! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6482,v 4.1 1997/02/17 16:39:11 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Karla Peterson ! Phone: 410-338-4774 , E-mail: peterson@stsci.edu ! Proposal_Information ! Section 4 Title: Weak Lensing in the Field of Luminous Quasars. Masses of Groups of Galaxies and Magnification Bias. Proposal_Category: GO Scientific_Category: COSMOLOGY Cycle: 6 Investigators PI_name: Bernard Fort PI_Institution: Observatoire de Paris CoI_Name: Peter Schneider CoI_Institution: Max-Planck-Institut fuer Astrophysik Contact: N ! Y or N (designate at most one contact) CoI_Name: Yannick Mellier CoI_Institution: Observatoire Midi-Pyrenees Contact: Y CoI_Name: Matthias Bartelmann CoI_Institution: Max-Planck-Institut fuer Astrophysik Contact: N ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) Some relatively bright QSOs have long been suspected to be gravitationally magnified. We have found along the line of sight towards some of them a coherent shear pattern of faint distant galaxies. Moreover there appear to be overdensities of galaxies concentric with the shear patterns which are probably responsible for the weak lensing effect and the QSO magnifications. These concentrations seem to have sizes and masses comparable to those of groups or clusters of galaxies. Although the gravitational shear of the galaxies is easily seen from the ground, an accurate measurement of the mass and the M/L ratio of the concentration require observations with the WFPC2. , We have selected 3 QSOs from our ESO-CFHT survey for which a coherent shear pattern has been unambiguously detected. The proposed HST observations will determine the amount of dark matter in this new class of lensing masses first selected from their weak lensing effect. Questions ! Free format text (please update) Observing_Description: We want to measure the shear and the mass ditribution of the deflector responsible for the gravitational distortion with resolution of 30 arcsec. To overcome noise in the weak shear pattern arising from the intrinsic orientations and shapes of faint galaxies, we need to average these parameters from a large number of galaxies per cell. To get a signal/noise >3, we require an rms noise in the shear per cell better than 4%. This imposes to reach 80 galaxies per arcmin^-2, or I=24.5. We choose the F702W filter as it is the most efficient to go deep in the shortest time. To increase the detection level and the geometry of galaxies, we need low sky background and very good flat fields. Low sky visibility and small shifts between each exposures are important to meet our scientific goals. Real_Time_Justification: None Calibration_Justification: None. Ground based imaging (VI) have been secured already and spectroscopic observations are scheduled for may 1996. Additional_Comments: The target position is centered on the clump responsible for the shear. This is our initial position for the first exposure and from which shifts will be done. After the first exposure, we will shift of about 1 arcsec. according to POS TARG, in both X and Y directions to avoid simple shifts along the rows or the columns of the CCD. The position given in Target is our central initial position. We will keep the ORIENT unchanged for ALL the exposure, to minimize data processing before co-addition of images. Following the documentation we computed 48 mn for low sky visity at dec=-24 and 8mn overhead+3 mn CCD readout time for each new visit, or 6mn overhead+3mn CCD readout for subsequent orbits. This is why our exposure have 2400s. each. Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: PKS0135-247-OFFSET Alternate_Names: Description: GALAXY Position: RA=1H 37M 35.4S +/- 0.1S, DEC=-24D 31' 14.1" +/- 1.0" Equinox: J2000 RV_or_Z: Z=0.8310 RA_PM: 0.0 ! Units are seconds of time per year Dec_PM: 0.0 ! Units are seconds of arc per year Epoch: 2000.0 Annual_Parallax: 0.0 Flux: V=17.33 ! Include at least V and B-V Comments: Target name and target position are our TRUE position, offsetted from the quasar position. ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ORIENT 40D TO 50D ! Uncomment or copy visit level special requirements needed ! Most of these requirements (including ORIENT) will limit scheduling ! PCS MODE [Fine | Gyro] ! GUIDing TOLerance ! DROP TO GYRO IF NECESSARY [NO REACQuisition] ! ORIENTation TO ! ORIENTation TO FROM ! ORIENTation TO FROM NOMINAL ! SAME ORIENTation AS ! CVZ ! PARallel ! SCHEDulability ! AFTER [BY [TO ]] ! AFTER ! BEFORE ! BETWEEN AND ! GROUP WITHIN