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Vol 49, No 4, April 2012 - BAA Lunar Section

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Director: Bill Leatherbarrow<br />

The British Astronomical Association<br />

<strong>Lunar</strong> <strong>Section</strong><br />

Circular<br />

<strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong><br />

Editor: Peter Grego<br />

J. Herschel, imaged by Bill Leatherbarrow on <strong>2012</strong><br />

February 2, 23:24 UT, Col. 47.0°. 12-inch MCT @<br />

f/20, DMK21 mono camera. Seeing AIII.<br />

From the Director<br />

While sporadic observation of lunar surface features is both enjoyable and rewarding, there can be no doubt<br />

that drawings and images secured with a specific purpose in mind are usually more so. Observing the Moon<br />

for pleasure alone is not to be scorned, of course, but a systematic approach can sometimes yield unexpected<br />

and valuable results. Two examples from the March <strong>2012</strong> LSC will illustrate my point.<br />

As Nigel Longshaw points out in his article on lighting effects in Plato, that crater is one of the most<br />

observed and imaged features on the lunar surface, and some of the results being achieved today display<br />

phenomenal resolution of fine detail. However, Nigel’s careful use of both historical and modern observations<br />

results in an intriguing account of the unexpected appearances produced by sunrise and sunset illumination<br />

of Plato’s interior, one that allows us to look afresh at many of the past reports of transient phenomena in that<br />

region. His systematic comparison of old and new observations clearly suggests that the appearance of<br />

illuminated ‘tendrils’ and patches of milky ‘half-light’ is probably nothing more than the natural outcome of<br />

a combination of lighting, local topography, and perhaps the reflection of light onto the floor of Plato from<br />

brightly illuminated walls. His article gives us a clear steer for further drawings and images of Plato under<br />

appropriate illumination in order to check his conclusions.


It was a pleasure to see a contribution from Barry Fitz-Gerald, who was an active member of the <strong>Lunar</strong><br />

<strong>Section</strong> some time ago and who has now returned to the fold. Barry’s piece on Catena Krafft shows the value<br />

of careful analysis of the vast repository of spacecraft imagery now available online. His view that Catena<br />

Krafft cannot be a secondary crater-chain originating from Krafft is undoubtedly correct, since it clearly<br />

impinges upon the floor and walls of that crater. The problem traditionally associated with regarding it as a<br />

secondary feature from Cardanus has been the fact that it is clearly not radial to Cardanus. I did wonder briefly<br />

whether it might be a secondary feature from Orientale, but the alignments don’t work out. Barry’s view that,<br />

along with the craterchain to the west with which it forms a triangle based on the N rim of Cardanus, this<br />

might be evidence of an oblique impact is certainly worth considering and I can think of no alternative<br />

account that fits the observational evidence. I am less persuaded by the suggestion that the central ridge<br />

crossing the floor of Alphonsus might be the result of an oblique impact that produced neighbouring Arzachel.<br />

The alignment of the ridge with other impact scars in the area suggests that, even if it is a deposit feature, it<br />

is more likely to have come from the impact that produced Imbrium. The evidence for oblique impacts on the<br />

Moon is growing daily (hardly surprisingly, since such impacts must have been plentiful), and there is much<br />

more evidence to be found both at the eyepiece and on images.<br />

On the question of impact ejecta, I attach an image of the crater J. Herschel, taken on <strong>2012</strong> February 3<br />

(shown on the front page). Despite the poorish seeing, what immediately struck me was the unusual nature of<br />

the rubbly infill that litters the crater’s interior (also shown in the LRO image below). This is presumably ejecta<br />

from Imbrium, and it is clear that J. Herschel took a real battering. However, although the SE half of the interior<br />

looks more or less as you might expect under such circumstances (apparently randomly distributed mounds and<br />

secondary impacts, including chains pointing back towards Imbrium), the NW half shows strange patterns in the<br />

distribution of ejecta material. It almost looks like martian dunes arranged in curved, arcing formation—and it<br />

does not appear to point a finger back at Imbrium. Moreover, there appear to be fewer secondary impact craters<br />

in this half. Chuck Wood has suggested that this effect is caused by the tendency of impact ejecta to ‘swirl’.<br />

Further analysis of existing imagery, both Earth-based and spacecraft, might help shed further light on this.<br />

So, plenty of things to think about and to direct our observations!<br />

Bill Leatherbarrow<br />

J. Herschel, imaged by LRO. Image: NASA / LRO LROC team.<br />

Director, <strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong><br />

2<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


Topographical notes<br />

compiled by Peter Grego<br />

Visual studies and observations<br />

Since March’s LSC, visual topographic lunar observations have been received from Peter Grego (St Dennis,<br />

UK), Chuck Hastorf (Arizona, USA), Philip Jennings (York, UK) and Phil Morgan (Tenbury Wells, UK).<br />

Some of these observations and accompanying notes are reproduced below.<br />

A note on submitting visual observations<br />

All visual observations should, in the first instance, be sent to the Director, Bill Leatherbarrow, by regular<br />

mail or, as is far more frequently the case these days, as email image attachments (Bill’s address is on the last<br />

page). If possible, please copy me in on the email with the attachments at editor@baalunarsection.org.uk, as<br />

it saves Bill the need to send them on to me for consideration for inclusion in the LSC.<br />

Please note that while observations are encouraged to be posted to the <strong>Lunar</strong> <strong>Section</strong> Visual Studies<br />

