! +====================+ ! | PED OUTPUT PRODUCT | ! +====================+ ! ! /home/chaboyer/hst/rps2/mine/6517.prop ! Generated by PREPROCESSOR, version 7.0 ! Date: Wed Jan 15 08:40:46 MST 1997 Proposal_Information Title: The Formation of the Inner Galactic Halo Proposal_Category: GO Scientific_Category: STELLAR POPULATIONS Cycle: 6 Investigators PI_Name: Brian Chaboyer PI_Institution: Steward Observatory, University of Arizona CoI_Name: Taft Armandroff CoI_Institution: Kitt Peak National Observatory, NOAO Contact: CoI_Name: Ata Sarajedini CoI_Institution: Kitt Peak National Observatory, NOAO Contact: Abstract: We propose to obtain WFPC2 observations of an inner halo globular cluster. These observations will be used to derive a precise colour-magnitude diagram in order to obtain an accurate age and hence, determine the formation chronology of the inner halo. The globular clusters chosen for observation is NGC 6652, a relatively metal-rich (Fe/H = -0.9) member of the inner halo which has been suggested to be extremely young. Obtaining an accurate age for this member of the inner halo will allow us to determine if the inner halo formed over an extended period of time, and if so, how long the formation process lasted. In order to reliably estimate the ages of these clusters, the location of the main sequence turn-off must be accurately determined. Given the extreme crowding and field contamination problems associated with observing these clusters, this is only possible with the spatial resolution of HST. Questions Observing_Description: The following calculations are based on the successful results of the Zinn et al. (GO-5366) group who have obtained photometry with S/N ~ 50 at 2 magnitudes below the main sequence turnoff for Galactic globular clusters in order to study their ages. Note that the short exposures will be used to photometer the horizontal branch stars and to check the photometric zero-point against ground-based observations. For NGC 6652 (V(TO) ~ 19.5), we need 4 x 400s in F555W and 4 x 700s in F814W along with short exposures of 2 x 40s in F555W and 2 x 60s in F814W. Each orbit is 53 minutes in duration with 7.5 minutes needed for guide star acquisition leaving 45.5 minutes for science activities. The total exposure + overhead time will be 137 minutes for NGC 6652, Adding up these exposure times and adjusting them to fit into orbits means that we need 3 orbits to complete this program. Real_Time_Justification: Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: NGC6652 Alternate_Names: Description: STELLAR CLUSTER,GLOBULAR CLUSTER Position: RA=18H 35M 45.7S +/- 0.1S,DEC=-32D 59' 26" +/- 1" Equinox: J2000 RV_or_Z: V = -112 RA_PM: 0.0 Dec_PM: 0.0 Epoch: B1950 Annual_Parallax: 0.0 Flux: V = 8.62+/-0.1 Comments: Solar_System_Targets Generic_Targets Scan_Data Visits Visit_Number: 01 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 10 Target_Name: NGC6652 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 3 Time_Per_Exposure: 23 S Special_Requirements: MAX DUR 100% POS TARG 0,16 Comments: Exposure_Number: 20 Target_Name: NGC6652 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 2 Time_Per_Exposure: 20 S Special_Requirements: MAX DUR 100% POS TARG 0,16 Comments: Exposure_Number: 30 Target_Name: NGC6652 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 3 Time_Per_Exposure: 20 S Special_Requirements: MAX DUR 100% POS TARG 0,-16 Comments: Exposure_Number: 40 Target_Name: NGC6652 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 3 Time_Per_Exposure: 23 S Special_Requirements: MAX DUR 100% POS TARG 0,-16 Comments: Exposure_Number: 50 Target_Name: NGC6652 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 3 Time_Per_Exposure: 23 S Special_Requirements: MAX DUR 100% Comments: Exposure_Number: 60 Target_Name: NGC6652 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 3 Time_Per_Exposure: 20 S Special_Requirements: MAX DUR 100% Comments: Exposure_Number: 70 Target_Name: NGC6652 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 12 Time_Per_Exposure: 160 S Special_Requirements: Comments: Exposure_Number: 80 Target_Name: NGC6652 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 12 Time_Per_Exposure: 160 S Special_Requirements: Comments: Data_Distribution ! Defaults indicated; change if desired Medium: 8MM Ship_To: Taft Armandroff, Kitt Peak National Obervatory, P.O. Box 26732, 950 North Cherry Avenue, Tucson, AZ 85719 Recipient_Email: tarmandroff@noao.edu ! Let us know what you think of this template and software! ! Please send a list of your likes and dislikes to your Program Coordinator