Hi everyone,
On the Dark Sky site, my imaging location (backyard) is
Bortle 5.
I never really believed that my sky was a
Bortle 5 because it really looked like crap most of the time. I have a large elementary school a block to the east in addition to a LED streetlight (non-shielded) in my front yard (also east).
I installed an
app on my phone “Dark Sky Meter” that worked okay, but sometimes gave wildly different results, however, the average was
Bortle 7 (it read in
SQM – sky quality meter).
I just looked up
Bortle scale on Google and at the Wikipedia page it has a
SQM/
Bortle scale.
https://en.wikipedia.org/wiki/Bortle_scale
So, today, I was reading a post on CN (Cloudy Nights forum) and ran across something very interesting that some of you probably might already know.
ASTAP software can easily calculate sky brightness (
SQM) accurately by simply supplying it with some of your imaging data.
I already had ASTAP installed on my system since I use it for plate solving in N.I.N.A.
To accurately calculate sky brightness from an image that you collected using ASTAP:
Open the ASTAP software. Click File, Load FITS or Other Format.
Load a dark file (that matches the temperature/sensor temperature) of the image that you want to analyze).
Again, click File, Load FITS or Other Format.
Load a flat file (that matches the image that you want to analyze).
Again, click File, Load FITS or Other Format.
Load a light frame that you want to analyze.
Click the Solve button.
Click Tools,
SQM report based on image.
NOTE: I have only used ASTAP with FITS files. I have no idea if it will work with other image formats.
Finally confirmation! Looks like when I image targets near the Celestial Equator, I start off at a high
Bortle 7, almost 8. When my target reaches the
meridian,
Bortle 6.
I know that Sharpcap offers a similar tool, but I don't use it since
NINA has the polar alignment plugin TPPA which uses ASTAP as my designated plate solver.
I hope that someone finds this as interesting as I did.
Jim
Scopes: Explore Scientific ED102 APO, Sharpstar 61 EDPH II APO, Samyang 135 F2 (still on the Nikon).
Mount: Skywatcher HEQ5 Pro with Rowan Belt Mod
Stuff: ASI EAF Focus Motor (x2), Orion 50mm Guide Scope, ZWO 30 mm Guide Scope, ASI 220mm min, ASI 120mm mini, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Mele Overloock 3C.
Camera/Filters/Software: ASI 533 mc pro, ASI 120mm mini, Orion SSAG, IDAS LPS D-1, Optolong L-Enhance, ZWO UV/IR Cut,
N.I.N.A., Green Swamp Server, PHD2, Adobe Photoshop CC, Pixinsight.
Dog and best bud: Jack
Sky: Bortle 6-7
My Astrobin:
https://www.astrobin.com/users/Juno16/