Edge of Cell Roll Off check

The edge rolloff was checked for a variety of science and flat field input exposures selected with observation dates after 2009-12-09. The rolloff was checked on all sides of cell xy53 on chip XY21. The main points are:

  • Although all sides appear to have some degree of rolloff in the raw exposures, the flat fielding corrects the effect for the right and left sides. This is consistent with the magic results, in which the new streaks were oriented horizontally.
  • The level of the rolloff scales with the background level, as can be seen in the clear ordering in the raw image profiles. This is true for both the science and flat input images.
  • The rolloff on the top is generally well corrected. Two science exposures have upturns in the flat corrected profile. One has a star in the profile box (exp_name = o5180g0252o), and the other has a substantially higher background level than the others (exp_name = o5192g0138o). PNG images of these cells are at the bottom. The flat input exposure with an upturn (exp_name = o5195g0002f) does not have a significantly different background that the other flat exposures, but does show an odd defect towards the top of the cell.
  • The rolloff at the bottom is the likely cause of the majority of the magic detections. The science exposures have an upturn in the bottom few rows that does not appear in the flat field exposures. This upturn carries through to the flat corrected profiles, causing a 5-10% spike for these rows.

Science exposures studied:

exp_id exp_name raw background level
113830 o5189g0311o 7665.45
111709 o5180g0252o 7964.01
111713 o5180g0257o 8140.44
112597 o5183g0010o 8403.45
113896 o5189g0377o 9206.13
111720 o5180g0261o 13431.88
114762 o5192g0138o 42120.74


Raw image Dark corrected image Flat corrected image
Top of cell
Right of cell
Bottom of cell
Left of cell


Flat exposures studied:

exp_id exp_name raw background level
117099 o5197g0001f 24884.11
113067 o5187g0008f 25077.79
113522 o5189g0003f 25125.63
114670 o5192g0046f 25155.90
113974 o5190g0014f 25275.45
116145 o5195g0002f 25397.96
117941 o5199g0001f 26487.14


Raw image Dark corrected image Flat corrected image
Top of cell
Right of cell
Bottom of cell
Left of cell


exp_id exp_name flat corrected image with regions
116145 o5195g0002f
114762 o5192g0138o
111709 o5180g0252o

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