Interpretation about anomalous phenomenon in Sirsalis crater
 
Raffaello Lena, Piergiovanni Salimbeni

Prepared 20 July  1999
 
 
Introduction
In date april 16, 1999 our group reported an article concerning an anomalous phenomenon in Sirsalis crater. Images of Sirsalis crater was 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,  suggesting a possible anomaly. We reported the random effect of the turbolence but also the intense variation (shadow in Sirsalis) must be considered. For this reason we reported  the suspect anomaly (possible TLP)  so that this area remained under scrutinity for a while.
We contacted also the ALPO (TLP Coordinator) and BAA. No answer was obtained.

In date july 5, 1999 the UAI Lunar Section reported a short note on the same phenomenon.
 In UAI paper, the authors report that is difficult to impossible the event on Sirsalis. Their interpretation was that electronic instrumental noises with the presence of turbolent conditions of atmosphere give a random effect.

GLR group in date april 16, 1999 considered the presence of turbolent conditions. Several features (point at high albedo)  change the relative bright (as points or elongated features) but the change in floor of Sirsalis (shadow) is  in the large surface!
 

This change is shown in one typical animation in figure .

 Animation model. It is visible an change of the shadow in the floor of Sirsalis.
 
In date 20 July 1999 Giuseppe Sorrentino reports his consideration in a short communication.
 

Also Sorrentino thinks that ONLY the seeing and noise cannot explain the phenomenon.
In this work  we report several considerations.

 
INTERPRETATION
 

The UAI Lunar section pointed out that the phenomenon is due to a combination of instrumental noise and seeing.
GLR group has a different opinion because we have seen all the Sorrentino's sequence (Frame N8 to N13). (see link )
CCD was not affect by problems in the next imaging sessions. The external reflex cannot give changes in different locations (random reflex). If you see our report and the sequence
the anomaly is similar  in 2 next frames (N12 and N13) taken at about 80-90 sec.
UAI interpretation does not clearly explain several points of view such as:
1) The reflex and/or electric problems were captured from  CCD  in the same way twice (!?).

2) 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 symptoms.
If there is a spurious origin the CCD have captured the same appearance twice (and then the phenomenon has not  a typical random fluctuation !?).
 Only the seeing may give a random effect. Furthermore the turbolent conditions affected only the high albedo features.For this reason you would find the bright spots blinking on and off . The shadows in  near craters don't change in evident appearance (see the animation). Only the inner of Sirsalis changes in the imaging session of Sorrentino. Sirsalis A and Sirsalis also show the albedo change in reverse way (... more bright and  more dark in reverse way...).
 It is very difficult to think   that a random effect  may give only fluctuation in Sirsalis shadows  while the fluctuation does not affect  (as expected by random effect) the shadow of near craters.
UAI section has not shown an different and indipendent frame imaged the same night by other observer in order to prove own conclusions ( no possible anomaly as real event ) .
 

Lena in date may 28, 1999 at 21.00 UT observed (seeing III Antoniadi scale and very turbolent) Sirsalis. Visual observation confirmed the expected floor in Sirsalis (colongitude of 73.7, day 13.3 and % illuminated frac of 0.98). The inner of Sirsalis was in shadow as expected.

 
 
  UAI thinks that the seeing gave  a random effect  and  in some images the brightness came through and in others it did not.
Furthermore the GLR data show the albedo change in Sirsalis crater under several  conditions of illumination during past lunations. Interpretation must  consider also the topographic and estimated albedo value which assign standard black condition in shadow of Sirsalis at time of the imaging session (January , 30, 1999 at 1.00- 1.20 UT ).
 

   Lunar Orbiter image

 For these reasons it is not very probable that only instrumental noise and seeing may to explain the event. Interpretation concerning only instrumental noise and seeing is almost ... restrictive.
On the contrary the  anomaly is possible. For this reason in date april, 16, 1999 we reported  the suspect behaviour of Sirsalis!
For colongitude corresponding to Sorrentino session (data GLR) the crater is dark (!) and a flash in the wall due to illumination of sun seems a fast phenomenon for the large area (about 40 Km).
The event is strange.

 There are observers that observed or imaged Sirsalis the night of January , 30, 1999 at 1.00- 1.20 UT ?
We encourage you to send us your observations .

 

Transient Lunar Phenomena