! +====================+ ! | PED OUTPUT PRODUCT | ! +====================+ ! ! /yon/data1/nkede/proposals/6625.prop ! Generated by PREPROCESSOR, version 6.6 ! Date: Wed Nov 13 09:43:09 EST 1996 Proposal_Information Title: The second-parameter effect and the formation history of the Milky Way Galaxy Proposal_Category: GO Scientific_Category: STELLAR POPULATIONS Cycle: 6 Investigators PI_Name: Roberto Buonanno PI_Institution: Observatory of Rome CoI_Name: Carlo Corsi CoI_Institution: Observatory of Rome Contact: CoI_Name: Gianni Marconi CoI_Institution: Observatory of Rome Contact: CoI_Name: Vitali Fabrizio CoI_Institution: Observatory of Rome Contact: CoI_Name: Giulia Stratta CoI_Institution: University of Rome Contact: CoI_Name: Ferraro Francesco CoI_Institution: Observatory of Bologna Contact: CoI_Name: Bellazzini Michele CoI_Institution: Observatory of Bologna Contact: CoI_Name: Francesco Paresce CoI_Institution: ESO Contact: Abstract: We propose to obtain HST V,I observations of a sample of Galactic globular clusters (GC's) in order to establish an unbiased correlation between the morphology of the horizontal branch (HB) and the age of the cluster (for fixed metallicity, the first parameter). After Searle and Zinn (1978) and Lee, Demarque and Zinn (1994, LDZ), it is widely accepted that differences in color between the HB's of GC's with the same metallicity can be explained in terms of differences in age (the candidate second parameter). On the other hand, according to Buonanno (1993) and Fusi Pecci et al. (1993), the HB-morphology is determined (perhaps with comparable weight) either by the age and by the cluster central mass density (the candidate third parameter). The problem is of substance because GC's classified as coeval by LDZ on the basis of their HB-morphology are, according to Buonanno (1993), different in age by 2-3 Gyrs and vice-versa. If this scenario is confirmed, the use of the HB-morphology as a clock must be revised and, in turn, the description of galaxy evolution could be modified. Questions Observing_Description: WFPC2 observations of the galactic globular clusters NGC5897, NGC6626, NGC2298, NGC6535, NGC6101, will be taken using 2 filters, i.e. F555W, F814W. In particular the PC1 will be pointing the cluster center for each of the 2 filters, while the three WFC mosaics will map adjacent fields in the same bands. We plan to measure as many stars as possible near the TO because the standard errors of the color difference TO-RGB is roughly proportional to n^-1/2, where n is the number of stars measured near the TO. Therefore with sigma_V-I ~eq 0.03 (conservative estimate), and n ~eq 100 the color difference TO-RGB will be determined with a precision of about 0.003 magnitudes, corresponding to an age uncertainty of ~0.3 Gyr. The observational strategy is to optimize the degree of completeness (down to a fixed magnitude limit, even at the very cluster center) and in particular the photometric quality of the individual measures. Hence, exposure times for each filter have been computed (using WFPC2 exposure time calculator at www.stsci.edu ) to be adequate to reach S/N=50 at about 2 mag below the turnoff, i.e. V ~ 22, in the wide band filters (VI), and to be subdivided into sets of appropriate sub-exposures short enough to avoid destructive blooming from the brightest (V~13) giants. In fact, strong charge transfer from highly saturated bright objects would prevent the detection and measure of fainter stars, so decreasing strongly the degree of completeness specially in the very crowded central regions. The exposure times have been computed by adopting a gain of 14 electrons/DN and the appropriate E(B-V) for