Yahoo! Groups website http://uk.groups.yahoo.com/group/baalunarsection-topography/ it’s important not to<br />

regard this as the official <strong>Lunar</strong> <strong>Section</strong> archive or the primary repository for observations. The site is meant<br />

to be an adjunct to the main work of the <strong>Lunar</strong> <strong>Section</strong>, and serves as a forum, so please ensure that if you do<br />

post observations there, also to send them to the Director (and me if possible). That way, nobody’s work will<br />

be missed and it will be officially archived, available for comment and analysis.<br />

Clarity in labelling image and observation files is important, both to avoid ambiguity and confusion and<br />

to make filing, archiving and accessing material easier and more efficient. Ideally, all image files should<br />

contain unambiguous date and time data, feature observed, instrument used and observer name. Other<br />

information pertaining to the observation, such as colongitude and libration, should be included in the<br />

covering notes, along with a written description (if any) of the observation.<br />

Vallis Alpes and possible dome in Montes Alpes, <strong>2012</strong> March 29<br />

Philip Jennings<br />

The last time I sketched this region I lingered on the area for too long, resulting in inaccuracies caused by<br />

previously invisible features popping up half-way through the session. To avoid making the same mistake this<br />

time round, I drew very<br />

quickly. Even so, it took<br />

me 75 minutes to<br />

complete my drawing.<br />

Under such a low<br />

illumination, I couldn’t<br />

find an accurate template<br />

to help me position<br />

features accurately, so I<br />

hope it looks about right.<br />

The valley was looking<br />

spectacular, but one<br />

feature that caught my<br />

attention that evening<br />

was a small, circular<br />

‘bump’ amongst the<br />

mountains (arrowed),<br />

apparently very low. I<br />

doubt it would be very<br />

evident at all if the angle<br />

of illumination was<br />

much higher. Could this<br />

be a rare example of a<br />

highland dome<br />

Full Moon at perigee<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 3


John C Vetterlein<br />

An inspection of a table for the Moon’s perigee in <strong>2012</strong> reveals that the event on May 06 has our natural<br />

satellite at a distance of 356,955 km compared to 369,886 km on January 17. This equates to an apparent<br />

diameter for the Moon of 33’ 28” and 32’ 18” respectively. Interesting in itself, but when one looks more<br />

closely at the data for May 06 we find that Full Moon occurs within less than two minutes of perigee itself.<br />

This struck me at once and so I made a quick survey of the coincidence of perigee and Full Moon over a<br />

period of 20 years and found nothing to compare with <strong>2012</strong> May 6. I contacted Jean Meeus, a well known<br />

authority on astronomical algorithms, who supplied me with a short table of incidences of Full Moon close<br />

to perigee between 1972 <strong>No</strong>vember 20 and 2034 <strong>No</strong>vember 25, as shown in the following table. All times<br />

reduced to Universal Time (UT).<br />

Date Full Moon Perigee Dif. (minutes)<br />

1972 <strong>No</strong>vember 20 23:07 24:02 55<br />

1992 January 19 21:28 22:13 45<br />

2011 March 19 18:10 19:09 59<br />

<strong>2012</strong> May 06 03:35 03:34 1<br />

2013 June 23 11:32 11:12 20<br />

2014 August 10 18:09 17:43 26<br />

2034 <strong>No</strong>vember 25 22:32 22:05 27<br />

One should state before we go any further that modern lunar theory has advanced considerably over recent<br />

years thereby rendering it possible to make predictions over a substantial period of time that would have been<br />

impossible 100 years ago.<br />

I decided to extend Jean’s analysis to cover the period between 1900 and 2121 (an interval of 221 years).<br />

Having done this I then contacted Jean again who verified my results for the most important events as follows:<br />

Date Full Moon Perigee Dif. (minutes.)<br />

1912 January 4 13:30 13:34 4 (6 min.)<br />

1953 September 23 04:16 04:26 10 (11 min.)<br />

<strong>2012</strong> May 06 03:35 03:34 1<br />

2095 October 13 09:31 09:26 5 (3 min.)<br />

2114 December 12 06:20 06:35 15<br />

Figures in brackets are from Jean Meeus himself. The concordance will be seen to be very good.<br />

In my analysis the original table of concordances for the 221 year period amounted to over 300 entries<br />

with differences in the two events amounting to no more than 10 hours. The five dates given in the above<br />

table stood out from the rest indicating that the <strong>2012</strong> May 06 is exceptional by any standard.<br />

The fact that on <strong>2012</strong><br />

May 06 as seen from the<br />

UK the Moon will be in a<br />

twilight sky, and within<br />

an hour of setting, is to an<br />

extent unfortunate but<br />

insignificant compared to<br />

the juxtaposition of the<br />

two events themselves.<br />

I should like to thank<br />

Jean Meeus for his<br />

prompt and helpful input<br />

to this investigation.<br />

The perigee Full Moon on<br />

<strong>2012</strong> May 06, 03:35 UT<br />

(twilight sky).<br />

4<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


Sunrise on Plato<br />

Nigel Longshaw<br />

In the last circular I discussed sunrise on Plato and the possibility of the duality of the ‘ashen light’ previously<br />

observed by Phil Morgan. As an example of early sunrise on Plato a drawing by Gerald <strong>No</strong>rth which appeared<br />

in the J<strong>BAA</strong> 1986, 96, 3, was reproduced. I was pleased to subsequently receive a note from Gerald regarding<br />

his drawing and further discussion in relation to early sunrise on Plato. Gerald forwarded me a copy of his<br />

original drawing from his observing notebook, the copy I used from the original journal paper was not<br />

reproduced very well. It is clear from the original drawing (Figure 1) that Gerald recorded two sunlight<br />

