Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4377c Report Date: 09-May-96:19:34 Version: ********** Check-in Date: ********** 1.Proposal Title: SOFT X-RAY TRANSIENTS: OUTBURSTS IN BLACK HOLE ACCRETION DISKS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID HOT STARS GO Target of Oppt. Sub Category X-RAY BINARIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Keith Horne STSCI USA ------------------------------------------------------------------------------------ 7. Abstract We will observe soft X-ray transients (SXTs) as targets of opportunity using the FOS at UV wavelengths. This is part of an extensive multiwavelength campaign to monitor newly discovered SXTs in outburst and throughout the subsequent decline. Recent work establishes that a high proportion of SXTs harbor black holes, so these observations provide an unrivalled opportunity to obtain high quality data from an accreting black hole. UV data is a keystone of the multiwavelength campaign because the disk regions of interest radiate predominantly in the UV. Emission lines will allow us to probe the kinematics of the inner disk region. We will examine the reprocessed X-ray flux emitted in the UV, and the UV flux generated by viscous heating in the accretion flow. Multiwavelength observations will probe the changing morphology of the accretion flow throughout the outburst. The observations will yield a detailed quantitative test of the thermal disk instability model for SXT outbursts. The interpretation of FOS observations of the SXT Nova Muscae 1991 demonstrated the critical importance to this test of recording the UV and optical spectrum during the decline. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 9.33 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4377c PI: Keith Horne Proposal Title: SOFT X-RAY TRANSIENTS: OUTBURSTS IN BLACK HOLE ACCRETION DISKS ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Keith Horne STSCI USA Fuhua Cheng STSCI USA Chris R. Shrader NASA GODDARD SPACE FLIGHT CENTER USA Carole A. Haswell STSCI USA Wan Chen NASA GODDARD SPACE FLIGHT CENTER USA Mario Livio STSCI USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We plan 1 visit to the target in quiescence. Details of the timing of the visit and the exposure times are given in section 4b. We plan to observe the target SXT with the FOS in each of the following modes: Blue digicon / G160L, PRISM Red digicon / G270H, G400H, PRISM to obtain spectral coverage from 1100A to 6000A. These exposures will operate in RAPID mode, with READ-TIME=6.18s. This allows us to monitor short timescale variability, with good spectral resolution (SUB- STEP=4). The exposures are interleaved to allow coverage of variations around the binary orbit cycle. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The HST/FOS observations will be wholly complementary to IUE observations in several important ways. The IUE instruments have limited dynamic range, and are incapable of obtaining measurements of sufficient signal-to-noise to address a number of important scientific issues. The broad, high excitation lines are rarely, if ever resolved above the instrumental broadening of IUE's spectrograph in low resolution mode, so that no real kinematic information is obtainable. The FOS with its higher spectral resolution will easily resolve such features. Also of importance is a precise determination of the galactic reddening correction. The 2000-2400A region is the least sensitive part of IUEs detectors, limiting the accuracy with which E(B-V) can be determined. FOS observations of Nova Muscae, determined E(B-V) to within a few percent. The combination of higher signal-to- noise continuum measurement over a broader band-pass than is possible with IUE can more significantly constrain the types of continuum model testing we discuss in section. By using the RAPID mode of the FOS we will also obtain higher time resolution than is possible with IUE. Finally, the greater sensitivity of HST will allow us to sample the UV emission over a much broader temporal baseline then has been possible with IUE (e.g. Nova Muscae 1991 became undetectable by IUE after about 4.5 months). We plan 1 visit to the target at quiescence. The following table gives details of the observing strategy, aiming to record the spectrum and light curve of GROJ0422+32. FOS/RD TA1, TA2, PRISM, G270H, PRISM, G400H 8 35 8 35 FOS/BL TA1, TA2, PRISM, G160L, PRISM, G160L, PRISM, G160L, PRISM 8 82 8 82 8 82 8 The numbers in the table above give exposure times in minutes. All observations are in RAPID mode with READ-TIME=6.18s. Interleaved prism exposures aid in combining spectra of variable target, and serve to monitor binary orbit variations. At Peg Stanley's request we've broken the proposal into 2 scheduling units to make it easier to schedule. This compromises science unless the two units are scheduled close together in time. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. The planned observations are now reduced to one visit because HST scheduling delays have allowed GROJ0422+32 to fade considerably, essentially back to its quiescent level. Cycle 1 HST observations of the SXT A0620-00, taken 14 years after its 1975 outburst, showed very low ultraviolet flux, indicating that accretion to the black hole had essentially halted. The present observations of GROJ0422+32 will test whether accretion is similarly halted, or whether it continues to occur in the early quiescent phase following its Aug 1992 outburst. The observations should therefore be made as soon as possible, subject to the Cycle 3 TAC requirement that this TOO proposal must not unduely disrupt the normal scheduling process. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The data reduction will be done at the STScI where we have all the experience and the means necessary to guarantee a high quality outcome. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. There is a significant likelihood of a major SXT occurring during the duration of this proposal. Recurrence times of an individual sources vary greatly, but there has been over the last 4 years about one major event per year. These events are readily detectable by the Burst and Transient Source Experiment (BATSE) onboard Compton GRO. For example, several recent, much less dramatic events were discovered: a recurrent outbursts of 4U 1543-47 in April 1992 (Harmon, B.A. et al. 1992 IAU Circular no. 5504) and EXO 1846-031 (Shrader,C.R. and Wagner,R.M. in preparation). At the time of this writing (phase I), a new transient event has been discovered, and localized to an accuracy of 0.2 degrees similarities (Harmon, et al. 1992 IAU circ. 5584). Since the distance, the intrinsic brightness,and the galactic extinction are all totally unknown prior to an outburst, we will need to update our detailed observation plan prior to activation of the program. As discussed in other sections of the proposal, our complementary target of opportunity programs on IUE and Compton GRO will supply us with the necessary information. As discussed in section 4, we will then use information obtained through our IUE target of opportunity program to assess the feasibility and scientific value of HST observations. Page 4 ------------------------------------------------------------------------------------ 9. Description of previous HST work. CS: Cycle 1: GO-3232 "Observations of X-ray nova Muscae 1991" [CoI] KH: Cycle 1: GO-3232 "Observations of X-ray nova Muscae 1991" [CoI] GO-2380 "Instabilities in accretion disks and the outbursts of dwarf novae" [PI] GO-2334 "Ultraviolet spectroscopy of the black hole A0620-00"[CoI] Cycle 2: GO-3578 "Line Eclipse Mapping of an Accretion Disk Wind" [CoI] GO-3824 "A search for silicon and carbon in GP Com" [CoI] GO-3600 "Oscillations, flaring, and tomography of AE Aquarii"[PI] GO-3683 "Accretion disk mapping in eclipsing cataclysmic variables" [PI] GO -3836 "Spectroscopic Observations of the Exposed WDs in the Dwarf Novae U Gem, WZ Sag, and VW Hyi" [CoI] GO-3232, GO-2334 are related to present project. GO- 2334: FOS spectra showed A0620-00 to be much fainter than expected, suggesting that the accretion disk viscosity shuts off completely in the quiescent periods between the outbursts of SXTs. GO-2380: FOS spectra of the eclipsing dwarf nova OY Car in quiescence (Dec 1991) and on the decline following a superoutburst (Apr -Jul 1992) are being used to discriminate between the disk instability and mass- transfer instability models of dwarf nova outbursts. A paper on the quiescent eclipse data has been accepted by the ApJ, while the data obtained following the superoutburst are under analysis. GO-3232: By combining HST/FOS, IUE, optical and x-ray spectra of Nova Muscae on the decline from outburst we place limits on the mass of the putative black hole in this system, and show that the cooling