! Proposal 5905, submission 1 ! PI: Gretchen L.H. Harris ! Received Thu Feb 23 11:09:51 EST 1995 ! From: harris@azalea.physics.McMaster.CA Proposal_Information ! Section 4 Title: The Stellar Halo Metallicity Distribution of the Giant Elliptical NGC 5128 Proposal_Category: GO Scientific_Category: Stellar Populations Cycle: 5 Investigators PI_name: Gretchen L.H. Harris PI_Institution: University of Waterloo CoI_Name: William E. Harris CoI_Institution: McMaster University Contact: N Abstract: We intend to measure the metallicity distribution function of the stellar halo of the nearby (d=3.5 Mpc) giant E0 galaxy NGC 5128 by direct color-magnitude photometry of its old red-giant stars. These data will allow us to determine accurately for the first time the mean metallicity and metallicity range of the oldest and most metal-poor field stars in a large elliptical galaxy, and thus constrain the level of enrichment which occurred during the earliest star formation. For the first time, we will then be able to compare the chemical enrichment history of giant E galaxies with galaxies of other types in the Local Group (spirals, dwarf ellipticals, and irregulars). Questions Observing_Description: NGC 5128 is 3.4 magnitudes more distant than M31. Our intention is to image one field at moderately large radius from the center of NGC 5128 at a projected distance corresponding to 20 kpc from the galaxy center. This field will be used to obtain direct color-magnitude photometry of the red-giant stars in the NGC 5128 halo, and thus to measure the metallicity distribution function of the halo. The standard V,I bands will be used. Our target field is to be centered near one of the known globular clusters belonging to NGC 5128 (number C44, Fe/H = -1.4). Comparison of the CMD's for the halo field and for the globular cluster itself will provide additional direct information on any systematic difference in the RGB loci between them. We will center the Planetary Camera CCD on the globular cluster. If the brightest red giants in NGC 5128 are similar to those in M31, they should resolve at V(RGB tip) = 26.4; however, they are likely to be up to half a magnitude fainter since the mean metallicity in the giant elliptical should be higher than in M31. To allow for this, we set a target V = 27.0 at high S/N. For each filter (V,I) we will obtain a 5 x 2400 sec and 4 x 200 sec exposure series for a total of 10 orbits. Real_Time_Justification: Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: NGC5128-C44 Alternate_Names: Description: EXT-CLUSTER,GLOBULAR CLUSTER Position: RA=13H 22M 35.6S +/- 2", DEC=-43D 03' 49" +/- 2" Equinox: 1950 RV_or_Z: V = +550 RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux: V = 27.0, B-V = 1.6 Comments: TARGET V MAGNITUDE CORRESPONDS TO RED GIANT STARS IN GALAXY HALO Visits Visit_Number: 1 Visit_Requirements: ORIENT 125D TO 125D Visit_Comments: POSITION ANGLE OF U3 AXIS = 135D N THROUGH E; ORIENTATION CAN BE +/- 30D ABOUT NOMINAL. Exposure_Number: 11 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F606W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 1200S Special_Requirements: POS TARG 0,0 Comments: EXPOSURES 11-19 ARE A 5-STEP SEQUENCE WITH 2.5-PIXEL STEPS Exposure_Number: 13 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F606W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 1300S Special_Requirements: POS TARG 0.341, -0.227 Exposure_Number: 15 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F606W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 1300S Special_Requirements: POS TARG 0.227, 0.114 Exposure_Number: 17 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F606W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 1300S Special_Requirements: POS TARG -0.114, 0.341 Exposure_Number: 19 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F606W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 1300S Special_Requirements: POS TARG -0.227, -0.114 Visit_Number: 2 Visit_Requirements: ORIENT 125D TO 125D Visit_Comments: VISIT 2 MUST HAVE SAME ROLL ANGLE AS VISIT 1, AND SAME POSITION TO WITHIN 2 ARCSECONDS, ALONG WITH CONSISTENT SET OF GUIDE STARS. Exposure_Number: 21 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 1200S Special_Requirements: POS TARG 0,0 Comments: EXPOSURES 21-29 ARE A 5-STEP SEQUENCE WITH 2.5-PIXEL STEPS Exposure_Number: 23 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 1300S Special_Requirements: POS TARG 0.341, -0.227 Exposure_Number: 25 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 1300S Special_Requirements: POS TARG 0.227, 0.114 Exposure_Number: 27 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 1300S Special_Requirements: POS TARG -0.114, 0.341 Exposure_Number: 29 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 1300S Special_Requirements: POS TARG -0.227, -0.114 Exposure_Number: 32 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F606W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: POS TARG 0.0, 0.0 Exposure_Number: 33 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: SAME POS AS 32 Exposure_Number: 34 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F606W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: POS TARG 0.341, -0.227 Exposure_Number: 35 Target_Name: NGC5128-C44 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: SAME POS AS 34 Data_Distribution Medium: 8MM Blocking_Factor: 10 Ship_To: PI_Address ! G. L. H. Harris ! Dept of Physics ! University of Waterloo ! Waterloo ON N2L 3G1 Canada Ship_Via: UPS