Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 2603c Report Date: 09-May-96:17:15 Version: ********** Check-in Date: ********** 1.Proposal Title: PARALLEL OBSERVATIONS OF H LY ALPHA EMISSION FROM THE LOCAL ISM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID INTERSTELLAR MEDIUM GO 2603 Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. John T. Clarke MICHIGAN, UNIVERSITY OF USA 313-747-3540 DOCTOR ------------------------------------------------------------------------------------ 7. Abstract We propose to observe the sky background H Ly alpha emission in parallel with scheduled observations to study the emission generated by local ISM hydrogen penetrating into the solar system. This component can be observed when the earth orbital motion Doppler-shifts the geocoronal line from the LISM vector. By defining the velocity vector of the interstellar wind (ISW) in the solar system we may identify which of several local clouds in the LISM encompasses the solar system. By a careful measurement of the ISW line shape we may study the temperature of the LISM and interaction of the ISW with the heliospheric bow shock and solar wind. This proposal is solely for parallel observing time. ------------------------------------------------------------------------------------ 8. Scientific Key Words: INTERPLANETARY MEDIUM, LISM GAS, SOLAR WIND ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 0 par: 24.00 10. Num targs pri: 0 par: 7 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 2603c PI: Dr. John T. Clarke Proposal Title: PARALLEL OBSERVATIONS OF H LY ALPHA EMISSION FROM THE LOCAL ISM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ P.I. John T. Clarke MICHIGAN, UNIVERSITY OF USA Hans Fahr BONN UNIVERSITY FRG X Jean-Loup Bertaux CNRS, DEPARTMENT OF AERONOMY FRANCE X Rosine Lallement CNRS, DEPARTMENT OF AERONOMY FRANCE X Francesco Paresce STSCI USA X ------------------------------------------------------------------------------------ 3. Description of proposed observations. We are proposing for parallel observations only, using the HRS and Echelle A grating. With the LSA we will obtain 0.10 A resolution and a count rate of 1.6 cts/sec-kR, whereas the SSA will give .013 A resolution and .026 cts/sec-kR. The ISW H Ly alpha emission may be 0.1 - 1.0 kR, depending on the angle of observation to the flow direction and the solar flux. For a 500 R emission and a 30 min. dark orbit integration with the LSA, we would get 1400 counts (S/N = 40) spread over 8 diodes. By centroiding we could measure the line of sight velocity of the ISW with an accuracy of roughly 1-2 km/sec. Our first priority is to obtain such measurements of the velocity and emission brightness over a range of lines of sight. No HST pointing is required as long as no other emission sources are in the aperture, since the ISW is diffuse over the sky. A minimum of 6 lines of sight is initially requested, all in parallel mode. The second priority is to measure the temperature of the ISW through the line shape determined from HRS SSA spectra at .013 A resolution. The line width is expected to be in the range 50- 100 mA, so that 13 mA resolution will easily resolve the line width and shape. In a 30 min. integration we would only achieve S/N of 5, however, so that longer integrations would be desired. We propose to use the HRS during the WF/PC UV- flood operation, when the HST will be pointed at the anti-sun for periods of 10- 20 orbits. Note: due to problems with side 1 of GHRS, we have changed our mode to GHRS 160M with the SSA - 2/92. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The scientific importance of observing the ISW separately from the LISM is discussed above. The only emission lines bright enough to be observed in the ISW are the UV resonance lines of H and He, and we are proposing to observe the brightest emission of H Ly alpha. The HST is the only instrument with sufficiently high resolution and UV sensitivity to study the emission velocity and line profile. Although the integration times are substantial, the observation requires no dedicated pointing and can be conducted entirely in parallel mode. The information derived from this study will complement the HST and ground- based studies of the LISM through absorption spectra of near-by stars, which we have pursued in the past (Lallement et al. 1986). ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. There are no tracking requirements, other than that the HRS aperture be "empty" except for sky background emission. Our data will be obtained in parallel during the 40 min. of dark orbit to minimize the brightness of the geocoronal emission, and as such no serial exposure time is required. The exposure times necessay to achieve useful S/N levels are discussed in the observing plan (see question 3). We wish to have the GHRS continue taking data through the entire orbit (yes, even while looking at the bright Earth) so that we may model the variation in the geocoronal emission over the orbit. Page 3 ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. We would like observations distributed about the general inflow or upwind direction ( alpha = 17 hrs, delta = -20 degrees) to determine the velocity vector and line profile, to be arranged with the HST schedule as opportunities permit. These opportunities will be limited to the WF/PC UV-flood's, as determined by the TAC. We understand that our GHRS observations will be conducted as a default procedure during all WF/PC UV-flood's after launch and through the end of the first GO cycle. The GHRS integrations may be performed in any order, and the SSA spectra stopped when nearing the end of the UV-flood. At least for the first observation, we would like the GHRS data-taking to continue through Earth occultation so that we may model the geocoronal Ly alpha emission background. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The GHRS spectra will be reduced using standard programs obtained from the ST ScI or GHRS team on facilities at the Univ. Michigan. There are no special calibrations or techniques required, other than a careful measurement of the ISW line velocity and the shape/profile of the ISW line. The analysis of the data will involve determination of the ISW velocity vector using existing programs, and the analysis of the ISW Ly alpha line shape by conventional techniques. The analysis of the local flow components in the LISM has been published by Lallement et al. (1986), and the analysis of the effects of modification of the flow at the heliospheric boundary be Fahr and Shizgal (1983). These workers will take the lead role in the interpretation of the ISW velocity vector and temperature derived from the HRS spectra. The interpretation of the ISW line profile will likely involve detailed modeling of different flow components and their interaction with the heliospheric bow shock. Although it appears that we will obtain only two spectra per UV-flood, the separation of the geocoronal emission and modeling of the ISW line will involve considerable work to interpret the data. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Complete computing facilities are in place and available within the Space Physics Research Lab. for use on this effort. Two VAX 750's and VAX 8600 are accessible via a local area network, in addition to the Michigan network (MERIT) and the SPAN network. A SUN 4/110 workstation running IDL has been purchased using University of Michigan funds. In addition to the above resources, three DEC color graphics workstations, with hard copy capability, are available to provide high quality output for publications. ------------------------------------------------------------------------------------ 11. Address Information Name: JOHN T. CLARKE Category: PI Institution: UNIVERSITY OF MICHIGAN Address: AOSS DEPARTMENT City: ANN ARBOR State: MI Zip Code: 481092143 Country: USA Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST c)Generic Targets ID = 2603c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 7 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Selection Criteria |Acqui|FLX| Flux data No | Name | Description | |Prblm|REF| | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 ISM OTHER: INTERPLANETARY OBSERVE DURING ALL WF/PC 1 SURF-LINE(1216) = 1.5 +/- 1 E-12 MEDIUM UV-FLOOD'S. 2 W-LINE(1216) = 0.1 +/- .05 Comments: PARALLEL OBSERVATION WITH GHRS DURING WF/PC UV -FLOOD: GHRS TO OBSERVE H LY ALPHA EMISSION FROM GEOCORONA AND ISM H WHILE POINTED AT ANTI-SOLAR POINT. NO GS ACQUISITION OR TRACKING. DO THIS DURING ALL UV-FLOODS. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2603c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 WAVE HRS ACCUM SC1 G160M 1223.0 STEP-PATT=DEF 1 100 S 2 CALIB FOR 2 STEP-TIME=1.0 SEQ 1-2 NON-INT PCS MODE G CYCLE 1 REPEAT 1-2 EVERY 90M +/- 10M Comments: WAVELENGTH CALIBRATION FOR SSA FOR 32 MORE TIMES SPECTRUM NEEDED TO MEASURE VELOCITY OF VLISM. ONE CALIBRATION/OBSERVATION PER ORBIT THROUGHOUT UV FLOOD (~20 ORBITS). ------------------------------------------------------------------------------------------------------------------------------------ 2 ISM HRS ACCUM 0.25 G160M 1223.0 STEP-PATT=DEF 3 600 S 1 CYCLE 1 STEP-TIME=1.0 PCS MODE G DOPPLER=ON FP-SPLIT=STD Comments: GHRS SSA SPECTRA TO MEASURE ISM H LINE PROFILE: REPEAT 1-2 AS LONG AS POSSIBLE DURING WF/PC UV-FLOOD. EXPOSE ALSO DURING EARTH OCCULTATION. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 2603c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters STEP-PATT STEP-TIME STEP-TIME=1.0 DOPPLER FP-SPLIT ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CALIB FOR 2; SEQ 1-2 NON-INT; PCS MODE G; CYCLE 1; REPEAT 1-2 EVERY 90M +/- 10M FOR 32 MORE TIMES; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names ISM ------------------------------------------------------------------------------------------------------------------------------------