Ken Fields reported us an interesting report about the  presence of a strange effect in Herschel  crater.

He recorded (using C14 telescope) an  original image at f/4 with the appearance of a specific feature which seems to be a Lunar plume.

In this evaluation  clearly  the structure  was not an artifact but rather a matter of resolution and it began to show clearly structure at f /11.

Futhermore  at f / 33 the plume disappeared and the structures of the surrounding craters were resolved.

This was a very valuable learning experience for many who viewed the original image and set standards for how such images should be evaluated.
 

Ken Fields used an ST7 at f/4 and a Meade 416 CCD at f /11. At  f/33 hooked to an OPtec flip mirror with a triple barlow.  The Telescope used was  the C14 .

On 14 June 2000 was recorded the image shown below.

 
 original image at f/4 with the appearance of a specific feature which seems to be a Lunar plume.

Data ST7 at -5-a 110 millisecond image through a blue filter .

The region of Sinus Iridium. Herschel (on the top) is in shadow. Image obtained by A. Bares and P. Gualdoni (with an HX516 camera fitted to a Mewlon Takahashi 250 mms at f/12)

We agree with Fields .
 

On 12 July 2000 Fields took a number of images at f33 with the following result:

At f / 33 the plume disappeared and the structures of the surrounding craters were resolved (image by Ken Fields).

With a low solar angle there is an extended structure having  high albedo. The structure  is a topographic feature located in the west rim of Herschel . The structure is an complex Hill and it shows an elongated extension in visual observations carried out by Lena. In this session the moon came back in the same shadow.

R. Lena- The Herschel crater on  10 August 2000 at 20.48 UT (Newton 114/900 180x seeing II Antoniadi Scale).

This discussion and the report of K. Fields shows how such images should be evaluated.

The structure is not an anomaly. Our observations shown the normal aspect of the crater.

We thank Ken Fields for the autorizathion to publish the images and the his excellent evaluation.