ACIS Bad Pixel List
Updated: 2013-5-25 (DOY: 145 / DOM: 5058)
Previously unknown bad pixels/columns appeared in the last 14 days:
||No New Warm Pixels|
||No New Hot Pixels|
||No New Bad Columns|
Current Bad Pixels/Columns
Click one of the cell under "Data" to see lists of warm pixels and other entires.
The description of each column is found below.
Bad Pixel Trend Plots
Columns in Table
|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|
A bad pixel was selected as follows:
- 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
A bad column was selected as follows:
- 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.
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