17145( 4) - 19-Feb-2024 19:10:30 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17145 Version: 4 Check-in Time: 19-Feb-2024 19:10:30 STScI Edit Number: 0 Title Clearing a Window Into Galaxy Formation: The Impact of Globular Cluster Metallicity Distributions ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. William Edgar Harris McMaster University Y CoI: Kate Hartman McMaster University N ------------------------------------------------------------------------------------ Abstract The MAST archive holds a rich legacy of imaging data for globular cluster (GC) systems in external galaxies that represents an investment of hundreds of HST orbits. But its full impact to make GCs key tracers of galaxy formation has yet to be realized. To achieve that, their true metallicity distribution functions (MDFs) must be established on an internally consistent base. Such MDF parameters as the mean metallicity, and the relative numbers of `blue' (metal-poor) and `red' (metal-rich) GCs are key predictions from current galaxy and GC formation theories that help decode the history of accretions versus in-situ formation. The observational barrier is that direct spectroscopic metallicities for GCs are hard to obtain in large numbers and are beyond reach for very distant galaxies. In most cases we have to work instead with the GC color distribution function (CDF), the photometric proxy for the MDF. But the many optical/NIR color indices that have been used to generate CDFs are all nonlinear functions of metallicity and give biased, misleading impressions of the true MDFs. We propose an efficient program of multifilter imaging of the Coma BCG NGC 4874, the richest GC system in the local universe, to measure all the commonly used GC color indices in a single system. Direct empirical transformations will be derived for every color into the fiducial index (g-z), which is the only one with a well established conversion into [Fe/H] based directly on spectroscopic metallicities. This program will take a major step towards defining the true MDFs for GC systems in almost 200 galaxies, and a new level of comparison with theory. ------------------------------------------------------------------------------------ Observations Description ------------------------ ACS/WFC and WFC/UVIS are used to image the region around NGC 4874, the central giant galaxy in the Coma cluster. The goal is to complete photometry of the globular cluster population in NGC 4874 in six different filters and thus to generate accurate, empirical transformations between color indices. These will be used as a basis for producing self-consistent metallicity distribution functions for globular clusters in a large number of galaxies. ------------------------------------------------------------------------------------ 17145( 4) - 19-Feb-2024 19:10:30 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-4874-WFC GALAXY, BCM, RA=12H59M37.2936S +/- 1", J2000 V = 11.4 3 ELLIPTICAL, HALO DEC=+27D58'25.99" +/- 1" Reference Frame: Other: SIMBAD Comments: Matches field selected by Cho et al. 2016, ApJ 822, 95. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-4874-ACS GALAXY, BCM, RA=12H59M36.1118S +/- 1", J2000 V = 11.4 ELLIPTICAL, HALO DEC=+27D57'41.11" +/- 1" Reference Frame: Other: SIMBAD Comments: Matches previous ACS exposures of NGC 4874 ------------------------------------------------------------------------------------------------------------------------------------ 17145( 4) - 19-Feb-2024 19:10:30 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.17 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 47.23 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type SPIRAL Pattern_Purpose DITHER Number_Of_Points 6 Point_Spacing 0.33 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 47.0 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17145( 4) - 19-Feb-2024 19:10:30 - [ 4] Visit: 01 (WFC3-01) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-4874-WF WFC3/UVI ACCUM UVIS F438W FLASH=14 1 835 S PATTERN 2 1 C3 S (2505 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-4874-WF WFC3/UVI ACCUM UVIS F475X 1 835 S PATTERN 2 2 C3 S (2505 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC-4874-WFC3 1 WFC3/UVI ACCUM UVIS F438W 1 none none none 1 N/A S NGC-4874-WFC3 1 WFC3/UVI ACCUM UVIS F438W 2 none none none 1 N/A S NGC-4874-WFC3 1 WFC3/UVI ACCUM UVIS F438W 3 none none none 1 N/A S NGC-4874-WFC3 2 WFC3/UVI ACCUM UVIS F475X 1 none none none 2 N/A S NGC-4874-WFC3 2 WFC3/UVI ACCUM UVIS F475X 2 none none none 2 N/A S NGC-4874-WFC3 2 WFC3/UVI ACCUM UVIS F475X 3 none none none 2 N/A S 17145( 4) - 19-Feb-2024 19:10:30 - [ 5] Visit: 05 (ACS-F606W) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-4874-AC ACS/WFC ACCUM WFCENTER F606W 1 745 S PATTERN 1 1 S (2235 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F606W 1 none none none 1 N/A NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F606W 2 none none none 1 N/A NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F606W 3 none none none 1 N/A 17145( 4) - 19-Feb-2024 19:10:30 - [ 6] Visit: 06 (ACS-F435W) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-4874-AC ACS/WFC ACCUM WFCENTER F435W 1 745 S PATTERN 3 1 S see below (4563 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F435W 1 none none none 1 748.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F435W 2 none none none 1 748.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F435W 3 none none none 1 748.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F435W 4 none none none 2 773.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F435W 5 none none none 2 773.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F435W 6 none none none 2 773.0 S 17145( 4) - 19-Feb-2024 19:10:30 - [ 7] Visit: 07 (ACS-F555W) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-4874-AC ACS/WFC ACCUM WFCENTER F555W 1 745 S PATTERN 3 1 S see below (4563 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F555W 1 none none none 1 748.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F555W 2 none none none 1 748.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F555W 3 none none none 1 748.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F555W 4 none none none 2 773.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F555W 5 none none none 2 773.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F555W 6 none none none 2 773.0 S 17145( 4) - 19-Feb-2024 19:10:30 - [ 8] Visit: 08 (ACS-F850LP) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-4874-AC ACS/WFC ACCUM WFCENTER F850LP 1 745 S PATTERN 3 1 S see below (4563 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F850LP 1 none none none 1 748.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F850LP 2 none none none 1 748.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F850LP 3 none none none 1 748.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F850LP 4 none none none 2 773.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F850LP 5 none none none 2 773.0 S NGC-4874-ACS 1 ACS/WFC ACCUM WFCENTER F850LP 6 none none none 2 773.0 S 17145( 4) - 19-Feb-2024 19:10:30 - [ 9] Visit: 51 (WFC3-01-repeat) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-4874-WF WFC3/UVI ACCUM UVIS F475X 1 835 S PATTERN 2 1 C3 S see below (2496 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC-4874-WFC3 1 WFC3/UVI ACCUM UVIS F475X 1 none none none 1 832.0 S S NGC-4874-WFC3 1 WFC3/UVI ACCUM UVIS F475X 2 none none none 1 832.0 S S NGC-4874-WFC3 1 WFC3/UVI ACCUM UVIS F475X 3 none none none 1 832.0 S S 17145( 4) - 19-Feb-2024 19:10:30 - [ 10] Summary Form for Proposal 17145 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS, WFCENTER ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=14 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 2 1, PATTERN 2 2, PATTERN 3 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F435W, F438W, F475X, F555W, F606W, F850LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC-4874-ACS, NGC-4874-WFC3 ------------------------------------------------------------------------------------------------------------------------------------