Reference Light for StarAlign: Calibrated or Uncalibrated

[Farzad_k]

Hello,

I am still learning the steps required for pre-processing and have a couple questions.

I believe alignment is a step after calibration. I am not sure why an uncalibrated Light should be used for star alignment when the calibrated ones are more cleaner.

Thanks

Farzad

[RickS]

I don't know of any reason why you shouldn't use a calibrated light as the registration reference.  I do it all the time...

[Farzad_k]

I don't see any reason either, which is why I asked. I have seen on some online videos they describe it that way.

In LRGB process, if calibration of the L and R, for example, are different for some reason, then the calibrated L frame that I am using as a reference may not necessarily work for alignment of the R images.

So you are doing it all the time and it works. Great, thanks.

[Geoff]

One reason for using an uncalibrated light frame is that it makes it convenient in the BatchPreprocessing script, where you have to specify the reference frame before you begin if you intend to use the script for both calibration and registration.
BTW, whether you use an uncalibrated or calibrated reference frame you should use the same one for all filters. 

[RickS]

BTW, whether you use an uncalibrated or calibrated reference frame you should use the same one for all filters.

And choose it carefully, picking a reference with good (low) FWHM and Eccentricity.

[Farzad_k]

BTW, whether you use an uncalibrated or calibrated reference frame you should use the same one for all filters.

And choose it carefully, picking a reference with good (low) FWHM and Eccentricity.

Roger that one. Thanks.