‘streaks’ on the crater floor. Gerald notes the following:<br />

As you can see it (Figure 1) shows<br />

the main spire of light together<br />

with a shorter and dimmer one,<br />

which was missed out of the LSC<br />

reproduction. This is vaguely<br />

reminiscent of the CCD image in<br />

Tony’s piece, coincidentally about<br />

Plato shadows, on p19 of the LSC<br />

(March issue). I don’t suppose<br />

readers of the LSC will realise that<br />

mine is not a topographic<br />

drawing, merely a quick sketch<br />

showing an effect that I deemed of<br />

note... perhaps it would be helpful<br />

to supply a little of my original<br />

notes from my observing log:<br />

Figure 1.<br />

Telescope: 18.25-inch (464 mm) Newtonian, 2.59 m focal length.<br />

Date: 1981 February 12<br />

Time: 18h 54m - 20h 56m UT<br />

Magnifications: 86×, 144×, 207×, 288×, 414×, 432×, 576×<br />

Transparency: Poorish due to haze (limiting magnitude approx. 3.0 - 3.5)<br />

Turbulence: Poorish at first but becoming better during the observation period (AIII-II)<br />

Then I make notes on the appearances of features of the Moon against times. I will leave most of these out<br />

but one of relevance is:<br />

19h 06m UT, Change to 144×: Interior of Plato a featureless inky blackness. I carry on commenting on other<br />

details in this entry and then I go on to make other entries, including occasional mentions of Plato but with<br />

no sign of the sunrise spires until:<br />

20h 40m UT, 414×. Plato—two misty streaks are seen on the floor of the crater—local dawn<br />

20h 44m UT, 207×. Impression confirmed. Used outline chart and marked in pencil the general appearance<br />

on the drawing. <strong>No</strong> attempt was made to fill in other fine details. 20h 56m Markings on outline chart<br />

completed and after a final check observations were terminated.<br />

Over the drawing which is now stapled in my observing log I have written:<br />

Plato: 1981 February 12d, 20h 53m UT—so that is the time at which I fixed the appearance of the spires.<br />

(…) notice that I show the tip of the brighter spire is brighter than the rest of it—indicative of higher ground<br />

As to the differing historical appearances of the morning spires (or spire plus broad lighter patch), it does<br />

occur to me that libration in latitude could make a significant difference. Accepting that the differing angle<br />

of sunlight incident on the western rim and skating the interior isn’t going to vary by very much, the lighting<br />

situation could be critical enough to produce the variations. Indeed, from an observer positioned near the<br />

centre of Plato the rising point of the Sun will appear several degrees different over a large span of lunations<br />

thanks to libration in latitude.<br />

In my article I queried why Molesworth did not record the sunlight spires on his drawing of the shadowed<br />

interior of Plato when colongitude values suggested he should have recorded these features. Gerald responded<br />

with the following further comments:<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 5


The usual figures for selenographic colongitude given in an ephemeris are defined with respect to the mean<br />

centre of the lunar disk (and so is 90 degrees exactly at exactly first quarter). Owing to libration in longitude,<br />

a feature can actually be up to 3.5 degrees either east or west of the terminator at the time when the ephemeris<br />

predicts that the feature should be on it. So the usual tabulated figures of selenographic colongitude only give<br />

the approximate position of a feature in relation to the terminator. After correcting for libration in longitude<br />

it might be that Molesworth really did observe earlier than the time of first appearance of the interior<br />

illumination of Plato.<br />

I am grateful to Gerald for the additional comments and the copy of his original observing notes and drawing.<br />

It is clear that the floor of Plato presents a number of unusual scenarios of light and shade under early sunrise<br />

and sunset and that the ephemeris might not tell the whole story in terms of what might be visible at the<br />

eyepiece.<br />

6<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


Encke, <strong>2012</strong> March 03<br />

Peter Grego<br />

<strong>No</strong>tes: Further to studies of Encke made on 2009<br />

<strong>April</strong> 5 and 6, an observation was made with the<br />

crater illuminated by an earlier morning Sun. Paul<br />

Stephens’ 9-inch f/11 Newtonian was used—as<br />

the Moon was high, the observation had to be<br />

made atop a pair of wooden stepladders dating<br />

back to the 1930s that had belonged to Paul’s<br />

grandfather. They knew how to make things to<br />

last in those days—neither I nor the ladders<br />

creaked in the slightest. <strong>No</strong> observational<br />

template was used—this observational drawing is<br />

a PhotoPaint enhanced version of the scanned<br />

original telescopic pencil sketch.<br />

Encke is distinctly polygonal in outline. About<br />

half of the crater’s floor was filled with shadow<br />

cast by its eastern rim. Several north-south ridges<br />

were discerned on Encke’s floor, and the western<br />

floor at the base of the inner western wall was<br />

dark. A kink in the outline of the western rim<br />

marked the brightest part of the crater; this was<br />

the location of the crater Encke N, but it was not<br />

obviously crater-like in this view. The western rim<br />

of Encke cast a serrated shadow to the west, and<br />

is depicted here as it appeared shortly after the<br />

observation was commenced; by the end of the<br />

observation session, however, the shadow had<br />

retreated noticeably eastward but still retained all<br />

the original individual shadow peaks.<br />

The north part of crater Encke H, southwest of<br />

Encke, joined Encke’s shadow; it has been<br />

depicted a little too large here. Broad, complex<br />

ridges run around the eastern side of Encke; these<br />

have not been depicted as accurately as I had<br />

hoped. The ridges form the eastern wall of a larger<br />

crater, Encke T, in which Encke itself lies.<br />

2009 <strong>April</strong> 5 notes: Shadow was being cast<br />

by the crater’s eastern rim onto Encke’s floor;<br />

illuminated points within the shadow were<br />

located at the 1 o’clock and 5 o’clock<br />

positions. Some floor detail was visible in the<br />

form of a pronounced north-south ridge, with<br />

a smaller scalloped ridge to its northwest. A<br />

little more time would have allowed a more<br />

detailed study of the floor, but deteriorating<br />

transparency prevented this. Encke’s inner<br />

western wall appeared indented in a couple of<br />

places, at around the 9 o’ clock and 11<br />

o’clock positions. Wrinkle ridges ran around<br />

the eastern glacis of Encke, the boldest of<br />

them running to the south of the crater.<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong><br />

