Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 3432c Report Date: 09-May-96:18:37 Version: ********** Check-in Date: ********** 1.Proposal Title: CIR-X1 REVISITED: SPECTROSCOPY THROUGHOUT THE 16.6 DAY CYCLE OF THE REAL OPTICAL CANDIDATE. ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO 3432 Sub Category X-RAY BINARIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Patrizia A Caraveo ISTITUTO DI FISICA COSMICA D ITALY 39-2-2367587 ------------------------------------------------------------------------------------ 7. Abstract Circinus X-1 is a very strong and highly variable X-ray, IR and radio source. Its optical identification was, until very recently, wrongly attributed to a star which recent NTT observations, done in superb seeing, have resolved in three objects.Of these one, very red, coincides with the accurate VLA position for the radio source (varying in phase with the X-ray), and is thus the real candidate. Only HST can now do meaningful work on the true counterpart of Cir X-1: even small seeing conditions variations would render incomparable measurements taken from the ground over the 16.6 day (binary\?) source cycle. A WFPC exposure for target acquisition and a sequence of 4 FOS spectra, taken at critical time during the cycle, will probably suffice to understand this 17-19 mag variable object, responsible for a truly bizarre X-ray/radio object. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 6.58 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS WF/PC ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 3432c PI: Patrizia A Caraveo Proposal Title: CIR-X1 REVISITED: SPECTROSCOPY THROUGHOUT THE 16.6 DAY CYCLE OF THE REAL OPTICAL CANDIDATE. ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Giovanni F Bignami ISTITUTO DI FISICA COSMICA DEL ITALY X CNR Pi Patrizia A Caraveo ISTITUTO DI FISICA COSMICA DEL ITALY X CNR ------------------------------------------------------------------------------------ 3. Description of proposed observations. After an EARLY ACQUISITION with the WFPC we plan to use the red detector of the FOS with the PRISM using a 0.5 arcsec aperture to obtain a low resolution spectrum of the proposal counterpart of Cir X-1. We have chosen this set-up in order to maximize the trhoughput of the instrument, given the relative faintness of our target, most probably of mr= 19, and the need to use a small aperture also to avoid contamination from the nearby (about 1.5 arcsec) field stars. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. In order to study the temporal behaviour of the Cir X1 optical counterpart, now known to lye 1.5 arcsec from two unrelated objects,one needs EXCELLENT and CONSTANT SEEING CONDITIONS. Clearly this can only be achievable with HST whose angular resolution is both very good and stable so that one can be sure to obtain directly comparable data sets taken at different phases of the 16.6 day cycle of this source This has been repeatedly tried from the ground, using ESO telescopes, but with no success owing to the need of a truly sub-arcsec seeing for long integration times and for several nights. The problem consists in taking good spectra throught the 16.6 day cycle ( say 3 spectra near maximum -before, during and after- and one well away from it) of an object of about mr 19. We believe the FOS on HST to be currently the only instrument for this job, even considering the degraded performance of the OTA. The wider PSF implies that we have to be particularly careful to avoid contamination from the two adjacent stars. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Since the strong and clearly correlated X-ray,Radio,IR flux variabilities of Cir X-1 are known to follow a 16.6 day cyclic behaviour, we propose to observe the source 4 times during such a cycle. In particular we ask for three observations near the expected maximum and for one in the quiet period of the cycle. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. As already mentioned, the current proposing team has significant experience with ground-based optical astronomy data analysis. In particular, the current P.I. is also Co.I. of an ESO Key Project dedicated to similar scientific goal as this proposal. At our institute in Milano we have directly available IRAF (with STSDAS), MIDAS on SUN WS and VAX. We plan, however, to make full use of the ECF facility in Garching, and also to interact strongly with STScI personnel, especially for the critical points of background and sky subtraction, as well as wavelength and flux calibrations. ------------------------------------------------------------------------------------ 9. Description of previous HST work. 2525: Searching for the GEMINGA Optical Counterpart with Multi-color Photometry Related to the present proposal only from the phylosophical point of view. The objects involved can be very different Page 3 