Anomalous phenomenon in Sirsalis crater and Albedo changes

 Authors: R. Lena, PG. Salimbeni, J. Lobo, H. Mauer.

  Observatorio do Capricornio de Campinas Jean Nicolini (OMCJN-OC)

Introduction

In previous papers  (april 16, 1999 and July, 20 1999)  our group reported an anomalous phenomeno in Sirsalis Crater and the interpretation concerning random effect of the turbolence that cannot give   the intense variation  recorded on January , 30, 1999 at 1.00- 1.20 UT by Sorrentino Giuseppe (Italy).  The phenomenon covers a significant area of the floor surface (shadow) and it shows the same appearance twice (N12 and N 13) without a typical random fluctuation of the seeing (in relation to the shadow).

Also Sorrentino in a short communication. thinks that ONLY the seeing and noise  cannot  explain the phenomenon.
He reports the suggestion that the event could be produced by the sun that illuminated (sunrise) the external wall of the crater (with also the effect due to the turbolence ).
In date 20 July, 1999 the GLR group reported  that a flash in the wall due to illumination of sun seems to be a fast phenomenon for the large area (about 40 Km) like the possible regression of the shadow. 

 Fig 1-Animation model. It is visible an change of the shadow in the floor of Sirsalis.
 

The anomaly had increased illumination of entire crater floor with fluctuation of shadow while the  shadow of the other near crater does not display any unusual!!

Our investigation have the following objectiv: relate visual observations to several altitude of the sun. In this communication we report the albedo changes on Sirsalis in response to condition of varying solar illumination.

OBSERVATIONS AND INTERPRETATION

In the Sorrentino's Session the colongitude was 65° and the inner of Sirsalis was in shadow.
The selenographic parameters were:
longitude and latitude selenographic  3.89 and 3.75 ° respectively. The solar altitude on Sirsalis was 4,788°. The Moon's age is corresponding to 12,38 days (% frac. Illuminated 0.967).

The expected floor is also shown in Fig 2 and 3 below.
 

                      Fig 2-Morio Higashida- Sirsalis crater

 
 
Fig 3- January 8, 1944 (day 12,79) by the Book Atlante fotografico della Luna (Hoepli ed.)
 

Lena observed the crater in several sessions. A study concerning the shadow was performed.
Only in Fig 6 (colongitude 87.3) was recorded a short shadow (extension about 1/4 of Sirsalis).

  
 
 Fig.4-5-6 visual observations (by Lena ) variation of the shadow.
 

Fig 7- Sirsalis in shadow, visual observation carried out by Lena (SC 250 mm f/10 250x) at 19.00 UT colongitude 68.1

 Data concerning Fig 4-5-6-7 were:
Fig 4
date May 5,1999
colongitude  74
 longitude and latitude selenographic  0.9 and -6.5 respectively.
solar altitude on Sirsalis was 13,7°.
The Moon's age  13,4 days (% frac. Illuminated  0.98)
 
 
Fig 5
date July 26, 1999
colongitude 74.8
 longitude and latitude selenographic -3.0 and -3.2 respectively.
solar altitude on Sirsalis was 14,1°.
The Moon's age  13,7 days (% frac. Illuminated  0.98)
 

Fig 6
date july 27, 1999
colongitude 87.3
 longitude and latitude selenographic  -3.9 and -1.8 respectively.
solar altitude on Sirsalis was 26.2°.
The Moon's age  14,8 days (% frac. Illuminated  0.99)

In next day Sirsalis was hard to detect (high illumination). The area was estimed of albedo 5.5 Elger Scale (Full Moon July 28, 1999).

Fig 7
date august  24, 1999
colongitude 68.1
 longitude and latitude selenographic  -4.4 and -0.9 respectively.
solar altitude on Sirsalis was 7.42°.
The Moon's age  13.3 days (% frac. Illuminated  0.95)

In order to study obtain albedo changes the corresponding gray values were obtained:
 
 

* (---  feature no detectable in shadow,  ps feature partially in shadow)
 
 

* (---  feature no detectable in shadow,  ps feature partially in shadow)
*** Wall 8 Elger Scale but the NW wall was higher albedo (8.5 Elger) like in Sorrentino Session

The black value (0 Elger Scale) was observed also in fig. 2 and 3. Furthermore the shadow is visible for colongitude of 74.8 (altitude of sun 14.1°) as shown in Fig 4-5.The central peak of Sirsalis seems to be visible near colongitude of 74°. The shadow is present in Fig 7 (session similar to Sorrentino's frame) at about same colongitude (68.1).

In the Sorrentino's Session the colongitude was 65°  and the floor in shadow (the value of altitude of sun was only 4.7).

The session corresponding to Fig.7 was similar to Fig 2 (Higashida's Image). At this time the colongitude was 68.1 and altitude of the sun was 7.42°.
Futhermore during the session of Fig.7 no  changes or   regression of the shadow was recorded in 40 minutes (!!).

The wall of Sirsalis was illuminated (high albedo features) in all the observations (Fig 2-3-4-5-6-7) but the shadow was recorded!

The effect of solar altitude is shown also in fig.8-13 obtained by Julio Lobo and H. Mauer with a Zeiss 500 mm f/10 telescope of the Campinas Observatory (Brazil), seeing II/III Antoniadi Scale.

Fig 8- Julio Lobo and H. Mauer. (Zeiss 500 mm f/10)- Images carried out in date 25 august 1999 at 1.35 UT (colong. 71.4, solar altitude 10.6)

Fig 9- Julio Lobo and H. Mauer. (Zeiss 500 mm f/10)- Images carried out in date 25 august 1999 at 3.34 UT (colong. 72.4, solar altitude 11.6)

Fig 10-11 Julio Lobo and H. Mauer (Zeiss 500 mm f/10)- Images carried out in date 26 august 1999 at 1.34 UT (on the left colong. 83.6, solar altitude 22.5) and 3.49 (on the right colong.83.8, solar altitude 23.6)

Fig 12-13 Julio Lobo and H. Mauer (Zeiss 500 mm f/10)- Images carried out in date 26 august 1999 at 3.57 UT (on the left colong. 83.8, solar altitude 23.7) and 4.07 UT(on the right colong.83.8, solar altitude 23.7)

The albedo changes reported in fig 6 are the same of the fig. 10-12 (see the sequence by Julio Lobo).

 Other images obtained by Lobo and Mauer (25 august 1999 frames imaged every 15 minutes average) don't show substantial changes in the shadow.

 For these reasons the inner of Sirsalis was in shadow at time of Sorrentino Session (as visible). Only instrumental noise and seeing  cannot  to explain the event. Albedo change was recorded only for colongitude about 75° and the solar altitude during the Sorrentino's session cannot give this variation.

CONCLUSION

 New data obtained by authors seem to confirm the suspect event in Sirsalis crater. The event was imaged by Sorrentino in date january, 30, 1999.

Furthermore a study concerning other albedo changes near Sirsalis is also in progress.