apsum definitions
Philip Massey wrote on May 21, 2010
Hi, Frank et al---
I'm in the process of measuring the Kitt Peak sky brightness (20 years and counting...) and I just want to make absolutely sure that I understand the number of pixels in my aperture using APSUM. I have an upper limit of +20 and a lower limit of -20. So, do I have 40 pixels or 41 pixels? (It makes a 2% difference in the derived surface brightness...) I would have guessed 41 but if I create an aperture that has an upper limit of 0 and a lower limit of 0 it contains no counts. Thanks.
---phil
I'm in the process of measuring the Kitt Peak sky brightness (20 years and counting...) and I just want to make absolutely sure that I understand the number of pixels in my aperture using APSUM. I have an upper limit of +20 and a lower limit of -20. So, do I have 40 pixels or 41 pixels? (It makes a 2% difference in the derived surface brightness...) I would have guessed 41 but if I create an aperture that has an upper limit of 0 and a lower limit of 0 it contains no counts. Thanks.
---phil
Mike Fitzpatrick wrote on May 21, 2010
Hi Phil,
Frank is away this week but you might still get a reply. A quick look through the code doesn't reveal an obvious answer and I don't want to give you the wrong answer. If I figure it out I'll follow up but will defer to Frank for the expert advise.
Cheers,
-Mike
Frank is away this week but you might still get a reply. A quick look through the code doesn't reveal an obvious answer and I don't want to give you the wrong answer. If I figure it out I'll follow up but will defer to Frank for the expert advise.
Cheers,
-Mike
Last post on May 21, 2010