Plate solving

[Olsin]

I keep seeing this expression written and talked about without really understanding what it is. So can anyone explain to me what plate solving is and how it increases imaging accuracy?

 

[vlaiv]

Plate solving is process of matching star patterns on one image to calculate precise coordinates of that image (center, corners, each star, etc).

It is done by identifying objects in the image and matching against catalogue of known stars / objects and their previously recorded positions (celestial coordinates).

It helps when imaging because goto systems on many mounts lack precision to put imaging frame each time exactly in the same place - they are able to get to vicinity of requested coordinates - you might have heard of "pointing precision" being expressed in arc minutes or arc seconds - this means that mount when issued goto to that particular location in general will miss no more than stated amount. It also helps with frame rotation - it can tell you by what amount to rotate frame to match that of previous session.

So it is useful when either doing multi night sessions and changing rotation in between (shooting something else in the meantime), or just to increase pointing precision - for example if you are shooting target that is too faint to be seen in frame and focus exposures (hence you don't quite know where it is in frame, but do know precise coordinates of it).

HTH

[Geoff Lister]

If you Google "plate solving astrophotography" there are several useful links. I quite liked the "Plate Solving for Dummies" at http://www.iceinspace.com.au/forum/archive/index.php/t-104367.html

[Olsin]

Ah i see. So you plate solve to acquire a solid reference point in the sky that you can refer back to for imaging purposes.

Point taken Geoff.

Thanks guys..