7


The Plato ‘hook’<br />

Phil Morgan<br />

On the evening of <strong>2012</strong> March 01, 18:25 UT, Col.13.1°, I was observing the Moon, but with nothing of<br />

particular interest on offer, I turned my attention to Plato and was struck by the sight of a particularly fine<br />

appearance of the famous Plato ‘hook’ effect.<br />

This was unexpected because I assumed that it would not be visible until the shadows had receded a bit<br />

more. Although the seeing was unsteady at first, when the mirror had cooled down it was quite good.<br />

Throughout the observing session the curve of ‘hook’ was always to the south. Just to check that this was<br />

indeed so I orientated myself so that the image of the Plato west facing shadows were facing down to my<br />

feet—that is to say that outer the western rampart was facing downwards instead of across my field of vision.<br />

Even with this orientation the curve of the ‘hook’ was always towards the right (southern) rampart, and those<br />

smaller shadows on the extreme northern half of the crater’s floor were always curving to the left (north).<br />

Other experienced lunar observers have also noted this hooked effect at a much greater shadow length<br />

than that recorded originally by Wilkins and Moore at Meudon in <strong>April</strong> 1952.<br />

At right (Figure 1) is an observation made by Eric<br />

Strach on the 1967 March 19, colongitude 13.2°,<br />

showing a curve of the longest shadow to the south.<br />

Below this at lower right (Figure 2) is an observation<br />

made by Roy Bridge on 1993 January 01 at 19:20 to<br />

20:45 UT, colongitude 12.2 to 12.9°. 184 mm spec.,<br />

261×. This observation depicts a long shadow spire<br />

on the southern floor area curving slightly to the<br />

south.<br />

There will always be some differences in the<br />

predicted colongitude and the actual recorded<br />

shadow length. This is because the selenographical<br />

colongitude is measured from the mean centre of the<br />

lunar disc. Plato, being at latitude 52 degrees north,<br />

will always tend to be subjected to variations in its<br />

predicted appearance,<br />

due to the Moon’s<br />

axial tilt of 1.5<br />

degrees. The resulting<br />

swing in the Sun’s<br />

selenographical<br />

latitude could, in the<br />

worst-case result in a<br />

variation of up to plus<br />

or minus 4 hours’<br />

difference in the<br />

observed shadow<br />

length for a given<br />

colongitude. Even<br />

with this orientation<br />

the ‘hook’ was always<br />

facing the southern<br />

rampart.<br />

Apologies for the<br />

poor reproduction of<br />

Figure 2. <strong>No</strong> higher<br />

resolution version<br />

could be found. Ed.<br />

Figure 2.<br />

Figure 1.<br />

8<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


Join us at our Yahoo! Group: <strong>Lunar</strong> Topographic Studies<br />

Many more lunar observational drawings, including observations<br />

featured in previous <strong>Lunar</strong> <strong>Section</strong> Circulars, can be found at:<br />

http://uk.groups.yahoo.com/group/baalunarsection-topography/<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 9


Right: Detail from David<br />

Finnigan’s CCD image of<br />

Vallis Alpes (reproduced<br />

in its entirety overleaf),<br />

taken on <strong>2012</strong> February<br />

29 more than an hour<br />

after Phil Morgan’s<br />

observational drawing<br />

above. In the original<br />

image the subtle shaft of<br />

sunlight illuminating<br />

Mare Imbrium beyond the<br />

Montes Alpes, shown in<br />

Phil’s drawing, can<br />

clearly be seen.<br />

10<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


Images<br />

Since March’s LSC, lunar imges have been received from Mike Brown (UK), Alan Clitherow (UK), Maurice<br />

Collins (New Zealand), Ed Crandall (USA), David Finnigan (UK), Rolf Hempel (Germany), Richard Hill<br />

(USA), Peter Hudson (UK), Bill Leatherbarrow (UK), Peter Oden (Germany), David Scanlan (UK), Larry<br />

Todd (New Zealand) and Tim Withers (UK) (not all contributors are <strong>BAA</strong> members). A selection of these<br />

images is featured below. My apologies to those contributors whose hard-won work is not featured in this<br />

issue; as usual space considerations mean that only a representative sample of material is included.<br />

Vallis Alpes, Aristoteles, Eudoxus. Image taken on <strong>2012</strong> February 29, 19:58-20:02 UT. Sun’s Col. 1.9 °,<br />

seeing 4/10, transparency good. 8-inch' Meade LX200 classic, f/25, DMK21AU04.AS camera, Baader IR<br />

pass filter. Image is a composite of 6 images: a total of 5040 frames at 30 fps processed in Registax 6,<br />

Paintshop Pro 8 and Serif software. Image by Dave Finnigan (Halesowen, UK). Detail below.<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 11


(detail below)<br />

12<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


(detail below)<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 13


14<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


Peter Oden took this detailed image of the crescent Moon on <strong>2012</strong> March 28. It is a composite of 50 single<br />

pictures (50 videos) taken with a 7-inch MCT and DMK21A04, stacked with AviStack2 und combined to<br />

one single photo with PaintShop. It took about two hours to take the videos, four hours to stack them and<br />

one more hour to combine them. Inset is a detailed study of Theophilus using the 7-inch MCT together with<br />

a Zeiss-Abbe-Barlow (5.4mm) and the DMK 2700mm-DMK21.<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 15


