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Instrument Science Report WFC3 2009-006

WFC3 Calibration Using Galactic Clusters
E. Sabbi, J. Kalirai, A. Martel, S. Deustua, S.M. Baggett, T. Borders, H. Bushouse, M. Dulude, B. Hilbert, J. Kim Quijano, V. Kozhurina-Platais, J. MacKenty, P. McCullough, C. Pavlovsky, L. Petro, A. Rajan, A. Riess, & M.H. Wong September 08, 2009

ABS

TRACT

WFC3 team will observe several galactic open and globular clusters to charatcerize and calibrate both the UVIS and IR channels. Here we present a short summary of the clusters that will be observed, providing information about exposure times and filters that will be used, focusing on the proposals that will have a major impact on high precision photometry.

1. Introduction
The Wide Field Camera 3 (WFC3) was installed in the Hubble Space Telescope (HST) during Servicing Mission 4 (SM4), in the radial scientific-instrument bay of HST. Therefore WFC3 will obtain on-axis direct images. WFC3 consists of two independent channels: the UVIS channel, sensitive to ultraviolet and optical wavelengths (~200 to 1000 nm), and the IR channel, sensitive at the near-infrared wavelengths (~800 to 1700 nm). A key feature of WFC3 is its panchromatic capabilities: by combining the two UV/optical CCDs with the near-infrared HgCdTe array, and thanks to the wide-, intermediate- and narrow-band filters, WFC3 will provide high-resolution wide-field imaging over the entire wavelength range from 200 to 1700 nm. During the Servicing Mission Orbital Verification (SMOV) and Cycle 17, the WFC3 team will do a major effort to understand the performances, characterize the stability and calibrate both the UVIS and IR channels. A total number of 255 external and 2135 internal orbits of HST will be used during Cycle 17 to pursue these goals. During both
Operated by the A ssociation of Univ ersities for Research in A stron omy, Inc., for the National A eron autics and Space Administration

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SMOV and Cycle 17 cluster observations will be used to provide the best calibration possible to the scientific community. Galactic globular and open clusters will be observed in 12 SMOV and 14 Cycle 17 WFC3-team proposals, covering the following topics: · Provide the low-frequency flat-fielding correction (L-flats); · Characterize the geometric distortion of both the channels and provide the correction; · Provide the photometric transformation between WFC3 and other HST photometric systems, as well as ground based photometric systems; · Test the filter wedge; · Measure the pixel cross-talk; · Measure the Charge Transfer Efficiency (CTE) for the 2 UVIS CCDs; · Characterize the UVIS CCD linearity; · Measure IR detector persistence; · Determine the imaging performances of both the UVIS and IR channels; · Calibrate the signal non-linearity for the IR array; · Quantify the impact of droplets on high-precision photometry. Some of these proposals will allow us to better understand the performances and the characteristics of the WFC3 detectors; some will provide information crucial to high precision photometry. A very important role will be played by the proposals for L-flat, geometric distortion and droplets analysis. These proposals will be discussed in detail in the following sections, while at the end of this ISR we will provide a quick summary of all the clusters that will be observed during SMOV and Cycle 17, the selected filters and the overlap (if any) with previous HST observations. Why star clusters? Galactic Globular Clusters (GGCs) are spherical associations of stars tightly bound by gravity. They orbit around the Bulge of the Milky Way, in the halo of the Galaxy. Stars in a GGC have very similar ages and chemical compositions, suggesting that they formed from the same parent molecular cloud and are approximately coeval. For this reason they are extensively studied to probe models of stellar evolution. The very high stellar density in GGCs' cores favors close stellar interactions and collisions, and therefore GGCs are an ideal laboratory to investigate the effects of dynamics on stellar evolution, and the formation of exotic objects such as millisecond pulsars, cataclysmic variables, and blue straggler stars. Observations of GGCs also play an important role in calibrating astronomical detectors. Their high stellar density allow us to obtain a fine sample of the entire field of view (FoV) of a detector with a single observation. Thus by observing the same group of stars across the detector we can obtain crucial information on its properties, such as the characteristics (e.g. encircled energy, sharpness, FWHM) and the stability of the stellar point spread function (PSF) across the detector FoV. By measuring the count rates for the same group of stars in different positions of the detector we can also probe the response of the detector across the FoV, as well as the variations in transmission of the filter and the optics of the telescope. Stars in GGCs may have very different temperatures (and thus colors). Therefore they can be used to tests the response of the detector+filter system to sources characterized by
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very different spectral energy distributions.

