Saturday, October 3, 2015

Bright spots on Neptune

Back in mid July of 2015 it was brought to the attention of several amateur astronomers like myself that there are bright spots on the cloud surface of Neptune.  A request was made by professionals to help observe these spots in red or narrowband IR.  I have had a string of poor weather and didn't have a chance until mid September.  On September 20th, I had some moderate conditions to try.  My method was to shoot wide field with the CCD as seen here.  I've superimposed an high-res RGB image on top to help identify Neptune.  The brightest and closest 'star' to Neptune is about the 7 o'clock position (lower left) and is actually the largest moon, Triton.

If you read the stats, Neptune was 241.3 light minutes away at the time of this photograph.  That's just over 4 light hours away.  For fun here's a size comparison via the wikipedia page.

At that distance Neptune is only 2.4 arc minutes in size and the top image that I took is fairly close to what you might see in a moderate telescope at medium magnification.

After some wide-field CCD shots, I put in my high-res planetary camera and took some LRGB as well as Infra-Red (742nm) shots.  Here's the aesthetically pleasing composite consisting of all 5 filters that also includes a Triton.

Finally for the detail oriented here's the full layout, including the sub channels used in derotation.

Also here's the alignment reference from the Neptune Ephemeris Generator (

Thanks for reading and please do some well wishes for more clear skies for me, they've been far and few between.

If anyone is interested all source tiffs, sharpened files and WinJupos measurements are on my public Google Drive share located here  and contained in a 30+MB .zip file - >

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