Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4798c Report Date: 09-May-96:19:57 Version: ********** Check-in Date: ********** 1.Proposal Title: THE PROPERTIES OF SINGLE INTERSTELLAR CLOUDS: HOPR REPEAT CYCLE 1, SIDE-2 OBSERVATIONS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID INTERSTELLAR MEDIUM GO 2 Long Term yrs 3993 Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Prof. L. M. Hobbs CHICAGO, UNIVERSITY OF USA (414) 245-5555 PROFESSOR ------------------------------------------------------------------------------------ 7. Abstract WE PROPOSE TO USE THE ECHELLE GRATING OF THE HIGH RESOLUTION SPECTROGRAPH OVER A TWO -YEAR PERIOD TO OBSERVE THE PROFILES OF INTERSTELLAR ABSORPTION LINES. THE COLUMN DENSITES OF 18 NEUTRAL OR IONIZED FORMS OF THE ELEMENTS C,N,O,Mg,Si,P,S,Fe, AND Zn WILL BE MEASURED IN THE APPROXIMATELY 100 INDIVIDUAL INTERSTELLAR CLOUDS ALONG THE LIGHT PATHS TO 18 BRIGHT, BROAD-LINED STARS OF EARLY SPECTRAL TYPE WITHIN 1 KPC OF THE SUN. THE PRIMARY PURPOSE OF THE OBSERVATIONS IS TO DETERMINE MORE ACCURATELY THAN WAS HITHERTO POSSIBLE THE FUNDAMENTAL PHYSICAL PROPERTIES OF THE RESOLVED CLOUDS, INCLUDING LINEAR SIZE, TEMPERATURE, TOTAL DENSITY, FRACTIONAL IONIZATION AND THE RELATIVE ABUNDANCES OF THE 9 SELECTED ELEMENTS. THE REST OF THIS OBSERVING PROGRAM IS CONTAINED IN APPROVED PROPOSAL ID = 2251; THE PROGRAM EUNUMERATED HERE CONSISTS OF THAT PART OF OUR ORIGINAL PROGRAM WHICH CAN BE CARRIED OUT USING ONLY SIDE 2 OF THE GHRS. THIS PROGRAM THEREFORE CONSISTS OF ECH-B OBSERVATIONS OF EACH OF 4 STARS AT 7 WAVELENGTHS. PROGRAM 2251 SHOULD BE CONSULTED FOR ADDITIONAL DETAILS. ------------------------------------------------------------------------------------ 8. Scientific Key Words: INTERSTELLAR CLOUDS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 9.06 par: 0 10. Num targs pri: 4 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4798c PI: Prof. L. M. Hobbs Proposal Title: THE PROPERTIES OF SINGLE INTERSTELLAR CLOUDS: HOPR REPEAT CYCLE 1, SIDE-2 OBSERVATIONS ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ P.I. L. M. Hobbs CHICAGO, UNIVERSITY OF USA Dr. D. C. Morton HERZBERG INSTITUTE OF CANADA ASTROPHYSICS Dr. L. Spitzer Jr. PRINCETON UNIVERSITY USA Dr. D. E. Welty CHICAGO, UNIVERSITY OF USA Dr. D. G. York CHICAGO, UNIVERSITY OF USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. FOR EACH OF 4 STARS, A SERIES OF 7 OR 8 EXPOSURES IS TO BE OBTAINED THROUGH THE SMALL SCIENCE APERTURE IN THE WSCAN MODE, WITH THE ECHELLE GRATING. SEVEN OBSERVATIONS, TYPICALLY OF ABOUT FOUR MINUTES EACH, ARE MADE IN THE ECH-B MODE (I.E. WITH THE CsTe DIGICON) IN THE WAVELENGTH INTERVAL BETWEEN 1740 AND 2380 ANGSTROMS. ONE ADDITIONAL SET OF EXPOSURES IS OBTAINED AT ONE OF THESE WAVELENGTHS FOR 2 OF THE STARS. THE VARIOUS EXPOSURE TIMES ARE CHOSEN TO YIELD APPROXIMATELY 10,000 COUNTS PER DIODE. FOR EACH SPECTRAL SETTING, THREE SEPARATE SUBEXPOSURES WILL BE MADE, WITH THE SPECTRUM MOVED PARALLEL TO THE DISPERSION TO THREE DIFFERENT POSITIONS ON THE PHOTOCATHODE, TO ALLOW SOME CORRECTION FOR NON- UNIFORMITIES OF THE CATHODE. ALL OF OUR TARGETS ARE BRIGHT STARS