ACIS Bad Pixel List

Updated: 2026-04-22 (DOY: 112)

Combined Front Side CCD and Column History Plots (Click to Enlarge)

Previously unknown bad pixels/columns appeared in the last 14 days:

Warm Pixels No New Warm Pixel
Hot Pixels No New Hot Pixel
Bad Columns No New Warm Column

Current Bad Pixels/Columns

CCD Warm Pixels Flickering Hot Pixels Flickering Warm Columns Flickering Warm Pixel History Hot Pixel History Bad Column History
CCD0 (786,117)
(283,278)
(798,494)
Data Plot
Past Warm Pixels		No History Data Plot
Past Warm Columns
CCD1 (910,239)
(787,181)
(427,125)
(802,665)
Data Plot
Past Warm Pixels		No History Data Plot
Past Warm Columns
CCD2 (104,31)
(803,225)
(526,66)
(178,149)
(99,899)
(665,25)
(345,12)
(837,378)
(353,201)
(726,537)
Data Plot
Past Warm Pixels		No History Data Plot
Past Warm Columns
CCD3 (21,95)
(680,391)
(811,637)
(617,159)
(318,53)
(394,80)
(917,232)
Data Plot
Past Warm Pixels		No History Data Plot
Past Warm Columns
CCD4 Data Plot
Past Warm Pixels		No History Data Plot
Past Warm Columns
CCD5 (263,317)
(728,340)
(877,408)
(282,385)
(369,376)
(357,303)
512
1022
510
Data Plot
Past Warm Pixels		No History Data Plot
Past Warm Columns
CCD6 (849,169)
(884,31)
(80,130)
(357,29)
(670,387)
(414,5)
(1000,214)
Data Plot
Past Warm Pixels		No History Data Plot
Past Warm Columns
CCD7 (335,412)
(126,856)
512
1022
Data Plot
Past Warm Pixels		No History Data Plot
Past Warm Columns
CCD8 (275,393)
(447,769)
(136,65)
(295,978)
(597,187)
(139,109)
(541,41)
(881,53)
(326,978)
(675,304)
(333,466)
(220,813)
(666,165)
(893,490)
(182,474)
(332,324)
(838,239)
Data Plot
Past Warm Pixels		No History Data Plot
Past Warm Columns
CCD9 Data Plot
Past Warm Pixels		No History Data Plot
Past Warm Columns

more than 70% of the time in the last two weeks, the pixel is listed as a warm pixel.
  • If a "warm" pixel candidate shows up more than 30% but less than 70% of the time in the last two weeks, the pixel is listed as a flickering pixel.
  • 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:

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