Opened 10 years ago

Last modified 6 years ago

#111 new task

Possible bad pixels or calibration for Hawk

Reported by: benj Owned by: benj
Priority: alpha 5 Milestone:
Component: Data collection Keywords:
Cc: mggr Other processors:

Description (last modified by benj)

Some Hawk pixels appear to either be bad or to have bad calibration. Spectrum spikes seem to occur in the raw data. If you take two points in the raw data from the same pixel on different scan lines they both have very similar spikes, suggesting bad pixels for specific bands on the sensor itself, eg:

8-pixel average over-water spectra from the same pixel on two different scan lines (raw data)

If you take two points in the raw data from different pixels on the same scan line, they both have spikes but in different places:

Spectra from different pixels on the same scan line (8-pixel average, raw data)

This suggests that most spatial pixels on the Hawk CCD have at least one bad spectral pixel (or that the calibration is bad on at least one spectral pixel per spatial pixel), but that it's not always the same spectral pixel that is bad.

This arose from ticket #106.

Attachments (2)

h_raw_samepixelspectrum.png (6.0 KB) - added by benj 10 years ago.
8-pixel average over-water spectra from the same pixel on two different scan lines (raw data)
h_raw_diffpixelspectrum.png (6.2 KB) - added by benj 10 years ago.
Spectra from different pixels on the same scan line (8-pixel average, raw data)

Download all attachments as: .zip

Change History (7)

Changed 10 years ago by benj

8-pixel average over-water spectra from the same pixel on two different scan lines (raw data)

Changed 10 years ago by benj

Spectra from different pixels on the same scan line (8-pixel average, raw data)

comment:1 Changed 10 years ago by benj

  • Description modified (diff)

comment:2 Changed 10 years ago by benj

  • Priority changed from immediate to high

comment:3 Changed 10 years ago by mggr

Bill says it's simple to manually add bad pixels to the bad pixel table (~arsf/calibration/2007/hawk/SN300011_150207_NUC1.bad), if we can figure out a way to detect them (the hard part).

comment:4 Changed 6 years ago by mggr

Given iopa's work on this, can we consider the ticket closed or do we need to do some follow up work (given it has some odd results at times)?

comment:5 Changed 6 years ago by benj

I don't think we finished this - Ioannis did a lot of work on detecting bad pixels, but the results weren't entirely consistent from run to run (think that's the sensor, not Ioannis' code) and I seem to remember it either didn't get them all or marked ones that seemed OK.

Basically, since we weren't happy enough to use the bad pixel file, I don't think we can call this closed.

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