WITH WELL DETERMINED POSITIONS, FOR WHICH THE ONBOARD ACQUISITION MODE SHOULD SUFFICE. MOST OF THE STARS ARE EITHER SPECTROSCOPIC BINARIES OR KNOWN VISUAL BINARIES WITH SEPARATIONS LESS THAN 1 ARCSEC. IN ALL SUCH CASES, THE BRIGHTEST MEMBER OF THE MULTIPLE SYSTEM SHOULD BE CENTERED IN THE SMALL SCIENCE APERTURE. NO UNUSUALLY STRINGENT REQUIREMENTS WITH RESPECT TO THE USE OF THE PT/NE OR FLAT-FIELD LAMPS OR OF THE SUBSTEPPING ROUTINES ARE ANTICIPATED, ALTHOUGH WE DO REQUIRE ABOUT 1% SPECTROPHOTOMETRIC ACCURACY (S/N = 100) AS WELL AS ACCURATE (1 KM/S) HELIOCENTRIC WAVELENGTH SCALES. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. THE PROPOSED SCIENTIFIC PROGRAM CANNOT BE CARRIED OUT WITH ANY OTHER EXISTING TELESCOPE AND SPECTROGRAPH. THE HIGHEST POSSIBLE SPECTRAL RE- SOLVING POWER IS REQUIRED TO INVESTIGATE SEPARATELY THE INDIVIDUAL CLOUDS. IN ADDITION, ONLY THE LARGE ARRAY OF ULTRAVIOLET RESONANCE LINES OF THE PRINCIPAL IONIZATION STAGES OF MANY ELEMENTS PROVIDES SUF- FICIENT SPECTROSCOPIC DIAGNOSTIC POWER TO ANALYZE RELIABLY EACH CLOUD'S PHYSICAL PROPERTIES. THE FULL OBSERVING PROGRAM IS CONTAINED IN APPROVED PROPOSAL ID = 2251; THE PROGRAM EUNUMERATED HERE CONSISTS OF THAT PART OF 2251 WHICH CAN BE CARRIED OUT USING ONLY SIDE 2 OF THE GHRS. THIS PROGRAM THEREFORE CONSISTS OF ECH-B OBSERVATIONS OF EACH OF 4 STARS AT 7 WAVELENGTHS. PROGRAM 2251 SHOULD BE CONSULTED FOR ADDITIONAL DETAILS; BEFORE 2251 IS SUBSEQUENTLY EXECUTED, HOWEVER, IT MUST BE MODIFIED IN ACCORDANCE WITH THIS PROGRAM AND WITH THE LIMITATIONS IMPOSED BY THE CURRENT FAILURE OF SIDE 1 OF THE SPECTROGRAPH. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. THE PROGRAM STARS,THE NUMBER OF EXPOSURES FOR EACH, AND THE ESTIMATED TOTAL TIME UTILIZED IN ALL OF THOSE EXPOSURES FOR EACH STAR ARE GIVEN BELOW IN THE EXPOSURE LOGSHEET. OBSERVED ABSOLUTE UV FLUXES EXTENDING TYPICALLY TO BELOW 1400 ANGSTROMS HAVE BEEN PUBLISHED FOR ALL OF THE PROGRAM STARS; SEE THE UV BRIGHT-STAR SPECTROPHOTOMETRIC CATALOGUE OF JAMAR ET AL (1976). THE ABSOLUTE SENSITIVITY OF THE HRS IS GIVEN IN THE GHRS INSTRUMENT HANDBOOK, VERSION 2.0. THIS COMBINATION ALLOWS STRAIGHTFORWARD ESTIMATES OF THE REQUIRED EXPOSURE TIMES. THE REGIONS CENTERED NEAR THE FOLLOWING SPECTRAL LINES ARE TO BE OBSERVED: Mg I 1747.8, Si II 1808.0, Mg I 1827.9, Mg I 2025.8, ZN II 2062.0, C II 2324.7, AND FE II 2366.9. AT LEAST ONE ADDITIONAL LINE NOT LISTED HERE WHICH IS OF IMPORTANCE TO OUR INVESTIGATION WILL BE RECORDED SIMULTANEOUSLY IN NEARLY ALL EXPOSURES; AN EXAMPLE IS ZN II 2025.5. AS AN EXAMPLE, CONSIDER THE OBSERVATION OF THE 1827.9 A LINE OF Mg I IN THE SPECTRUM OF HD72127. FROM JAMAR ET AL, THE INCIDENT FLUX IS F = 4.89( -10) ERG/S/CM2/A; FROM THE GHRS HANDBOOK, A SENSITIVITY OF S = 8.2(+10) (COUNT/DIODE/S)/(ERG/S/CM2/A) APPLIES TO THE OTA + 0.25 ARCSEC APERTURE + GHRS SYSTEM. IN AN INTEGRATION TIME T = 81 SEC, THEREFORE, FxSxT = 3250 COUNTS/DIODE. AFTER SLIGHT DISPLACEMENTS OF THE SPECTRUM ALONG THE DIGICON ARRAY, TWO MORE IDENTICAL EXPOSURES ARE THEN OBTAINED. IN A TOTAL OF 243 SEC = 4.1 MIN, ALMOST ALL DIODES WILL RECORD ABOUT 10,000 COUNTS, AS DESIRED. THE TOTAL EXPOSURE TIME UTILIZED FOR HD 72127 AT 7 SUCH SPECTRAL LINES WORKS OUT SIMILARLY TO BE 53 MIN. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. IN ADDITION TO THE 7 STELLAR EXPOSURES DESCRIBED ABOVE, ONE OBSERVA- TION OF THE ONBOARD PT/NE CALIBRATION LAMP WILL TYPICALLY BE REQUIRED FOR EACH STAR, UNDER INSTRUMENTAL SETUPS IDENTICAL TO THOSE FOR THE CORRESPONDING STELLAR EXPOSURES. THE PURPOSE OF THESE COM- PARISON LAMP SPECTRA IS TO CALIBRATE THE ABSOLUTE WAVELENGTH SCALES TO AN ACCURACY OF ABOUT 1 KM/S. DETAILS ARE GIVEN IN THE EXPOSURE LOGSHEET BELOW. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. OUR PLAN IS TO USE THE CALIBRATED SCIENCE DATA WHICH ARE PROVIDED AS THE OUTPUT OF THE ROUTINE SCIENCE DATA PROCESSING (RSDP) AND THE CALIBRATION DATA BASE (CDBS) SOFTWARE, AT THE ST ScI. SINCE WE WILL ANALYZE ALMOST EXCLUSIVELY ABSORPTION LINE PROFILES, WE DO NOT REQUIRE PRECISE INFORMATION ABOUT THE ABSOLUTE FLUXES. ALTHOUGH WE WILL UNDOUBTEDLY MAKE ADDITIONAL USE OF THE SCIENCE DATA ANALYSIS SYSTEM (SDAS) AT THE INSTITUTE, ESPECIALLY AS WE GAIN EXPERI- ENCE WITH ITS DETAILED FEATURES, THE BULK OF THE ENSUING SCIENTIFIC ANALYSES, SUCH AS LINE-PROFILE FITTING AND EQUIVALENT-WIDTH INTEGRA- TIONS, PROBABLY WILL BE CARRIED OUT AT OUR HOME INSTITUTIONS. FOR MORE THAN FIFTEEN YEARS WE HAVE BEEN REDUCING AND ANALYZING SUCH UV AND OP- TICAL DATA, INCLUDING GROUND-BASED ECHELLE/DIGICON SPECTA, STARTING IN ITS RAW FORM. THEREFORE, A FLEXIBLE AND POWERFUL ARRAY OF APPROPRIATE PROGRAMS HAS BEEN THOROUGHLY TESTED AND USED. WHILE THIS NUMERICAL ANALYSIS IS STRAIGHTFORWARD AND RELATIVELY SIM- PLE, THE AMOUNT OF DATA TO BE PROCESSED AND ANALYZED WILL BE MODERATELY LARGE. THE PRINCIPAL RESPONSIBILITY FOR THIS TASK THEREFORE HAS BEEN ASSIGNED TO WELTY, WHO WILL WORK CLOSELY WITH HOBBS AND YORK. IN THE ANALYSIS OF THE INTERSTELLAR LINES, WE SHALL TAKE ADVANTAGE OF THE CONTINUING EFFORTS OF MORTON AND HIS COLLEAGUES IN COLLECTING THE BEST AVAILABLE LABORATORY DATA ON THE WAVELENGTHS AND THE OSCILLATOR STRENGTHS OF THE LINES OBSERVED. THUS, WE WILL BE ABLE TO OBTAIN THE MOST RELIABLE RADIAL VELOCITIES, COLUMN DENSITIES, AND LINE WIDTH PARAMETERS FROM THE DATA. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). AS INDICATED IN QUESTION 7 ABOVE, EXTENSIVE DATA-ANALYSIS CAPABILITIES WHICH ARE TAILORED PRECISELY FOR THIS KIND OF OBSERVATIONAL DATA AND ITS INTERPRETATION EXIST AT, AND WILL BE MADE AVAILABLE BY, OUR HOME INSTITUTIONS. Page 4 ------------------------------------------------------------------------------------ 11. Address Information Name: L. M. HOBBS Category: PI Institution: CHICAGO, UNIVERSITY OF Address: YERKES OBSERVATORY City: WILLIAMS BAY State: WI Zip Code: 531910258 Country: USA Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4798c [ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 14 HD141637 1 STAR; TYPE=B2.5 V RA= 15H 47M 57.94S +/- 1950 V= +03 1 V=4.68+/-0.02, TYPE=B2.5V, E(B- SCO 0.01S, 2 V)=0.16 DEC= -25D 36' 03.0" +/- 0.1" 3 F-CONT(1480)=7.27 E-10 4 F-CONT(1600)=5.65 E-10 5 F-CONT(2000)=2.96 E-10 F-CONT(2400)=2.17 E-10 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B 