Left: Reworked image of Mare<br />

Orientale by Peter Hudson,<br />

originally taken on 2010<br />

September 01 when there was a<br />

very favourable libration.<br />

Above: An LTVT simulation by<br />

Maurice Collins of Mare<br />

Orientale as it would have<br />

appeared on 2010 August 04 at<br />

10:28 UT from Palmerston<br />

<strong>No</strong>rth, New Zealand.<br />

The two images concur in almost<br />

every respect.<br />

16<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 17


Transient lunar phenomena, <strong>April</strong> <strong>2012</strong><br />

Tony Cook<br />

Routine observations for February <strong>2012</strong> were received from the following observers: Jay Albert (Lake Worth,<br />

FL, USA) observed: Aristarchus, Bessel, Fracastorius, Kepler, Mare Crisium, Maskelyne, Plato, Proclus,<br />

Sabine, and Theophilus. Raffaello Braga (Italy) observed Eudoxus, Maskelyne, Maurolycus, and Proclus.<br />

Maurice Collins (New Zealand) took an image of Einstein and whole disk images of the Moon. Marie Cook<br />

(Mundesley, UK) observed: Eudoxus and Gassendi. I took time lapse video of the Moon and also took video<br />

of Earthshine, looking for impact flashes from Aberystwyth University. Rolf Hempel (Germany) took whole<br />

disk images of the Moon. Kevin Kilburn (Manchester, UK) imaged Rumker, Sinus Medii, and several<br />

features. <strong>No</strong>rman Izett (New Zealand) took a whole disk image of the Moon. Anthony Jennings (Manchester)<br />

imaged a whole disk image of the Moon. Terry King (Southwick, UK) imaged the Montes Apenninus. Nigel<br />

Longshaw (Olhham, UK) sketched Aristarchus. Pietre Malinski (Poland) imaged several areas of the Moon.<br />

Brendan Shaw (UK) imaged Arago, Aristarchus, Atlas, Censorinus, Linne, Peirce, Piazzi-Smyth, Plato,<br />

Poisson, Proclus, Promontorium Agarum, Ptolemaeus, and Ross D.<br />

News: I have received an email from Antonio Marino of the Amateur Astronomer’s Union of Naples to say<br />

that their group has started to actively take lunar spectra of Aristarchus, using the Capodimonte observatory<br />

of the National Astrophysical Institute of Naples. Using a Celestron C11 telescope and a home made<br />

spectroscopic equipment, they are achieving a spectroscopic scale of 0.08nm per pixel. An observational run<br />

on 2011Jul 12 revealed that some of the lines had a “higher spectral intensity” than the same lines on three<br />

later nights. Also, there was a decrease in spectral intensity of some lines down the blue end of the spectra. I<br />

would rather not say any more about this until they have done a ratio of spectra on different nights and<br />

published their results. But if I hear any more news I shall pass this onto you.<br />

I would like to thank Bob O’Conner for pointing out the following next two stories:<br />

Experimental and computer simulation research by Dutch scientists suggest that the Moon’s interior is at<br />

least 30% molten between 1200 and 1350 km beneath, hence the surface has been volcanically dead for some<br />

time now. However it could become active again in the distant future due to the way the interior melt<br />

crystallizes and changes buoyancy with respect to surrounding rocks—see<br />

www.nature.com/ngeo/journal/v5/n3/full/ngeo1402.html for further information.<br />

Secondly, Dr Thomas Watters from the Smithsonian Institution has been studying NASA LROC images.<br />

He has already found that there were plenty of examples of lobate scarps that suggest that the Moon is<br />

shrinking. He has now found some examples of small graben which infer that the crust is also moving apart<br />

in places. As some of these intersect very recent craters, this would imply that some of the graben themselves<br />

are very geologically young. You can see a video about this on: www.youtube.com/watchv=1Ba-9ntruCs .<br />

Many of these small graben are in close proximity to known Moon quake sites. This is interesting because it<br />

means that at least some graben could well be forming now as you read this article! A paper by Alan Binder<br />

in Geophysical Research Letters back in 1980 discusses the release of argon during shallow Moon quakes, so<br />

perhaps we have here a mechanism to kick up some dust at these sites and cause TLP Alas it seems from the<br />

chart of recent graben that Tom Watters shows, very few of these correlate with TLP sites.<br />

Routine Reports: As usual, space is rather limited to describe all of the supply of routine reports sent in, and<br />

the observations sent in were all of excellent quality, but here are just a few highlights from February <strong>2012</strong>:<br />

1) Cauchy: On 1969 Jul 29 UT 06:00-06:22 Pamplona, and two other observers from Brazil, using a 2”<br />

refractor, found Cauchy to be very bright, clear and pulsating. A repeat illumination image by <strong>No</strong>rman Izett<br />

(New Zealand) taken on <strong>2012</strong> Feb 07 at 09:43 UT shows that the crater is bright, but cannot tell us if it was<br />

pulsating or not. For now I am leaving this TLP at a weight of 3.<br />

2) Bessel: On 1877 Jun 17 Dennett thought that he could detect a minute point of light shining out of the dark<br />

crater. Jay Albert reobserved under the same illumination conditions but could not see the claimed spot of<br />

light. Therefore this TLP remains at an ALPO/<strong>BAA</strong> weight of 3.<br />

