ACIS Bad Pixel List

Updated: 2013-5-25 (DOY: 145 / DOM: 5058)

Click one of the cell under "Data" to see lists of warm pixels and other entires. The description of each column is found below.

CCD	Data	Warm Pixel History	Hot Pixel History	Bad Column History	Data List
CCD0	Bad Pixels Today	Change	Change	Change	Data Used
CCD1	Bad Pixels Today	Change	No History	Change	Data Used
CCD2	No Bad Pixels Today	Change	No History	Change	Data Used
CCD3	Bad Pixels Today	Change	No History	Change	Data Used
CCD4	No Bad Pixels Today	Change	Change	Change	Data Used
CCD5	No Bad Pixels Today	Change	Change	Change	Data Used
CCD6	No Bad Pixels Today	Change	No History	Change	Data Used
CCD7	No Bad Pixels Today	Change	No History	Change	Data Used
CCD8	No Bad Pixels Today	Change	No History	Change	Data Used
CCD9	No Bad Pixels Today	Change	No History	Change	Data Used

Warm Pixel:	a list of warm pixels currently observed
Flickering:	any warm pixels which were on and off 3 times or more in the last 3 months
Past Warm Pixels:	a list of all pixels appeared as warm pixels in past
History:	history of when a particular warm pixel was on or off
Hot Pixel:	a list of hot pixels currently observed
Flickering:	any hot pixels which were on and off 3 times or more in the last 3 months
Past Hot Pixels:	a list of all pixels appeared as hot pixels in past
History:	history of when a particular hot pixel was on or off
Warm Column:	a list of warm columns currently observed
Flickering:	any warm columns which were on and off 3 times or more in the last 3 months
Past Warm Columns:	a list of all columns appeared as warm columns in past
History:	history of when a particular warm columns was on or off

acis*bias0.fits in a given period were obtained
compute an average of ADU for each CCD
compare the value of each pixel to the CCD average, if a pixel value was 5 sigma higher than the average, a local average (32x32) was computed
if the pixel value was still 5 sigma higher than the local average, it was marked as a possible candidate for a warm pixel.
if three consecutive(sp) bias frames had the same pixel marked as a warm pixel candidate, the pixel was listed as a warm pixel.
if the pixels appear and disappear repeatedly during the last three months the pixels are listed in flickering pixels
if the pixels which appeared in "current warm pixels" list, even once in the past the pixels are parmanently listed in "Past Warm Pixels" list
hot pixels are defined as warm pixels with an adu value of greater than the CCD average +1000.
if the pixel was located at the edge of the CCD (y = 1023, 1024), it is ignored and not included on either the list.
for a hot pixel, a process was same, except a threshold was a ccd average plus 1000 counts

each column was averaged out, and compared to an average for an entire ccd.
if the average of the column was 5 sigma higher than the average of the ccd compare the column average to a local average (10 columns).
if the column was still 5 sigma higher than the local average, mark it as a bad column candidate
if the column appeared as a bad column for a 3 consecutive frames, it was marked as a real bad column.

If you have any quesitons about this page, please contact swolk@head.cfa.harvard.edu.