iraf.net

Hello all. I'm wondering if someone could suggest a set of tasks to use in order to perform the photometry of a set of trailed stars. The images were acquired while tracking an asteroid so in this case stars describe trails, approx 3 times de fwhm in length. Mosaic images are from gmos detector at Gemini North.Unfortunately I need to achieve the photometry of about 70-80 of such stars in several frames. I will appreciate any suggestion that users from this forum might add.
Thank you in advance!
Sincerely,Sebastian

Hello Sebastian,I don't have much experience with the photometry tools I think you need nor did I write them. What I think you need is the digiphot.polyphot task which allows you to define special apertures for aperture photometry. The "experimental" graphical photometry xapphot can be used for this type of photometry as well.What I don't know is how easy it is to apply these tools to larger volumes of data (number of sources and number of frames).I hope this helps.Yours,
Frank Valdes

Hello Frank, than you for your reply. Yes, what I had in mind was to use polyphot, define a couple of regions and to measure the flux within them. Then measure the sky levels from 5 or more boxes surrounding that regions in order to get an estimative sky value. Since the trail length is close to 3 times the fwhm, I will compare those values with the ones coming form a circular aperture and then decide what to do.
About xapphot, it didn't work well on my machine, still looking for solution though.
Thank you.Sincerely, Sebastian