WFPC2 Warm Pixel Lists

Please Note: These tables are updated every 49 days.

This page contains a listing of the warm pixel lists available for creating your own warm pixel corrections, prepared regularly. These lists can be useful, either to check on specific pixels or to be converted "by hand" into data quality files - it should not be too difficult to write such a task in a way that is suitable to your purposes.

Warm pixel lists formatted for use with the STSDAS task 'warmpix' are also available.

The warm pixel files are all listed at the bottom of this page. From there they can be easily downloaded to your computer.

The HDF warm pixel files derived from the darks taken for the Hubble Deep Field are also available.

The lists are also available via anonymous ftp to stsci.edu in the form of compressed ASCII files and are kept in the STEIS directory /instrument_news/WFPC2/Wfpc2_hotpix. To retrieve the files in this manner, do the following:

	ftp ftp.stsci.edu
	(username) anonymous
	(password) use your full e-mail address
	cd /instrument_news/WFPC2/Wfpc2_hotpix  (and then the year you're interested in - e.g. 2005)
	binary
	prompt
	mget filename (include wildcards to select the
		files for the period of interest)
	quit

There are four files, one for each chip, for each month-long period between decontaminations. The files have names such as:

	vary_940827_940924_1.dat.Z
	       ^     ^     ^
	       |     |     |
	       |     |     Chip no. (1=PC, 2=WF2, etc.)
	       |    End date
	      Start date

When on your local UNIX system, use:

	uncompress *.Z

to obtain the ASCII files (same names, without the .Z suffix). If you do not have access to a UNIX system, please let me know, and we will upload the plain ASCII files instead.

Each file consists of 8 header lines, which give basic information about the list (number of dark stacks used, typical current, cut-off criteria), plus one line for each pixel deemed potentially hot. Within each line, the columns indicate:

	1) Chip number (1=PC, 2=WF2, etc.)
	2) Sequence number
	3) x coordinate (1-800)
	4) y coordinate (1-800)
	5) Average dark current for pixel (all currents 
		in milli-ADU/s at 7e-/ADU)
	6) Rms variation of dark current   
	7) Minimum measured value of dark current
	8) Maximum measured value of dark current
	9) Pixel index (internal information useful 
     		for debugging purposes)
	10) Dark current measured at each date

Pixels are included in this list if they satisfy any _one_ of the following criteria:

	Average dark current > (avg for the chip) 
     		+ 5*(rms variation for the chip)

	Rms variation > 4*(rms variation for the chip)

	Maximum current > fixed value (typically 5 mADU/s 
     		at -88° C, 10 mADU/s at -76° C)

	Peak-to-peak variation in dark current > fixed 
		value

Criteria may change slightly from month to month. In any event, most applications would consider such criteria overly conservative, resulting in too many flagged pixels; you may prefer to determine your own set of criteria, which can be easily done with a simple filter based on the values of the average, rms, minimum and maximum given in the file.

NOTE: Warm pixel files retrieved before 04 April, 1995 may be corrupted; we advise that any files retrieved before this date be retrieved again.

Warm Pixel Lists for WFPC2:

Choose the year(s) of your observations and then select the files you wish to download. After they appear in your browser window, use the "Save as..." option to save to your local disk.

HDF Warm Pixel Lists:

Users should "right-click" on these links, and use the "Save Link Target" option to download these files to the desktop.