Society for Popular Astronomy

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Author:  David Frydman [ Wed May 15, 2019 4:50 pm ]
Post subject:  Halo

2019 May 15 1415 UT to 14.20UT.

Very bright upper 22 degree halo.
Weak lower 22 degree halo.

Upper concave Parry arc very bright but limited in extent to the extent of the 22 degree halo top portion. (I think it is the Parry arc looking at illustrations).
Parry arcs about 100 times rarer than 22 degree halo.

The photos show the complete 22 degree halo, although the weak parts not seen unaided eyes and polarised sunglasses.

I looked for other rare halos but didn't find any.

I don't know how to post photos.

13.50UT wind 100 degrees 5 kn, visibility 30km cloud few 5,000ft broken 30,000ft 20C dewpoint 6C 1025 hPa.

Can somebody tell me the Sun's elevation for Greenwich at 14.15 UT today?


Author:  Brian [ Wed May 15, 2019 7:54 pm ]
Post subject:  Re: Halo

Hi David.
Taken from SkyMap Pro for location Greenwich:

2019 May 15 14.15UT
Sun alt 47deg 38min 37sec
Sun az 232deg 39min 07sec


Author:  David Frydman [ Wed May 15, 2019 8:12 pm ]
Post subject:  Re: Halo

Thank you very much Brian.

The Parry arcs vary in form depending on sun elevation.
About once a year for a dedicated observer.
I don't think that I have seen one from England before.


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