5786( 0) - 07/18/95 17:59 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5786 Version: ********** Check-in Date: ********** 1.Proposal Title: A Three Dimensional Map of the Galactic Halo ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Interstellar Medium AR 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: J. C. Blades Space Telescope Science Institute CoI: Katherine Roth Space Telescope Science Institute N CoI: D.G. York University of Chicago N CoI: D.V. Bowen Space Telescope Science Institute N ------------------------------------------------------------------------------------ 6. Abstract Our purpose is to develop a map of the distribution of interstellar species in the halo of the Galaxy. Our intent is to establish the scale height of various atomic species, including neutrals (C I, O I, and Mg I), singly ionized species, (Zn II, Cr II, and the like) and highly ionized species (C IV, Si IV, and N V), and to search for evidence of High Velocity Clouds and manifestations of the postulated galactic fountain and other large scale phenomena, e.g., supernovae shells. We shall use galactic and extragalactic sources that are shining through the halo at a variety of z- distances and galactic locations, with sources taken from principally the GHRS archive, supplemented where necessary with FOS data. This archive proposal was funded last year. Since then, we have inspected the entire GHRS archive and selected 120 targets so far, many of which were not originally obtained for ISM studies. We have compared equivalent widths for interstellar lines common to both Copernicus and HST to establish the veracity of our measurements, and, as a pathfinder, we have begun a study of the Zn II, Mg I and Cr II halo scale-heights. In the current year, we propose to complete our work with the GHRS and FOS archives and establish scale height measurements for all species, as well as to examine the C IV and Si IV distributions and re-examine whether their column density ratio is constant. We shall produce a preliminary version of the three-dimensional distribution of gas in the halo. ------------------------------------------------------------------------------------ Observations Description ------------------------ Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 5786( 0) - 07/18/95 17:59 - [ 2] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5786( 0) - 07/18/95 17:59 - [ 3] Summary Form for Proposal 5786 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category AR ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Interstellar Medium ------------------------------------------------------------------------------------------------------------------------------------