Random Spots on Sky Investigation

[STSpencer]

From Rich

Checking a few random places on the sky at random times. And can then see in each field how many stars would produce a contrast against the background NSB significant enough to be detected in the slow signal chain.

This should be easy to do, albeit a bit compute heavy. Probably best to select mag 4 stars at random and then select a few observable dates/times based on that (no moonlight).

With multiple mag 4 stars we should be able to make some degree of determination of how stellar temperature affects NSB rate.

[STSpencer]

I've run 3 mag 4 stars through NSB so far, I can run more if needed. The results are reasonably interesting.

Here's HIP 88601, m_V=4.03, T=4350K Here's HIP 64004, m_V=4.27, T=20790K Here's HIP 106551, m_V=4.87, T=4650K .

The peak brightness in the image (which is all we can really use to estimate the star brightness given the pointing issues) appears uncorrelated with the m_V of the target star, however looking at the fields under ESA sky explains why this is.

The brightest star in the HIP88601 field is likely the mag 3 Cebalrai, the brightest star in the HIP64004 field is the mag 0 G Centauri, and the brightest star in the HIP 106551 field is the mag 4 Tau Cygni. This suggests a peak value of 305.2 MHz coresponds to a mag 4 star, the peak brightness of a mag 0 star is still around 1GHz (lambda stars moving between pixels as before), and the peak brightness for a mag 3 star is inbetween (as it should be). After looking at the hess_basic model in NSB a bit more this makes sense (to me at least), as the brightness in a pixel isn't a linear function of B_Gaia. This is as its an integral over a larger area of sky than just the star in question (as I've added to the report, the stellar mag limit is 15), plus the Krisciunas star brightness might also differ.

I could try going through Hipparcos to find more mag 4 stars that are isolated if it's important, but that might be a bit time and labour intensive.