18<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


Figure 1. A modified sketch of<br />

Aristarchus by Nigel Longshaw<br />

from <strong>2012</strong> Feb 08, confirming the<br />

diffuse appearance of the interior<br />

of the crater at this stage in the<br />

illumination. <strong>No</strong>rth towards top.<br />

3) Aristarchus: On <strong>2012</strong> February<br />

08 at 23:00 UT Nigel Longshaw<br />

sketched Aristarchus, in the hope<br />

of seeing what it looked like back<br />

in 1983 October 22 when Peter<br />

Foley was supposed to have seen a<br />

TLP there. Nigel’s sketch indicates<br />

blue tint on the northern wall, a<br />

deep violet apron to the north and<br />

a diffuse bluish grey to the east.<br />

His sketch also depicts a bright<br />

extended spot on the eastern wall,<br />

extending beyond the crater. Here I have to apologize humbly, it seems that in my database I transposed the<br />

reports for 1983 Oct 22, and 23, by one day, and so Nigel’s sketch (see Figure 1) corresponds more closely<br />

with Geoff Amery’s TLP of 1983 Oct 22 UT 23:10 when it was reported that Aristarchus was bright and<br />

difficult to see detail internally, and furthermore was so bright that no measurement could be made with the<br />

CED (Crater Extinction Device). I have now corrected the entry in the TLP database.<br />

Figure 2. <strong>No</strong>rth is at the top. (Left) A completely shadow filled Ptolemaeus in an image by Brendan Shaw<br />

from <strong>2012</strong>Feb29 UT 20:21. (Right) An ALVIS simulation of what the floor should have looked like at the<br />

end of the 1970 Travnik TLP.<br />

4) Ptolemaeus: Back in 1970Apr 14 between 00:45 and 01:30 UT Brazilian astronomer Travnik, using a 4”<br />

refractor, observed ‘A kind of glimmering mist lifted and wafted inside the shady hollow of the crater’. On<br />

<strong>2012</strong> Feb 29 at UT 20:21 Brendan Shaw re-imaged the crater under very similar illumination conditions that<br />

matched to within 9 minutes the start of Travnik’s TLP. Fig 2 (left) shows what Brendan saw–it at least<br />

confirms that the floor was shadow filled, but shows no sign of any detail. I tried modelling the appearance<br />

of the floor at the end of the Travnik TLP and as Fig 2 (right) shows, we can see the raised floor breaking<br />

through the shadow and some characteristic shadow spires like one gets with Plato. In fact the Travnik TLP<br />

has some similarities to an article that I write with GLR’s Raffaello Lena in the <strong>BAA</strong> Journal <strong>Vol</strong> 114, p136-<br />

139 in 2004. However as we cannot completely explain the glimmering mist lifting and wafting effects<br />

(though these might be resolution and seeing related), I am lowering the weight of this observation to from 3<br />

to a 2.<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 19


Figure 3. Extracts from Rolf Hempel’s image mosaic from <strong>2012</strong> Feb 06 with north at the top. From left to<br />

right: Aristarchus, Menelaus, Censorinus and Proclus.<br />

5) Aristarchus: When Sir Patrick Moore observed Aristarchus on 1983 Oct 20, at 23:40 he reported that<br />

Aristrachus was brighter than normal (using a CED), and more so than Censorinus, Menelaus, and Proclus in<br />

turn. On <strong>2012</strong> Feb 06 Rolf Hempel took a whole Moon image mosaic between 21:16 and 22:02 UT under<br />

very similar illumination. In order of brightness here are the corresponding maximum digital number values:<br />

Aristarchus (253), Censorinus (255), Menelaus (253) and Proclus (255). However this does not tell the whole<br />

story as not all parts of each crater is at peak brightness. Figure 3 shows that Proclus and Censorinus appear<br />

‘visually’ to be the brightest, or rather have more bright pixels per unit area. So for now I will leave the weight<br />

of this observation at a 2 as it is possible that viewing angle (libration) may have some effect too.<br />

TLP Reports: One TLP report was received: on Feb 28 at UT 19:45-20:00 Raffaello Braga (Italy, 100 mm<br />

refractor, seeing III, transparency very good)) when he examined Maurolycus and found that the central peak<br />

of the crater was bright in red light but disappeared in blue light. Interestingly this matched what Staedke of<br />

Berlin saw back in 1971 May 01 under similar illumination.<br />

Suggested Features to observe in <strong>April</strong>: For those of you without access to the internet (in the UK), below<br />

is a list of repeat conditions for when a feature will exhibit the same illumination and libration as was seen<br />

for a historical TLP observation from the past. By re-observing and submitting your observations, we will get<br />

a clear understanding of what the feature ought to have looked like at the time. Only this way can we really<br />

fully analyze past TLP reports.<br />

<strong>2012</strong>-Apr-01 UT 18:37-20:02 Ill=70% Proclus observed by Darling on 1988-07-24: Please image or sketch.<br />

<strong>2012</strong>-Apr-02 UT 00:17-02:39 Ill=72% Promontorium Laplace observed by Cameron on 1994-04-21: Can<br />

you see or image any colour here<br />

<strong>2012</strong>-Apr-02 UT 18:39-21:20 Ill=79% Proclus observed by Davis on 1988-07-25: Please sketch or image<br />

the interior of the crater.<br />

<strong>2012</strong>-Apr-02/03 UT 23:34-03:04 Ill=81% Posidonius observed by Dzaplashvilli on 1952-07-03: Try<br />

observing the crater through a polaroid filter (or glasses) and rotate the filter – anything happen<br />

