American Association of Variable Star Observers (AAVSO)
Thu, 02/09/2023 - 15:18

I feel I must be doing something incorrectly because placing apertures in VPhot sets much harder than it should be.

If I have an image that I need to create a sequence for, I first locate the target star.  To do so I choose Catalog > Variable Star Index.  This places (in my case) 30 apertures on the field.  My target is one of these but now I must manually delete all the others, by clicking the X one-by-one.  Choosing Catalog > GCVS adds only 8 apertures, but I'm sure that in past cases there were many more in cases.  Again, I have to delete the unneeded ones manually.

I've resorted to placing all the apertures, noticing which star is the target, and then:

1. Delete all apertures using the Delete All button

2. Clicking on the remembered star and manually setting the name for it in the popup window.

This seems a bit error prone and again cumbersome.  I also worry that the aperture place this way might be slightly different than when VPhot automatically places it.  I assume when I do it, it uses the centroid to place the aperture whereas VPhot is using an RA/Dec.

It seems there needs to be some checkboxes alongside the apertures listed on the left side of the image window.  I would like to check one or more and then say "Delete Unchecked".  This would also help with placing apertures for the comp stars.

Is there a better way to do this?



American Association of Variable Star Observers (AAVSO)
Can you choose Catalog >…

You can choose Catalog > Variable Star Index. Delete the ones you don't want to do photometry on, delete the comps you don't want, pick the check star.  Then save-as the sequence with your own meaningful name attached. Then, every time you use it, it is quick and easy. I use as many as ten sequences for some fields.



American Association of Variable Star Observers (AAVSO)
Sure, that is basically what…

Sure, that is basically what I do.  But deleting 50 unused stars one-by-one seems tedious.  That's why I wondered if there was a better way.

Yes, if it is a sequence I've already created then it is quick to just reuse it.

American Association of Variable Star Observers (AAVSO)
Can be Tedious BUT only needed once. Alternatives?


Yes, if you use the VSX catalog to identify target variables, you obtain ALL the variables identified in VSX in the FOV. It can be / is tedious to delete each undesired target by clicking  the X in the star list at the upper left. You do only need to do it once and save the final sequence. As the VSX grows, the list will only get larger but it is the best up-to-date catalog for variables. Have you ever thought about analyzing all those other targets at the same time?

You could adjust (increase) the minimum SNR settings to limit the inclusion of all the faint variables. It may help somewhat?

Alternatively, you could always start with the GCVS catalog. It is a much smaller/older subset of all the current VSX targets. Yields many fewer variables to remove.

You could download the available chart for the field and enter the single target manually and then save it in a sequence. You can them download the available comps and save again. You can make the decision of which you want to include, as few or many as you desire. Save at the end of the process and you are ready for the next future image. 

So yes, we have thought about filtering the VSX list based on some criteria BUT frankly it's complicated and not high on the priority list. There are a few alternatives that may be tedious but not insurmountable!?