Batch processing integration questions

[astrodoc71]

The tutorial was very helpful, however I have 3 initial questions:
1) Would there be a reason ever to use a different rejection algorithm other than winsorized sigma?
2) It was not clear from the video why the sigma high and sigma low sliders were adjusted from the default settings. What reasons would there be for doing this?
3) Should the reference image be the best resolved image or does this matter?

Regards,
Dave

[troypiggo]

Strongly recommend you read the excellent ImageIntegration (II) documentation by Juan.  Very comprehensive and helps you understand a lot about the process.

Note that the II feature of the BatchPreProcessing (BPP) script is only there to give you a feel for the results.  The recommendation is to tweak II after using the BPP script to do the image calibration and registration.  You can get a better signal/noise ratio by playing with the rejection algorithms and values.  Winsorized sigma with 4 high and 3 low is I think generally accepted as a good starting point, but if you have many subs (like over 10) the Linear Fit algorithm appears to give better results.  All covered in the doc I linked above.

So to answer your questions directly:

1) Yes.  By trial and error as explained in the docs.
2) Ditto
3) This is more an image registration question rather than integration.  Docs here on star alignment.

[mschuster]

Good info. I will add this:

1) The docs recommend various rejection schemes based on number of subs.
2) To improve SNR the idea here is to reject as few pixels as possible, only those involved in noise structures. Jordi Gallego as a good tutorial "Image integration techniques" on this page. For my integrations I usually leave sigma low at 4 and increase sigma high from 2 to 2.4 or so.
3) Good question. I have been using the sub with the best subjective compromise between the least FWHM, the roundest stars and the least noise as measured by the NoiseEvaluation script.

Mike

[astrodoc71]

That's great! Thanks guys
Regards,
Dave