<strong>2012</strong>-Apr-03 UT 18:41-19:03 Ill=88% Herodotus observed by Bartlett 1971-07-05: Any sign of pseudo peak<br />

on the floor<br />

<strong>2012</strong>-Apr-04 UT 19:20-22:14 Ill=94% Aristarchus observed by Bartlett on 1964-10-19: Any colour visible<br />

on the east part of the floor<br />

<strong>2012</strong>-Apr-04/05 UT 22:19-02:12 Ill=95% Herodotus observed by Manske on 1989-06-17: Is there a<br />

nebulous spot near to Herodotus Is it brighter or darker in red or blue filters<br />

<strong>2012</strong>-Apr-04/05 UT 23:01-02:51 Ill=95% Aristarchus and Copernicus observed by Scarf on 1963-10-30:<br />

Are either of these craters brighter at 540 nm or in an orange filter than in yellow or red light<br />

<strong>2012</strong>-Apr-05 UT 00:51-03:<strong>49</strong> Ill=95% Schroter’s Valley observed by Louderback on 1981-11-10: Is there<br />

any colour visible at the Cobra’s Head<br />

<strong>2012</strong>-Apr-05/06 UT 23:32-03:28 Ill=99% Aristarchus observed by Moore on 1983-10-20: How bright is<br />

Aristarchus compared to Censorinus, Menelaus and Proclus Which is brighter than which<br />

20<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


<strong>2012</strong>-Apr-06 UT 00:21-04:04 Ill=99% Aristarchus observed by Bartlett on 1965-09-10 and Manchester<br />

University: Please look for detail and colour on the floor and is the crater brighter in red, specifically at 545<br />

nm and 673 nm<br />

<strong>2012</strong>-Apr-06 UT 00:21-04:11 Ill=99% Aristarchus observed by Bartlett on 1965-09-10, LeCroy on 1976-<br />

02-14 and Manchester University on 1963-11-01: Please look for detail and colour on the floor, elsewhere,<br />

and is the crater brighter in red, specifically at 545 nm and 673 nm<br />

<strong>2012</strong>-Apr-06 UT 01:19-04:11 Ill=99% Copernicus observed by Manchester University astronomers on<br />

1963-11-01: Is the crater brighter in red, specifically at 545 nm and 673 nm<br />

<strong>2012</strong>-Apr-07 UT 01:05-04:35 Ill=100% Plato observed by Moore on 1980-09-24: Can you see anything<br />

resembling an obscuration on the NW wall or floor Any colour seen<br />

<strong>2012</strong>-Apr-07 UT 01:26-04:35 Ill=100% Fracastorius observed by Robinson on 1980-09-24: Any colour<br />

visible on the northern side Try using red and blue filters.<br />

<strong>2012</strong>-Apr-07 UT 02:47-04:35 Ill=100% Aristarchus observed by Moore on 1980-09-24: Can you see any<br />

colour on/in the crater<br />

<strong>2012</strong>-Apr-12 UT 04:26-05:21 Ill=64% Rimae Triesnecker observed by Markhov on 1915-07-03: Please<br />

image or sketch.<br />

<strong>2012</strong>-Apr-14 UT 04:07-05:17 Ill=42% Schroter’s Valley observed by Pickering on 1891-09-25: Please<br />

sketch or image.<br />

<strong>2012</strong>-Apr-17 UT 04:02-04:50 Ill=15% Mare Crisium observed by Arsyukhin on 1982-11-11: Please image<br />

or sketch in Earthshine.<br />

<strong>2012</strong>-Apr-23 UT PM Ill=6% Aristarchus observed by Celis on 1970-08-04: How bright is Aristarchus and<br />

can you see any colour in the crater in Earthshine<br />

<strong>2012</strong>-Apr-24 UT 21:23-22:05 Ill=11% Aristarchus observed by Celis on 1970-08-05: How bright is<br />

Aristarchus in Earthshine<br />

<strong>2012</strong>-Apr-25 UT 21:25-22:52 Ill=17% Aristarchus observed by Celis on 1970-08-06: How bright is<br />

Aristarchus and can you see any colour in the crater in Earthshine<br />

<strong>2012</strong>-Apr-25 UT 20:03-21:07 Ill=17% Please check Earthshine for sporadic meteor impact flashes.<br />

<strong>2012</strong>-Apr-26 UT 20:05-21:50 Ill=26% Please check Earthshine for sporadic meteor impact flashes.<br />

<strong>2012</strong>-Apr-27 UT 20:07-22:28 Ill=35% Please check Earthshine for sporadic meteor impact flashes.<br />

<strong>2012</strong>-Apr-28 UT 20:09-23:00 Ill=45% Please check Earthshine for sporadic meteor impact flashes.<br />

<strong>2012</strong>-Apr-28/29 UT 20:11-00:06 Ill=44% Picard observed by Hua on 1994-04-28: Is the rim of this crater<br />

dark<br />

<strong>2012</strong>-Apr-30 UT 19:27-20:25 Ill=65% Mons La Hire observed by Klein on 1887-02-02: Any colour or<br />

shadow present<br />

<strong>2012</strong>-Apr-30 UT 19:27-20:08 Ill=65% Plato observed by Bartlett on 1964-11-14: Any colour on the rim<br />

For repeat illumination (only) TLP predictions for the coming month, these can be found on the following<br />

web site: http://users.aber.ac.uk/atc/tlp/tlp.htm .For members who do not have access to the internet, please<br />

drop me a line and I will post predictions to you. If you would like to join the TLP telephone alert team, please<br />

let me know your phone <strong>No</strong>. and how late you wish to be contacted. If in the unlikely event you see a TLP,<br />

please give me a call on my cell phone: +44 (0)798 505 5681 and I will alert other observers. <strong>No</strong>te when<br />

telephoning from outside the UK you must not use the (0). When phoning from within the UK please do not<br />

use the +44! Twitter TLP alerts can be accessed on http://twitter.com/lunarnaut.<br />

