Sky Brightness location compared

Somewhere to ask questions about the best way to use SharpCap
Forum rules


If you have a problem or question, please check the FAQ to see if it already has an answer : https://www.sharpcap.co.uk/sharpcap-faqs
Post Reply
donboy
Posts: 256
Joined: Sat Mar 25, 2017 1:57 am

Sky Brightness location compared

#1

Post by donboy »

Hi Robin,

My friend Chris and I were both imaging the other day and his sky brightness measured with the brain was .77e- and his SQM was about 18.7. Where my sky brightness with brain was around 2.4 and my SQM was around 19.1. I would have thought the sky brightness would track the SQM. Could you explain why his sky brightness was way lower than mine. He was using a ASI1600MC and I was using an ASI294Pro.

Don
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Sky Brightness location compared

#2

Post by admin »

Hi Don,

the pixel size and the f-ratio of your scope come into play to calculate the electron rate from the sky brightness. Higher f-ratio will give you a lower rate (inversely proportional to the square of the f-ratio). Higher pixel size will give you a higher rate (proportional to the pixel area).

cheers,

Robin
donboy
Posts: 256
Joined: Sat Mar 25, 2017 1:57 am

Re: Sky Brightness location compared

#3

Post by donboy »

Thanks Robin. His F ratio was higher and my pixel size was larger.
Post Reply