! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! Id: 6101 ! ! For help call your Program Coordinator: Max Mutchler ! Phone: 410 338-1321 , E-mail: mutchler@stsci.edu Proposal_Information Title: The young double cluster NGC 1850 in the Large Magellanic Cloud Proposal_Category: GO Scientific_Category: Stellar Populations Cycle: 5 Investigators PI_name: Roberto Gilmozzi PI_Institution: European Southern Observatory CoI_Name: Nino Panagia CoI_Institution: Space Telescope Science Institute Contact: N ! Y or N (designate at most one contact) CoI_Name: Shawn Ewald CoI_Institution: California Institute of Technology Contact: N ! Y or N (designate at most one contact) CoI_Name: Ellyne Kinney CoI_Institution: Space Telescope Science Institute Contact: Y ! Y or N (designate at most one contact) CoI_Name: Salvatore Scuderi CoI_Institution: Space Telescope Science Institute Contact: N ! Y or N (designate at most one contact) Abstract: We propose to study the stellar population of the young double cluster NGC 1850 in the LMC. Our plan includes WFPC2 imaging both in broad band filters (to study the general properties of stars) and THE narrow band filter HAlpha to identify PMS stars. Previous observations have shown that both subclusters, NGC 1850A and NGC1850B, are quite young (50 and 4 Myr, respectively) while the field stars have ages between 500 Myr and 6 Gyr, at least. In addition, the two clusters are distinct not only in age but also in their IMFs (the younger has a steeper slope) and in their spatial distributions (the younger one is more widely spread). Therefore, NGC 1850 and its surrounding field represent an ideal astrophysical laboratory where to study different stellar populations and many aspects of stellar evolution. In particular, in the younger cluster we expect to detect hundreds of PMS stars. Questions Observing_Description: noindent Imaging with WFPC2 2mm We plan to complement the observations made in Cycle 4 (i.e. imaging with UV(1700Angstrom) 2000s, B 1000s, V 200s and I 1000s) by obtaining new images in R (F675W, 30+500s). All long exposures will be CR-split. To isolate the PMS stars we will also take narrow band images in H Alpha (F656N, 1000s). The grand total for the imaging part of the proposal is 5 CVZ orbits, including overheads and CR-splits. Exposure times for broad band imaging were calculated using SYNPHOT (after adjustments based on the Cycle 4 observations) to reach mag at least 26 in each filter (absolute magnitude about 7.5, or 0.7). The H Alpha filter exposure time was chosen to yield a S/N ~ 7Sigma for a R=23 T Tau star with W_eq ~ 20Angstrom so that discrimination against other stars of similar magnitude can be done at the 5 Sigma level. 2mm noindent Control Observations 2mm We plan to obtain images of three control fields with a comparable set of filters and exposure times as done for the main field. In particular, we will expose the 170, B, V, R, I and H Alpha filters for 2000s, 1000s, 200s, 500s, 1000s, 1130s. Real_Time_Justification: We wish to take these observation in the CVZ because it uses spacecraft time most efficiently. The maximum CVZ duration of a CVZ interval at the position of NGC 1850 is 28 hours (for a total of about 58 hours in a year). Fixed_Targets Target_Number: 1 Target_Name: NGC1850 Alternate_Names: Description: STELLAR CLUSTER, OPEN CLUSTER Position: RA = 05H 08M 59S +/- 1.0S, DEC = -68D 49' 24" +/- 5.0" Equinox: 1950 RV_or_Z: RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: SURF(V)=9.3 Comments: Target_Number: 2 Target_Name: NGC1850-FIELD-1 Alternate_Names: Description: STELLAR CLUSTER, OPEN CLUSTER Position: RA = 05H 08M 52S +/- 1.0S, DEC = -68D 45' 54" +/- 5.0" Equinox: 1950 RV_or_Z: RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: SURF-BKG(V)=24.5 +/-0.5 Comments: Control field for NGC1850 Target_Number: 3 Target_Name: NGC1850-FIELD-2 Alternate_Names: Description: STELLAR CLUSTER, OPEN CLUSTER Position: RA = 05H 08M 54S +/- 1.0S, DEC = -68D 51' 39" +/- 5.0" Equinox: 1950 RV_or_Z: RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: SURF-BKG(V)=24.5 +/-0.5 Comments: Control field for NGC1850 Visits Visit_Number: 1 Visit_Requirements: CVZ ! ORIENT 105D TO 110D (incompatible with CVZ windows) On_Hold_Comments: Visit_Comments: Exposure_Number: 1 Target_Name: NGC1850 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F656N Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 2000S Special_Requirements: Exposure_Number: 2 Target_Name: NGC1850 