2. Low-frequency flat-fielding correction
Appropriate flat-fields should normalize the system illumination pattern and pixel-topixel non-uniformities independently of the position on the detector. In the spring of 2008 the WFC3 team carried out an intense ground-based campaign during the third and last thermal vacuum test (TV3) to, among other purposes, create flat-fields that will be used for the reduction of on-orbit data. Ground-based flat fields have been obtained by simulating sky illumination of the UVIS CCDs (Sabbi et al. 2009) and the IR array (Bushouse 2008) using the optical stimulus (CASTLE). In principle these data should include both the high frequency pixel-to-pixel (P-flat) and the low frequency (L-flat) structures. The low order structure over the field of view is mostly due to a different response of the detector to the incoming photons across the detector (i.e. caused by thickness variations, non-uniform doping, etc.). Another source of the L-flat structure can come from variations in the filter transmission. The L-flat structure therefore is a function of wavelength. The TV3 ground-based CASTLE flat fields are expected to differ from the on-orbit flats principally because of the real HST+WFC3 illumination pattern, and because of the tilt of the WFC3 focal plane with the respect to the incoming light. Because of this, different regions on the detectors will receive a different amount of light. These quantities can be estimated by measuring the count rates for the same star in different position across the detector, using images flat-fielded with the ground-based flats (Mack et al. 2002, Sirianni et al. 2005). In the case of UVIS data, this approach will also provide an estimate of the chip-to-chip normalization. Star clusters allow us to accurately sample the entire field of view of our detectors, and therefore are ideal targets for this exercise. During SMOV and Cycle 17 we will characterize the L-flats of several of the most frequently requested filters of both the UVIS and IR channels. For each filter we will observe the core of a globular cluster at nine offset positions, separated by ј of the FoV (see Figure 1). As a result we will measure the flux of each star in nine largely separated positions. In doing this we will derive a fourth order polynomial L-flat correction for each of the selected filters.

Fig. 1 Lef t: The nine-poin t dith er pattern that will be u sed for the generation of the L-flats. Right: UVIS/WFC3 FoV projected on the core of Cen tauri.

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During SMOV, we will acquire data to characterize the L-flat (proposals 11452, and 11453) for three of the most requested optical UVIS filters (F438W, F606W, and F814W), and four of the broadband IR channel filters (F105W, F125W, F140W, and F160W). We will do this using two different fields, the first being the same region of NGC 104 (47 Tuc), which was used by the ACS team to built the WFC flat fields and to derive the solution for geometric distortion that affects ACS, and the second being a field in the Large Magellanic Cloud. We will also collect data to generate L-flats in the broadband UV filters F225W, F275W and F336W. However, since 47 Tuc is a metal rich globular cluster with very few bright blue stars (see Fig. 2, left panel), it would require very long exposure times to collect enough stars with high S/N (>50) in the UV. For this reason the UV L-flat will be obtained by observing the core of NGC 5139 ( Cen), the most massive globular cluster in the Milky Way, which has a very rich blue horizontal branch (see Fig. 2, right panel).

Fig.2 A CS/WFC color ­magnitude diagr ams of 47 Tu c (on the lef t) by Sarajed ini et al. (2007), and Cen (on the r ight) by And erson and V an der Mar el (2009).

