Hesiodus crater ray phenomenon

[Nyctimene]

Once again, this lunar light-shadow phenomenon will be observable Thursday evening. A cleft in the wall of the neighbouring crater Pitatus projects a triangular light ray (like a searchlight) across the floor of crater Hesiodus for several hours. Beginning: March 30th, 20.20 (UT).

Next occasion will be May 28th, 22h00min UT, according to this:

http://www.lunar-occultations.com/rlo/rays/hesiodusp.htm

A magnification of 100x and more is recommended; and you may have a look, if you can spy the concentricity of the small crater Hesiodus A close by.

Good luck with the hunt!

Stephan

Edited March 31 by Nyctimene

[Grump Martian]

Thanks for your post Stephan. I call myself a visual observer. Having looked at your picture of Hesiodus crater and trying to find it in my Hamlyn Atlas of The Moon, failed to correctly locate it. Clouds swept in and that was it. I will do some more learning before the next event.

[Nyctimene]

Was lucky enough to spot the Hesiodus ray just now in a short cloud gap between two rain showers. The Heritage 130 P Flextube, equipped with the 2.25x Baader Turret barlow and the Seben 8-24 mm zoom, showed again it's qualities as a perfect grab-and-go scope. At 22h 30min CEST, I found the light ray already fully evolved, as a tiny searchlight, projecting an obvious light spot at the W crater rim. Hesiodus' floor was still completely dark, as was the interior of Hesiodus A, so no concentricity visible here. Seeing was moderate, allowing magnifications of around 150-170x. The third time for me to spot this event. Next time, I'll try to observe the opposite phenomenon, the Pitatus ray, but for that I will have to rise in the morning hours (waning moon). Have a look:

http://www.lunar-occultations.com/rlo/rays/pitatus.htm

Stephan

Edited March 30 by Nyctimene

[maw lod qan]

I wanted to get a look, but oh my is Sol still bright in our sky!

I also had to work with an occasional cloud.

Searched through Lunar maps and was able to locate the crater in Mare Nubrium.

I am always amazed when reading information about the Lunar surface. 4000' height on the crater walls.

 

[Littleguy80]

Thanks Stephan! Managed to catch this tonight. A first for me with my 80mm frac and Nagler zoom. Really neat to see this. Enjoyed the straight wall feature too. Has always been a favourite.

[Knighty2112]

Just been out with my 80mm ED ‘frac and spotted this with 5mm EP with 2x Barlow fitted. Moon was hazy to see but beam on crater floor was easy to spot still. Thanks for heads up.  

Edited March 30 by Knighty2112

[josefk]

That is absolutely lovely - the sketch that is. I am putting a reminder in my phone for the 26th July so thanks for the tip off!

Edit - i've just taken a look at the table on your link - what value is it in that table that gives the hint that the 26th July is good but not 29th April, 28th May etc. i am completely new to this level of "detail" in more ways than one.

Cheers

Edited March 31 by josefk

[Nyctimene]

6 hours ago, josefk said:

That is absolutely lovely - the sketch that is. I am putting a reminder in my phone for the 26th July so thanks for the tip off!

Edit - i've just taken a look at the table on your link - what value is it in that table that gives the hint that the 26th July is good but not 29th April, 28th May etc. i am completely new to this level of "detail" in more ways than one.

Cheers

The drawing is taken from the net - my own drawing skills are very rudimentary. It's showing the details more clearly than most of the photos I've found.

To answer your question: you pointed me to a mistake I've made accidentally! Of course, the ray's visibility will depend  on the moon's night visibility. So, the second column, giving the UT time, is important. April 29th, the ray will appear at 9h36min UT; and I assume, that it can't be made out in the daylight, due to low contrast. But I omitted the next occasion May 28th, 22h00min UT - a good opportunity (albeit starting at midnight); I cannot recall, why I made this mistake. I shall correct this in my first post. Thank you for the hint!

Stephan

[josefk]

Thanks. I shall put several dates in my phone then 👍🏼