Photometric colour calibration

[dpaul]

I read the recent software tutorial explaining the new ''Photometry based colour calibration'' and tried in vain to use it.
I have version 1.8.5 version which has ''Photometric colour calibration'' in the programs menu. I tried using this on various galaxy images that were not yet stretched (and in fits files format). I continually get the same message:

FAILURE TO PLATE SOLVE IMAGE, then in more detail it says:
0 star pair matches found - need at least eight matches pairs
Error - unable to find an initial set of putative star pair matches
Error - the image could not be aligned with the reference star field.

Can someone help - the tutorial doesn't seem to explain how to actually use the program.

Thanks

David

[dpaul]

I now got it to work on 'some' images. I now realise it needs a reference image. However on 3 out of 6 different subjects it didn't seem to work, these had less stars visible

David

[andreasmax]

hi,

didi you mean this tutorial? http://pixinsight.com/tutorials/PCC/

if yes:
i think it is already well explained in there.
if not:
have a look at it. at the bottom of the article the tool will be explained step-by-step.
a) you need to have a reference star at the center of your image, search for it in the tool.
b) enter the focal length of your scope and pixel-size of your cam.
c) get a preview of your background and use it in the tool for further calibrating help.
that´s it.
i tried the tool on some of my images taken with a 200mm sigma-lens, a 500 apo refractor, a 800mm newton and even was able to get a result with older images taken with 50mm nikon-lenses.
no trouble here. if think the image solver is less restricitive than the normal image solver tool of PI.

otherwise we need more information of your setup.

hope this helps.

cheers from austria,

andreas

[cmarcus]

One possible thing, that I got wrong the first time I tried to use this:
I was using drizzled data and for that you need to change the focal length or pixel size setting.
Of course this only applies to drizzling, so maybe it's not applicable to your case.
regards

[dpaul]

Andreas,

thanks for note, I agree I need to read the tutorial in more detail - for example the noise level was zero it works better if higher.

Regards

David

[dpaul]

Thanks for the note about the drizzle, I haven't been using this

Regards

David