! From harris@azalea.physics.McMaster.CA (for PI Hesser) ! Wed Mar 1 09:37:27 1995 ! ! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! Id: 6106 ! ! For help call your Program Coordinator: Max Mutchler ! Phone: 410 338-1321 , E-mail: mutchler@stsci.edu Proposal_Information Title: The Formation of the Galaxy: Ages for Globular Clusters in the Remote Halo Proposal_Category: GO Scientific_Category: Stellar Populations Cycle: 5 Investigators PI_name: James E. Hesser PI_Institution: Dominion Astrophysical Observatory CoI_Name: Roger A. Bell CoI_Institution: University of Maryland Contact: N CoI_Name: Michael Bolte CoI_Institution: University of California at Santa Cruz Contact: N CoI_Name: Howard E. Bond CoI_Institution: Space Telescope Science Institute Contact: N CoI_Name: Gregory G. Fahlman CoI_Institution: University of British Columbia Contact: N CoI_Name: William E. Harris CoI_Institution: McMaster University Contact: N CoI_Name: Robert D. McClure CoI_Institution: Dominion Astrophysical Observatory Contact: N CoI_Name: Harvey B. Richer CoI_Institution: University of British Columbia Contact: N CoI_Name: Peter B. Stetson CoI_Institution: Dominion Astrophysical Observatory Contact: N CoI_Name: Don A. VandenBerg CoI_Institution: University of Victoria Contact: N CoI_Name: Sidney van den Bergh CoI_Institution: Dominion Astrophysical Observatory Contact: N Abstract: We propose HST imaging observations that will allow us to measure the age of the globular cluster Eridanus, located in the distant halo of the Milky Way. This object is one of the five known globular clusters with Galactocentric distances larger than 75 kpc. We are already observing three others (NGC 2419, Pal 3, and Pal 4) during Cycle 4. The Cycle 5 observations of Eridanus will help complete our program aimed at mapping the ages of far-halo clusters relative to nearby globulars (R ~ 10 kpc) with a precision of 1 Gyr or better. This age comparison is an essential component of reconstructing early Galactic formation history, and is complementary to ongoing HST programs being carried out by other groups to measure ages of globular clusters in the Galactic bulge. Questions Observing_Description: WFPC2 exposures will be taken in the standard V (F555W) and I (F814W) bandpasses, on the distant-halo globular cluster Eridanus. 3 short exposures (3 x 180 sec) and 6 long exposures (3 x 1200 sec, 3 x 1100 sec) in V will be taken, along with 3 short (3 x 230 sec) and 8 long (4 x 1200 sec, 4 1100 sec) in I. Sub-pixel shifts will be used between each long exposure for cosmic-ray removal. Two very bright stars flanking the cluster imply that a fairly narrow range of camera orientations is required. We specify a nominal orientation angle for WFPC2 of 315 +/- 20 degrees (see Visit_Comments). Please note that this nominal angle may also be shifted 90 deg either clockwise or counterclockwise, i.e. to values of 45 +/- 20 degrees, or 225 +/- 20 degrees. In each case, the pointing aperture (WF2, WF3, or WF4) is chosen so that the center of the target cluster will be located in the southeast corner of the WFPC2 array. This range of orientations is listed to increase scheduling flexibility as much as possible. Real_Time_Justification: Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: ERIDANUS Alternate_Names: C0422-213 Description: STELLAR CLUSTER, GLOBULAR CLUSTER Position: RA=4H 24M 44.4S +/- 1", DEC=-21D 11' 15" +/- 1", PLATE-ID=04LR Equinox: J2000 RV_or_Z: V = -24 RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: V = 27.5, B-V = 0.6 Comments: THE TARGET FLUX LEVEL REFERS TO THE FAINT MAIN SEQUENCE STARS IN THE CLUSTER. Visits Visit_Number: 01 Visit_Requirements: ORIENT 295D TO 335D Visit_Comments: POSITION ANGLE OF U3 AXIS SHOULD BE 45 DEGREES WEST OF NORTH, WITH RANGE +/- 20D. A NOMINAL ORIENTATION EITHER +90D OR -90D FROM THE GIVEN VALUE IS ALSO ACCEPTABLE. IF +90D DIFFERENT, THEN WE REQUIRE ORIENT 35D TO 65D AND APERTURE = WF2-FIX FOR ALL EXPOSURES. IF -90D DIFFERENT, THEN WE REQUIRE ORIENT 205D TO 245D AND APERTURE = WF4-FIX FOR ALL EXPOSURES. Exposure_Number: 11 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 3 Time_Per_Exposure: 180S Special_Requirements: POS TARG 0.0, 0.0 Exposure_Number: 12 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 3 Time_Per_Exposure: 230S Special_Requirements: SAME POS AS 11 Exposure_Number: 21 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1200S Special_Requirements: SAME POS AS 11 Comments: EXPOSURES 21-26 ARE A 6-STEP SEQUENCE WITH 1.5-PIXEL (WF) STEPS IN A HEXAGONAL PATTERN Exposure_Number: 22 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1100S Special_Requirements: POS TARG 0.15, 0.15 END ORBIT; EXPAND Exposure_Number: 23 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1200S Special_Requirements: POS TARG 0.15, 0.30 Exposure_Number: 24 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1100S Special_Requirements: POS TARG 0.0, 0.45 END ORBIT; EXPAND Exposure_Number: 25 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1200S Special_Requirements: POS TARG -0.15, 0.30 Exposure_Number: 26 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F555W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1100S Special_Requirements: POS TARG -0.15, 0.15 END ORBIT; EXPAND Exposure_Number: 31 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1200S Special_Requirements: SAME POS AS 11 Comments: EXPOSURES 31-38 ARE AN 8-STEP SEQUENCE WITH 1.5-PIXEL SHIFTS IN AN OCTAGONAL PATTERN Exposure_Number: 32 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1100S Special_Requirements: POS TARG 0.15, 0.0 END ORBIT; EXPAND Exposure_Number: 33 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1200S Special_Requirements: POS TARG 0.30, 0.15 Exposure_Number: 34 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1100S Special_Requirements: POS TARG 0.30, 0.30 END ORBIT; EXPAND Exposure_Number: 35 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1200S Special_Requirements: POS TARG 0.15, 0.45 Exposure_Number: 36 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1100S Special_Requirements: POS TARG 0.0, 0.45 END ORBIT; EXPAND Exposure_Number: 37 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1200S Special_Requirements: POS TARG -0.15, 0.30 Exposure_Number: 38 Target_Name: ERIDANUS Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1100S Special_Requirements: POS TARG -0.15, 0.15 END ORBIT; EXPAND Data_Distribution Medium: 8MM Blocking_Factor: 10 Ship_To: Howard Bond (CoI) Space Telescope Science Institute ext. 4718 bond@stsci.edu Ship_Via: Howard Bond will pick up the tapes __Diagnostic-Sum-Section__ Software-Version (Controller= 2.0) Preprocessor (Errors= 0 Fatal-Errors= 0 ) Validation (Errors= 0 Fatal-Errors= 0 ) Transformation (Errors= 7 Fatal-Errors= 0 ) CASM (Errors= 1 Fatal-Errors= 0 ) __User-Comments__ Phase II form submitted on behalf of J. E. Hesser. Please communicate back to Hesser, who will inform the rest of the team. Note especially under the Program Description and Visit Comments the three possible orientation angles for the camera. These are put in to maximize the schedulability of the program. W.E.Harris