6711( 5) - 05/31/97 18:36 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6711 Version: 5 Check-in Date: 31-May-1997 18:36:08 1.Proposal Title: Confirmation of a New Small-Separation Gravitational Lens Candidate ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle COSMOLOGY GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: ROBERT JEDRZEJEWSKI SPACE TELESCOPE SCIENCE INSTITUTE CoI: Peter Jakobsen Astrophysics Division, ESA/ESTEC N CoI: Perry Greenfield Space Telescope Science Institute N ------------------------------------------------------------------------------------ 6. Abstract Cycle 4 HST FOC objective prism images of the luminous z=3.16 quasar UM670 suggest that this object may be gravitationally lensed, with the components having a separation of only 0.1" and a magnitude difference of about 2 magnitudes. Such a small-separation object would be unique among known lens candidates and would require revision of inputs to models of gravitational lens statistics. We propose to confirm this finding through high-resolution imaging using the FOC. ------------------------------------------------------------------------------------ 6711( 5) - 05/31/97 18:36 - [ 2] Observations Description ------------------------ We will take observations using the F/96 relay of the FOC, with filters F342W and F220W. This will give a count rate of approximately 0.6 count/sec/pixel in the center of the PSF for the F342W+F2ND+F1ND filter (assuming a QSO flux of 2x10^-16 flam), and similar with the F220W filter (assuming 2x10^-16 flam, but could be a factor of 2 lower). Exposure times will be 1000s. This will provide approximately 100-200 counts in the central pixel for the fainter component, allowing estimation of the flux to 10\\% or so. Use of the F480LP filter would have put the fainter component right on the first diffraction ring of the primary, so it was necessary to use filters where the ring was smaller - hence the use of F342W and F220W. If the (F342W-F220W) color of the secondary is the same as that of the primary, then it would be strong evidence of a lensed component, since not many celestial sources have such a color (essentially a power law in Flam with index 0). Real Time Justification ----------------------- None None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: ------------------------------------------------------------------------------------ 6711( 5) - 05/31/97 18:36 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 UM670 GALAXY,QSO RA=01H 17M 23.34S +/- 0.1S, DEC= 2000 Z=3.53 V = 17.8 -08D 41' 32.4" +/- 1" 6711( 5) - 05/31/97 18:36 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 UM670 FOC/96 IMAGE 512X512 F342W, 3410 1 900 S F2ND,F1ND ------------------------------------------------------------------------------------------------------------------------------------ 2 UM670 FOC/96 IMAGE 512X512 F220W 2280 1 1200 S ------------------------------------------------------------------------------------------------------------------------------------ 6711( 5) - 05/31/97 18:36 - [ 5] Summary Form for Proposal 6711 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOC/96 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COSMOLOGY ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F342W,F2ND,F1ND F220W ------------------------------------------------------------------------------------------------------------------------------------ Target Names UM670 ------------------------------------------------------------------------------------------------------------------------------------