by Raffaello Lena ( GLR group)
Data collected by R. Lena, C. Fattinnanzi, KC Pau, Pg Salimbeni, M. Cicognani, G. Mengoli, L. Comolli and A. Zanazzo
 
 

Introduction
The NSSDC catalog includes all reported  phenomena regardless of the perceived weight of the observation.
During a GLR project we studied a preceding observation by  Kelsey, 1967 April 18.
The event is described: " Streak on Plato's floor showed slight enhancement in red filter
compared  to blue filter. Later, a 2nd streak formed. Probably the sun shining thru a valley in the rim. Red enhancement permananet? (Wise suspected a blink here 6h eaelier). Weight=3"

The observations  carried out on May 9 2003 match the lighting condition to within +- 0.1 for the
Plato event by Kelsey.
The local altitude of the Sun H, azimuth of the Sun , A, and its colongitude C, were calculated with the Lunar Observer's tool kit software by H. D. Jamieson.
For may 9 2003 at 19:00 UTC
 Solar Altitude  over Plato =   1.101°
 Solar Azimuth =  91.933°
  Co-longitude =  11.499°
An event described by Kelsey
Lena reported :"At 20:15 UTC i saw 2 streaks on the Plato's floor. The floor was in shadow.
Over the next 30 minutes i saw the shadow's retration, showing how rapidly the appearance of this area changes with increasing solar elevation.
 

The reported streaks by the Kelsey, 1967 April 18, were very well visible.
The streaks showed an "apparent blink" using blue  filter (W 80A) and red filter (W 25A).
In fact the 2 streaks on Plato's floor showed slight enhancement in red filter compared  to blue filter. Blink was conducted every 5 minutes

The observation by Lena was carried out using a refractor 100 mm f/15 at  150-170 x , under a seeing of II-III Antoniadi .
Using the Elger scale their albedo values was estimated as follows:

Blue light= 2.0 +- 0.5
Red light= 3.0 +-0.5

So the streaks show a red component.

This GLR observation that match the  Kelsey's   event, on different date but at the same colongitude, suggest strongly that this phenomenon is a normal effect

Albedo Variation
We have studied , and documented , the albedo changes in response to conditions of varying solar illumination.  Furthermore the following notes and drawings are a representative selection of these features and give a basis for further observations.These data may be used in order to study future TLP events.
 
 
 
 
 

KC Pau  13 november 2002    11:10 UT - 13:46 UT, Takahashi CN212  colongit.  12.77° - 14.09° - H  2.56° - 3.37°.

C. Fattinnanzi ,  20 may 2002   at 19:31 UT, Newton 200 mm C= 16.46°  H= 4.03°.
 

R. Lena , 12 may  2000   at 18:30 UT, Refractor  100 mm, C= 18.60°  H= 4.90°.

R. Lena ,  15 september    2002   at  20:10 UT, Refractor  100 mm, C= 18.80° H= 6.60°.

M. Cicognani ,  2 february   2001 at   19:00 UT, Cassegrain 41 cm C= 22.52°  H= 7.60°.
 
 

C. Fattinnanzi ,  22  april  2002   at 20:10 UT, Newton 200 mm  webcam Vesta Pro,  C= 34.95° H=14.67°.
 
 

M. Cicognani ,  23 april 2002 at   21:00 UT, Cassegrain 41 cm C= 47.55° H=21.68°.
 
 

M. Cicognani , 5 february   2001  at  22:00 UT, Cassegrain 41 cm C= 60.46° H=28.32°.
 

M. Cicognani ,  20 octobre 2002  at  20:00 UT, Refra ctor 120 mm, C=84.89°  H= 38.10°.
 

M. Cicognani,  (sunset) 8 august 2001  at  03:00 UT, Cassegrain 41 cm C= 135.81°
H=  30.91°.
 
 

M. Cicognani,  (sunset) 9 august  2001  at   03:00 UT, Cassegrain 41 cm C= 148.01°
H= 25.12°.
 

M. Cicognani, (sunset)  10 august  2001  at   03:00 UT, Cassegrain 41 cm C= 160.22°
H= 18.46°.
 
 

A. Zanazzo e L. Comolli, (sunset) 30 august  2002 at  05:00 TU , Trischiefspiegler  30 cm and  webcam Vesta pro, C= 175.11°  H= 9.98°.
 
 

G. Mengoli, (sunset)  31 august  2002 at  02:50 TU ,   Takahashi Mewlon  20 cm   HX516 Starlight-Xpress. C= 186.21°  H=3.12°.
 
 

Rome 14 may 2003

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