During Cycle 17 the L-flat will be derived using Cen as the only target for both of the WFC3 channels. UVIS L-flats will be derived for F225W, F275W, F336W, F390W, F438W, F555W, F606W, F775W, F814W, and F850LP filters (proposal 11911), and IR L-flats for F110W, F125W, F160W, F098M, and F139M filters (proposal 11928). L-flat corrections for the remaining narrow-, intermediate- and broad-band filters will be obtained using a linear interpolation between the observed data. The choice of Cen as the only target has several advantages. First this approach will guarantee obtaining a uniform sampling of the L-flats over the entire wavelength range from the near UV to the near IR. This aspect is crucial since we will use a linear interpolation to obtain the low-frequency correction in the remaining filters. The wavelength overlap between the UVIS F850LP and the IR F098M filters will also

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provide an independent validation of the consistency between the UVIS and IR zero points. Another reason to choose Cen is that its core is wide and flat: the lack of a stellar density gradient will guarantee that each portion of the detectors will be equally weighted, minimizing the introduction of artificial substructures. The observations will be repeated after three months for UVIS and after three and six months for IR, to measure the detector stability over time. L-flats will be delivered to the calibration database, and will be available for downloading from the HST archive and from the CDBS iref directory ftp://ftp.stsci.edu/cdbs/iref.

3. Geometric distortion
Because of the folding of the light path within the optical-bench envelope of the instrument, the WFC3 focal plane arrays are tilted with respect to the incoming rays. As a result both UVIS and IR images will exhibit geometric distortion: pixels will be more elongated along the direction tangential to the OTA than along the radial direction, and the pixel area subtended on the sky will vary across the detector(s) (WFC3 Data and Instrument Handbooks). As a consequence the relative projected distance of a group of stars on a detector will differ from their relative distance on the sky. There are several techniques to determine the astrometric solution of an astronomical image, and among them, we chose to measure the geometric distortion by cross-correlating WFC3 photometric catalogs with already existing astrometric catalogs. A high number of stars with high S/N is necessary to minimize the errors, and considering the relatively small FoV of the WFC3 channels, we chose to observe GGCs. During SMOV we will execute two proposals (11444 ­ UVIS; 11445 ­ IR) to calibrate the geometric distortion using observations of the rich globular cluster NGC 104 (47 Tuc). Geometric distortion will be characterized using the F606W filter for UVIS, and F160W for IR. In both the cases we will observe the same astrometric field used by the ACS team. During Cycle 17 UVIS and IR geometric distortions will be determined using the dataset we will acquire for the L-flat fields (proposals 11911 and 11928). This approach will allow us to obtain an independent validation of the polynomial solutions, to characterize the wavelength dependency of the solution, and to monitor its behavior with time. The coefficients of the polynomial fit used to transform the image coordinates from distorted data to an undistorted space as a function of wavelength will populate the IDCTAB table. This table will be available in the CDBS iref directory ftp://ftp.stsci.edu/cdbs/iref.

4. UVIS window contamination (Droplets)
Analysis of TV3 data shows that the outer window of the UVIS detector is most likely contaminated by mineral condensations (droplets, Fig. 3). Ground-based tests were performed using both point source and flat-field illumination. The photometric scatter for a point source stepped across a strong droplet increases from ~0.5% to ~1%. Because the light in the core of the point spread function is redirected to the near wings, this effect will be removed by flat-fields. TV3 tests also showed that the modulation of the light caused by the droplets varies with wavelength. (Brown et al. 2008).
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The impact of droplets on high precision photometry will be further investigated during Cycle 17 (proposal 11904) through observations of the globular cluster NGC 6752 with the UVIS filters F225W, F555W, F814W, and F502N. For each filter we will acquire 5 exposures, each with 20 pixel offset with the respect to the previous exposure, to monitor the variations of the PSF as a star steps through a droplet. NGC 6752 has been chosen because its bright stars cover a very wide range in colors (see Fig. 4) and therefore it will allow us to verify the impact of the droplets through different filters.

Fig . 3: 800x800 pixel subsection of an F438 W flat-field image taken with external illu mination . Several droplets are v isib le across the image (Brown et al. 2 008).

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Fig. 4: V vs (U-V) and (B-V) color-magnitude d iagrams of the globular cluster NGC 6752 by Ferr aro et al. (2003), showing the ex tended and r ich horizontal branch.

Results from this analysis will be discussed in a forthcoming instrument science report (ISR) available at http://www.stsci.edu/hst/wfc3/documents/ISRs.