1950.00 -0.0013 +/- 0.0000 -0.0270 +/- 0.0000 0.0050 +/- 0.0050 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4798c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 201.1 DEFINE # HRS ACCUM 0.25 ECH-B 2324.31 1 22S # 5 # SEQ 201.1-203.6 NO AUX GAP Comments: C II; VACUUM WAVELENGTH ------------------------------------------------------------------------------------------------------------------------------------ 201.2 DEFINE WAVE HRS ACCUM SC2 ECH-B 2324.31 1 DEF 30 1 # CALIB FOR 201.100 AUX NO SLEW Comments: 0.25 ARCSEC APERTURE ------------------------------------------------------------------------------------------------------------------------------------ 201.3 DEFINE # ^ ^ 0.25 ^ 2325.30 1 22S # 5 # AUX Comments: C II; VACUUM WAVELENGTH ------------------------------------------------------------------------------------------------------------------------------------ 201.4 DEFINE WAVE ^ ^ SC2 ^ 2325.30 1 DEF 30 1 # CALIB FOR 201.300 AUX NO SLEW Comments: 0.25 ARCSEC APERTURE ------------------------------------------------------------------------------------------------------------------------------------ 201.5 DEFINE # ^ ^ 0.25 ^ 2326.29 1 22S # 5 # AUX Comments: C II; VACUUM WAVELENGTH ------------------------------------------------------------------------------------------------------------------------------------ 201.6 DEFINE WAVE ^ ^ SC2 ^ 2326.29 1 DEF 30 1 # CALIB FOR 201.500 AUX NO SLEW Comments: 0.25 ARCSEC APERTURE ------------------------------------------------------------------------------------------------------------------------------------ 202.1 DEFINE # ^ ^ 0.25 ^ 2324.41 1 22S # 5 # AUX Comments: C II; VACUUM WAVELENGTH ------------------------------------------------------------------------------------------------------------------------------------ 202.2 DEFINE WAVE HRS ACCUM SC2 ECH-B 2324.41 1 DEF 30 1 # CALIB FOR 202.100 AUX NO SLEW Comments: 0.25 ARCSEC APERTURE ------------------------------------------------------------------------------------------------------------------------------------ 202.3 DEFINE # ^ ^ 0.25 ^ 2325.40 1 22S # 5 # AUX Comments: C II; VACUUM WAVELENGTH ------------------------------------------------------------------------------------------------------------------------------------ 202.4 DEFINE WAVE HRS ACCUM SC2 ECH-B 2325.40 1 DEF 30 1 # CALIB FOR 202.300 AUX NO SLEW Comments: 0.25 ARCSEC APERTURE ------------------------------------------------------------------------------------------------------------------------------------ 202.5 DEFINE # ^ ^ 0.25 ^ 2326.39 1 22S # 5 # AUX Comments: C II; VACUUM WAVELENGTH ------------------------------------------------------------------------------------------------------------------------------------ 202.6 DEFINE WAVE HRS ACCUM SC2 ECH-B 2326.39 1 DEF 30 1 # CALIB FOR 202.500 AUX NO SLEW Comments: 0.25 ARCSEC APERTURE ------------------------------------------------------------------------------------------------------------------------------------ 203.1 DEFINE # ^ ^ 0.25 ^ 2324.51 1 22S # 5 # AUX Comments: C II; VACUUM WAVELENGTH ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4798c [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 203.2 DEFINE WAVE ^ ^ SC2 ^ 2324.51 1 DEF 30 1 # CALIB FOR 203.100 AUX NO SLEW Comments: 0.25 ARCSEC APERTURE ------------------------------------------------------------------------------------------------------------------------------------ 203.3 DEFINE # ^ ^ 0.25 ^ 2325.50 1 22S # 5 # AUX Comments: C II; VACUUM WAVELENGTH ------------------------------------------------------------------------------------------------------------------------------------ 203.4 DEFINE WAVE ^ ^ SC2 ^ 2325.50 1 DEF 30 1 # CALIB FOR 203.300 AUX NO SLEW Comments: 0.25 ARCSEC APERTURE ------------------------------------------------------------------------------------------------------------------------------------ 203.5 DEFINE # ^ ^ 0.25 ^ 2326.49 1 22S # 5 # AUX Comments: C II; VACUUM WAVELENGTH ------------------------------------------------------------------------------------------------------------------------------------ 203.6 DEFINE WAVE HRS ACCUM SC2 ECH-B 2326.49 1 DEF 30 1 # CALIB FOR 203.500 AUX NO SLEW Comments: 0.25 ARCSEC APERTURE ------------------------------------------------------------------------------------------------------------------------------------ 614.1 HD141637 HRS ACQ 2.0 MIRROR-A2 SEARCH-SIZE=5 1 5S 95 3 1 ONBOARD ACQ FOR BRIGHT=RETURN 614.2 LOCATE=YES SEQ 614.1-614.5 NO GAP CYCLE 1 / 614.1- 614.5 Comments: STEP-TIME = 0.2 SEC; 1 SCO ------------------------------------------------------------------------------------------------------------------------------------ 614.2 HD141637 HRS ACQ/ 2.0 MIRROR-A2 1 9.2S 3 1 ONBOARD ACQ FOR PEAKUP 614.3-614.5 Comments: STEP-TIME = 0.2 SEC; 1 SCO ------------------------------------------------------------------------------------------------------------------------------------ 614.3 HD141637 HRS IMAGE 2.0 MIRROR-A2 1 96.8S 3 1 Comments: STEP-TIME = 0.2 SEC; TAKE MAP AFTER CENTERING; 1 SCO ------------------------------------------------------------------------------------------------------------------------------------ 614.5 USE AUX HD141637 X7.20 141 1 Comments: 1 SCO ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4798c [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ^ ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ^ ACQ ACQ/PEAKUP IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=5 BRIGHT=RETURN LOCATE=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 9.06 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 201.1-203.6 NO GAP CALIB FOR 201.100 NO SLEW CALIB FOR 201.300 NO SLEW CALIB FOR 201.500 NO SLEW CALIB FOR 202.100 NO SLEW CALIB FOR 202.300 NO SLEW CALIB FOR 202.500 NO SLEW CALIB FOR 203.100 NO SLEW CALIB FOR 203.300 NO SLEW CALIB FOR 203.500 NO SLEW ONBOARD ACQ FOR 614.2; SEQ 614.1-614.5 NO GAP; CYCLE 1 / 614.1-614.5 ONBOARD ACQ FOR 614.3-614.5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements ECH-B ^ MIRROR-A2 ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD141637 1 SCO ------------------------------------------------------------------------------------------------------------------------------------