! +====================+ ! | PED OUTPUT PRODUCT | ! +====================+ ! ! /yon/data1/nkede/proposals/6607.prop ! Generated by PREPROCESSOR, version 7.1c ! Date: Wed Apr 02 15:22:41 EST 1997 Proposal_Information Title: The Origin and Nature of UV Bright stars in Globular Clusters II Proposal_Category: GO Scientific_Category: STELLAR POPULATIONS Cycle: 6 Investigators PI_Name: Francesco Ferraro PI_Institution: Osservatorio Astronomico CoI_Name: Ben Dorman CoI_Institution: Laboratory for Astronomy and Solar Physics, NASA/Goddard Space Flight Center Contact: CoI_Name: Robert O'Connell CoI_Institution: University of Virginia Contact: CoI_Name: Robert Rood CoI_Institution: University of Virginia Contact: CoI_Name: Robert S. Hill CoI_Institution: Laboratory for Astronomy and Solar Physics, NASA/Goddard Space Flight Center Contact: CoI_Name: Wayne Landsman CoI_Institution: Laboratory for Astronomy and Solar Physics, NASA/Goddard Space Flight Center Contact: CoI_Name: Flavio Fusi Pecci CoI_Institution: Osservatorio Astronomico of Bologna Contact: CoI_Name: Carla Cacciari CoI_Institution: Osservatorio Astronomico of Bologna Contact: Abstract: We propose an investigation of the UV-bright stellar populations of NGC 1904, NGC 6254, and NGC 5904. These are Galactic globular clusters that are known to be bright at far-UV wavelengths, with the two known to possess extended blue HB tails. These observations will complement data obtained during Cycle 5 and during the UIT Astro-1 flight in December 1990. The object of this investigation is twofold: (a) to explore the relationship between the HB mass distribution in clusters with blue HB tails (BT clusters) to the clusters' structural and dynamical properties and (b) to gain further samples of blue straggler stars in the cores of such clusters. These observations will allow a probe of the variation in mass loss processes close to the tip of the red giant branch. The clusters have been selected as follows: NGC 1904 and NGC 6254 are similar in HB morphology to NGC 6205 for which we have scheduled Cycle 5 observations, and are both more centrally concentrated. In addition, UIT observations indicate a deficit of blue HB stars in the core of NGC1904. NGC 5904 has similar metallicity and concentration to both NGC 1904 & NGC 6254, and was observed by the ANS to be brighter in the far-UV than its optical HB morphology suggests. Our original target list contained also NGC 6266, which has a larger continuous range in HB colour than any other cluster, extending from the red to the blue extreme, and would have provided information about a cluster with high HB mass dispersion. However the exposure times that we derived in Phase 1 using the WFPC2 Exposure Time Calculator provided by the STScI resulted significantly underestimated because of an error in the ETC. As a result of that, we decided to drop NGC 6266, which is highly reddened and requires long exposure times, in order to obtain acceptably good photometric quality on the other 3 clusters. Questions Observing_Description: We will image fields in the cluster centers in the F160BW, F255W, and F336W ultraviolet passbands. A short exposure in the Visual band F555W is also required to provide a long wavelength baseline for the HB observations and to allow the calculation of integrated 16 -V and 25-V colors. The V observations will also allow the detection of spurious cool sources arising from the redleak in the F336W passband. We propose to spend four orbits each on NGC 1904 and NGC 6254, and three orbits on NGC 5904. The exposure times have have been calculated in order to reach approximately S/N=50 at V=Vo(HB)+4.5 mag in the filter F555W for a G0 star, and S/N=30 in the bands F160BW, F255W, and F336W for a B0, A0, and F0 star respectively. In the Woods filter, a part from the error in the WFPC2 ETC mentioned above, we have some reason to believe, from the exposure times used by the WFPC2 IDT for NGC6681 and their reported accuracy, that the S/N is overestimated for a given exposure because of the variability of the PSF due to chromatic aberration. We are also aware that the contamination in the UV renders the calibration uncertain at the few \\% level. We have thus increased our S/N requirement where this is possible, aiming to get data that are limited by other sources of error than photometric uncertainties. In this way we plan to measure with the best possible accuracy EHB stars down to the faint end of the BT and BSS which can be found at the turnoff luminosity level. Note that in the case of NGC 1904 we have not requested the the mid-UV F255W exposures requested for the other clusters in order to avoid duplication with GO 6095. Whenever possible, the exposures will be dithered on 2 or 3 positions (default values) for the twofold purpose of (1) mapping the PSF for a better photometric accuracy, and (2) identifying and cleaning from CR events and other blemishes. Multiple exposures will also help in avoiding the blooming in the V images (no blooming is expected in the ultraviolet bands). The detailed observing strategy aims at using the available time with the maximum possible efficiency. Real_Time_Justification: None. Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: NGC1904 Alternate_Names: M79 Description: STELLAR CLUSTER, GLOBULAR CLUSTER Position: RA=5H 24M 10.6S +/- 0.1S,DEC=-24D 31' 27.0" +/- 1" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: Annual_Parallax: 0.0 Flux: SURF(V) = 16.18+/-0.1 B-V = 0.64 E(B-V) = 0.01 Comments: Target_Number: 2 Target_Name: NGC6254 Alternate_Names: M10 Description: STELLAR CLUSTER, GLOBULAR CLUSTER Position: RA=16H 57M 8.9S +/- 0.1S,DEC=-04D 5' 58.0" +/- 1" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: Annual_Parallax: 0.0 Flux: SURF(V) = 17.70+/-0.1 B-V = 0.89 E(B-V) = 0.28 Comments: Target_Number: 3 Target_Name: NGC5904 Alternate_Names: M5 Description: STELLAR CLUSTER, GLOBULAR CLUSTER Position: RA=15H 18M 33.8S +/- 0.1S,DEC=02D 4' 58.0" +/- 1" Equinox: J2000 RV_or_Z: RA_PM: 0.0 Dec_PM: 0.0 Epoch: Annual_Parallax: 0.0 Flux: SURF(V) = 16.05+/-0.1 B-V = 0.71 E(B-V) = 0.03 Comments: Above flux values refer to the integrated cluster, for ACQ purposes only. For individual stars see observing description. Solar_System_Targets Generic_Targets Scan_Data Visits Visit_Number: 01 Visit_Requirements: On_Hold_Comments: Visit_Comments: OBSERVATIONS CONTAIN FAR UV EXPOSURES: PLEASE ATTEMPT TO SCHEDULE SOON AFTER DECONTAMINATION Exposure_Number: 1 Target_Name: NGC6254 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F255W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1700 S Special_Requirements: EXPAND MAX DUR 200% Comments: Exposure_Number: 2 Target_Name: NGC6254 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F336W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 500 S Special_Requirements: Comments: Exposure_Number: 3 Target_Name: NGC6254 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 30 S Special_Requirements: Comments: Exposure_Number: 4 Target_Name: NGC6254 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F255W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1700 S Special_Requirements: POS TARG 0.3535,0.3535 Comments: Exposure_Number: 5 Target_Name: NGC6254 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F336W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 500 S Special_Requirements: POS TARG 0.3535,0.3535 Comments: Exposure_Number: 6 Target_Name: NGC6254 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 30 S Special_Requirements: POS TARG 0.3535,0.3535 Comments: Exposure_Number: 7 Target_Name: NGC6254 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F255W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1700 S Special_Requirements: POS TARG 0.707,0.707 Comments: Exposure_Number: 8 Target_Name: NGC6254 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F336W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 500 S Special_Requirements: POS TARG 0.707,0.707 Comments: Exposure_Number: 9 Target_Name: NGC6254 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F160BW Wavelength: Optional_Parameters: CR-SPLIT=NO,DITHER-TYPE=LINE,DITHER-LINE-STEPS=2 Number_of_Iterations: 1 Time_Per_Exposure: 1100 S Special_Requirements: Comments: Visit_Number: 02 Visit_Requirements: On_Hold_Comments: Visit_Comments: OBSERVATIONS CONTAIN FAR UV EXPOSURES: PLEASE ATTEMPT TO SCHEDULE SOON AFTER DECONTAMINATION Exposure_Number: 20 Target_Name: NGC1904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,DITHER-TYPE=LINE,DITHER-LINE-STEPS=3 Number_of_Iterations: 1 Time_Per_Exposure: 100 S Special_Requirements: Comments: Exposure_Number: 21 Target_Name: NGC1904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,CR-SPLIT=0.5 Number_of_Iterations: 1 Time_Per_Exposure: 6 S Special_Requirements: MAX DUR Comments: Exposure_Number: 22 Target_Name: NGC1904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F160BW Wavelength: Optional_Parameters: CR-SPLIT=NO,DITHER-TYPE=LINE,DITHER-LINE-STEPS=3 Number_of_Iterations: 1 Time_Per_Exposure: 1100 S Special_Requirements: Comments: Exposure_Number: 24 Target_Name: NGC1904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F336W Wavelength: Optional_Parameters: ATD-GAIN=15,CR-SPLIT=NO,DITHER-TYPE=LINE,DITHER-LINE-STEPS=2 Number_of_Iterations: 1 Time_Per_Exposure: 1100 S Special_Requirements: Comments: Exposure_Number: 25 Target_Name: NGC1904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F336W Wavelength: Optional_Parameters: ATD-GAIN=15,CR-SPLIT=NO,DITHER-TYPE=LINE,DITHER-LINE-STEPS=2 Number_of_Iterations: 1 Time_Per_Exposure: 1100 S Special_Requirements: Comments: Visit_Number: 03 Visit_Requirements: On_Hold_Comments: Visit_Comments: OBSERVATIONS CONTAIN FAR UV EXPOSURES: PLEASE ATTEMPT TO SCHEDULE SOON AFTER DECONTAMINATION Exposure_Number: 30 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F255W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1200 S Special_Requirements: EXPAND MAX DUR 110% Comments: Exposure_Number: 31 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F336W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 350 S Special_Requirements: EXPAND MAX DUR 120% Comments: Exposure_Number: 32 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,CR-SPLIT=0.5 Number_of_Iterations: 1 Time_Per_Exposure: 60 S Special_Requirements: Comments: Exposure_Number: 33 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 30 S Special_Requirements: Comments: Exposure_Number: 34 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F555W Wavelength: Optional_Parameters: ATD-GAIN=15,CR-SPLIT=0.5 Number_of_Iterations: 1 Time_Per_Exposure: 6 S Special_Requirements: MAX DUR Comments: Exposure_Number: 35 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F160BW Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 500 S Special_Requirements: Comments: Exposure_Number: 36 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F255W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1200 S Special_Requirements: POS TARG 0.3535,0.3535 EXPAND Comments: Exposure_Number: 37 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F336W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 350 S Special_Requirements: POS TARG 0.3535,0.3535 EXPAND Comments: Exposure_Number: 38 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F160BW Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 500 S Special_Requirements: POS TARG 0.3535,0.3535 Comments: Exposure_Number: 39 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F255W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 1200 S Special_Requirements: POS TARG 0.707,0.707 EXPAND Comments: Exposure_Number: 40 Target_Name: NGC5904 Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F336W Wavelength: Optional_Parameters: ATD-GAIN=15 Number_of_Iterations: 1 Time_Per_Exposure: 350 S Special_Requirements: POS TARG 0.707,0.707 EXPAND 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