5. Targets and Observations
In this appendix we provide a list of the clusters that will be used to characterize the perfomances of the WFC3 UVIS and IR channels with a short descriptions of the observations. 5.1. SMOV During SMOV, 61 orbits are devoted to observing open and globular clusters. NGC 188 We will observe NGC 188 with broad, medium and narrow filters with the UVIS and IR channels. This is one of the older open clusters in the Milky Way and is a well-known astrometric standard field. Its low stellar density makes it suitable to characterize both UVIS and IR PSFs (encircled energy, sharpness, FWHM, Phase Retrieval). Observations will be centered at R.A. = 00:47:4.4540 and Dec. = +85:16:32.70 (J2000). Table 1 presents a summary of the observations, the proposal ID, goals, the list of the filters that will be used and the exposure time. Table 1

PROPOSAL ID

UVI S PURPOSE

FILTER

# x Exp. Time

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(sec)
11424 11434 11442 11436 UVIS Initial Alignmen t UVIS Fin e A lignment FGS-UVIS A lignment UVIS Imag e Qu ality F4 1 0 M F4 1 0 M F4 1 0 M F6 2 1 M F2 7 5 W 18x10, 18x120 21x10, 21x200 3x228 3x60 2x1360, 2x1280

PROPOSAL ID
11425 11435 11437

IR PURPOSE
IR Initial A lignment IR Fine Alignmen t IR Image Quality

FILTER
F1 2 7 M F1 2 7 M F1 6 4 N F1 2 7 M F0 9 8 M F1 0 5 W F1 6 0 W F1 2 8 N F1 2 8 N

# x SAMP SEQ (NSAMP)
18xRAPID(15) 22xRAPID(15) 1xSPARS25(7) 1xSPARS25(5) 4xSPARS25(7) 4xSPARS25(7) 4xSPARS25(7) 4xSPARS25(7) 3xSPARS25(15)

11443

FGS-IR A lignmen t

NGC 104 NGC 104 has been extensively observed both with the Wide Field (WFC) and High Resolution (HRC) Channels of the Advanced Camera for Surveys (ACS). During SMOV we will observe the same region used to determine the astrometric solution for ACS data both in the optical and in the infrared. These data will be used to derive a first set of Lflat fields and geometric distortion for UVIS and IR data. Observations will be centered at R.A. = 00:22:38.5000 and Dec.= -72:04:4.00 (J2000). The log of the observations is presented in Table 2. Table 2

PROPOSAL ID
11444 11452

UVI S PURPOSE
UVIS Plate Scale UVIS Flat Field Uniformity

FILTER
F F F F 6 6 8 4 0 0 1 3 6 6 4 8 W W W W

# x Exp. Time (sec)
24x350 1x35, 9x350 1x35, 9x350 1x35, 9x350

IR PROPOSAL
11445 11453

PURPOSE
IR Plate Scale IR Flat Field Un iformity

FILTER
F F F F F 1 1 1 1 1 6 6 2 4 1 0 0 5 0 0 W W W W W

# x SAMP SEQ (NSAMP)
1 1 1 1 1 9 8 8 8 6 x x x x x S S S S S TEP TEP TEP TEP TEP 2 2 2 2 2 ( ( ( ( ( 1 1 1 1 1 5 5 5 3 0 ) ) ) ) )

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NGC 5139 NGC 5139 ( Centauri) is the most massive and extended globular cluster in the Milky Way. It has an extended and well populated blue horizontal branch. These hot and bright stars are ideal targets to generate UV L-flats with a modest investement of time. Therefore the core of Centauri will be observed during SMOV with the UVIS channel. Observations will be centered at R.A. = 13:26:47.2400 and Dec.= -47:28:46.45 (J2000). The log of the observations is presented in Table 3. Table 3

PROPOSAL
11452

UVI S PURPOSE
UVIS Flat Field Uniformity

FILTER
F6 F8 F4 F3 F2 F2 06W 14W 38W 36W 75W 25W

# x Exp. Time (sec)
1x35 1x35 1x35 9x350 9x350 9x350

5.2. Cycle 17 During Cycle 17 the WFC3 team will invest 97 orbits of HST to observe open and globular clusters. These data will be used to characterize the performances of UVIS and IR WFC3 channels. NGC 6791 The rich open cluster NGC 6791 will be observed during Cycle 17 with the IR channel to measure the persistence caused by the observation of bright sources. NGC 6791 will also be observed with UVIS to characterize the CTE induced losses in photometry and astrometry. NGC 6791 is preferred to other globular clusters to minimize the number of pixels "contaminated" from nearby sources of light prior to the charge transfer. UVIS observations will be centered at R.A. = 19:20:53.9500 and Dec. = +37:48:9.60, the IR channel will be centered at R.A.= 19:20:53.2000 and Dec.= +37:46:19.00 (J2000). The log of the observations is presented in Table 4. Table 4

