! Proposal 6807, submission 1 ! PI: Hans-Walter Rix ! Received Mon Feb 12 18:40:05 EST 1996 ! From: rix@as.arizona.edu ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! Id: 6807 ! ! 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: Mutchler ! Phone: 410-338-1321 , E-mail: mutchler@stsci.edu Proposal_Information ! Section 4 Title: The spatial distribution of dust extinction through spiral disks Proposal_Category: GO Scientific_Category: GALAXIES & CLUSTERS Cycle: 6 Investigators PI_name: Hans-Walter Rix PI_Institution: Steward Observatory Abstract: ! Free format text (please update) I propose WFPC2 imaging in V and I of a special galaxy pair (UGC 5041) in which the light of an early-type galaxy is seen through the disk of a foreground spiral. These systems provide an excellent opportunity to map with high spatial resolution the dust extinction, tau_Lambda(\vecR), light passing through a galaxy disk. Knowing the extinction distribution within galaxies is important (1) for interpreting the broad-band colors of galaxies, (2) for the statistics of gravitationally lensed objects and (3) for estimating the total hydrogen content of the damped LyAlpha absorber population. Ground-based observations of these two galaxy pairs indicate optical depths, averaged over (600 pc)^2 resolution elements, of tau_ V=0.3-1.2. However, each 1^ resolution element is much larger than the width of dust lanes seen in more nearby galaxies and therefore it contains areas of both much larger and much smaller optical depth. The proposed HST observations provide the unprecedented opportunity to probe the dust extinction over a contiguous area with a resolution (~ 60pc) comparable to the width of the prominent dust lanes. Consequently, the data would provide a greatly improved estimate of which portion of a spiral galaxy disk is opaque (Tau_Lambda>> 1) or transparent (Tau_Lambda<< 1). Compared to ground-based observations, the high resolution WFPC2 observations will also increase the contrast of the small dust lanes and patches by nearly two orders of magnitude. Questions ! Free format text (please update) Observing_Description: Real_Time_Justification: Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: UGC5041 Alternate_Names: Description: Galaxy Position: RA=09H 27M 53.01S +/- 1S, !Most common specification is DEC=32D 39' 04.9" +/- 1", PLATE-ID=01RX Equinox: J2000 RV_or_Z: RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux: V=13.4 ! Include at least V and B-V B-V=0.5 Comments: ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! Section 6 Visit_Number: 01 Visit_Requirements: ! Section 7.1 ! 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