Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5692 Report Date: 18-Jul-95:17:51 Version: ********** Check-in Date: ********** 1.Proposal Title: A STUDY OF THE ARCSECOND GRAVITATIONAL LENS 1422+231 CYCLE 4 CARRYOVER ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID QUASARS & AGN GO/CAR 4402 Sub Category GRAVITATIONAL LENSES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Chris D. Impey STEWARD OBSERVATORY USA 602-621-6522 ------------------------------------------------------------------------------------ 7. Abstract We propose spectroscopy and imaging of the four components of the candidate gravitational lens 1422+231. This is the brightest of the few known examples of subarcsecond multiply imaged quasars. It was selected from a survey of 1750 flat spectrum radio sources which should be particularly effective at finding subarcsecond lenses. With V = 16.5 (all components) and z = 3.62, this is one of the most apparently luminous objects in the universe. Spectroscopy of optical counterparts to the four radio components will clearly establish whether or not the system is a gravitational lens, and imaging with the FOC (in prop 5699) is very likely to identify the lens, even if it is a highly subluminous galaxy. A system with four components offers the prospect of a large number of constraints on the lensing model. Moreover, the radio sources are compact and highly polarized, and so very likely to be variable. 1422+231 could therefore be used in a VLA or VLBA monitoring campaign to derive a new estimate of the Hubble constant using up to three time delays. Confirmation of the lens can only be done from space. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 4.00 par: 0 10. Num targs pri: 5 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5692 PI: Chris D. Impey Proposal Title: A STUDY OF THE ARCSECOND GRAVITATIONAL LENS 1422+231 CYCLE 4 CARRYOVER ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Chris D. Impey STEWARD OBSERVATORY USA Craig B. Foltz MULTIPLE MIRROR TELESCOPE USA Ian W. Browne NUFFIELD RADIO ASTRONOMY UNITED KING X LABORATORIES Alok R. Patnaik NUFFIELD RADIO ASTRONOMY UNITED KING X LABORATORIES Irwin Shapiro HARVARD SMITHSONIAN CENTER FOR USA ASTROPHYSICS ------------------------------------------------------------------------------------ 3. Description of proposed observations. We propose two observations of the candidate gravitational lens 1422+231. The first is spectroscopy of individual radio components A, B, C, and D using the FOS red side with grating G570H which gives wavelength coverage from 4600 to 6800 Angstroms. Exposure times are calculated assuming that the system is indeed a lens, and that the optical fluxes scale with the radio fluxes. Fluxes for the sum of A+B+C are taken from Figure 2. The 0.3 arcsec circular aperture will be used; any larger and the components will not be separated, any smaller is not practical with the PSF of the HST. An integration time of 1500 seconds will give a S/N = 15 per resolution element in the continuum at 4800 Angstroms for components A and B, and 3000 seconds will give S/N = 14 for component C. High S/N spectra of A, B, and C are essential to confirm the lens hypothesis. High redshift quasars generally have similar continuum shapes, and there is already one case of an (unlensed) quasar pair with virtually identical spectra and a small velocity difference (Djorgovski et al. 1987, Ap.J., 321, L17). Limited S/N has so far hampered the interpretation of one other subarcsecond lens (Bahcall et al. 1992, in press); we note however that 1208+101 is considerably fainter than our candidate system. If D is a lens component, an integration time of 6200 seconds will be used to get a S/N = 7 in the putative Lyman-alpha line, allowing a clear- cut test of this fourth component. Addition by P. Stanley: This program consists of 2 visits. Visit 1 uses the FOS in imaging mode to obtain data on whether the onboard tar acq s/w acquires A or B. Offsets are performed from the acq assumed to be of component B - the 1st offset is to A, the second in the opposite directions. If images 1,2 contain the expected components, lines 10-14 will be used in visit 2. If images 1,3 contain the components, it means we acquired component A instead of B and lines 20-24 will executed. We will use the SAVE EPHEMERIS (Re-use target offset capability) prior to executing the subsequent visit. