3 november 2001
Lunar occultation of Saturn
by Lorenzo Comolli

In Europe this occultation was awaited as one of the nicest events of 2001. For record this event I've realized a film with my camcorder.

I've used a 20cm f/10 Schmidt-Cassegrain telescope with a Panoptic 22mm eyepiece for afocal projection with the digital camcorder Panasonic DS-15, in gain up mode (1/10s exposures) and with optical zoom set to 14x (9x during reappearance). The camcorder was adapted to the telescope so that the objective is on the eyepiece. The seeing was quite good, II in Antoniadi scale. All the images and film are correctly oriented, with north up and east left.

AVI films
Click on the images
Disappearance (640kb)
Duration: 1'59"
Frame rate: 10 fps
Reappearance (310kb)
Duration: 58"
Frame rate: 10 fps
For reading this films you need to have the Div-X decoder/encoder, a plugin for the AVI format. If you don't have, download here (700kb). Even if you don't want to see the Saturn films, download it because it's wonderful! This films are compressed at 150:1 and however their quality is good!


This images were realized elaborating many frames of the film.
The more exciting phase is the gradual disappearance of the disk and rings of Saturn behind the Moon. This phase lasted about a minute and half!
Mean of about 60 frames, unsharp mask.
A reconstruction of the reality: the great difference in brightness make impossible to expose correctly both the Moon and Saturn. So at the end of the disappearance I've adjusted the camcorder sensitivity to mach for the Moon. Then during the elaboration I've put the correct Moon above the saturated one. 
Mean of about 60 frames fo Saturn plus 20 frames for the Moon, unsharp mask.
This phase was more difficult to register because it was nearly impossible to guess the exact position were Saturn will reappear! So I've lost the first 15-20s of reappearance.
Mean of about 20 frames, unsharp mask.
Saturn imaged a while after the end of the occultation.
Mean of about 110 frames, unsharp mask.

Picture of 24 images of disappearance(each one is a mean of 20 frames)

Picture of 16 images of reappearance (each one is a mean of 20 frames)

Occultation data (computed)

Occultation Predictions for Tradate in novembre 2001
E.Long.    8 54 29,5   Lat.  45 42 48,0   Alt. 300m.   T.dia 200mm.   dMag 0,0

phenomena           TU     height  azimut    P.A.   duration*
Disappearance    20.54.58    31°      91°     69°     38s
Reappearance     21.59.40    42°     104°    251°     42s

* the duration refer only to the disk, the rings time is about 90s.

Illuminated fraction            92% waning
Longitude libration             -4°,77
Latitude libration              +1°,78
axis A.P.                       354°,4
Phase angle                     85°,2

A.R.                            4h50',3
Declination                     +20°35'
Constellation                   Taurus
Distance from Earth             8,218 AU = 1.229 million of km
Equatorial and polar diameters  20",3 x 18",5
Mv                              -0,1
Sun elongation                  148° west
Ring dimension                  45",7 x 20",1
B Sun                           -26°,0
B Earth                         -26°,0

Thanks to Simone Bolzoni for the data about Moon and Saturn

For any comments (also about my bad English), write to: comolli@libero.it

HTML Editing and Publishing by Lorenzo Comolli. Email me at comolli@libero.it.
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