front predicted by disk instability model was not seen. a paper has been published in the ApJ 1992 October issue. GO-3578 will use HRS to investigate line profile changes during the eclipse of an accretion disk wind. GO-3600 will use FOS to investigate oscillations and flickering in an enigmatic CV with a magnetized and rapidly spinning accreting white dwarf. GO-3683 will obtain FOS observations of the eclipsing dwarf nova IP Peg in quiescence and on decline from an outburst to search for the cooling front in the disk as it cools and to study the disk structure. GO-3824 aims to determine metal abundances in the nearly pure helium disk in the ultra-short period system GP Com. GO-3836 is a GHRS study of white dwarfs in three quiescent dwarf novae. "The HST observations of X-ray Nova Muscae 1991 and its spectral evolution" F. H. Cheng, K. Horne, N. Panagia, C. R., Shrader, R. Gilmozzi, F. Paresce and Lund, ApJ, 1992, 397, 664. "The Dim Inner Accretion Disk of the Quiescent Black Hole A0620-00" J. McClintock, K. Horne, R. Remillard submitted. "HST Eclipse Mapping of Dwarf Nova OY Car in Quiescence: An `FeII Curtain' with Mach ~ 6 Velocity Dispersion Veils the White Dwarf" K. Horne, T. Marsh, F. H. Cheng, I. Hubeny and T. Lanz, ApJ, 1993, accepted. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Salary and basic computer facilities are being provided for the P.I. and most of the Co-Is. ------------------------------------------------------------------------------------ 11. Address Information Name: Keith Horne Category: PI Institution: STScI Address: 3700 San Martin Drive City: Baltimore State: MD Zip Code: 21218 Country: USA Telephone: 410-338-4955 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4377c [ 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 GROJ0422+32 A,161,162,164,165 RA-OFF = +0.218S +/- 0.002S, 2000 1 V = 15.1 +/- 0.2 NOVA-PERSEI- DEC-OFF = -22.27" +/- 0.2", 2 E(B-V) = 0.4 +/- 0.07 1992 FROM 2 3 F-CONT(1500)= 1.0 +/- 0.25 E-14 Comments: OFFSET FROM 2 (MOVE E AND S) AUG 13.17 1993 UT, RISE AUG 25 1993 IUE SPECTRUM APPROX FNU=NU**1/3 DE-REDDENED. OBJECT NOT APPARENT ON GASP PLATES POSN FROM MARK WAGNER ASTROMETRY ASSUME FNU=NU**1/3, V=20.0, E(B-V)=0.4 FOR EXP. CALCS. RA = 04H 21M 42.787S +/- 0.2", DEC = +32D 54' 27.09" +/- 0.2" ------------------------------------------------------------------------------------------------------------------------------------ 2 GROJ0422- I,603 RA = 04H 21M 42.569S +/- 2000 1 V = 16.69 +/- 0.2 OFFSET 0.2", DEC =+32D 54' 49.36" +/- 0.2" Comments: OFFSET STAR POSN FROM MARK WAGNER ASTROMETRY OFFSET STAR IS NORTH AND SLIGHTLY WEST OF GRO J0422. CLOSE ENOUGH THAT NO ADDNL GUIDE STAR ACQS REQD. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4377c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1.1 GROJ0422- FOS/RD ACQ/ 4.3 MIRROR SEARCH-SIZE-X=1 1 10S 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE-Y=4 1.2 SCAN-STEP-Y=1.4 SEQUENTIAL 1.1 - 3.2 NO GAP CYCLE 3 / 1.1 - 3.2 Comments: OBSERVE ASAP. B-V UNKNOWN. OK TARG OF OPP / 1.1 TO RE-ORDER EXPOSURES, BUT 2.1 - 3.2 AND 3.1 NOT IN SAME HST ORBIT. GROUP 1.1-11 TO PERMIT COORDINATED WITHIN 2D OBSERVATIONS, PLEASE NOTIFY CO- I, CAROLE HASWELL. ------------------------------------------------------------------------------------------------------------------------------------ 1.2 GROJ0422- FOS/RD ACQ/ 1.0 MIRROR SEARCH-SIZE-X=6 1 15S 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE-Y=2 1.3 SCAN-STEP-X=0.7 SCAN-STEP-Y=0.7 Comments: GASP PLATE EXTRACTIONS FOR THIS FIELD HAVE ERRORS ~1". USING PRECISE (0.2") ASTROMETRY FROM MARK WAGNER FOR COORDS & AND OFFSETS. SCAN PATTERN COVERS DISCREPANCY BETWEEN GASP & WAGNER ------------------------------------------------------------------------------------------------------------------------------------ 1.3 GROJ0422- FOS/RD ACQ/ 1.0 MIRROR SEARCH-SIZE-X=3 1 15S 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE-Y=3 2.1-3.2 SCAN-STEP- X=0.35 SCAN-STEP- Y=0.35 Comments: ACQUIRE WITH FOS/RD TO MINIMIZE TIME. ------------------------------------------------------------------------------------------------------------------------------------ 2.1 GROJ0422+32 FOS/RD RAPID 4.3 PRISM READ-TIME=6.18 1 475.86S 1 Comments: NOT IN SAME ORBIT AS 3.1 ------------------------------------------------------------------------------------------------------------------------------------ 2.2 GROJ0422+32 FOS/RD RAPID 4.3 G270H