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The small separation of the components of this candidate gravitational lens system mean that observations from HST are essential for these observations. The overall extent of the radio source is 1.3 arcsec, the separation between A and B is 0.5 arcsec, and the separation between B and C is 0.8 arcsec (see Figure 1). While imaging of 1422+231 might be possible from the ground under the very best conditions, FOC observations still offer substantial advantages. Since the PSF gives a core of 10% of the image flux with a FWHM of only 0.07 arcsec, the bright components A, B, and C are expected to be well separated. Moreover, the presence of three bright point sources in the field means that image deconvolution will be well constrained, which is an advantage in the search for the lens. Confirmation of the 1422+231 system as a gravitational lens relies mostly on spectroscopy of components A, B, and C. The capabilities of HST in making this observation are unique, no ground-based facility can compete. Successful HST confirmation of the lens system will lead to important ground-based follow-up at radio wavelengths. The lens conponents are well separated with the VLA or VLBA, and are compact and polarized. Compactness and high polarization implies that they are also highly likely to be variable. A radio monitoring program offers the exciting possibility of a new geometric determination of the Hubble Constant, in a system where up to three time delays can be measured. (FOC exps in prop 5691) Figure 2 shows the flux density of the sum of the three brightest components A, B, and C. The FOS exposure time calculations are based on the assumption that the relative fluxes of all four components is given by their relative radio fluxes (this assumption is confirmed by recent, unpublished imaging of the system in the near infrared). Count rates are calculated at two wavelength, in the middle of the continuum shortward of Lyman-alpha at 4800 Angstroms, and at the half power of the Lyman- alpha line around 5700 Angstroms. The calculated count rates for components A, B, C, and D are 0.18, 0.18, 0.088, and 0.0044 ct/s/diode at 4800 Angstroms, and 0.60, 0.60, 0.30, and 0.015 ct/s/diode at 5700 Angstroms (this assumes that all the components have Lyman-alpha with the same equivalent width). The exposure times are calculated to give S/N = 15 for components A (1500 sec), B (1500 sec), and C (3000 sec), and to give S/N = 7 at half power of the predicted Lyman-alpha line in component D (6200 sec). ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Due to the minimal separation and nearly equal brightness of components A and B, the offsets performed by the 4 stage peakup in lines 1-4 will be measured and uplinked prior to the start of visit 2 (lines 10-14 or 20-24). The selected visit 2 observations must be at the same roll and with the same guide stars as visit 1. ------------------------------------------------------------------------------------ 9. Description of previous HST work. a. List HST program numbers and titles: GO Program 2524 "Spectropolarimetry of Bright Quasars" - not related GO Program 3732 "Spectropolarimetry of Bright Quasars" - not related GO Program 3648 "Imaging of BL Lac Host Galaxies and Environments" - not related b. Summarize the main results obtained from previous related programs: GO Program 2524 - Cycle 1, data received and reduced, paper submitted GO Program 3732 - Cycle 2, data received and reduced, paper submitted GO Program 3648 - Cycle 2, data recieved and reduced, paper in preparation ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The University of Arizona will provide central computing services (hard disks, networks, tape drives) in support of this project. One undergraduate will be able to work on this project through funds provided by the Arizona Space Grant. We will also be supported by the University of Arizona in follow-up ground-based activities, such as VLA and VLBA monitoring of the radio lens components for brightness variations that could lead to a new determination of the Hubble constant. Page 4 ------------------------------------------------------------------------------------ 11. Address Information Name: CHRIS D. IMPEY Category: PI Institution: Steward Observatory Address: STEWARD OBSERVATORY UNIVERSITY OF ARIZONA City: TUCSON State: AZ Zip Code: 85721 Country: USA Telephone: 602-621-6522 Telex (or e-mail): 467175 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5692 [ 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 QSO1422P231- E, 314, 323 RA = 14H 24M 38.094S +/- 2000 Z=3.62 1 B = 18.4 +/- 0.2 B PKS 0.004S, 2 B-V = 1.7 DEC = +22D 56' 00.59" +/- 3 F-LINE(1216) = 5 +/- 1 E-15 