Ephemeris alignment, scaling.

[Andrey D.]

Hello.
I have images of the comet with different fov and focal lenght.
In order to stack it with ephemeris alignment should I perform "Calibration and aligment only" first. And then stack. Or would ASTAP do that first step automatically?

[han.k]

Ephemeris alignment goes in one step.

First organise the annotation of the comet. In viewer go to Tools, Asteroid and comet annotation. Download select the database from JPL via the link and browse button.
Once annotation works:

Load the mage in the light tab.
In tab alignment "Select ephmeris alignment.
In tab alignment, press the button "Analyse the selected file...
In tab alignment select in the combox the comet found
Press stack button below

Han

[Andrey D.]

Yep .
I'm familiar with ephemeris alignment and already did it before.
Was just curuios if I combine images from different devices should there be any additional steps or not.

[han.k]

Different scale in arcsec/pixel will not work well but you can try it. Never tested but probably best is to put the image with smallest scale first. Process should be the same. You just get overlapping pixels (good) or unused space (bad). Reverse mapping is as far I remember not implement for ephemeris stacking: https://www.hnsky.org/reverse_mapping.htm

Refering to your previous question about saturation, coming day I will work on a new "Selective Saturation" slider to improve colour of faint parts of an image. Make the sliders also longer.

[Andrey D.]

My idea was to try to bring all images to the same scale first then use them for ephemeris alugnment stacking.
Ok, will check it once I have my laptop at hand.

Thanks!