Looks Legit!

I've been looking at the possibility of doing photometric measurements of stars and other targets in these all-sky camera images.  Since magnitudes are being computed for the meteors and the stars detected in each FOV, I can only assume that I can get pretty nice calibrated photometry.

I was all ready to start diving into the RMS code to find the info I need to do the translations between pixel values and magnitudes, when it dawned on me that if I did differential photometry, I wouldn't have to worry about any of the problems associated with trying to get an actual magnitude.  I'm fine with magnitude differences.

As a reminder, the difference in astronomical magnitude is defined as:

M2 - M1 = -2.5 log10 (I2 / I1)

I can measure I1 and I2, which are the sky subtracted sum of pixel values centered on the reference or target.

Here's the I1 and I2 values as a function of time for the reference (rho Per, red dots) and target (Algol, beta Per, black dots):

... and when I compute the differences in magnitude, I get this:

What this is telling me is that over this time period (which as you can see lasted from about the beginning of the eclipse to just barely past the mid-point), the difference in magnitude goes from about 0.25 to 1.3 (+/- 0.1).

The actual difference at mid-eclipse IS 1.3 magnitudes!!!! (https://en.wikipedia.org/wiki/Algol).

I also measured the precision of the reference star.  There were 1200 total data points.  Of those, a few were obvious problems.  In the end, I used 1163 data points (96.9% of the data), and got a precision of about 10%.  I can tighten up on the data points selection a little but (eliminating outliers), and actually get down to about a 6% spread.  That's acceptable for the data I have!

This is all very encouraging.  I'd like to get a full eclipse.  The next one that'll be visible from my side of the planet is on 21/22 December (UTC):

start: 22 Dec 2021 07:52 (00:52)   mid: 22 Dec 2021 12:41 (05:41) end: 22 Dec 2021 17:30 (10:30)

and then a better one on 27/28 December (UTC) that'll be going on all night:

start: 28 Dec 2021 01:30 (18:30)    mid: 28 Dec 2021 06:19 (23:19)    end: 28 Dec 2021 11:08 (04:08)

Good times!