Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5255c Report Date: 09-May-96:20:29 Version: ********** Check-in Date: ********** 1.Proposal Title: MULTIWAVELENGTH OBSERVATIONS OF THE FLARES AND OSCILLATIONS AE AQR ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO/DD Sub Category ERUPTIVE BINARIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Keith Horne STSCI USA 301-338-4964 ------------------------------------------------------------------------------------ 7. Abstract The cataclysmic variable AE Aquarii is unique among the objects of its class because of its large-amplitude, aperiodic flaring activity, which presents a puzzle to our understanding of the underlying powerhouse. It also harbors the most rapidly spinning white dwarf known (spin period: 33s). Although AE Aqr has been the subject of systematic scrutiny at many different bands, and with a variety of observatories and instruments (including the HST), many puzzling aspects of its behavior are still not understood. In appreciation of the potential importance of AE Aqr as a laboratory for studying the physics of accretion, the Astronomical community has decided to undertake a large, coordinated campaign for monitoring this system across the electromagnetic spectrum. We propose to participate in this undertaking by using the HST to obtain near-UV spectra of AE Aqr with high time resolution simultaneously wiht other space-based and Earth-based observatories, in particular with the ROSAT observatory which is scheduled to observe the system in the soft X- ray band. This project plays up to the particular strengths of the HST, namely its high sensitivity and spectral resolution in the near-UV band, which is not accessible by Earth-based telescopes, and its ability to carry out spectroscopy with extremely high time resolution. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.00 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5255c PI: Keith Horne Proposal Title: MULTIWAVELENGTH OBSERVATIONS OF THE FLARES AND OSCILLATIONS AE AQR ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Keith Horne STSCI USA X Michael Eracleous STSCI USA Mario Livio STSCI USA William F. Welsh STSCI USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will use the FOS with Blue digicon and G160L grating in RAPID readout mode with SUB-STEP=2 and READ-TIME=3.2 to obtain 2-second esposures every 3.2s (assuming a dead time of approx 1.2s). This will provide roughly 10 exposures per 33s oscillation period. The ultraviolet spectral range 1150-2300 Angstroms will be recorded in 1st order while a simultaneous record of optical (3500A) variations is recorded in 0th order. The read time is the shortest that will permit use of 32-kbit recording on the on-board tape recorder with an acceptable duty cycle. We need to observe AE Aqr for 5 hours during one of three ROSAT observing windows, which are as follows: window ROSAT Date Time dwell sequence (UT) (UT) (mins) 1 300395 20-Oct-93 01:28-01:39 11m 20-Oct-93 04:42-05:06 24m 20-Oct-93 06:19-06:46 27m 2 300396 20-Oct-93 19:11-19:41 30m --+ 20-Oct-93 20:49-21:17 28m | 21-Oct-93 01:21-01:33 32m | Preferred 21-Oct-93 02:58-03:20 22m | Window 21-Oct-93 04:35-05:00 25m | 21- Oct-93 06:13-06:39 26m --+ 3 300393 21-Oct-93 19:05-19:35 30m --+ 21-Oct- 93 01:14-01:28 14m | Second Choice 21-Oct-93 02:52-03:14 26m __+ Window 2 is preferred. We wish to cover a complete orbit of AE Aqr in order to determine the pulse-timing orbit of the UV oscillations, and to perform the tomographic mapping of the emission-line regions. This will require 7 HST orbits. A total on-target exposure time of 5 hours will be accumulated given that the earth will occult AE Aqr roughly half the time, permitting 35-45m observing per HST orbit. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. HST is needed to provide UV sensitivity and time resolution sufficient to detect the 33 and 16.5s oscillations, and the flares. IUE has been used to define the time-averaged spectrum of AE Aqr (see figure), but it is useless for the high time-resolution observartions we need here. Ground-based studies have been important in establishing the basic nature of the AE Aqr system, the existence of flares and oscillations, the binary orbit and white dwarf spin period, and have raised the questions that are being addressed in this HST experiment. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. We need observations on 7 consecutive HST orbits to cover the full 9.88 hour binary orbit period. