The Charge‐Transfer Efficiency and Calibration of WFPC2

By A. Dolphin. 2000

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A new determination of WFPC2 photometric corrections is presented, using HSTphot reduction of the WFPC2 ω Centauri and NGC 2419 observations from 1994 January through 2000 March and a comparison with ground‐based photometry. No evidence is seen for any position‐independent photometric offsets (the “long‐short anomaly”); all systematic errors appear to be corrected with the charge‐transfer efficiency (CTE) and zero‐point solution. The CTE loss time dependence is determined to be very significant in the Y‐direction, causing time‐independent CTE solutions to be valid only for a small range of times. On average, the present solution produces corrections similar to those of Whitmore and coworkers, although with an improved functional form that produces less scatter in the residuals and determined with roughly a year of additional data. In addition to the CTE loss characterization, zero‐point corrections are also determined as functions of chip, gain, filter, and temperature. Of interest, there are chip‐to‐chip differences of order 0.01–0.02 mag relative to the calibrations of Holtzman and coworkers, and the present study provides empirical zero‐point determinations for the nonstandard filters such as the frequently used F450W, F606W, and F702W.

Subfields: Astronomy and Astrophysics, Atmospheric Science

View Paper: https://www.semanticscholar.org/paper/0c9e0007ff1b91d5fa97dcca9119be4c5867e8a8

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Citations in the corpus

DISCOVERY OF PRECURSOR LUMINOUS BLUE VARIABLE OUTBURSTS IN TWO RECENT OPTICAL TRANSIENTS: THE FITFULLY VARIABLE MISSING LINKS UGC 2773-OT AND SN 2009ip (2009, methodology): “The HST photometry for the progenitors is measured with HSTphot (Dolphin 2000a, 2000b) and listed in Tables 1 and 2.”
The SAURON project - IV. The mass-to-light ratio, the virial mass estimator and the Fundamental Plane of elliptical and lenticular galaxies (2005, methodology): “It was converted to a surface densityin solar units using the WFPC2 calibration of Dolphin (2000) while assuming anI-band absolute magnitude for the Sun ofMI,⊙ = 4.08 mag (all the absolute magnitudes of the Sun in this paper, in the I , R andK-band, are taken from Table 2.1 of Binney & Merrifield…”
New distances to galaxies in the Centaurus A group (2002, methodology): “Charge-transfer efficiency (CTE) corrections and calibrations were then applied, which are based on the Dolphin (2000b) formulae, producing V I photometry for all stars detected in both images.”
The Effect of Metallicity on Cepheid-based Distances (2004, background): “Updated calibrations do exist, using improved charge transfer efficiency corrections (e.g., Stetson 1998; Dolphin 2000).”
Toward a Mass and Radius Determination of the Nearby Isolated Neutron Star RX J185635–3754 (2001, methodology): “We corrected for the chargetransfer efficiency following (Dolphin 2000).”
Tip of the Red Giant Branch Distances. II. Zero-Point Calibration (2007, methodology): “Conversion from the HST flight system to the JohnsonCousins system has been performed using the recipes presented in Sirianni et al. (2005) for ACS and those in Dolphin (2000a) and Holtzman et al. (1995) for WFPC2.”
Distances to nearby galaxies in Sculptor (2003, methodology): “For photometric measurements we used the HSTphot stellar photometry package developed by Dolphin (2000a).”
The very local Hubble flow (2002, methodology): “We estimate the uncertainty of the photometric zeropoint to be within 0.m05 (Dolphin 2000b).”
Detection of a Supernova Signature Associated with GRB 011121 (2002, methodology): “We corrected the observed countrate using the formulation for CTE correction in Dolphin (2000) with the most up-todate parameters16; such corrections, computed for each individual exposure, were never larger than 8% (typically 4”
Deviations from the Local Hubble Flow. I. The Tip of the Red Giant Branch as a Distance Indicator (2002, methodology): “The final stellar magnitudes are calibrated using the charge-transfer efficiency and zero-point corrections derived in Dolphin (2000a).”
THE ANTENNAE GALAXIES (NGC 4038/4039) REVISITED: ADVANCED CAMERA FOR SURVEYS AND NICMOS OBSERVATIONS OF A PROTOTYPICAL MERGER (2010, methodology): “We also applied Charge Transfer Efficiency (CTE) corrections to the WFPC2/F336W photometry based on the prescription given by Dolphin (2000).1 We computed the X and Y coordinates for each object on the original images for each dither position.”
Surface brightness profiles and structural parameters for 53 rich stellar clusters in the Large Magellanic Cloud (2002, methodology): “For photometric measurements we have found Dolphin’s HSTphot (Dolphin 2000a) to be the most suitable software package.”
Properties of Globular Cluster Systems in Nearby Early-Type Galaxies (2001, methodology): “We note that the recent recalibration of WFPC2 data reduced with HSTphot (Dolphin 2000) would cause V −I colors to be redder by 0.02 mag compared to the Holtzman et al. calibration.”
THE EXTRAGALACTIC DISTANCE DATABASE: COLOR–MAGNITUDE DIAGRAMS (2009, methodology): “This method also incorporates the results of artificial star tests performed on the HST images using HSTPHOT or DOLPHOT.”
Comparing the properties of local globular cluster systems: implications for the formation of the Galactic halo (2004, methodology): “Next we reduced each image using HSTPHOT (Dolphin 2000a).”
Local galaxy flows within 5 Mpc (2002, methodology): “For photometric measurements we used the HSTphot stellar photometry package developed by Dolphin (2000a).”
GRB 080503: IMPLICATIONS OF A NAKED SHORT GAMMA-RAY BURST DOMINATED BY EXTENDED EMISSION (2008, methodology): “6 F606W image we found a faint point source, with a magnitude of F606W = 27.01 ± 0.20 after charge-transfer efficiency correction following Dolphin (2000).”