WCS

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WCS

Robert
This post was updated on .
Hi

I am a new french user of AstroimageJ, friend of Guy, with some knowing about ImageJ. We have to experiment exoplanet observations at the begenning of August, in an observatory 2930 m high in the Alpes mountains.

I read the Dennis Conti paper about exoplanet and I try to do the example with his files: bias, dark, flat and ScienceImages.

I have a trouble with WCS. I cannot run the process up to the last image. It fails after 10 or 29 or 40 slices.
I use my personal key to access astrometry.net; I set up number of stars to 15.
I try to run WCS on raw images or calibrated images with the same issue.

I try the process with Ubuntu 16.04LTS and Windows 10 ... just in case. With the latter,  memory management is very very poor ! I can't load all the images into the memory unlike Ubuntu on the same machine !

Thank you for your support.
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Re: WCS

karenacollins
Administrator
Hi Robert,

Welcome to AIJ. Do your plate solves always fail exactly at slices 10, 29, and 40? If so, does this same pattern occur
when using a different stack of images?

Some more feedback for now:

I would use more like a max of 50 stars for the plate solve, if there are that many in the field (although I don't
expect this is the source of your problem).

There is a known issue where at times one or more of the astrometry.net server's processor cores hang, which causes
plate solves to fail every ~N images (where N is the number of cores on the astrometry.net server (N=8 the last time I
had this problem)). Also, network problems can cause random failures. If one of those two things is happening, the only
choice is to run astrometry again on the images that didn't solve. If you enable "Skip Images with WCS" in the
astrometry setup panel, AIJ will only attempt to re-solve image slices that do not already have a valid WCS header, so
you will not have to go through by hand and find the images that failed.

If you are using a Windows based PC, I'd recommend installing the local astrometry.net server as described here:

http://astroimagej.1065399.n5.nabble.com/AstroImageJ-3-2-0-Released-new-local-astrometry-net-server-supported-for-Windows-users-td338.html

It is more reliable than the network connected version.

Karen



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Re: WCS

Robert
Thank you Karen for your answer.

The plate solve fail occurs randomly. I check the box Constrain Sky Location and I resolve up to 178 images before the fail  along 2H45!

I am trying the ansrv solution under Windows, but I would like have one under Linux-Ubuntu, cause memory issue with Windows. In fact, we can use line command from astrometry.net, we just lack a graphic interface to automatize the process. Unfortunately I am not a programer !

Best regards.

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Re: WCS

karenacollins
Administrator
That sounds like the random network or server failures that are known. It's easy to restart the plate solve to finish
the run, but it can be frustrating. If memory is a problem on the PC, try using the "Virtual Memory" option when you
open the stack.

Karen
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Re: WCS

Robert
At last a friend of mine write a script to solve localy all the images of a directory.
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Re: WCS

karenacollins
Administrator
Nice. If you want to share the script here, others users might find it useful. If you do, please write a short overview
of the requirements (i.e. if 3rd party software is required) and provide some user instructions.

Karen

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