Hubble Space Telescope
WFPC2 CTE Estimation Tool for Point Sources

This tool allows users of WFPC2 to estimate the effects of CTE losses on point sources. We have three tools on this page, based on three different publications. We believe the first one, the latest by Andrew Dolphin, to be the most accurate one.

The correction formulae for this CTE tool were taken from Andrew Dolphin's website (09/17/2002 version), where they are described in detail (if this link does not work, here is an updated copy of Andy's webpage). Further information can also be found in the help file. The CTE loss is expressed in magnitudes. The input counts and background are expected in electrons.

The correction formulae for this CTE tool were taken from Andrew Dolphin's website (05/31/2002 version), where they are described in detail; here is an updated local version of Andy's webpage. Further information can also be found in the help file. The CTE loss is expressed in magnitudes. The input counts and background are expected in electrons. This is the version used in the current WFPC2 Instrument Handbook.

The correction formulae for this CTE tool were taken from Whitmore, et al., PASP, 1999, 111, 1559, and are shown in the help file. The corrected source counts are given in DN.

For detailed information on CTE and its effects, see:

• Andrew Dolphin's CTE Website. A local copy of Dolphin's website.
• WFPC2 ISR-0203: Charge Transfer Efficiency for Very Faint Objects and a Reexamination of the Long-vs-Short Problem for the WFPC2.
• WFPC2 ISR-0109: The WFPC2 Photometric CTE Monitor.
• WFPC2 ISR-0004: How CTE Affects Extended Sources.
• WFPC2 ISR-0003: Update on Charge Trapping and CTE Residual Images in WFPC2.
• WFPC2 ISR-9904: Time Dependence of CTE from Cosmic Ray Trails.
• WFPC2 ISR-9802: The Long vs. Short Anomaly in WFPC2 Images.
• WFPC2 ISR-9708: New Results on Charge Transfer Efficiency and Constraints on Flat-Field Accuracy.
• WFPC2 ISR-9705: Charge Trapping and CTE Residual Images in the WFPC2 CCDs.
• The WFPC2 Instrument Handbook.
• Posters and presentations from the CTE Workshop held at STScI, January 2000.
• CTE Library.
• The CTE Poster presented at the May 2002 AAS meeting. (PDF)
• The CTE Poster presented at the June 2001 AAS meeting. (PDF)
• The CTE Poster presented at the January 2001 AAS meeting. (PDF)
• The CTE Poster presented at the June 2000 AAS meeting. (PDF)