READ-TIME=6.18 1 2095.02 1 Comments: PLEASE EXTEND EXPOSURE TO FILL OUT SPACECRAFT ORBIT ------------------------------------------------------------------------------------------------------------------------------------ 3.1 GROJ0422+32 FOS/RD RAPID 4.3 PRISM READ-TIME=6.18 1 475.86S 1 Comments: NOT IN SAME ORBIT AS 2.1 ------------------------------------------------------------------------------------------------------------------------------------ 3.2 GROJ0422+32 FOS/RD RAPID 4.3 G400H READ-TIME=6.18 1 2095.02 1 Comments: PLEASE EXTEND EXPOSURE TO FILL OUT SPACECRAFT ORBIT ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4377c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 4.1 GROJ0422- FOS/BL ACQ/ 4.3 MIRROR SEARCH-SIZE-X=1 1 30S 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE-Y=4 4.2 SCAN-STEP-Y=1.4 SEQUENTIAL 4.1 - 11 NO GAP CYCLE 3 / 4.1 - 11 TARG OF OPP / 4.1 Comments: OBSERVE ASAP. B-V UNKNOWN. TO - 11 PERMIT COORDINATED OBSERVATIONS , PLEASE NOTIFY CO-I, CAROLE HASWELL. DO FOS/RD ACQ IF 4.1 - 4.3 WILL NOT SCHEDULE. ------------------------------------------------------------------------------------------------------------------------------------ 4.2 GROJ0422- FOS/BL ACQ/ 1.0 MIRROR SEARCH-SIZE-X=6 1 49S 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE-Y=2 4.3 SCAN-STEP-X=0.7 SCAN-STEP-Y=0.7 ------------------------------------------------------------------------------------------------------------------------------------ 4.3 GROJ0422- FOS/BL ACQ/ 1.0 MIRROR SEARCH-SIZE-X=3 1 49S 1 ONBOARD ACQ FOR 5- OFFSET PEAK SEARCH-SIZE-Y=3 11 SCAN-STEP- X=0.35 SCAN-STEP- Y=0.35 ------------------------------------------------------------------------------------------------------------------------------------ 5 GROJ0422+32 FOS/BL RAPID 4.3 PRISM READ-TIME=6.18 1 475.86S 1 ------------------------------------------------------------------------------------------------------------------------------------ 6 GROJ0422+32 FOS/BL RAPID 4.3 G160L READ-TIME=6.18 1 4919.28 1 Comments: SPLIT/EXTEND EXPOSURE TO FILL OUT SPACECRAFT ORBITS ------------------------------------------------------------------------------------------------------------------------------------ 7 GROJ0422+32 FOS/BL RAPID 4.3 PRISM READ-TIME=6.18 1 475.86S 1 ------------------------------------------------------------------------------------------------------------------------------------ 8 GROJ0422+32 FOS/BL RAPID 4.3 G160L READ-TIME=6.18 1 4919.28 1 Comments: SPLIT/EXTEND EXPOSURE TO FILL OUT SPACECRAFT ORBITS ------------------------------------------------------------------------------------------------------------------------------------ 9 GROJ0422+32 FOS/BL RAPID 4.3 PRISM READ-TIME=6.18 1 475.86S 1 ------------------------------------------------------------------------------------------------------------------------------------ 10 GROJ0422+32 FOS/BL RAPID 4.3 G160L READ-TIME=6.18 1 4919.28 1 Comments: SPLIT/EXTEND EXPOSURE TO FILL OUT SPACECRAFT ORBITS ------------------------------------------------------------------------------------------------------------------------------------ 11 GROJ0422+32 FOS/BL RAPID 4.3 PRISM READ-TIME=6.18 1 475.86S 1 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4377c [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK RAPID ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=1 SEARCH-SIZE-Y=4 SCAN-STEP-Y=1.4 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 SCAN-STEP-X=0.7 SCAN-STEP-Y=0.7 SEARCH-SIZE-X=3 SEARCH-SIZE-Y=3 SCAN-STEP-X=0.35 SCAN-STEP-Y=0.35 READ-TIME=6.18 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 9.33 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category X-RAY BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 1.2; SEQUENTIAL 1.1 - 3.2 NO GAP ; CYCLE 3 / 1.1 - 3.2 ; TARG OF OPP / 1.1 - 3.2 ; GROUP 1.1-11 WITHIN 2D; ONBOARD ACQ FOR 1.3; ONBOARD ACQ FOR 2.1-3.2; ONBOARD ACQ FOR 4.2; SEQUENTIAL 4.1 - 11 NO GAP ; CYCLE 3 / 4.1 - 11 ; TARG OF OPP / 4.1 - 11 ; ONBOARD ACQ FOR 4.3; ONBOARD ACQ FOR 5-11; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR PRISM G270H G400H G160L ------------------------------------------------------------------------------------------------------------------------------------ Target Names GROJ0422+32 NOVA-PERSEI-1992 GROJ0422-OFFSET ------------------------------------------------------------------------------------------------------------------------------------