6665( 5) - 04/22/96 15:28 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6665 Version: 5 Check-in Date: 22-Apr-1996 15:24:14 1.Proposal Title: Galaxy Rotation Curves at Large Radius using Ly-alpha Absorption Lines ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle COSMOLOGY GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Stephanie Cote ESO CoI: Tom Broadhurst University of California, Berkeley N CoI: Claude Carignan Universite de Montreal N CoI: Ken Freeman Mount Stromlo Observatory N CoI: Rosie Wyse Johns Hopkins University N ------------------------------------------------------------------------------------ 6. Abstract It is possible to detect a gaseous disk in absorption in the spectrum of a bright background quasar, down to HI column densities of only 10E13 atoms/cm2. We propose to investigate the outer rotation curves of two spiral galaxies at very large galactocentric radii by using the kinematical information from Ly-alpha absorption lines in the spectrum of background quasars. This will enable us to measure the disc rotation at 5 times greater radius than what is possible in HI. By constraining the rotation at these large radii one may hope to observe the expected turn down from flat rotation, determining for the first time the size of the dark matter halo and hence measure the total mass and mass-to-light ratio of disc galaxies. ------------------------------------------------------------------------------------ 6665( 5) - 04/22/96 15:28 - [ 2] Observations Description ------------------------ We want to target our 2 QSOs with the GHRS Blue side with the G140L grating to detect an absorption feature at 1220 Angstrom , with a velocity precision of about 1/3 of the resolution (50 km/s). The SSA aperture will be preferred over the LSA because the LSA slightly degrades the full resolution and more importantly we have to make sure that the Geocoronal LyAlpha pollution does not spread over to 1220 Angstrom . Our QSOs are respectively V=15.6 and V=15.83, with low E(B-V) of 0.00 and 0.02. PG1309+355 has a measured flux at 1220 Angstrom from IUE (Courvoisier and Paltani 1992) of F_1220 = 4 * 10E-15 ergs/s/cm2/Angstrom. For PG0923+201 we have calculated the flux to be expected at 1220 Angstrom , knowing its redshift and using a template of the rest-frame spectral energy distribtion of a quasar built from the IUE archives (Schneider et al 1993), and with reddenings corrections this comes to F_1220=6.8*10E-16 ergs/s/cm2/Angstrom. Using a sensitivity S_Lambda =55 * 10E11 counts/s/diode (this takes account of a 50% loss with the SSA), this leads to count rates of 2.2 * 10E-2 and 3.8 * 10E-3 counts/s/diode. Fortunatly we only need a S/N of about 3, to get to a equivalent width of 0.35 Angstroms. The requested exposure times are 35 minutes and 5.2 hours respectively, using the CENSOR option to reduce the dark counts. We will need to do the target aquisitions with Side 2. Counting with this and the other overheads, this comes to a total of 2 orbits and 8 orbits. Real Time Justification ----------------------- None Calibration Justification ------------------------- None Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6665( 5) - 04/22/96 15:28 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PG0923+201 GALAXY,QSO RA=09H 25M 54.71S +/- 0.05S, J2000.0 Z=0.19 V = 15.83+/-0.2 DEC=+19D 54' 04.39" +/- 0.3", B-V = 0.15+/-0.2 PLATE-ID=01G6 E(B-V) = 0.02 F(1220)=6.8+/-10e-16 2 PG1309+355 GALAXY,QUASAR RA=13H 12M 17.74S +/- 0.05S, J2000.0 Z=0.184 V = 15.6+/-0.2 DEC=+35D 15' 20.61" +/- 0.3", B-V = 0.15+/-0.2 PLATE-ID=01PR E(B-V) = 0.0 F(1220)=4+/-1e-15 6665( 5) - 04/22/96 15:28 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 101 PG0923+201 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 103.5S ONBOARD ACQ FOR 102 SEQ 101-102 NON-INT EARCH-SIZE=3 Comments: STEP-TIME= 11.50S ------------------------------------------------------------------------------------------------------------------------------------ 102 PG0923+201 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 287.5S ONBOARD ACQ FOR 103-106 KUP Comments: STEP-TIME= 11.50S ------------------------------------------------------------------------------------------------------------------------------------ 103 PG0923+201 HRS ACCUM 0.25 G140L 1333.0 FP- 8 598.4S SPLIT=NO,STEP- PATT=DEF,CENSOR =YES Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 104 PG0923+201 HRS ACCUM 0.25 G140L 1333.0 FP- 8 598.4S SPLIT=NO,STEP- PATT=DEF,CENSOR =YES Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 105 PG0923+201 HRS ACCUM 0.25 G140L 1333.0 FP- 8 598.4S SPLIT=NO,STEP- PATT=DEF,CENSOR =YES Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 106 PG0923+201 HRS ACCUM 0.25 G140L 1333.0 FP- 7 598.4S SPLIT=NO,STEP- PATT=DEF,CENSOR =YES Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 6665( 5) - 04/22/96 15:28 - [ 5] Visit: 02 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 ------------------------------------------------------------------------------------------------------------------------------------ 201 PG1309+355 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 105.75S ONBOARD ACQ FOR 202 EARCH-SIZE=3 Comments: STEP-TIME= 11.75S ------------------------------------------------------------------------------------------------------------------------------------ 202 PG1309+355 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 293.75S ONBOARD ACQ FOR 203-204 KUP Comments: STEP-TIME= 11.75S ------------------------------------------------------------------------------------------------------------------------------------ 203 PG1309+355 HRS ACCUM 0.25 G140L 1333.0 FP- 4 598.4S SPLIT=NO,STEP- PATT=DEF,CENSOR =YES Comments: STEP-TIME= 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 204 PG1309+355 HRS ACCUM 0.25 G140L 1333.0 FP- 1 54.4S SPLIT=NO,STEP- PATT=DEF,CENSOR =YES Comments: STEP-TIME= 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 6665( 5) - 04/22/96 15:28 - [ 6] Summary Form for Proposal 6665 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=3 SEARCH-SIZE=5 CENSOR=YES STEP-PATT=DEF FP-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COSMOLOGY ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 102 SEQ 101-102 NON-INT ONBOARD ACQ FOR 103-106 ONBOARD ACQ FOR 202 ONBOARD ACQ FOR 203-204 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names PG0923+201 PG1309+355 ------------------------------------------------------------------------------------------------------------------------------------