each cluster to estimate the total exposure time (to obtain the desired S/N). We have also computed the maximum lenght of each sub-exposure (to avoid destructive blooming from bright giant stars at ~eq 90000 electrons/central px.) Considered the requirement of high statistics, our observations will be obtained with the PC1 chip centered on the clusters, while the WFs chips will observe the adiacent regions. Two broadband filters * ~ 0.9 hours/filters = 2 orbits for clusters NGC 5897, NGC 2298 and NGC 6101; two broadband filters * ~ 1.3 hours/filters = 3 orbits for clusters NGC 6535 and NGC 6626 for a grand total of 12 orbits. Real_Time_Justification: We already have ground-based observations for the bright end of the clusters sample. These observations will allow a direct calibration of the HST targets, and add photometry of the brighter parts of the CMD. In addition, we will submit an ESO proposal to observe uncrowded stars which will be found on the WFPC2 chips in order to ceck HST calibrations. Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: NGC5897 Alternate_Names: 1514-208 Description: STELLAR CLUSTER,GLOBULAR CLUSTER, Position: RA=15H 17M 25.0S +/- 1.0",DEC=-21D 0' 37.5" +/- 0.5" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: Annual_Parallax: 0.0 Flux: SURF-BKG(V) = 20.60+/-0.2 V = 13.0+/-0.1 V = 16.25+/-0.1 V = 20.00+/-0.1 TYPE=K0 TYPE=F0 E(B-V) = 0.09+/-0.02 Comments: Flux1=central surface brightness in mag/arcsec-2 for ACQ only. Flux2, 3 and 4 are : V-magnitude of RGB tip, V-magnitude of HB and V-magnitude of TO for exposure time calculation. Spectral types are referred to flux2 and 4. Target_Number: 2 Target_Name: NGC6626 Alternate_Names: 1821-249 Description: STELLAR CLUSTER,GLOBULAR CLUSTER, Position: RA=18H 24M 32.9S +/- 1.0",DEC=-24D 52' 12.0" +/- 0.5" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: Annual_Parallax: 0.0 Flux: SURF-BKG(V) = 15.99+/-0.2 V = 12.90+/-0.15 V = 15.60+/-0.1 V = 19.4+/-0.15 E(B-V) = 0.37+/-0.05 TYPE=K0 TYPE=F0 Comments: Flux1=central surface brightness in mag/arcsec-2 for ACQ only. Flux2, 3 and 4 are : V-magnitude of RGB tip, V-magnitude of HB and V-magnitude of TO for exposure time calculation. Spectral types are referred to flux2 and 4. Target_Number: 3 Target_Name: NGC2298 Alternate_Names: 0647-359 Description: STELLAR CLUSTER,GLOBULAR CLUSTER, Position: RA=06H 48M 59.2S +/- 1.0",DEC=-36D 0' 19.0" +/- 0.5" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: Annual_Parallax: 0.0 Flux: SURF-BKG(V) = 18.98+/-0.2 V = 13.0+/-0.1 V = 16.20+/-0.1 V = 20.00+/-0.15 E(B-V) = 0.15+/-0.03 TYPE=K0 TYPE=F0 Comments: Flux1=central surface brightness in mag/arcsec-2 for ACQ only. Flux2, 3 and 4 are : V-magnitude of RGB tip, V-magnitude of HB and V-magnitude of TO for exposure time calculation. Spectral types are referred to flux2 and 4. Target_Number: 4 Target_Name: NGC6535 Alternate_Names: 1801-003 Description: STELLAR CLUSTER,GLOBULAR CLUSTER, Position: RA=18H 3M 50.7S +/- 1.00",DEC=-00D 17' 49.0" +/- 0.5" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: Annual_Parallax: 0.0 Flux: SURF-BKG(V) = 21.28+/-0.2 V = 12.90+/-0.1 V = 15.85+/-0.1 V = 19.60+/-0.1 E(B-V) = 0.33+/-0.05 TYPE=K0 TYPE=F0 Comments: Flux1=central surface brightness in mag/arcsec-2 for ACQ only. Flux2, 3 and 4 are : V-magnitude of RGB tip, V-magnitude of HB and V-magnitude of TO for exposure time calculation. Spectral types are referred to flux2 and 4. Target_Number: 5 Target_Name: NGC6101 Alternate_Names: 1620-72 Description: STELLAR CLUSTER,GLOBULAR CLUSTER, Position: RA=16H 25M 48.6S +/- 1.0",DEC=-72D 12' 6.0" +/- 0.5" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: Annual_Parallax: 0.0 Flux: SURF-BKG(V) = 20.30+/-0.2 V = 13.2+/-0.05 V = 16.76+/-0.08 V = 20.3+/-0.1 E(B-V) = 0.04+/-0.03 TYPE=K0 TYPE=F0 Comments: Flux1=central surface brightness in mag/arcsec-2 for ACQ only. Flux2, 3 and 4 are : V-magnitude of RGB tip, V-magnitude of HB and V-magnitude of TO for exposure time calculation. Spectral types are referred to flux2 and 4. Solar_System_Targets Generic_Targets Scan_Data Visits Visit_Number: 01 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 1 Target_Name: NGC2298 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=3 Number_of_Iterations: 1 Time_Per_Exposure: 2.60 S Special_Requirements: Comments: 3 exposures of 3 sec each to avoid blooming from V=13 KO stars. Exposure_Number: 2 Target_Name: NGC2298 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=6 Number_of_Iterations: 1 Time_Per_Exposure: 100 S Special_Requirements: Comments: 3 + 3 exposures of 160 sec each to reach SNR 50 ~ 2 mag below turnoff stars. Exposure_Number: 3 Target_Name: NGC2298 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=2 Number_of_Iterations: 1 Time_Per_Exposure: 2.60 S Special_Requirements: Comments: 2 exposures of 3 sec each to avoid blooming from V=13 KO stars. Exposure_Number: 4 Target_Name: NGC2298 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=4 Number_of_Iterations: 1 Time_Per_Exposure: 160 S Special_Requirements: Comments: 2 + 2 exposures of 200 sec each to reach SNR 50 ~ 2 mag below turnoff stars Exposure_Number: 5 Target_Name: NGC2298 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 260 S Special_Requirements: Comments: 1 exposure of 300 sec to reach SNR 40 ~ 2 mag below turnoff stars Visit_Number: 02 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 1 Target_Name: NGC5897 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=3 Number_of_Iterations: 1 Time_Per_Exposure: 2.60 S Special_Requirements: Comments: 3 exposures of 3 sec each to avoid blooming from V=13 KO stars. Exposure_Number: 2 Target_Name: NGC5897 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=6 Number_of_Iterations: 1 Time_Per_Exposure: 100 S Special_Requirements: Comments: 3 + 3 exposures of 140 sec each to reach SNR 50 ~ 2 mag below turnoff stars Exposure_Number: 3 Target_Name: NGC5897 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=2 Number_of_Iterations: 1 Time_Per_Exposure: 2.60 S Special_Requirements: Comments: 2 exposures of 3 sec each to avoid blooming from V=13 KO stars. Exposure_Number: 4 Target_Name: NGC5897 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=4 Number_of_Iterations: 1 Time_Per_Exposure: 160 S Special_Requirements: Comments: 2 + 2 exposures of 180 sec each to reach SNR 50 ~ 2 mag below turnoff stars Exposure_Number: 5 Target_Name: NGC5897 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 200 S Special_Requirements: Comments: 1 exposures of 230 sec to fill the orbit Visit_Number: 03 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 1 Target_Name: NGC6101 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=2 Number_of_Iterations: 1 Time_Per_Exposure: 3 S Special_Requirements: Comments: 2 exposures of 3 sec each to avoid blooming from V=13.2 KO stars. Exposure_Number: 2 Target_Name: NGC6101 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=6 Number_of_Iterations: 1 Time_Per_Exposure: 160 S Special_Requirements: Comments: 3 + 3 exposures of 160 sec each to reach SNR 50 ~ 2 mag below turnoff stars Exposure_Number: 3 Target_Name: NGC6101 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 160 S Special_Requirements: Comments: 1 exposures of 160 sec to fill the orbit. Exposure_Number: 4 Target_Name: NGC6101 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=3 Number_of_Iterations: 