletion patterns and abundances which should prove extremely interesting, especially in the High Velocity Cloud. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The improvement in resolution and S/N that is made available through teh GHRS on HST is required to carry out the scientific aims of the proposal. We have fully analyzed the IUE spectra which provide some tantalizing hints at what is out there, particularly with regard to the HVC detection. However, the IUE is simply not able to provide the quality of data required to make a quantitative program of halo gas measurement as envisioned here, particularly for a star of V=11.2. Of course, the ultraviolet regime is required because of the wide range of ion species available for study that are not available from the ground. \medskip Observations of HD 93521 with Copernicus are available in the literature, and provide even more useful ions, including O VI. \medskip The PI also has observed this field using the 140' single dish radio telescope at NRAO-Greenbank (with E. Albert) and using the Westerbork Interferometric Radio Telescope (with B. Wakker and H. Van Woerden). These data are being analyzed currently to provide the best information on the small scale variations in the H I distribution. The ultraviolet fluxes for the G160M grating setting observations of BD +38 2182 were measured directly from our IUE spectra of the stars. No additional corrections (i.e. for interstellar extinction) are required. The count rates (in counts/sec/diode) were determined by multiplying the fluxes by the throughputs for the GHRS/G160M and for the LSA/SSA aperture ratio given in the GHRS Instrument Handbook (Version 4.0, January 1993). \medskip We were not able to measure directly the fluxes from BD +38 2182 longward of 2000$\AA$ as we do not have any LWP spectra of this star (it's magnitude and early spectral type made it unfeasible to observe in an IUE shift). To determine the flux, we scaled from IUE spectra toward a standard B2V star, HD 32612 (LWP 7007). The count rates were determined as above for the Echelle-B throughputs, and were also scaled by the normalized blaze function given in Figure 7-11 of the Handbook. \medskip For all the grating settings, the count-rates were above the instrumental background. Exposure times were determined by t=(S/N)$^2$/(count-rate). They are listed in Section 2. For the Echelle-B settings, the inter-order scattered light had to be included in the S/N calculations. In the cases of $\lambda$1805 and $\lambda$2602, the count-rates were low enough that the instrumental background had to also be considered. The exposure times listed in Section 2 were calculated according to section 3.3.5.1 in the Handbook, as explained. \medskip The S/N ratios were chosen to give limiting equivalent widths that would compare reasonably with the Echelle data taken by L. Spitzer in his GTO program. In order to make a meaningful comparison, we have tried to optimize our program to create a uniform data set, given the limitation that the Echelle-A is no longer available. In the event that the Echelle-A becomes available, we wish to reconsider these set-ups. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. none ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. GHRS wavelength calibrations for all spectra Page 4 ------------------------------------------------------------------------------------ 8. Additional comments or special requests. This proposal is one of several programs (including three accepted GO programs; see Question 8) designed to study gas in the environments of galaxies. These programs have been tailored specifically to meet the objectives outlined in the P.I.'s (accepted) Hubble Fellowship proposal. The goal of the Hubble Fellowship research is to study gas which is in the vicinity of a variety of galaxies, and is therefore subjected to a range of interstellar and intergalactic environments. Central to this research is a detailed study of the production and maintenance of Milky Way halo gas, where we can expect to obtain the highest quality data and develop the most detailed models. Accurate means to interpret quantitative spectroscopic data are critical to the interpretation of QSO absorption lines. \medskip Related Cycle 3 proposals includ14: \bigskip Galacti15: \smallskip $\bullet$ ``New Probes for the Intermediate Velocity Arch" (Danly, L. and Kuntz, K.D.) \medskip $\bullet$ ``The Distance of High Velocity Clouds" (Wakker, B. P., Danly, L., Schwarz, U. J., and Van Woerden, H.) \bigskip Extragalactic: \smallskip $\bullet$ ``Quasar Absorption Line Studies of Starburst Galaxy Environments" (Norman, C.N., Blades, J.C., Danly, L., and Heckman, T) \medskip $\bullet$ ``The Structure of the Coma Cluster: A Search for Cool Absorbing Gas" (Urry, C.M., Branduardi-Raymont G., Danly, L., Fitchett, M.J., Mushotzky, R.F.) \medskip $\bullet$ ``An Investigation of Strong Local Ly$\alpha$ Systems" (Urry, C. M., Bowen