0.05", plate-id=01TM Comments: SUBARCSECOND GRAVITATIONAL LENS COMPONENT B, VLBI RADIO POSITION; Component from which remainder of B offset positions are derived. ------------------------------------------------------------------------------------------------------------------------------------ 2 QSO1422P231- E, 314, 323 RA-OFF=+0.028S+/- 0.05S, 2000 BOFF1 PKS DEC-OFF=+0.32" +/- 0.05", FROM 1, plate-id=01TM Comments: First offset position for visit 1; Should be component A ------------------------------------------------------------------------------------------------------------------------------------ 3 QSO1422P231- E, 314, 323 RA-OFF=-0.028S +/- 0.05S, 2000 BOFF2 PKS DEC-OFF=-0.32" +/- 0.05", FROM 1, plate-id=01TM Comments: Second offset position for visit 1; Should be blank ------------------------------------------------------------------------------------------------------------------------------------ 4 QSO1422P231B E, 314, 323 RA-OFF=+0.028S +/- 0.05S, 2000 -OFF-A PKS DEC-OFF=+0.32" +/- 0.05", FROM 1, plate-id=01TM Comments: OFFSET FROM B TO A ------------------------------------------------------------------------------------------------------------------------------------ 5 QSO1422P231B E, 314, 323 RA-OFF=-0.024S +/- 0.05S, 2000 -OFF-C PKS DEC-OFF=-0.75" +/- 0.05", FROM 1, plate-id=01TM Comments: OFFSET FROM B TO C ------------------------------------------------------------------------------------------------------------------------------------ 6 QSO1422P231B E, 314, 323 RA-OFF=+0.068S +/- 0.05S, 2000 -OFF-D PKS DEC-OFF=-0.81" +/- 0.05", FROM 1, plate-id=01TM Comments: OFFSET FROM B TO D ------------------------------------------------------------------------------------------------------------------------------------ 7 QSO1422P231A E, 314, 323 RA = 14H 24M 38.122S +/- 2000 PKS 0.05", DEC = +22D 56' 00.91" +/- 0.05", plate-id=01TM Comments: Component from which remainder of A offset positions are derived. ------------------------------------------------------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5692 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 8 QSO1422P231A E, 314, 323 RA-OFF=-0.028S +/- 0.05S, 2000 -OFF-B PKS DEC-OFF=-0.32" +/- 0.05", FROM 7, plate-id=01TM Comments: OFFSET FROM A TO B ------------------------------------------------------------------------------------------------------------------------------------ 9 QSO1422P231A E, 314, 323 RA-OFF=-0.052S +/- 0.05S, 2000 -OFF-C PKS DEC-OFF=-1.07" +/- 0.05", FROM 7, plate-id=01TM Comments: OFFSET FROM A TO C ------------------------------------------------------------------------------------------------------------------------------------ 10 QSO1422P231A E, 314, 323 RA-OFF=+0.040S +/- 0.05S, 2000 -OFF-D PKS DEC-OFF= -1.13" +/- 0.05", FROM 7, plate-id=01TM Comments: OFFSET FROM A TO D ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5692 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 QSO1422P231 FOS/RD ACQ/ 4.3 MIRROR SCAN-STEP- 1 5S 1 1 CYCLE 4 / 1-24 -B PEAK Y=1.23 ONBOARD ACQ FOR 2 SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SCAN-STEP- X=1.23 ------------------------------------------------------------------------------------------------------------------------------------ 2 QSO1422P231 FOS/RD ACQ/ 1.0 MIRROR SCAN-STEP- 1 5S 1 1 ONBOARD ACQ FOR 3 -B PEAK Y=0.61 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 SCAN-STEP- X=0.61 ------------------------------------------------------------------------------------------------------------------------------------ 3 QSO1422P231 FOS/RD ACQ/ 0.3 MIRROR SCAN-STEP- 1 30s 1 1 ONBOARD ACQ FOR 4 -B PEAK Y=0.17 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP- X=0.17 ------------------------------------------------------------------------------------------------------------------------------------ 4 QSO1422P231 FOS/RD ACQ/ 0.3 MIRROR SCAN-STEP- 1 38s 1 1 ONBOARD ACQ FOR 5- -B PEAK Y=0.052 7 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP- X=0.052 Comments: SAVE ACQ INFORMATION FROM 1-4 FOR USE IN 10-14 OR 20-24. ------------------------------------------------------------------------------------------------------------------------------------ 5 QSO1422P231 FOS/RD ACQ 4.3 MIRROR 1 640.0S non-int -B ------------------------------------------------------------------------------------------------------------------------------------ 6 QSO1422P231 FOS/RD ACQ 4.3 MIRROR 1 640.0S 1 non-int -BOFF1 Comments: This image should contain the A comp. if B was correct acquired. Will be blank if A was acquired. ------------------------------------------------------------------------------------------------------------------------------------ 7 QSO1422P231 FOS/RD ACQ 4.3 MIRROR 1 640.0S non-int -BOFF2 Comments: This image will be blank if B was correctly acquired. Will contain B if A was acquired. