Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4247c Report Date: 09-May-96:16:42 Version: ********** Check-in Date: ********** 1.Proposal Title: UV OBSERVATIONS OF GEMINGA ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO/DD Sub Category NEUTRON STARS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Stephen S. Holt NASA/GODDARD SPACE FLIGHT CE USA (301) 286 6066 DIRECTOR CODE 600 ------------------------------------------------------------------------------------ 7. Abstract The gamma-ray source Geminga (identified with the X-ray source 1E0630+178) is a near -by neutron star detected as a 237 ms pulsar in both the X-ray and gamma-ray region of the spectrum (Halpern and Holt, 1992). It is not detected as a radio pulsar, however. We will observe the proposed optical counterpart of Geminga (star G" in the list of Halpern and Tytler, 1988) in the UV (140 - 300 nm) with the High Speed Photometer in an attempt to detect the 237 ms pulsation. An offset of 1.3 arcmin from GSC 01333.01169 will be required to acquire G". A positive detection of the 237 ms period will confirm the identity of G" as Geminga and extend our knowledge of the spectrum of a neutron star into the UV; a negative result may place important constraints on the standard model of neutron star emission. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 1.50 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HSP ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4247c PI: Dr. Stephen S. Holt Proposal Title: UV OBSERVATIONS OF GEMINGA ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Stephen S. Holt NASA/GODDARD SPACE FLIGHT CENTER USA Demosthenes Kazanas NASA/GODDARD SPACE FLIGHT CENTER USA James D. Biggs UNIVERSITIES SPACE RESEARCH USA ASSOCIATION Joseph F. Dolan NASA/GODDARD SPACE FLIGHT CENTER USA ------------------------------------------------------------------------------------ 2. Scientific Justification. Candidate star G" will be acquired by offset of 1.8 arcmin from GSC 01333.01169. A 40 minute (one orbit) non-interrupted observation of G" will be obtained with 1 ms time resolution using the F140LP filter (140 - 300 nm) on the High Speed Photometer. The data will be searched for the signature of the 237 ms pulsar period from Geminga. ------------------------------------------------------------------------------------ 3. Description of proposed observations. The proposed observations require the following capabilities of HST: (1) High time resolution (1 ms) with no scintillation noise - necessary to obtain the highest signal-to-noise ratio possible in searching for a 237 ms period signal from a faint star. (2) Access to the UV (140 - 300 nm) - the spectrum of a neutron star is expected to be brighter in the UV than in the visible, and the UV spectrum of a pulsar is unobservable from the ground. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The HSPSIM routine on the SCIVAX computer was used to simulate the count rate of star G" through the F140LP filter given the results obtained by the HSP Team on the Crab pulsar (time-averaged V = 16) through the same filter. Given V = 25.3 (Halpern and Tytler, 1988), we estimate 0.3 counts per second detected. 1 ms time resolution should allow us to detect any signal at a 237 ms period; the data can be co-added on the ground to produce coarser time bins if necessary for detection. A 40 minute, one-orbit observation would obtain 700 photons from the source, or a S/N of 25. This will allow us to detect any 237 ms signature in the signal with a pulsed fraction > 1%. It will also allow us to detect the presence of any unpulsed component of the flux if that component contains > 5% of the total flux. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Standard data analysis techniques, including FFT analysis, will be carried out on the data using the standard packages developed and used on the Crab pulsar observations by the HSP Team at NASA Goddard Space Flight Center. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. Previous HST Time: GTO 1101 "Optical and UV Observations of Radio Pulsars" Establishes the Crab pulsar photometric light curve in the UV. Paper in preparation. ------------------------------------------------------------------------------------ 9. Description of previous HST work. Computing facilities will be supplied by home institution. Page 3 ------------------------------------------------------------------------------------ 11. Address Information Name: STEPHEN S. HOLT Category: PI Institution: NASA/GODDARD SPACE FLIGHT CENTER Address: MAIL CODE 681 City: GREENBELT State: MD Zip Code: 20771 Country: USA Telephone: (301) 286 5920 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4247c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 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 GSC01333- A, 160 RA = 06H 33M 49.14S +/- 2000 1 V=11.4 01169 0.02S, GEMINGA- DEC = +17D 47' 30.7" +/- OFFSET 0.3" ------------------------------------------------------------------------------------------------------------------------------------ 2 GPRIMEPRIME A,160 RA = 06H 30M 59.06S +/- 1950 1 V=25.3 GEMINGA- 0.02S, CANDIDATE DEC = +17D 48' 32.75" +/- 0.3" ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4247c [ 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 DEFINE GSC01333- HSP/ ACQ 1 10S 15 1 1 SEQ 1-2 NO GAP PHOT 01169 UV1 ONBOARD ACQ FOR 2 Comments: THIS IS THE OFFSET ACQ FOR 2 OFFSET SLEW REQUIRED FROM GSC01333.01169 TO GPRIMEPRIME ------------------------------------------------------------------------------------------------------------------------------------ 2 ^ ^ GPRIMEPRIME HSP/ SINGLE 1.0-C F140LP SAMPLE- 1 40M 100 1 1 CYCLE 2 UV1 TIME=0.001 RT-ANALYSIS Comments: EXPOSURE TIME = 40M OR MAXIMUM TIME POSSIBLE IN ONE ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 3 USE CYCLE 2 PHOT ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4247c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HSP/UV1 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ SINGLE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMPLE-TIME=0.001 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/DD ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 1.50 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category NEUTRON STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 1-2 NO GAP; ONBOARD ACQ FOR 2; CYCLE 2; RT-ANALYSIS; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F140LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names GSC01333-01169 GEMINGA-OFFSET GPRIMEPRIME GEMINGA-CANDIDATE ------------------------------------------------------------------------------------------------------------------------------------