A moderately sized telescope has been used with an image intensifier, CCD surveillance camera, video recording equipment and a Macintosh computer, to obtain high resolution images of the lunar surface. The captured images are examined and processed with computer software to achieve increased resolution for transient lunar phenomena (TLP) study and for comparison with project Clementine satellite images of the moon. The Association of Lunar and Planetary Observers (ALPO) have analysed several of these images and they report a possible TLP. The equipment and imaging techniques are described and the Calwell Lunar Observatory images are compared with those from Clementine.
During a program of collaboration with the Association of Lunar and Planetary Observers (ALPO) and the Clementine survey of the Moon, a technique to enlarge and enhance high resolution images of the lunar surface by computer was developed at the Calwell Lunar Observatory (Soulsby, 1994, 1995). The primary instrument used was a 15 cm f/7.3 Newtonian telescope shown in Figure 1. The telescope was quartz clock driven on an equatorial mount and was fitted with an image intensifier consisting of a 2 X Barlow lens and 6 mm orthoscopic eyepiece which magnified the image to 350X.
The images were recorded by a monochrome surveillance CCD video camera of 650 lines resolution. The image intensity was controlled by an iris taken from a camera lens and mounted between the secondary flat and the image intensifier. The iris was manually set by a remote control attached to the telescope also shown in Figure 1.
The instrumentation was housed in a slide-off roof observatory and wide angle images were obtained for calibration purposes, using a Sony HandyCam mounted behind one half of a set of binoculars to form a counterweight, as shown in Figure 2.
Observation of the Mare Crisium area was conducted for the ALPO Clementine Project (Soulsby, 1994, 1995) to capture images of the craters Proclus and Picard. The area of interest is shown in the lunar surface chart in Figure 3 below.
An image obtained by 12.5 mm eyepiece projection, was enhanced and enlarged by computer software to around 610X as shown in Figure 4 below. However, later use of an image intensifier provided greater magnification, and when images from this system were analysed with the National Institute of Health software Image (Versions 1.55-FPU and 1.58-68K), a greyscale surface plot from the software provided up to seven times further enlargement. It was found that the useful magnification could be effectively pushed to 2,450 times .
The first high resolution images obtained by computer enhancement were of the crater Picard as part of the ALPO 1995 Program for TLPs. A possible transient lunar phenomena event was observed visually and was captured on a video record at the same time. Analysis of the video gave an interesting result which showed brightening of the image on the floor of Mare Crisium to the west of the crater. This is shown in one typical image in Figure 5, taken from the one minute video sequence which has been recently independently analysed by the ALPO.
Some other Calwell Lunar Observatory images were compared with those from the Clementine data base found on the Internet at: * Link to Clementine Images
. Of particular interest was the partial image of Proclus identified as lua42714.151 and shown in Figure 6, including my computer generated contour surface plot to allow a comparison with other images of this crater in figures 7, 8 and 9 below.
My first imaging of Proclus with the image intensifier processed with NIH Image is shown at a reduced scale in Figure 7. The surface plot of the marked area on the right can be compared with the Clementine image above. This image is saturated at the centre of Proclus where a flat plateau was produced in that area of the contour plot.
From another series of images of Proclus, figure 8 was captured from a video scan of the Moon using the same instrumentation on 1995 September 12 commenced at 21:15 (UT) when the crater was near the terminator.
With a low angle of incidence of sunlight this image produced less saturation of the west crater rim, as can be seen in the excellent software contour plot in figure 9.
Downloads of Clementine features are compared with other Calwell Lunar Observatory images. Some of these features were not part of the author's ALPO TLP Project, but have been examined to help establish the usefulness and accuracy of this imaging method for future TLP searches. Such documented "hard copy" records would verify visual observations made by others in the program, and act as a back up to these visual TLP reports.
The Clementine images of Plato are far superior to the Calwell Lunar Observatory image taken on 1995 September 12 shown below. This was due in part, to the high angle of incidence of the Sun leading to saturation of the image and poor contrast. However, the contour plot in figure 15 does show the crater at a relatively high resolution, and sufficiently enlarged to detect any TLP activity.
