Subtracting background stars for asteroid photometry?

[basilr]

This may be beyond the scope of this project, but would it be possible/relatively easy to add an option to subtract specific background stars from a multi-aperture plot?

I use AIJ for a preliminary look at lightcurve analysis for asteroids. As the target moves through the field it passes over/close to background stars, causing peaks in the plot. It would be great if I could select individual stars along the targets path (probably during the multi aperture selection?), then “subtract” the star as the asteroid passes over/close. Or, maybe there already is a way to do this in AIJ?

Again, this may be beyond the scope of the project- exoplanet transit photometry – but I feel it would be a very helpful feature for the asteroid photometrists and maybe the exoplanet work?

Thanks for a fantastic program, I use it all the time!

Basil

[karenacollins]

Hi Basil,

Unfortunately this wouldn't be very easy to implement in code, so I can't commit to getting it done any time soon. However it is a good idea and would be useful for measuring any moving object, so I will add your request to my (long) list of requested AIJ features (many of the requests are related to measuring moving objects).

I think the only way to easily handle it right now is to chop out the frames where the asteroid passes in front of a star.

If you wanted to put the time into it, the underlying ImageJ features that are brought forward into AIJ allow you to manipulate an images pixels. I can't provide detailed instruction on how to do it, but there are lots of ImageJ documenation out there, or maybe someone on the ImageJ user forum could provide input. In summary, I think you could copy a nearby region of the image where there is no star (or just measure the average value) and replace the pixels that include the offending stars PSF with those values in the frames where the asteroid is blended with it. If there are lots of offending stars, that might be a lot of work though.

Thanks for the suggested improvement to AIJ!

Karen