From:  Ross Sackett 
Date:  Thu Oct 7, 2004  7:22 am
Subject:  Pitatus sunset spoke

Perhaps this is a common sight, but I haven't seen it
mentioned in my observing books. This morning I was
watching sunset on the southern highlands and noticed
a very pretty spoke of light across the floor of
Pitatus, running east from the breach in Pitatus' rim
where it contacts Hesiodus, directly to Pitatus'
central peak. The floor of the crater was entirely in
shadow except for the thin straight line of light and
the starlike central peak. The waning moon just
before (terrestrial) dawn always surprises me!

Ross

Pitatus Lunar Sunset Ray

Observer: Tony Donnangelo 
Date/time of observation: 2004/08/09 06:30 U.T.
Site location: Weiser State Forest, PA, USA 
Site coordinates: N. 40°30’51.7” (40.51437°) W. 76°46’40.5” (76.77791°)
Site elevation:  524 meters (1,720feet)
Site classification: State forest wilderness area 
Instrument: 14.5” Starmaster Dob.
Magnification: 203x, 267x, 351x 
Object: Pitatus (flooded walled plain)

It was a poor night for observing. That isn’t anything new in Pennsylvania this year. There were many clouds as astronomical twilight ended. There were periods of total cloud cover. There was little wind and only slight dew. I had the opportunity to take many breaks and napped for a few hours.

I arrived at the site before sunset and set up my equipment. When seeing completely deteriorated by 03:30 U.T., I took a nap and awoke at 06:00 U.T. The sky partially cleared enough to start observing again. By 06:30 U.T., the moon rose sufficiently above the trees and was clear of the clouds. I looked for signs of a ray predicted to occur a few hours later at 10:03 U.T. in the crater Pitatus. The crater was still illuminated. Rimae were obvious on the floor of the crater. The floor of crater Wurzebauer, southwest of Pitatus, appeared very unusual. Most of the floor looked like a raised sponge-like dome. Don’t pass up observing Rima Hesiodus. Look at the Clavius lunar light ray that is now occurring. See my report on this website.

By 08:50 U.T., slight shadows appeared on the floor. Within fifteen minutes, they were noticeably wider. The eastern half of the crater lied within the terminator. The summit of the eastern rim was bright.

By 09:15 U.T., shadows lengthened considerable and shaded most of the floor south of the central peak. Within another fifteen minutes, the southern half of the crater was mostly shadowed with several cone-shaped beams of light visible. The one that most resembled a ray was the one furthest south at approximately 30.5° S. It was dim, narrow, and rather short. Shadows in the northern half had lengthened and broadened.

At 09:44 U.T., the southern half of the crater was almost completely shadowed. Any illumination in this area was dim. The most southern beam of light still appeared as a ray. The northern half remained mostly illuminated, particularly north and west of the central peak. There was a particularly bright shaft of light emanating from the northwest wall to almost the central peak. It may be due to raised ridge formations located in that area. Another patch of light had a shadow cast onto it. Nothing in the northern half resembled a ray.

I now ended my observing session; clouds again entered the area. Civil twilight started, and sunrise was in twenty-eight minutes.

To answer Jay Reynolds’ question that he posed in his original report on this website: It is possible for the same formation to cause a lunar light ray to occur in opposite directions during sunset and sunrise. Other instances have been reported since your original posting.

There were several reports made on the sci.astro.amateur newsgroup. The following was submitted:

From DonTabbutt@worldnet.att.net Tue Feb  4 18:53:49 1997
Date: Mon, 3 Feb 1997 09:56:18 -0500
From: Donald Tabbutt 
To: Rob Robinson 
Subject: Re: Pitatus Ray

The Moon started rising over the hills surrounding Lake Cumberland at about
2:30 AM EST (07:30 UT) on Saturday morning. As the view to the east is
mostly over this huge lake, seeing was pretty good even at the horizon. I
observed the Moon for an hour, trying to make sure of what I was seeing.
Unfortunately, I think Pitatus and Hesiodus had just been thrown into
darkness by the terminator before moonrise (my longitude was ~85W). In
fact, although I won't stake my life on it, I believe the central peak of
Pitatus and one of its western ridges were still illuminated. The two
points of light I could see were exactly where Pitatus should have been,
and I consulted my book, The Moon, by Michael T. Kitt, to try and be sure.

Jay then sent me the following:

From freeman@netcom.com Tue Feb  4 18:53:36 1997
Date: Sun, 2 Feb 1997 23:12:14 -0800
From: Jay Reynolds Freeman 
To: robinson@sky.net
Subject: Re:  Pitatus

I checked a few of your times against my rough calculations, and we are
now in agreement within about half an hour.  I think you should run some
predictions for the east and west coasts, however, in case something is
visible there at a time when the Moon is not above the horizon for you.
Thus, I think the March event, nominally at about 21 hours UT on the
second, may be worth looking at on the west coast -- the nominal event
(geometric, smooth sphere) occurs after moonset, but if it actually
happens earlier we may get to see it...