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

Posted by BPVietje on Mar 24, 2017; 4:54pm
URL: http://astroimagej.170.s1.nabble.com/Perform-differential-photometry-on-an-object-moving-across-a-field-tp240p639.html

I used to be able to do this in MDL 5.18, but after an upgrade to version 6, I could not get the moving object photometry to work for me, and I got no real help from Cyanogen.  It seems the alignment of the stack is critical, but they provide no instructions for this alignment.  Autoguiding was not used for some of these series, so there was a need to align the stack.

I have had very good success in AIJ (well, to be exact, it was ImageJ with the Astronomy Plug-ins), by first using the Align Stack command with a few large apertures, then performing the photometry on the aligned stack with aperture & annulus sized for photometry.  I did nothing special, and IJ tracked the asteroid through well over 200 frames like a champ!

Now that I've had a bit of training in AIJ (Exoplanet class with Dennis Conti), I'll try to revisit some Asteroid time series and see if things are any different in the newest version of AIJ, but I expect it will work very well.  Importing orbital elements, or marking first and last image for vector computation would be nifty, though I haven't tried photometry on a target moving so fast that it was needed.  My time series of NEO's like TB-145, back in October, 2015, were moving so crazy-fast that I didn't even try.  I was guiding on the target, and the stars were too elongated to be useful.

Clear skies,

Brad Vietje
Newbury, VT
www.nkaf.org