Astrophotography by Amir H. Abolfath | سایت عکاسی و عکاسی نجومی امیرحسین ابوالفتح

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Canon EOS5DMKII
Vixen VC200L

More info: https://www.atoptics.co.uk/fza190.htm


During Mercury transit I took a photo with a strange phenomena. I send it to Les Cowley from https://www.atoptics.co.uk/ to check it. He asked me to need a second opinion and sent it to Professor Young in California as an expert on mirages and atmospheric refraction.

And there was some good news for me from Les:


"Dear Amir,

I have good news. Andrew Young has confirmed that your peculiar green feature above the sun’s upper limb was real. Not a camera or processing artefact.

The effect probably arose from a combination of (1) optical ducting from a weak temperature inversion (2) your position relative to the duct and (3) the hazy Tehran atmosphere.

Ducting is a phenomenon where a temperature inversion causes sunset rays to be refracted up and down and so travel considerable distances. More about ducts here:
https://www.atoptics.co.uk/fza150.htm

Ducts produce images and green flashes. The appearance of them depends on your altitude and the height of the temperature inversion/duct.

What you imaged is a type of sub-duct refraction seen when you are just below the duct. It would only have lasted a few seconds which accounts for it not showing on your other images. It is very rare."