! +====================+ ! | PED OUTPUT PRODUCT | ! +====================+ ! ! /data/frodo1/aroman/work/6701.prop ! Generated by PREPROCESSOR, version 7.1e ! Date: Thu Apr 24 19:42:44 EDT 1997 Proposal_Information Title: Photometry of the globular cluster system of the Sagittarius dwarf galaxy Proposal_Category: GO Scientific_Category: STELLAR POPULATIONS Cycle: 6 Investigators PI_Name: Rodrigo Ibata PI_Institution: Department of Astronomy, University of British Columbia, Canada CoI_Name: Gregory Fahlman CoI_Institution: Department of Astronomy, University of British Columbia, Canada Contact: CoI_Name: Gerard Gilmore CoI_Institution: Institute of Astronomy, Cambridge, UK Contact: CoI_Name: Michael Irwin CoI_Institution: Royal Greenwich Observatory, Cambridge, UK Contact: CoI_Name: Harvey Richer CoI_Institution: Department of Astronomy, University of British Columbia, Canada Contact: Abstract: We propose to use the WFPC2 to obtain deep V (F555W) and I (F814W) band images of the globular clusters of the Sagittarius dwarf galaxy: M54 (NGC 6715), Ter 7, Ter 8 and Arp 2. Isochrone fits to these data will yield the accurate ages of M54, Ter 8 and the Sagittarius dwarf galaxy (Sgr). These age estimates are needed to model the dynamics and evolution of the Sgr system and its interaction with the Milky Way. Sgr is in the final stages of tidal disruption (Velazquez & White 1995), so its globular clusters will drift away from their parent galaxy and soon disperse into the Galactic halo. Therefore at least some of the globular clusters of giant spiral galaxies like the Milky Way will have been captured from tidally destroyed dwarf galaxies. This statement has fundamental and wide ranging implications for the formation and evolution of globular clusters and spiral galaxies. It is therefore essential to conduct a detailed and accurate comparative study of the stellar populations of the Sgr and Galactic globular clusters, as we propose here. This, in turn, will allow detailed modeling of the chemical and dynamical evolution of Sgr and its globular clusters. Questions Observing_Description: We are proposing to undertake a comparative study of the globular clusters of the Sagittarius dwarf galaxy with those of the Milky Way. This requires as much information on the stellar populations of the clusters as can be obtained in a reasonable time. We will use a single orbit (53 minutes at the declination of these clusters) per field per filter, to obtain S/N > 7 photometry down to V=26, which is sufficient to achieve our scientific goals. Data acquisition in each field should start with the F814W filter. (We have assumed colors appropriate for a G dwarf). The time budgets are as follows: F814W: 12 minutes for guide-star acquisition 4x(17 seconds) CCD clearing 4x(2 minutes) CCD readout 4x(1 minute) dithering which leaves 4x400 seconds of exposure. This gives S/N > 8 at I=25. F555W: 6 minutes 23 seconds for guide-star re-acquisition 4x(17 seconds) CCD clearing 4x(2 minutes) CCD readout 4x(1 minute) dithering which leaves 4x500 seconds of exposure. This gives S/N > 7 at V=26. The photometric reductions will be accomplished using the latest version of P. Stetson's DAOPHOT photometry package. Four frames each in V & I are sufficient to remove cosmic rays since the positions of the stellar images can be found on a frame which is the median of all eight frames in a field. Real_Time_Justification: We request that for the M54 observations, the PC field be centered on the core of the cluster. Our team is conducting several parallel studies of the Sgr system. We have obtained high and medium resolution spectra at CTIO and the AAT for many hundred member stars, and taken photographic plates with the UK-Schmidt Telescope and successfully determined the proper motion of Sgr. These data are currently being modelled. We also have Ca II triplet line -strength measurements of velocity confirmed Sgr members and members of M54, from which we have derived accurate abundances. We are currently applying for time at the AAT to obtain medium resolution spectra to delimit the size and mass of this fascinating dwarf galaxy. Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: ARP2 Alternate_Names: Description: STELLAR CLUSTER,GLOBULAR CLUSTER Position: RA=19H 28M 44.1S +/- 5",DEC=-30D 21' 14" +/- 5" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: J2000 Annual_Parallax: 0.0 Flux: V = 26 Comments: Target_Number: 2 Target_Name: TER7 Alternate_Names: Description: STELLAR CLUSTER,GLOBULAR CLUSTER Position: RA=19H 17M 43.7S +/- 5",DEC=-34D 39' 27" +/- 5" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: J2000 Annual_Parallax: 0.0 Flux: V = 26 Comments: Target_Number: 3 Target_Name: TER8 Alternate_Names: Description: STELLAR CLUSTER,GLOBULAR CLUSTER Position: RA=19H 41M 45.0S +/- 5",DEC=-34D 0' 1" +/- 5" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: J2000 Annual_Parallax: 0.0 Flux: V = 26 Comments: Target_Number: 4 Target_Name: GAL-185503-304242 Alternate_Names: Description: GALAXY,DWARF SPHEROIDAL Position: RA=18H 55M 3.3S +/- 5",DEC=-30D 42' 42" +/- 5" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: J2000 Annual_Parallax: 0.0 Flux: V = 26 Comments: Target_Number: 5 Target_Name: NGC6715 Alternate_Names: Description: STELLAR CLUSTER,GLOBULAR CLUSTER Position: RA=18H 55M 3.3S +/- 5",DEC=-30D 28' 42" +/- 5" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: J2000 Annual_Parallax: 0.0 Flux: V = 26 Comments: Solar_System_Targets Generic_Targets Scan_Data Visits Visit_Number: 01 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 100 Target_Name: ARP2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 110 Target_Name: ARP2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 260 S Special_Requirements: Comments: Exposure_Number: 150 Target_Name: ARP2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 160 Target_Name: ARP2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 350 S Special_Requirements: Comments: Visit_Number: 02 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 200 Target_Name: TER7 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 210 Target_Name: TER7 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 260 S Special_Requirements: Comments: Exposure_Number: 250 Target_Name: TER7 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 260 Target_Name: TER7 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 350 S Special_Requirements: Comments: Visit_Number: 03 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 300 Target_Name: TER8 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 310 Target_Name: TER8 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 260 S Special_Requirements: Comments: Exposure_Number: 350 Target_Name: TER8 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 360 Target_Name: TER8 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 350 S Special_Requirements: Comments: Visit_Number: 04 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 400 Target_Name: GAL-185503-304242 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 410 Target_Name: GAL-185503-304242 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 260 S Special_Requirements: Comments: Exposure_Number: 450 Target_Name: GAL-185503-304242 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 460 Target_Name: GAL-185503-304242 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 350 S Special_Requirements: Comments: Exposure_Number: 500 Target_Name: NGC6715 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 510 Target_Name: NGC6715 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 260 S Special_Requirements: Comments: Exposure_Number: 550 Target_Name: NGC6715 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 560 Target_Name: NGC6715 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 350 S Special_Requirements: Comments: Visit_Number: 13 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 300 Target_Name: TER8 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 310 Target_Name: TER8 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 260 S Special_Requirements: Comments: Exposure_Number: 350 Target_Name: TER8 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 5 Time_Per_Exposure: 300 S Special_Requirements: Comments: Exposure_Number: 360 Target_Name: TER8 Config: WFPC2 Opmode: IMAGE Aperture: WFALL-FIX Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 350 S Special_Requirements: Comments: Data_Distribution ! 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