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. ------------------------------------------------------------------------------------ 9. Description of previous HST work. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Page 3 ------------------------------------------------------------------------------------ 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: 410-338-4964 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5255c [ 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 AE-AQR A,151,154,161 PLATE-ID = 02C4, J2000 1 V = 10.8 +/- 1.1 RA = 20H 40M 9.02S +/- 0.5", 1 B-V = 0.8 DEC = -0D 52' 15.5" +/- 0.5" 2 F-CONT(1500) = 3 +/- 1 E-13 Comments: VARIABLE STAR, UV MAY VARY BY 1MAG IN 10MIN. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5255c [ 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 AE-AQR FOS/BL ACQ/ 4.3 G160L 1 10S 1 1 ONBOARD ACQ FOR AEAQR PEAK 1.5 GROUP 1-3 NO GAP SPATIAL SCAN AT 20-OCT- 93:17:41:00 +/- 2H Comments: BRIGHT VARIABLE STAR. UV MAY VARY BY 1MAG IN 10MIN. ------------------------------------------------------------------------------------------------------------------------------------ 1.5 DEFINE AE-AQR FOS/BL ACQ/ 1.0 G160L 1 10S 1 1 ONBOARD ACQ FOR 2- AEAQR PEAK 3 SPATIAL SCAN ------------------------------------------------------------------------------------------------------------------------------------ 2 DEFINE AE-AQR FOS/BL RAPID 4.3 G160L READ-TIME=3.2 1 15M 1 AEAQR SUB-STEP=2 Comments: RAPID READOUTS FOR FLARES, AND 16.5S OSCILLATIONS. USE THIS 15M EXPOSURE IN SAME HST ORBIT AS TARGET ACQUISITION IF POSSIBLE. OTHERWISE BOOST EXPOSURE TIME AND USE TO FILL NEXT HST ORBIT. ------------------------------------------------------------------------------------------------------------------------------------ 2.5 DEFINE AE-AQR FOS/BL RAPID 4.3 G160L READ-TIME=3.2 7 40M 1 AEAQR SUB-STEP=2 Comments: 9.88 HR BINARY PERIOD TAKES 7 OR MORE CONSECUTIVE HST ORBITS. ASSUME 40M PER HST ORBIT. RAPID READOUTS FOR FLARES, AND 16.5S OSCILLATIONS. BOOST EXPOSURE TIME TO FILL OUT THE HST ORBIT. ------------------------------------------------------------------------------------------------------------------------------------ 3 DEFINE AE-AQR FOS/BL RAPID 4.3 PRISM READ-TIME=3.2 1 5M 2 AEAQR SUB-STEP=2 Comments: RAPID READOUT REQUIRED FOR FLARES, AND 16.5 AND 33 SEC OSCILLATIONS. OK TO ADJUST EXPOSURE TIME AND USE TO FILL IN A GAP E.G. BEFORE OR AFTER THE ROSAT WINDOW. ------------------------------------------------------------------------------------------------------------------------------------ 4 USE CYCLE 3 / 1-4 AEAQR Comments: TAKE UV SPECTRA DURING ROSAT WINDOW FROM UT 20-OCT:19:11 TO 21-OCT:06:39. START TARGET ACQUISITION EARLY ENOUGH TO ALLOW TIME FOR PEAKUP BEFORE START OF ROSAT WINDOW. 2ND CHOICE WINDOW IS UT 21- OCT:19:05 TO 22-OCT:03:14. ------------------------------------------------------------------------------------------------------------------------------------ Scan Paramters Form Proposal ID: 5255c [ 6] ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 1 Exposure Logsheet lines: 1 FGS Scan: DWELL Dwell Only: dwell points/line: 3 Seconds per dwell: 1.00 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 2.8000 Angle between sides (degrees) 90.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 0.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 1.4000 Width Offset (arc-sec): 0.0 ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 2 Exposure Logsheet lines: 1.5 FGS Scan: DWELL Dwell Only: dwell points/line: 6 Seconds per dwell: 1.00 Scan width (arc-secs): 0.7000 Scan length (arc-secs): 3.5000 Angle between sides (degrees) 90.00 Number of lines: 2 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 90.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 1.7500 Width Offset (arc-sec): 0.3500 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5255c [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK RAPID ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters READ-TIME=3.2 SUB-STEP=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/DD ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ERUPTIVE BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 1.5; GROUP 1-3 NO GAP; SPATIAL SCAN; AT 20-OCT-93 17 41 00 +/- 2H; ONBOARD ACQ FOR 2-3; CYCLE 3 / 1-4 ; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G160L PRISM ------------------------------------------------------------------------------------------------------------------------------------ Target Names AE-AQR ------------------------------------------------------------------------------------------------------------------------------------