Anomalous Phenomenon on Sirsalis crater

  By Geologic Lunar Researches group and Lunar Observatory Apuleio

 
Giuseppe Sorrentino, Raffaello Lena, Piergiovanni Salimbeni, Guido Santacana, Eric Douglass, Morio Higashida.
Prepared 16 April 1999



Abstract:

Images of Sirsalis crater have been recorded on January , 30, 1999 at 1.00- 1.20 UT. The captured CCD images are examined and processed with computer software to achieve increased resolution for TLP study and for comparison with Lunar Orbiter images of the moon. The results obtained may indicate a possible real event.
 

 Introduction

During a program of collaboration with the Lunar Apuleio Observatory (LOA) the Geologic Lunar Researches Group (GLR) has developed a technique to enhance high resolution images of the lunar surface by computer software. The gray scale analysis may be used also for TLP events. Transient Lunar Phenomena are short lived changes in the appearance of lunar features. The cause of these changes is as yet unknown but may include Tidal stress induced on the Moon by the Earth, the moons passage trough the Earths magnetic tail, meteor strikes and gas release.
 

Crater Imaging

A possible presence of anomaly (suspected TLP event)  was recorded by G. Sorrentino on january, 30, 1999 at 1.00 UT. The CCD frames were obtained by Schmidt Cassegrain telescope of 200 mm of diameter f/10, seeing III-IV (Antoniadi Scale). Wratten 25 filter (red) was used. The frames were carried out by a momochrome CCD video camera  (TC 398) of 380 lines resolution and sensibility of 0.03 lux.
The several frames were taken from the typical sequence of two minutes.
The area of interest is shown in Figure 1 below, corresponding to Sirsalis crater.

 

Fig.1 colongitude 65.38, The boxed area is Sirsalis crater. (G. Sorrentino on january, 30, 1999 at 1.00 UT SCT 200 mm f/10).

At this time the corresponding selenographic parameters were:

colongitude was 65.38 °, longitude and latitude selenographic was 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) and phase angle was 21.5°.
Sirsalis was imaged from 1.00 UT to 1.20 UT but some  intermediate frames (deleted) were not available.
In fact the seeing was instable and only the next day it was possible to analyse the images' sequence.  In date April, 12, 1999 Sorrentino sent the available sequence, in order to have a preliminary analysis by GLR group.
The frame N3 was the first image (hour 1.00 UT) , lines -------represent frames N4-N7 (deleted), frame N8 was similar to N3 (1.10 UT), lines -------- represent frames N9-N11 (deleted), frame N12 showed the  brightening of the image on the floor of Sirsalis (1.18 UT), frame N13 was the next (1.20 UT) and lines -------- represent the last frames deleted.
 
 
 

    ------------ --------

N3                                                N4-N7                        N8                           N9-11
 

  ---------

N12                                                N13
 

Fig.2- The sequence

Probably , in frame N13  the shot (angle of view)  is shifted. However the floor of Sirsali is dark from N3 to N8 and it is clear from N12 to N13.  The difference between N8 and N12 was about 8 minutes.

This change is shown in one typical animation in figure 3.

Fig.3 Animation model. It is visible an change of the shadow in the floor of Sirsalis.
 

Frames obtained in the next days were not affecting by deformations and/or pixel alterations.

Observations (visual and CCD) conducted in the past (and same conditions) no showed anomalies. In  the CCD image obtained by Higashida (Japan) is visible the expected floor of Sirsalis (Figure 4).
 






















Fig.4- Sirsalis crater  recorded by M. Higashida (Japan).


 

Gray Level and MSH Values

When the Eyedropper is selected, the  MSH values of the pixel under the Eyedropper are displayed. The values obtained give an adequate definition of the several pixels.

The boxed area has been analysed to produce the corresponding values of the pixels.

 

Fig.5- Sirsalis, on the right is reported the values of shadow, midtone and highlight


Fig.6- Sirsalis, on the right is reported the values of shadow, midtone and highlight.
In frame N8 the shadow and midtones values were 8,7 % and 86,6 % respectively. The change was recorded in the frame N12. In this frame the values of shadow amd midtone were 7,8% and 88,1% respectively.
We have also examined other nearby features to see if the seeing was affecting them but the gray level was  similar. Only the crater floor and the boxed area in figure 7   increased the illumination. Some variations might be due also to turbolent conditions of the atmosphere.

 
Fig.7- Feature and relative equalization
Histogram Analysis

A histogram is a graph of the distribution of  luminance values in an image. The values appear on the horizontal axis from dark to light (left to right). The vertical axis indicates the number of pixels of the value at each point. At a point where there are many pixels of a value, the corresponding line spikes; where there are no pixels, it lies at the bottom of the graph.
The number of pixels that match the histogram’s maximum and  minimum, and the average value were obtained. The luminance spectrum appears on the histogram's horizontal axis, ranging from zero luminance (black) to full luminance (white). The vertical axis indicates the percentage of the source image that matches a point on the luminance spectrum.
 
Different spectrum was obteined for the floor of Sirlasis and no change was noted in surrounding area and craters.

 
 

 
 
 

Fig 8- Relative spectra (contour traces) in Sirsalis frames.

In one profile the absorption bands (contour traces) was deeper. It is correspond , principally, to  distribution of midtone.



 
 

Fig 9- Comparison of the contour traces corresponding to frame N8 and N12.

In the imaging session there are  turbolent conditions but the change observed is clearly in the surface and not part of an atmospheric related events.

 Image Comparison

 The our elaboration  of the marked area (fig 11)  can be compared with the  image 12 used as control. This comparison shows a different illumination of the crater. The zone sited to north west (IAU), on the left box  in fig 11,  also shows an anomalous change of albedo. Furthermore the frame N12 shows a faint change of albedo for the craters F and J.

 
Fig 11- Elaboration of the frame N8 and N12 in blu filter (Salimbeni PG.)

Fig 12- Elaboration of the Higashida's image in blu filter as a control frame (Lena R.). The image is corresponding to Sorrentino's frames. On the right of Sirsalis there are the small craters F and J. On the left the presence of craters B and C is evident (see Rukl chart 39).

 Lena, Salimbeni and Santacana  have studied the frames and the relative histograms that show the change in the light conditions. Several images were analized in order to determine the presence of specific features  which might serve as efficient reflectors under different altitude of sun. However Lena and Salimbeni concluded that if a high albedo feature was imaged at a moment of high clarity it cannot give a similar flash in a large area (about 40 Km). The random effect of the turbolence is possible but also the intense variation must be considered.  It seems to be a brightening event. No data concerning TLP events in Sirsalis were obtained in literature.
 

 
 

Conclusion

 The histograms  show the change in the light conditions. Furthermore the phenomenon covers a significant area of the surface,  suggesting a possible anomaly. For this reason we report the suspect TLP so that this area remains under scrutinity for a while. Future observations and CCD images are encouraged. We hope in a future collaboration of several observers in the world !
 
 
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