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5692 [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 QSO1422P231 FOS/RD ACQ/ 0.3 MIRROR SEARCH-SIZE-X=5 1 38S SAME ORIENT FOR 10 -B PEAK SEARCH-SIZE-Y=5 -14 as 1 SCAN-STEP- AFTER 1 BY 20D Y=0.052 COND IF B FOUND/10 SCAN-STEP- -14 X=0.052 ONBOARD ACQ FOR 11 Comments: Req ephemeris correction /10-14 -14 Use SAME GS and ORIENT as /10- 14 ------------------------------------------------------------------------------------------------------------------------------------ 11 QSO1422P231 FOS/RD ACCUM 0.3 G570H 1 1200S 35 1 1 SEQ 10-14 NO GAP -B Comments: S/N AT 6000 ANGSTROMS BLOCKING FILTER WG 375 ------------------------------------------------------------------------------------------------------------------------------------ 12 QSO1422P231 FOS/RD ACCUM 0.3 G570H 1 1200S 35 1 1 B-OFF-A Comments: S/N AT 6000 ANGSTROMS BLOCKING FILTER WG 375 ------------------------------------------------------------------------------------------------------------------------------------ 13 QSO1422P231 FOS/RD ACCUM 0.3 G570H 1 2400S 35 1 1 B-OFF-C Comments: S/N AT 6000 ANGSTROMS BLOCKING FILTER WG 375 ------------------------------------------------------------------------------------------------------------------------------------ 14 QSO1422P231 FOS/RD ACCUM 0.3 G570H 2 2400S 8 1 1 B-OFF-D Comments: S/N AT 6000 ANGSTROMS BLOCKING FILTER WG 375 ------------------------------------------------------------------------------------------------------------------------------------ 20 QSO1422P231 FOS/RD ACQ/ 0.3 MIRROR SEARCH-SIZE-X=5 1 38S SAME ORIENT FOR 20 -B PEAK SEARCH-SIZE-Y=5 -24 as 1 SCAN-STEP- SEQ 20-24 NO GAP Y=0.052 AFTER 1 BY 20D SCAN-STEP- COND IF A FOUND/20 X=0.052 -24 Comments: Req ephemeris correction /20-24 ONBOARD ACQ FOR 21 ; Use SAME GS and ORIENT as /20 -24 -24 ------------------------------------------------------------------------------------------------------------------------------------ 21 QSO1422P231 FOS/RD ACCUM 0.3 G570H 1 1200S 35 1 1 -B Comments: S/N AT 6000 ANGSTROMS BLOCKING FILTER WG 375 ------------------------------------------------------------------------------------------------------------------------------------ 22 QSO1422P231 FOS/RD ACCUM 0.3 G570H 1 1200S 35 1 1 A-OFF-B Comments: S/N AT 6000 ANGSTROMS BLOCKING FILTER WG 375 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5692 [ 9] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 23 QSO1422P231 FOS/RD ACCUM 0.3 G570H 1 2400S 35 1 1 A-OFF-C Comments: S/N AT 6000 ANGSTROMS BLOCKING FILTER WG 375 ------------------------------------------------------------------------------------------------------------------------------------ 24 QSO1422P231 FOS/RD ACCUM 0.3 G570H 2 2400S 8 1 1 A-OFF-D Comments: S/N AT 6000 ANGSTROMS BLOCKING FILTER WG 375 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5692 [ 10] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-Y=1.23 SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SCAN-STEP-X=1.23 SCAN-STEP-Y=0.61 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 SCAN-STEP-X=0.61 SCAN-STEP-Y=0.17 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP-X=0.17 SCAN-STEP-Y=0.052 SCAN-STEP-X=0.052 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/CAR ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 4.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QUASARS & AGN ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category GRAVITATIONAL LENSES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4 / 1-24; ONBOARD ACQ FOR 2; ONBOARD ACQ FOR 3; ONBOARD ACQ FOR 4; ONBOARD ACQ FOR 5-7; non-int; SAME ORIENT FOR 10-14 as 1; AFTER 1 BY 20D; COND IF B FOUND/10-14; ONBOARD ACQ FOR 11-14; SEQ 10-14 NO GAP; SAME ORIENT FOR 20-24 as 1; SEQ 20-24 NO GAP; COND IF A FOUND/20-24; ONBOARD ACQ FOR 21-24; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G570H ------------------------------------------------------------------------------------------------------------------------------------ Target Names QSO1422P231-B PKS QSO1422P231-BOFF1 QSO1422P231-BOFF2 QSO1422P231B-OFF-A QSO1422P231B-OFF-C QSO1422P231B-OFF-D QSO1422P231A QSO1422P231A-OFF-B QSO1422P231A-OFF-C QSO1422P231A-OFF-D ------------------------------------------------------------------------------------------------------------------------------------