Hi
Please find attached a narrowband version of an astrograph design spreadsheet (as foreshadowed in
http://www.iceinspace.com.au/forum/s...d.php?t=151000). The layout is the same as in the earlier post, but the underlying maths tries to take into account the specifics of narrowband imaging. You do not need to be bothered with any maths to use it though - just plug in data and play.
the spreadsheet essentially puts most of the theory in one place - you can enter your sky conditions, target brightness, telescope, mount guiding, filter, camera characteristics and desired imaging time. It will tell you:
your sampling/resolution,
the expected FWHM at the focal plane,
the field of view,
the overall SNR performance with different sub lengths,
the optimum sub length,
the effective well depth after stacking and
the ADU value that you should see in the sky background of a sub.
It is a protected excel spreadsheet, but it also runs under openoffice. Best to unzip and scan it first. Excel will try to protect you and query if you
really want to use a web sourced spreadsheet. In openoffice, you will probably need to enable editing to get it to work. It has no macros and has been zipped for attachment through IIS. I use a fully up-to-date win10 system with the Microsoft security suite.
this version has only been validated on my system and should be suitable for available filters with optics of f4 and above - if anyone uses it, would be grateful for feedback - I will incorporate any changes needed to improve it. It allows different systems to be compared or any "what if" changes to an existing system to be assessed - before spending any money. It may be of real value to anyone considering one of the low read noise CMOS cameras or 3nm vs 7nm filters - do they really make a difference with narrowband? I have tried to put in instructions and explanatory notes - are they sufficient?
thanks for looking - regards Ray