Proposal_Information Title: Spectra of the Gravitationally Lensed QSO PG 1115+080 Proposal_Category: GTO/FOS Scientific_Category: QUASARS Cycle: 5 Investigators PI_name: E. MARGARET BURBIDGE PI_Institution: UNIVERSITY OF CALIFORNIA, SAN DIEGO CoI_Name: RICHARD J. HARMS CoI_Institution: APPLIED RESEARCH CORPORATION CoI_Name: J. ROGER P. ANGEL CoI_Institution: UNIVERSITY OF ARIZONA CoI_Name: FRANK BARTKO CoI_Institution: UNAFFILIATED CoI_Name: EDWARD BEAVER CoI_Institution: UNIVERSITY OF CALIFORNIA, SAN DIEGO CoI_Name: RALPH C. BOHLIN CoI_Institution: SPACE TELESCOPE SCIENCE INSTITUTE CoI_Name: ARTHUR F. DAVIDSEN CoI_Institution: JOHNS HOPKINS UNIVERSITY CoI_Name: HOLLAND C. FORD CoI_Institution: SPACE TELESCOPE SCIENCE INSTITUTE CoI_Name: GEORGE F. HARTIG CoI_Institution: SPACE TELESCOPE SCIENCE INSTITUTE CoI_Name: BRUCE H. MARGON CoI_Institution: UNIVERSITY OF WASHINGTON Questions Observing_Description: A specially designed series of peak-ups will be performed to center the brightest object to +/-0.04" and G270H and G400H ACCUM observations performed with the 0.3" aperture and red detector. The observations are designed to achieve a signal-to-noise per diode of 33 in the region of lowest sensitivity for each grating. A blind offset of 0.485" will be made to the second brightest object and another pair of ACCUM observations will be made. Because the two targets are separated by only 0.485", a conventional peakup beginning with the 4.3" aperture would not work, while starting with a binary search places restrictions on the orientation and still requires a complex peakup because of the relatively large positional uncertainty following BSTA. Likewise for an interactive target acquisition. The errors in the measurements of offset stars and possible proper motion are too large to allow any simple scheme of offsets followed by peakups. The error budget is very small because the separation of the two brightest components is 0.48" so the maximum error that can be tolerated is 0.24" which means the one sigma error along the line connecting the two brightest components should not exceed 0.08". There are no WF images of the PG1115+080 field and the PC images of PG 1115+080 do not include the best offset stars. Ground based images (from CFHT) include the best offset stars but appear rotated relative to the PC images by 1.35 degrees. The error in the correction of the CCD rotation combined with centering and offset errors plus plausible proper motion (over 5 years) exceed the error budget allowable for acquisition of one of the fainter gravitational lens images and completely rule out direct offsets to either of the two brightest components from the best offset star about 51" away. Abstract: Variations in the velocity and column density of Lyman alpha forest clouds and associated absorption systems on small scales will be studied with observations of a closely spaced pair of QSOs. Accurate measurements of Lyman alpha and beta lines and CIV lines in the two brightest components of PG1115+080 will be made using FOS spectra with the G270H and G400H gratings. Fixed_Targets Target_Number: 1 Target_Name: PG1115+080A1 Description: GALAXY,QSO,GRAVITATIONAL LENS,BLR,EXT-MEDIUM,ABSORPTION LINE SYSTEM,IGM Position: RA=11H 18M 16.934S +/- 0.067S, DEC= 7D 45' 58.53" +/- 1.00", PLATE-ID=00ZW, Equinox: J2000 Rv_or_z: Z = 1.722 Flux: V = 17.0 +/- 1.0, F(2500.0) = 1.5 +/- 0.3 E-15 Comments: These are the coordinates of the blended image measured from the guide star plates. Target_Number: 2 Target_Name: PG1115+080A2 Description: GALAXY,QSO,GRAVITATIONAL LENS,BLR,EXT-MEDIUM,ABSORPTION LINE SYSTEM,IGM Position: R=0.485", PA=18.4D, FROM 1, PLATE-ID=00ZW, Equinox: J2000 Rv_or_z: Z = 1.722 Flux: V = 17.3 +/- 1.0, F(2500.0) = 1.1 +/- 0.3 E-15 Comments: Offsets were measured from PC and ground based images. Visits Visit_Number: 01 Exposure_number: 10 Target_Name: PG1115+080A1 Config: FOS/RD Opmode: ACQ/PEAK Aperture: 1.0 Sp_Element: MIRROR Number_of_iterations: 1 Time_Per_Exposure: 1.39S Optional_Parameters: SEARCH-SIZE-Y=5, SCAN-STEP-Y=0.602, SEARCH-SIZE-X=5, SCAN-STEP-X=0.602 Special_Requirements: ONBOARD ACQ FOR 15 Comments: This step is desgned to find the 1" region containing the brightest (or both) target(s) Exposure_number: 15 Target_Name: PG1115+080A1 Config: FOS/RD Opmode: ACQ/PEAK Aperture: 0.5 Sp_Element: MIRROR Number_of_iterations: 1 Time_Per_Exposure: 1.5S Optional_Parameters: SEARCH-SIZE-Y=4 SCAN-STEP-Y=0.3 SEARCH-SIZE-X=4 SCAN-STEP-X=0.3 Special_Requirements: ONBOARD ACQ FOR 20 Exposure_number: 20 Target_Name: PG1115+080A1 Config: FOS/RD Opmode: ACQ/PEAK Aperture: 0.3 Sp_Element: MIRROR Number_of_iterations: 1 Time_Per_Exposure: 1.58S Optional_Parameters: SEARCH-SIZE-Y=5, SCAN-STEP-Y=0.17, SEARCH-SIZE-X=5, SCAN-STEP-X=0.17 Special_Requirements: ONBOARD ACQ FOR 25 Comments: Searches a 1" region for the brightest target. Accurate to 0.12 Exposure_number: 25 Target_Name: PG1115+080A1 Config: FOS/RD Opmode: ACQ/PEAK Aperture: 0.3 Sp_Element: MIRROR Number_of_iterations: 1 Time_Per_Exposure: 15.8S Optional_Parameters: SEARCH-SIZE-Y=5, SCAN-STEP-Y=0.057, SEARCH-SIZE-X=5, SCAN-STEP-X=0.057 Special_Requirements: ONBOARD ACQ FOR 30-31 Comments: Accurate to 0.04" Exposure_number: 30 Target_Name: PG1115+080A1 Config: FOS/RD Opmode: ACCUM Aperture: 0.3 Sp_Element: G400H Wavelength: 4000.0 Number_of_iterations: 1 Time_Per_Exposure: 1590S Exposure_number: 31 Target_Name: PG1115+080A1 Config: FOS/RD Opmode: ACCUM Aperture: 0.3 Sp_Element: G270H Wavelength: 2700.0 Number_of_iterations: 1 Time_Per_Exposure: 6190S Visit_Number: 02 Visit_Requirements: AFTER 01 BY 2D to 9D Visit_Comments: This visit should reuse the target offset from the first visit. The centering in the 0.3" aperture must be accurate, so the time between visits should be minimized. Exposure_number: 40 Target_Name: PG1115+080A2 Config: FOS/RD Opmode: ACCUM Aperture: 0.3 Sp_Element: G400H Wavelength: 4000.0 Number_of_iterations: 1 Time_Per_Exposure: 1810S Exposure_number: 41 Target_Name: PG1115+080A2 Config: FOS/RD Opmode: ACCUM Aperture: 0.3 Sp_Element: G270H Wavelength: 2700.0 Number_of_iterations: 1 Time_Per_Exposure: 7080S Data_Distribution Medium: 8MM Blocking_Factor: 10 Ship_To: ROSS COHEN CASS 0111 9500 GILMAN DRIVE LA JOLLA, CA 92093-0111 Ship_Via: UPS Recipient_Email: ross@cassfos03.ucsd.edu