! +====================+ ! | PED OUTPUT PRODUCT | ! +====================+ ! ! /yon/data1/nkede/proposals/6660.prop ! Generated by PREPROCESSOR, version 6.5c1 ! Date: Mon Oct 28 09:56:35 EST 1996 Proposal_Information Title: White Dwarf Distance and Precision Age for Globular Clusters Proposal_Category: GO Scientific_Category: COOL STARS Cycle: 6 Investigators PI_Name: Angela Bragaglia PI_Institution: Osservatorio Astronomico Bologna CoI_Name: Francesco Ferraro CoI_Institution: Osservatorio di Bologna Contact: N CoI_Name: Alvio Renzini CoI_Institution: European Southern Observatory Contact: N CoI_Name: Sergio Ortolani CoI_Institution: Osservatorio di Padova Contact: N CoI_Name: Eugenio Carretta CoI_Institution: Osservatorio di Bologna Contact: N CoI_Name: Gianni Marconi CoI_Institution: Osservatorio di Roma Contact: N CoI_Name: Jay B. Holberg CoI_Institution: Lunar and Planetary Laboratory Contact: N CoI_Name: Ralph Bohlin CoI_Institution: Space Telescope Science Institute Contact: N CoI_Name: R. Michael Rich CoI_Institution: Columbia University Contact: N CoI_Name: Roberto Gilmozzi CoI_Institution: ESO Contact: N CoI_Name: Francois Wesemael CoI_Institution: Universite de Montreal Contact: N Abstract: This proposal is the natural complement of our Cycle 4 and 5 programs aimed at using the White Dwarf cooling sequence for the calibration of the globular cluster distance scale, the determination of accurate distances being a critical prerequisite for the estimate of reliable cluster ages. In Cycle 4 we obtained data on NGC6752, while in Cycle 5 we got images of 47Tuc. These two clusters will test whether there really exists a measurable age difference between the metal poor and the metal rich clusters, as has been inferred from some horizontal branch luminosity- metallicity calibration. While reducing our Cycle 4 data we have realized that a few short exposures would greatly help to accurately subtract the wings of the heavily saturated images in the field of view, hence to improve the accuracy of the faint star fotometry in the crowded field of the cluster. We therefore apply for one orbit for each of the two clusters in order to get shallow images of our Cycle 4 and 5 fields. The observed cooling sequences for the clusters (for DA and non-DA WDs) will then be fit to the corresponding FCSs to determine the cluster distance moduli. Moreover, directly fitting to each other the WD cooling sequences of the two clusters will provide very accurate relative distances (hence ages). Questions Observing_Description: We need to observe the 2 clusters in exactly the SAME positions given for the Cycle 4 (i.e. 125" from the center for NGC6752) and Cycle 5 (i.e. 300" from the center for 47Tuc) and with the SAME position angles. We wish to measure with high photometric precision the Turn Off region (at a V mag level of ~ 17.5 for both clusters). This means to be able to measure stars about 2 mag above/belove the TO, avoiding saturation and too low S/N. For this program, we are using the U, B, V, I filters (BVI for NGC6752 and UVI for NGC104). For B, V, I we require at least 3 exposure each, to remove cosmics and increase the photometric accuracy. The U filter exposures have a lower priority, and we will take only the ones fitting into the sigle orbit. The exposure times have been computed from the general formula in the WFPC2 Handbook, and Biretta (March 9, 1995) with a change related to the read-out-noise. The following table illustrates the computed exposure times and S/N for both clusters, since their distance moduli and E(B-V) are very similar (respectively: 13.1, 0.03 for NGC6752, and 13.3, 0.04 for 47Tuc). -------------------------------------- band exptime S/N S/N S/N (sec) (V=14.5) (TO) (V=21) -------------------------------------- V 20 - 70 15 I 20 - 90 15 B 300 - 90 15 U 120 55 25 - -------------------------------------- Real_Time_Justification: No special scheduling required. The two clusters could be observed in CVZ, but we do not strictly require it. Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: NGC6752-TO Alternate_Names: Description: STELLAR CLUSTER, GLOBULAR CLUSTER Position: RA=19H 6M 36.6S +/- 1",DEC=-60D 6' 10.5" +/- 1",REGION Equinox: B1950 RV_or_Z: RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: V = 17.5 B-V = 0.4 E(B-V) = 0.04 Comments: Flux of Turn Off from Main Sequence Target_Number: 2 Target_Name: NGC104-TO Alternate_Names: 47TUC Description: STELLAR CLUSTER,GLOBULAR CLUSTER, Position: RA=00H 22M 40.0S +/- 0.01S,DEC=-72D 4' 0.0" +/- 0.1",REGION Equinox: J2000 RV_or_Z: RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: V = 17.5 B-V = 0.4 E(B-V) = 0.04 Comments: Flux of Turn Off from Main Sequence Solar_System_Targets Generic_Targets Scan_Data Visits Visit_Number: 01 Visit_Requirements: ORIENT 259D TO 262D On_Hold_Comments: Visit_Comments: SAME ORIENT AS EXPOSURES IN ID 5439 (PA 80.5, ORIENT 260.5) Exposure_Number: 1 Target_Name: NGC6752-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F555W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15 Number_of_Iterations: 2 Time_Per_Exposure: 120 S Special_Requirements: Comments: Exposure_Number: 2 Target_Name: NGC6752-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F555W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 20 S Special_Requirements: Comments: Exposure_Number: 3 Target_Name: NGC6752-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F814W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15 Number_of_Iterations: 2 Time_Per_Exposure: 120 S Special_Requirements: Comments: Exposure_Number: 4 Target_Name: NGC6752-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F814W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 20 S Special_Requirements: Comments: Exposure_Number: 5 Target_Name: NGC6752-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15,CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1100 S Special_Requirements: Comments: Exposure_Number: 6 Target_Name: NGC6752-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 230 S Special_Requirements: Comments: Visit_Number: 02 Visit_Requirements: ORIENT 22.2D TO 25.2D On_Hold_Comments: Visit_Comments: SAME ORIENT AS EXPOSURES IN ID 6114 (PA 203.7, ORIENT 23.7) Exposure_Number: 7 Target_Name: NGC104-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15 Number_of_Iterations: 2 Time_Per_Exposure: 120 S Special_Requirements: Comments: Exposure_Number: 8 Target_Name: NGC104-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15 Number_of_Iterations: 2 Time_Per_Exposure: 20 S Special_Requirements: Comments: Exposure_Number: 9 Target_Name: NGC104-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15,CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 120 S Special_Requirements: Comments: Exposure_Number: 10 Target_Name: NGC104-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15 Number_of_Iterations: 2 Time_Per_Exposure: 20 S Special_Requirements: Comments: Exposure_Number: 11 Target_Name: NGC104-TO Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F336W Wavelength: Optional_Parameters: CLOCKS=YES,ATD-GAIN=15,CR-SPLIT=NO Number_of_Iterations: 2 Time_Per_Exposure: 600 S Special_Requirements: Comments: Data_Distribution ! Defaults indicated; change if desired Medium: 8MM Ship_To: PI_Address Recipient_Email: ! Let us know what you think of this template and software! ! Please send a list of your likes and dislikes to your Program Coordinator