Action to add calibrators from PanSTARRS

[juanep97]

This PR adds an action to the AstroSource admin for automatically adding calibrators from PanSTARRS.

[joteros]

Use ApMag instead of PSFMag
Set condition on the number of observations of each star, ApMagNpt>=5
Set condition on the ApMagStd<0.01

If with those conditions, we cannot find stars, then relax in a second step iteration those for ApMagNpt and ApMagStd

[juanep97]

@joteros what do you think of those constraints? I think they are a reasonable minimum. Then we just take the top 10 results, by number of observations.

[joteros]

Looks good to me. I usually use as minimum magnitude allowed 17 instead of 16, but this is a minor change.
At some point we should add a second iteration search in case the search does not find any star in the FoV, relaxing a bit the criteria (it happened to me a couple of times), increasing the Std threshold, lowering the minimum magnitude and the number of observations required, but this can be done afterwards.

[juanep97]

Looks good to me. I usually use as minimum magnitude allowed 17 instead of 16, but this is a minor change. At some point we should add a second iteration search in case the search does not find any star in the FoV, relaxing a bit the criteria (it happened to me a couple of times), increasing the Std threshold, lowering the minimum magnitude and the number of observations required, but this can be done afterwards.

I am hesitant to perform this automatic lowering of the quality constraints, since the user would not know about this and would have no choice, at least through this GUI (if we added an interactive tab for it, perhaps). Another option would be to add two different actions, with two different sets of constraints (e.g. "Automatically add field stars from PanSTARRS" and "Automatically add field stars from PanSTARRS (relaxed)").

[joteros]

Looks good to me. I usually use as minimum magnitude allowed 17 instead of 16, but this is a minor change. At some point we should add a second iteration search in case the search does not find any star in the FoV, relaxing a bit the criteria (it happened to me a couple of times), increasing the Std threshold, lowering the minimum magnitude and the number of observations required, but this can be done afterwards.

I am hesitant to perform this automatic lowering of the quality constraints, since the user would not know about this and would have no choice, at least through this GUI (if we added an interactive tab for it, perhaps). Another option would be to add two different actions, with two different sets of constraints (e.g. "Automatically add field stars from PanSTARRS" and "Automatically add field stars from PanSTARRS (relaxed)").

Sounds like a good solution. In any case, as I said this can be implemented (and even refined) afterwards, and my expectation is that it won't happen too often