Dr Anthony Cook, Institute of Mathematical and Physical Sciences, University of Wales Aberystwyth,<br />

Penglais, Aberystwyth, Ceredigion, SY23 3BZ, Wales, United Kingdom.<br />

Email: atc @ aber.ac.uk.<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 21


Occultation news, <strong>April</strong> <strong>2012</strong><br />

Tim Haymes<br />

Double star occultation detected with video in the UK<br />

Alex Pratt (Leeds) reports that ZC3524, a mag. 6.9 star in Pisces which was occulted on 2011 <strong>No</strong>vember 06,<br />

was indeed a step event. Closer examination of the video by Jan Manek (IOTA total occultations regional<br />

coordinator for Europe) clearly indicated two stars separated in time by 11 video frames, a time difference of<br />

0.4 sec. The reduced light curve (see diagram) shows the fainter component disappearing first.<br />

Alex writes: ‘The recording was made with a Mintron video camera operating at 25 frames per second, at the<br />

prime focus of my 20cm aperture f/20 Maksutov-Cassegrain telescope. Embedded times accurate to 1ms were<br />

generated by a GPS video time inserter’.<br />

Right: Frame from Alex Pratt’s<br />

video of the occultation of<br />

ZC3524 on 2011 <strong>No</strong>vember 06.<br />

‘Observing conditions were not<br />

good. The gibbous Moon was<br />

86% illuminated in a hazy sky,<br />

with the disappearance occurring<br />

at a small cusp angle of 19°’.<br />

The recording is being analysed<br />

further by Brian Loader (NZ) who<br />

is expecting to obtain improved<br />

orbital data and magnitude<br />

differences for the double.<br />

Doubles listed for <strong>April</strong> are<br />

included with the general<br />

predictions for Birmingham. Observations of these are most welcome.<br />

22<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


Graze occultations<br />

ZC 1198 on <strong>2012</strong> March 04. The coordinator attempted to observe the graze of 2B Cnc near the Aylesbury<br />

AS observatory (aided by the Society Chairman) but was clouded out. Gusts of wind could have been a<br />

problem for the planned video observation.<br />

ZC 1950 on 2000 Jan 27. A reduction has been recieved and this old observation will be included in the next<br />

Occult update.<br />

Occultation predictions for <strong>April</strong> <strong>2012</strong><br />

List computed for Birmingham, UK (W. Longitude 001 44 44.0, Latitude 52 27 41.0), alt. 50m, 20cm<br />

aperture. Event times elsewhere in the UK may differ by up to 5 min<br />

Occultations Co-ordinator: Tim Haymes, Hill Rise, Knowl Hill Common, Reading, RG10 9YD.<br />

occultation@baalunarsection.org.uk<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 23


<strong>Lunar</strong> librations for <strong>April</strong> <strong>2012</strong> (from a program by J.M.H. Hill)<br />

24<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong>


<strong>Lunar</strong> data for <strong>April</strong> <strong>2012</strong>, lunations 1104/1105 (from a program by Gareth Williams)<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Contacts<br />

Director<br />

Bill Leatherbarrow<br />

director@baalunarsection.org.uk<br />

Assistant Directors<br />

Tony Cook (with responsibility for TLP work)<br />

tlp@baalunarsection.org.uk<br />

Peter Grego (Circulars Editor)<br />

editor@baalunarsection.org.uk<br />

Committee Members<br />

Tim Haymes (Occultations)<br />

occultation@baalunarsection.org.uk<br />

Robert Garfinkle (Historical Consultant)<br />

history@baalunarsection.org.uk<br />

Bruce Kingsley (Imaging Consultant)<br />

photography@baalunarsection.org.uk<br />

Nigel Longshaw<br />

Brendan Shaw (Archivist)<br />

archives@baalunarsection.org.uk<br />

Computing Consultant (position vacant)<br />

compute@baalunarsection.org.uk<br />

To receive B&W printed copies of the <strong>Lunar</strong> <strong>Section</strong><br />

Circular, please send a supply of stamped addressed<br />

envelopes to the <strong>Lunar</strong> <strong>Section</strong> Director. Envelopes at<br />

least 11 x 22 cm will ensure no damage in transit.<br />

Members who have Internet access may receive their<br />

Circulars (colour version) in PDF format by email<br />

(please contact the Director) or by downloading them<br />

directly from the <strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> website at<br />

http://www.baalunarsection.org.uk/circulars.htm.<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Director: Bill Leatherbarrow,<br />

9 Stumperlowe Avenue, Sheffield, S10 3QN, UK.<br />

Email: director@baalunarsection.org.uk<br />

Observations and items related to a specific area of<br />

lunar study should be sent to the appropriate member<br />

of the <strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Committee, but send any<br />

material of a more general nature to the Editor.<br />

Deadline for items for the May <strong>2012</strong><br />

<strong>Lunar</strong> <strong>Section</strong> Circular:<br />

15 <strong>April</strong> <strong>2012</strong><br />

Circulars Editor: Peter Grego, 7 Parc-An-Bre Drive,<br />

St Dennis, St Austell, Cornwall, PL26 8AS, UK.<br />

Email: editor@baalunarsection.org.uk<br />

<strong>BAA</strong> <strong>Lunar</strong> <strong>Section</strong> Circular <strong>Vol</strong>. <strong>49</strong> <strong>No</strong>. 4 <strong>April</strong> <strong>2012</strong> 25

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