1 Time_Per_Exposure: 3 S Special_Requirements: Comments: 3 exposures of 3 sec each to avoid blooming from V=13.2 KO stars. Exposure_Number: 5 Target_Name: NGC6101 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=4 Number_of_Iterations: 1 Time_Per_Exposure: 200 S Special_Requirements: Comments: 2 + 2 exposures of 200 sec each to reach SNR 50 ~ 2 mag below turnoff stars Exposure_Number: 6 Target_Name: NGC6101 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 350 S Special_Requirements: Comments: 1 exposure of 350 sec to reach SNR 40 ~ 2 mag below turnoff stars Visit_Number: 04 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 1 Target_Name: NGC6535 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=6 Number_of_Iterations: 1 Time_Per_Exposure: 160 S Special_Requirements: Comments: 3 + 3 exposures of 200 sec each to reach SNR 50 ~ 2 mag below turnoff stars Exposure_Number: 2 Target_Name: NGC6535 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=3 Number_of_Iterations: 1 Time_Per_Exposure: 2.60 S Special_Requirements: Comments: 3 exposures of 3 sec each to avoid blooming from V=12.9 KO stars. Exposure_Number: 3 Target_Name: NGC6535 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 3 Time_Per_Exposure: 180 S Special_Requirements: Comments: 3 exposures of 200 sec each to reach SNR 50 ~ 2 mag below turnoff stars Exposure_Number: 4 Target_Name: NGC6535 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=3 Number_of_Iterations: 1 Time_Per_Exposure: 2.60 S Special_Requirements: Comments: 3 exposures of 3 sec each to avoid blooming from V=12.9 KO stars. Exposure_Number: 5 Target_Name: NGC6535 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=4 Number_of_Iterations: 1 Time_Per_Exposure: 140 S Special_Requirements: Comments: 4 exposures of 160 sec each to reach SNR 50 ~ 2 mag below turnoff stars Exposure_Number: 6 Target_Name: NGC6535 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=4 Number_of_Iterations: 1 Time_Per_Exposure: 140 S Special_Requirements: Comments: 4 exposures of 160 sec each to reach SNR 50 ~ 2 mag below turnoff stars Visit_Number: 05 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 1 Target_Name: NGC6626 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=6 Number_of_Iterations: 1 Time_Per_Exposure: 160 S Special_Requirements: Comments: 3 + 3 exposures of 200 sec each to reach SNR 50 ~ 2 mag below turnoff stars Exposure_Number: 2 Target_Name: NGC6626 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=3 Number_of_Iterations: 1 Time_Per_Exposure: 2.60 S Special_Requirements: Comments: 3 exposures of 3 sec each to avoid blooming from V=12.9 KO stars. Exposure_Number: 3 Target_Name: NGC6626 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 3 Time_Per_Exposure: 180 S Special_Requirements: Comments: 3 exposures of 200 sec each to reach SNR 50 ~ 2 mag below turnoff star Exposure_Number: 4 Target_Name: NGC6626 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=3 Number_of_Iterations: 1 Time_Per_Exposure: 2.60 S Special_Requirements: Comments: 3 exposures of 3 sec each to avoid blooming from V=12.9 KO stars. Exposure_Number: 5 Target_Name: NGC6626 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=4 Number_of_Iterations: 1 Time_Per_Exposure: 140 S Special_Requirements: Comments: 4 exposures of 160 sec each to reach SNR 50 ~ 2 mag below turnoff star Exposure_Number: 6 Target_Name: NGC6626 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-SPACING=0.1767,DITHER-LINE-STEPS=4 Number_of_Iterations: 1 Time_Per_Exposure: 140 S Special_Requirements: Comments: 4 exposures of 160 sec each to reach SNR 50 ~ 2 mag below turnoff star 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