PROPOSAL
11924

UVI S PURPOSE
UVIS CTE Monitoring

FILTER
F6 0 6 W F5 0 2 N

# x Exp. Time (sec)
9x30, 9x360 9x60, 9x420

PROPOSAL

IR PURPOSE

FILTER

# x SAMP SEQ (NSAMP)

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11927

IR Persistence

F1 1 0 W

4xSPARS10(5), gain=2 4xSPARS200(15), gain=2

NGC 1850 NGC 1850 is a young cluster in the bar of the LMC. After the 30 Doradus complex, it is the brightest of the LMC clusters, and is quite compact and very rich. This cluster will be observed with UVIS to calibrate its linear response. The brightness of the cluster allows us to cover a range of detector ADU levels with very short exposure times. Observations will be centered at R.A. = 05:08:44.7000 and Dec. = -68:45:42.00 (J=2000). The log of the observations is presented in Table 5. Table 5

PROPOSAL
11925

UVI S PURPOSE
UVIS Linear ity

FILTER
F4 6 7 M

# x Exp. Time (sec)
4x10, 2x20, 2x50, 2x100, 2x500

NGC 188 The old open cluster NGC 188 will be observed also during Cycle 17 to characterize both UVIS and IR PSFs. Observations will be centered at R.A.= 00:47:4.4540 and Dec.= +85:16:32.70 (J2000). The log of the observations is presented in Table 6. Table 6

PROPOSAL ID
11918

UVI S PURPOSE
UVIS Imag e Qu ality

FILTER
F6 2 1 M F2 7 5 W

# x Exp. Time (sec)
12x60 6x1500, 3x1800, 3x1900

IR PROPOSAL ID
11920

PURPOSE
IR Image Quality

FILTER
F1 6 4 N F1 2 7 M F1 6 0 W F0 9 8 M F1 0 5 W

# x SAMP SEQ (NSAMP)
3xSPARS25(7) 3xRAPID(15) 4xRAPID(7) 3xRAPID(15) 3xRAPID(15)

NGC 104 Observations of the ACS astrometric field (R.A.= 00:22:27.8446, Dec.= -72:04:4.75, J2000) will be acquired with WFC3/IR to quantify the non-linear signal behavior of this channel, as well as to create the IR channel non-linearity calibration reference file. 47 Tuc will also be observed to calculate the photometric transformations between UVIS filters and other HST instruments (see Kalirai et al., 2009 for a detailed description of

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these observations). The log of the observations is presented in Table 7. Table 7

PROPOSAL
11903

UVI S PURPOSE
UVIS photometric zero po ints

FILTER
F200LP F2 2 5 W F2 7 5 W F3 0 0 X F3 3 6 W F350LP F3 9 0 W F4 3 8 W F4 7 5 W F4 7 5 X F5 5 5 W F600LP F6 0 6 W F6 2 5 W F7 7 5 W F8 1 4 W F850LP

# x Exp. Time (sec)
1x100 1x900 1x400 1x467 1x360 1x95 1x300 1x1600 1x465 1x275 1x1160 1x560 1x900 1x1200 1x1500 1x1300 1x1500