The Calwell Lunar Observatory image of Plato in figure 15 was marginal due to the almost overhead Sun, which give poor contrast. Recent images show the degree of improvement possible when optimised seeing and illumination of the feature is achieved. This image in figure 16 was optimised by capturing the feature on-line and under remote control, with improved results. A contour plot from the marked area is shown in figure 17.
An independent analysis of some of my images has been conducted by the ALPO. Their first analysis concerned my star like flash reported in Picard. Dave Darling and Gilbert Lubcke (Darling, 1995) found a bright spot inside Picard on my second image (see figure 5) which caused them some excitement. However, the spot took on the form of a crescent (see figure 9) and when further enhanced they identified this as a normal feature in the Hamlyn Atlas of the Moon by Antonin Rukl [see page 197, photograph 13, Proclus]. However, in my copy of the Hamlyn Atlas, there does not appear to be a crescent, but only a bright ring.
They concluded that the possible cause of the flash reported on the inner terrace of Picard and imaged by the high resolution system described here, was a high albedo feature imaged at a moment of high clarity which appeared to flash on my screen (video monitor).
The second ALPO report concerned my earlier low resolution observations of Grimaldi during the Clementine mission (Soulsby, 1994-5). Winifred Cameron a TLP specialist, made the following comments in her recent paper (Darling, 1995):
"The last noted phenomena was on April 28 in Grimaldi in Byron Soulsby's data. He provided profiles from his video camera CCD equipment on a 152 mm [diameter] 1097 mm [focal length] reflector, in Calwell, Australia in a A-1 (excellent) seeing. It was noted that in one profile, one of the absorption bands [contour traces] was deeper than the other two profiles, thus suggesting a possible anomaly occurred and may constitute a real phenomena, thus weight is given at 3 (possible to probable). Grimaldi was imaged from 12h 08m to 12h 32 m [UT on 1994 April 28]."
In the BAA Lunar Section Circular for 1995 October (Cook, 1995) some email received from the ALPO (not sent to me) was published with the same conclusion on the Picard report, and discusses the use of the software MIRA used by the ALPO.
Following the favourable ALPO report on the examination of the Proclus/Picard images and the "possible to probable" TLP concerning Grimaldi (see Appendix), it is considered that the instrumentation and software described here, has proven successful in producing high resolution images and surface contour plots of adequate definition to document observed and possible transient lunar phenomena.
It is planned to use the technique for future lunar observations, including a recent improvement of remote control of the telescope tracking by the addition of a simple declination motor drive. Images can now be captured in "real time" at the computer, with remote control correction of both axes of the equatorial mounting of the telescope.
The encouragement from Jeremy Cook and Gerald North, of the British Astronomical Association Lunar Section, and TLP Sub-section, and from David Darling and David Weier of the Association of Lunar and Planetary Observers is gratefully acknowledged. The recent ALPO report concerning their analysis of my video images of Picard and Grimaldi are also appreciated and acknowledged.
Soulsby, B.W., Brakel A.T., 1994. The Clementine Project and transient lunar phenomena (TLPs), Australian Journal of Astronomy, 5, (6), pp 201-210.
Soulsby, B.W., Brakel A.T., 1995. Clementine and Transient Lunar Phenomena, Southern Sky, May/June 1995, pp 50-54.
Darling, D. O., 1995. Private communication from the Association of Lunar & Planetary Observers, Lunar Transient Phenomena Section, 1995 October 4.
Cook, J., 1995. TLP Subsection, BAA Lunar Section Circular, 31, (10), pp 125.
Grimaldi Analysis
A second imaging session for 1994 was recorded on April 29 from 12h 04m to 12h 32m (UT) and analysed using a frame grabber and image analysis to give a gray scale trace passing through several images of Grimaldi and included 3D gray scale surface plots.
Conditions during imaging session were slightly cloudy but calm with an observatory temperature of 14oC. While no TLP activity was recorded, a sequence of images in one minute steps from 12h 04m to 12h 24m (UT) was used to illustrate the accuracy and consistency of the method. One of these images with three grayscale contour traces which could indicate TLP activity, are included above. A survey of the complete video record did not reveal any TLP activity.
Conclusions
Considering the condition of the original image (Figure A-1) it is unlikely that a TLP did occur, but it is interesting that a "possible to probable" weight was given.
I think this shows that the image analytical methods used here are quite new to the TLP fraternity and should be further developed.