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Bias Frames

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Nick Atkinson's picture
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Last seen: 1 hour 35 min ago
Joined: 11/03/2014 - 23:17
Bias Frames

PixInsignt has a script to calibrate images; alternatively Image Intigration can be used to produce a master bias frame in which case use average as the combination method after loading and selecting the bias files.with no normalisation twice and winsorised sigma clipping. However, I find that pixinsight will not accept bias frames with a low signal. Is this an error on my part?

Currently I am using advanced calibration in AIP4 win which for the large number of frames is tedious and time consuming.

clear skies

Nick

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Last seen: 2 weeks 4 days ago
Joined: 05/03/2014 - 00:00
Create Bias Master using PixInsight

Nick.

Not had the issues you describe creating Bias Masters with the Image Integration module in PixInsight and input data from a QSI683.

For a Bias Master I use typically 999 frames (maximum frames possible in PI’s II module) to create a manual “Super Bias” and do not use PI‘s ‘Super Bias‘ module which I find tends to generate inaccurate Master Bias frames with data from the QSI683.

Under Image Integration:

Combination = Average.

Normalization = No Normalization.

Weights = Don't Care, All Weights = 1.

Disable (uncheck) Evaluate Noise.

Under Pixel Rejection (1):

Rejection Algorithm = Linear Fit Clipping (use if >20 frames, otherwise Winsorized Sigma Clipping for 10-20 frames or averaged Sigma Clipping for <10 frames).

Normalization = No Normalization.

Disable (un-check) Clip Low Range and Clip High Range.

Enable (check) Clip Low Pixels & Clip High Pixels.

Pixel Rejection (2).

All settings = Default.

Pixel Rejection (3).

All settings = Default.

Apply Global.....

With the above settings all my bias frames are accepted and the Super Bias Master created works as expected, the same settings should work with your data, selecting the appropriate Rejection Algorithm method in Pixel Rejection (1) according to the number of frames that you are combining.

If PI is still refusing to use all the frames then review the Process Console window after the Image Integration module completes for clues as to why it rejected your frames.

HTH.

William.