D., Maraschi, L., Danly, L., Bruhweiler, F. C., Falomo, R., Grady, C.) ------------------------------------------------------------------------------------ 9. Description of previous HST work. No. 3706 -- ``The Nature of Gaseous Loops in the Milky Way Halo" No. 2644 -- ``The Environments of Starburst Galaxies: Absorption Line Studies of Galactic Outflows" \bigskip The nature of both of these programs is described in Question 8. In particular, No. 3706 is closely related to the current proposed program, and is described in the Scientific Justification. No. 3706 -- one spectrum has been taken and is being analyzed. No. 2644 -- one spectrum has been taken and is being analyzed. ------------------------------------------------------------------------------------ 11. Address Information Name: Laura Danly Category: PI Institution: Space Telescope Science Institute Address: 3700 San Martin Drive City: Baltimore State: Md Zip Code: 21218 Country: USA Telephone: 410-338-4422 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5503 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 BD+38D2182 G,508,509,510, PLATE-ID=01R8, J2000 V=79 1 V=11.2, TYPE=B2V, E(B-V)=0.02 GSC03009- A,110 RA= 10H 49M 12.9S +/- 0.1S, 2 B-V=-0.22 02485 DEC= +38D 0' 14.5" +/- 1" 3 F-CONT(1240) = 36 E-13 4 F-CONT(1300) = 24 E-13 5 F-CONT(1400) = 22 E-13 6 F-CONT(1800) = 12 E-13 7 F-CONT(2400) = 7 E-13 8 F-CONT(1200) = 20 E-13 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5503 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 BD+38D2182 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 1.8S 1 1 CYCLE 4/ 1.0 - 9.2 ONBOARD ACQ FOR 1.01 Comments: STEP-TIME = 0.2 ------------------------------------------------------------------------------------------------------------------------------------ 1.01 BD+38D2182 HRS ACQ/ 0.25 MIRROR-A2 SEARCH-SIZE=5 1 40S 1 1 ONBOARD ACQ FOR PEAKUP 1.10 - 9.20 Comments: STEP-TIME = 1.6 ------------------------------------------------------------------------------------------------------------------------------------ 1.1 WAVE HRS ACCUM SC2 G160M 1312 1 DEF 1 CALIB FOR 1.2 SEQ 1.1-1.2 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 1.2 BD+38D2182 HRS ACCUM 0.25 G160M 1312 FP-SPLIT=STD 1 12M 30 4 1 ------------------------------------------------------------------------------------------------------------------------------------ 2.1 WAVE HRS ACCUM SC2 G160M 1343 1 DEF 1 CALIB FOR 2.2 SEQ 2.1-2.2 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 2.2 BD+38D2182 HRS ACCUM 0.25 G160M 1343 FP-SPLIT=STD 1 12M 30 4 1 ------------------------------------------------------------------------------------------------------------------------------------ 3.1 WAVE HRS ACCUM SC2 G160M 1205 1 DEF 1 CALIB FOR 3.2 SEQ 3.1-3.2 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 3.2 BD+38D2182 HRS ACCUM 0.25 G160M 1205 FP-SPLIT=STD 1 37M 30 3 1 ------------------------------------------------------------------------------------------------------------------------------------ 5.1 WAVE HRS ACCUM SC2 ECH-B 2370 STEP-PATT=7 1 DEF 1 CALIB FOR 5.2 SEQ 5.1-5.2 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 5.2 BD+38D2182 HRS ACCUM 0.25 ECH-B 2370 FP-SPLIT=STD 1 44M 30 7 1 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ 6.1 WAVE HRS ACCUM SC2 ECH-B 2602 STEP-PATT=7 1 DEF 1 CALIB FOR 6.2 SEQ 6.1-6.2 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 6.2 BD+38D2182 HRS ACCUM 0.25 ECH-B 2602 FP-SPLIT=STD 1 25M 20 7 1 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ 7.1 WAVE HRS ACCUM SC2 G160M 1249 1 DEF 1 CALIB FOR 7.2 SEQ 7.1-7.2 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 7.2 BD+38D2182 HRS ACCUM 0.25 G160M 1249 FP-SPLIT=STD 1 15M 30 3 1 ------------------------------------------------------------------------------------------------------------------------------------ 9.1 WAVE HRS ACCUM SC2 G160M 1860 1 DEF 1 CALIB FOR 9.2 SEQ 9.1-9.2 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 9.2 BD+38D2182 HRS ACCUM 0.25 G160M 1860 FP-SPLIT=STD 1 43M 30 3 1 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5503 [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=5 FP-SPLIT=STD STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ABSORPTION LINES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4/ 1.0 - 9.2; ONBOARD ACQ FOR 1.01 ONBOARD ACQ FOR 1.10 - 9.20 CALIB FOR 1.2; SEQ 1.1-1.2 NO GAP CALIB FOR 2.2; SEQ 2.1-2.2 NO GAP CALIB FOR 3.2; SEQ 3.1-3.2 NO GAP CALIB FOR 5.2; SEQ 5.1-5.2 NO GAP CALIB FOR 6.2; SEQ 6.1-6.2 NO GAP CALIB FOR 7.2; SEQ 7.1-7.2 NO GAP CALIB FOR 9.2; SEQ 9.1-9.2 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 MIRROR-A2 G160M ECH-B ------------------------------------------------------------------------------------------------------------------------------------ Target Names BD+38D2182 GSC03009-02485 ------------------------------------------------------------------------------------------------------------------------------------