IR PROPOSAL
11931 11933

PURPOSE
IR Count Lin ear ity IR Rate-D ependen t NonLinearity

FILTER
F1 6 0 W F1 1 0 W

# x SAMP SEQ (NSAMP)
24xSPARS10(10) 24xSPARS25(15) 76xSPARS50(6)

NGC 5139 The extended and flat core of Cen will be observed during Cycle 17 in several UVIS and IR filters. The data will used to obtain a uniform sampling of the L-flats over the entire wavelength range from the near UV to the near IR. The good wavelength overlap between the UVIS F850LP and the IR F098M filters will also provide an independent validation of the consistency between the UVIS and IR zero points. Other IR images will be acquired to characterize the intrapixel sensitivity. Data for L-flats and geometric distortions will be centered at R.A. = 13:26:46.2800 and Dec. = -47:28:44.60, the intrapixel sensitivity at R.A.= 13:25:37.6000 and Dec.= -47:35:34.30 (J2000). The log of the observations is presented in Table 8. Table 8

PROPOSAL

UVI S PURPOSE

FILTER

# x Exp. Time (sec)

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11911

UVIS L-Flats & G eometr ic Distor tion

11922

UVIS Fringing

F6 0 6 W F5 5 5 W F3 9 0 W F2 7 5 W F7 7 5 W F4 3 8 W F8 1 4 W F850LP F2 2 5 W F3 3 6 W F6 5 6 N F9 5 3 N

18x40 18x40 18x350 18x800 18x350 18x350 18x40 18x60 18x900 18x350 5x500 5x850

IR PROPOSAL
11916

PURPOSE
IR Intr apixel Sensitivity

FILTER
F1 1 0 W F1 6 0 W F0 9 8 M F0 9 8 M F1 1 0 W F1 3 9 M F1 2 5 W F1 6 0 W

# x SAMP SEQ (NSAMP)
4xSPARS25(13) 4xSPARS25(14) 9xSPARS25(12) 27xSPARS25(15) 1xSPARS25(10) 1xSPARS50(11) 1xSPARS25(12) 1xSPARS50(11)

11928

IR L-Flats and G eometr ic Distor tion

NGC 6752 NGC 6752 will be observed in the three broadband filters F225W, F555W, and F814W as well as the narrow band filter F502N to characterize the effects of contaminants (i.e. droplets) on high-precision photometry. The five points line dither with a step of 20 pixels will be used to step the stars randomly on and off the droplets. NGC 6752 has been chosen because it contains both hot and cool stars, and will provide uniform density of stars over the global image. The log of the observations is presented in Table 9. Table 9

PROPOSAL
11904

UVI S PURPOSE
UVIS droplets

FILTER
F2 2 5 W F5 5 5 W F5 0 2 N F8 1 4 W

# x Exp. Time (sec)
18x120 18x670 15x550 15x550

NGC 2419 The globular calculate the instruments. together will cluster NGC 2419 will be observed with several UVIS broadband filters to photometric transformations between UVIS filters and other HST NGC 2419 is more metal poor than 47 Tucanae, therefore, these two clusters provide an adequate color baseline to test for transformation dependency on

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colors. Kalirai et al. (2009) provides a detailed description of these observations. The log of the observations is presented in Table 10. Table 10

PROPOSAL
11903

UVI S PURPOSE
UVIS photometric zero po ints

FILTER
F200LP F2 2 5 W F2 7 5 W F3 0 0 X F3 3 6 W F350LP F3 9 0 W F4 3 8 W F4 7 5 W F4 7 5 X F5 5 5 W F600LP F6 0 6 W F6 2 5 W F7 7 5 W F8 1 4 W F850LP

# x Exp. Time (sec)
1x100 1x900 1x400 1x467 1x360 1x95 1x300 1x1600 1x465 1x275 1x1160 1x560 1x900 1x1200 1x1500 1x1300 1x1500

NGC 3603 The bright and hot stars in the core of NGC 3603 (the nearest starburst in the Large Magellanic Cloud) will be observed through all the WFC3 (UVIS ­ proposal 11923, and IR ­ proposal 11913) broad, medium and narrow filters to check that the filters meet the Contract End Item (CEI) specification for image displacements (a.k.a. filter wedge tests). Data will be acquired using 512x512 sub-arrays only. GO calibration proposals Several WFC3 filters have been designed to obtain precise estimates of stellar metallicities, however these filters do not exactly match those used for this purpose on the ground. Two General Observer (GO) programs have been approved in Cycle 17 to determine the color transformations for this set of filters using stellar clusters with wellknown metallicities. Holtzman et al. (GO11729: Photometric Metallicity Calibration with WFC3 Specialty Filters) will observe the clusters NGC 6791, 47 Tuc, NGC 6752, M92, and NGC 5927 in the F336W, F390M, F395N, F410M, F467M, and F547M, by acquiring for each filter short and long exposures. Six well-studied globular and open clusters (NGC6528, NGC 5927, 47Tuc, NGC 6752, NGC 6341, and NGC 6791) will also be observed by Brown et al. (GO11664: The WFC3 Galactic Bulge Treasury Program: Populations, Formation History and Planets) to calibrate photometric indices, provide empirical population templates, and transform the theoretical isochrone libraries into the WFC3 filter system. For each cluster short, intermediate and long exposures will be

