Re: Perform differential photometry on an object moving across a field

Posted by karenacollins on Feb 21, 2016; 6:19am
URL: http://astroimagej.170.s1.nabble.com/Perform-differential-photometry-on-an-object-moving-across-a-field-tp240p350.html

Hi Christophe,

I think the routines described would work for telescopes with good
guiding and tracking. However, it seems that many setups don't seem to
provide that capability robustly. I will not have time to work on this
in the next couple of months, but when I do get time, I'm thinking that
a way to make the routine more robust is to identify the moving source
when placing the apertures. When the first image is processed, a list of
all peak locations above some threshold will be stored, along with the
net integrated flux measured within an aperture at that source. Then,
for all subsequent images, the routine could search for the nearest
source to the original location that is not in the original list of
stationary sources (the stationary source positions would be updated
after each new image is processed) and that matches to within some
limits the integrated counts in the previous image. As the routine
starts up and progresses, it could keep an average of the motion to help
the algorithm find the moving object in the subsequent images. I'm
mostly writing this response as notes for myself when I get time to
implement it, but I welcome comments to critique the plan to make it
better, or to suggest ways that the algorithm would fail (which would
save me time implementing a bad algorithm).

Karen