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F656N Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1000S Special_Requirements: Exposure_Number: 3 Target_Name: NGC1850 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F656N Wavelength: Optional_Parameters: ATD-GAIN = 15 Number_of_Iterations: 1 Time_Per_Exposure: 90S Special_Requirements: Exposure_Number: 4 Target_Name: NGC1850 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F675W Wavelength: Optional_Parameters: ATD-GAIN = 15 Number_of_Iterations: 1 Time_Per_Exposure: 30S Special_Requirements: Exposure_Number: 6 Target_Name: NGC1850 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F675W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: Visit_Number: 2 Visit_Requirements: Exposure_Number: 7 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F170W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 2000S Special_Requirements: Exposure_Number: 8 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F791W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1000S Special_Requirements: Exposure_Number: 9 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1000S Special_Requirements: Exposure_Number: 10 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F675W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: Exposure_Number: 11 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F656N Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1000S Special_Requirements: Exposure_Number: 12 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F569W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: Exposure_Number: 13 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F675W Wavelength: Optional_Parameters: ATD-GAIN = 15 Number_of_Iterations: 1 Time_Per_Exposure: 30S Special_Requirements: Exposure_Number: 14 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F656N Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 2000S Special_Requirements: Exposure_Number: 30 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F170W Wavelength: Optional_Parameters: ATD-GAIN = 15 Number_of_Iterations: 1 Time_Per_Exposure: 60S Special_Requirements: Exposure_Number: 31 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F791W Wavelength: Optional_Parameters: ATD-GAIN = 15 Number_of_Iterations: 1 Time_Per_Exposure: 30S Special_Requirements: Exposure_Number: 32 Target_Name: NGC1850-FIELD-1 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: ATD-GAIN = 15 Number_of_Iterations: 1 Time_Per_Exposure: 30S Special_Requirements: Visit_Number: 3 Visit_Requirements: Exposure_Number: 17 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F170W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 2000S Special_Requirements: Exposure_Number: 18 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1000S Special_Requirements: Exposure_Number: 19 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F569W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: Exposure_Number: 20 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F675W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 500S Special_Requirements: Exposure_Number: 22 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F675W Wavelength: Optional_Parameters: ATD-GAIN = 15 Number_of_Iterations: 1 Time_Per_Exposure: 30S Special_Requirements: Exposure_Number: 23 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F791W Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1000S Special_Requirements: Exposure_Number: 25 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F656N Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1000S Special_Requirements: Exposure_Number: 26 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F656N Wavelength: Optional_Parameters: ATD-GAIN = 15, CR-SPLIT = 0.7, CR-TOLERANCE = 0.0 Number_of_Iterations: 1 Time_Per_Exposure: 2000S Special_Requirements: Exposure_Number: 30 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F170W Wavelength: Optional_Parameters: ATD-GAIN = 15 Number_of_Iterations: 1 Time_Per_Exposure: 60S Special_Requirements: Exposure_Number: 31 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F791W Wavelength: Optional_Parameters: ATD-GAIN = 15 Number_of_Iterations: 1 Time_Per_Exposure: 30S Special_Requirements: Exposure_Number: 32 Target_Name: NGC1850-FIELD-2 Config: WFPC2 Opmode: IMAGE Aperture: WFALL Sp_Element: F439W Wavelength: Optional_Parameters: ATD-GAIN = 15 Number_of_Iterations: 1 Time_Per_Exposure: 30S Special_Requirements: Comments: Data_Distribution ! 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