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The Istituto di Fisica Cosmica has VAX and SUN WS equipped with MIDAS and IRAF (with STSDAS). Students from the Istituto di Fisica of the Milano University normally take active part in the data analysis. Funds will be provided by the Agenzia Spaziale Italiana and by CNR ------------------------------------------------------------------------------------ 11. Address Information Name: PATRIZIA A CARAVEO Category: PI Institution: ISTITUTO DI FISICA COSMICA DEL CN Address: VIA BASSINI, 15 City: MILANO 20133 State: Zip Code: Country: ITALY Telephone: 39-2-2367587 Telex (or e-mail): 313839 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 3432c [ 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 STAR-1520- 165 RA = 15H 16M 48.4S +/- 1950 1 R = 19.0 +/- 0.5 5710 CIR-X1 0.07S, 1 V = 20.0 +/- 0.5 DEC = -56D 59' 11" +/- 1.0" 1 I = 18.5 +/- 0.5 Comments: EARLY ACQUISITION FOR 2 AND 3 ------------------------------------------------------------------------------------------------------------------------------------ 2 CIR-X1- 603 RA = 15H 16M 48S +/- 30", 1950 OFFSET DEC =-56D 59' 11"+/- 30" Comments: TO BE FOUND OFFSET STAR ------------------------------------------------------------------------------------------------------------------------------------ 3 STAR-1520- 165 RA-OFF = 0.05S +/- 5S, 1950 1 R = 19.0 +/- 0.5 5710- DEC-OFF = 0.05" +/- 1', 1 V = 20.0 +/- 0.5 SPECTRUM CIR FROM 2 1 I = 18.6 +/- 0.5 -X1 Comments: OFFSET FROM 2 TO BE MEASURED ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3432c [ 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 STAR-1520- WFC IMAGE WFALL F785LP 1 5M 30 1 1 EARLY ACQ FOR 2-9 5710 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 2 CIR-X1- FOS/RD ACQ/ 4.3 MIRROR 1 30S 10 1 ONBOARD ACQ FOR OFFSET BINARY 2.1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 2.1 CIR-X1- FOS/RD ACQ/ 0.3 MIRROR SEARCH-SIZE=3 1 6S 10 1 ONBOARD ACQ FOR 3 OFFSET PEAK SCAN-STEP=0.15 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 STAR-1520- FOS/RD ACCUM 0.5 PRISM 1850- 1 86M 10 1 1 PHASE 0.0 +/- 0.01 5710- 8000 PERIOD 16.5669D +/ SPECTRUM - 0.0000D ZERO-PHASE JD 2443077.47 +/- 0.01D CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 4 CIR-X1- FOS/RD ACQ/ 4.3 MIRROR 1 30S 10 1 ONBOARD ACQ FOR OFFSET BINARY 4.1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 4.1 CIR-X1- FOS/RD ACQ/ 0.3 MIRROR SEARCH-SIZE=3 1 6S 10 1 ONBOARD ACQ FOR 5 OFFSET PEAK SCAN-STEP=0.15 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 5 STAR-1520- FOS/RD ACCUM 0.5 PRISM 1850- 1 86M 10 1 1 PHASE 0.05 +/- 5710- 8000 0.01 SPECTRUM PERIOD 16.5669D +/ - 0.0000D ZERO-PHASE JD 2443077.47 +/- 0.01D CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 6 CIR-X1- FOS/RD ACQ/ 4.3 MIRROR 1 30S 10 1 ONBOARD ACQ FOR OFFSET BINARY 6.1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 6.1 CIR-X1- FOS/RD ACQ/ 0.3 MIRROR SEARCH-SIZE=3 1 6S 10 1 ONBOARD ACQ FOR 7 OFFSET PEAK SCAN-STEP=0.15 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 7 STAR-1520- FOS/RD ACCUM 0.5 PRISM 1850- 1 86M 10 1 1 PHASE 0.95 +/- 5710- 8000 0.01 SPECTRUM PERIOD 16.5669D +/ - 0.0000D ZERO-PHASE JD 2443077.47 +/- 0.01D CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 8 CIR-X1- FOS/RD ACQ/ 4.3 MIRROR 1 30S 10 1 ONBOARD ACQ FOR OFFSET BINARY 8.1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3432c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 8.1 CIR-X1- FOS/RD ACQ/ 0.3 MIRROR SEARCH-SIZE=3 1 6S 10 1 ONBOARD ACQ FOR 9 OFFSET PEAK SCAN-STEP=0.15 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 9 STAR-1520- FOS/RD ACCUM 0.5 PRISM 1850- 1 86M 10 1 1 PHASE 0.5 +/- 0.1 5710- 8000 PERIOD 16.5669D +/ SPECTRUM - 0.0000D ZERO-PHASE JD 2443077.47 +/- 0.01D CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 3432c [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACQ/BINARY ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=3 SCAN-STEP=0.15 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 6.58 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category X-RAY BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements EARLY ACQ FOR 2-9; CYCLE 2 ONBOARD ACQ FOR 2.1; CYCLE 2; ONBOARD ACQ FOR 3; PHASE 0.0 +/- 0.01; PERIOD 16.5669D +/- 0.0000D; ZERO-PHASE JD 2443077.47 +/- 0.01D; ONBOARD ACQ FOR 4.1; ONBOARD ACQ FOR 5; PHASE 0.05 +/- 0.01; ONBOARD ACQ FOR 6.1; ONBOARD ACQ FOR 7; PHASE 0.95 +/- 0.01; ONBOARD ACQ FOR 8.1; ONBOARD ACQ FOR 9; PHASE 0.5 +/- 0.1; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F785LP MIRROR PRISM ------------------------------------------------------------------------------------------------------------------------------------ Target Names STAR-1520-5710 CIR-X1 CIR-X1-OFFSET STAR-1520-5710-SPECTRUM ------------------------------------------------------------------------------------------------------------------------------------