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acquired in the UVIS filters F390W, F555W, and F814W, and in the IR filters F110W, and F160W. 5.3. Overlap with Previous HST Observations Table 11 provides a list of clusters that will be observed with WFC3 and that have been already observed with ACS, WFPC2 and/or NICMOS in similar filters. WFC3/UVIS filters are in blue and WFC3/IR filters in red. Table 11

CLUSTER WFC3 ACS/WFC ACS/HRC ACS/SBC WFPC2 NICMOS F606W YES YES YES NGC 104
F814W F438W F200LP F275W F225W F300X F336W F350LP F475X F475W F555W F600LP F625W F775W F850LP F110W F160W F140W YES F4 7 5 W YES YES F6 0 6 W YES YES F4 5 3 W YES F4 3 5 W F2 2 0 W F2 5 0 W F2 2 0 W F3 3 0 W F3 3 0 W F3 3 0 W F4 7 5 W YES YES F6 0 6 W YES YES YES F785LP YES YES YES YES YES F4 3 5 W YES F6 5 8 N YES YES YES YES YES YES YES YES YES YES YES YES YES F4 3 9 W F4 5 0 W F4 5 0 W YES F2 1 8 W F3 0 0 W YES YES F4 3 9 W F2 1 8 W

NGC 5139

F606W F438W F814W F656N F555W F336W

NGC 6791 NGC 6752 NGC 2419

F606W F110W F555W F814W F200LP

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F275W F300X F336W F350LP F438W F475W F475X F555W F600LP F606W F625W F775W F814W F850LP F4 3 5 W YES F4 7 5 W YES F6 0 6 W YES YES YES YES YES

F2 5 0 W F3 3 0 W F3 3 0 W F3 3 0 W F4 3 5 W YES F4 7 5 W YES F6 0 6 W YES YES YES YES YES YES YES F3 0 0 W YES F3 3 6 W F4 3 9 W F4 5 0 W F4 5 0 W YES

6. Conclusions
In this ISR we have summarized the galactic globular and open clusters that will be used during SMOV and Cycle 17 by WFC3 to characterize the performance, prove the stability and calibrate both the UVIS and IR channels. For each cluster we provided the filters used and the exposure times. Several ISRs will provide more detailed descriptions of the data acquired and of the calibration products once the data have been acquired.

References
Anderson, J., & van d er Mar el, R.P. 2009, ApJ (submitted) astro-ph/0905.0627 Brown, T. Hartig, G ., & Baggett, S. 2008, ISR WFC3-20 08-09, "WFC3 TV3 Testing: UVIS W indow Contamin ation" Bushouse, H. 2008, ISR WFC3-2008-28, "WFC3 I R Ground P-flats" Ferraro, F.R., Possenti, A., Sabbi, E., Lag ani, P., Rood, R.T., D'A mico, N. & Or iglia, L. 2003, ApJ, 595, 179 Kalirai, J. et al. 2009, ISR WFC3-2009-05 Mack, J., Bohlin, R. C., Gilliland, R. L., van d er Marel, R., Blakeslee, J. P., & D e March i, G . 2002, ISR ACS-2002-08 "A CS L-Flats for the WFC" Sabbi, E., Dulude, M., Martel, A., Baggett, S., & Bushouse 2009, WFC3-2008-46, "UVIS Ground P-Flats" in prepar ation. Sarajedin i, A. et al. 2007, A J, 133, 1658 Sirianni, M. et al. 2005, PA SP, 117, 1049

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