Observing Report - Lunar 100 Update 23/5/2010

[Moonshane]

Observing Report 23rd May 2010

Location Stockport, England Latitude: +53.42 (53°25'12"N)

Longitude: -2.17 (2°10'12"W)

Equipment – f5.3 300mm Orion Optics UK Dobsonian, TV Radian and Panoptic /Powermate / WO 33mm SWAN

Main Target: Lunar 100 List

I am really enjoying building my list of observations for the Lunar 100 list. As I don’t get the chance to observe that often (although I have had a good run lately), I set myself an aggressive target of twenty new objects tonight. I started early and the sky was still relatively blue but some of the features listed were visible from the start; others became more obvious as the sky darkened and contrast on the lunar surface increased.

Broadly I try to follow the list in numerical order although I picked out the twenty most likely targets along the line of the terminator. It’s incredible how different objects look under different lighting and a good example of this is Rupes Recta, ‘Straight Wall’. I have seen this several times previously and it’s a really excellent feature. The other night when I showed my wife it was right next to the terminator and showed a really hard edge which she likened to a dagger; being an English teacher with a love of Shakespeare I suppose that was not a big surprise. It also pointed straight at three ‘Lord of the Rings’ peaks’ shadows which stretched like dog’s teeth across the surface – no idea what they were. Tonight the shadow of Rupes Recta had softened greatly and the Tolkein shadows had disappeared completely.

I then started to look at my targets in earnest and had a very successful night. I failed on some of the targets (lack of preparation as in some cases I was not really sure what I was looking for) but gained one which I did not expect. A summary of my findings (or non-findings) is provided below. In all I added a further eleven objects to my Lunar 100 list. As usual, for those features located, I have included links to an image of the feature – usually off Wikipedia.

28 Hipparchus – Success

http://the-moon.wikispaces.com/Hipparchus

Although determined to see this large crater I was not looking at the best time and assume it would be a lot more obvious when close to the terminator. I found it readily by using other, more defined craters and effectively ‘crater hopping’ to the spot using Halley, Hind and Horrocks. The key feature which confirmed I had located Hipparchus was the semi-circular remnant of crater wall/debris which in itself was an interesting feature.

29 Aridaeus Rille – Success

http://the-moon.wikispaces.com/Rima+Ariadaeus

Another object which was not readily seen given the angle of illumination. However, I located the position of this long straight Rille using Rima Hyginus which seemed to be much more obvious, despite similar lighting. Once aware of the position of Aridaeus, I could then see it with prolonged viewing. Averted vision also helped to tease out a little more detail. It ran parallel to the eastern half of Rima Hyginus and north of Silberschlag but south of Silberschlag A. This one will certainly reward viewing at a better time; the larger craters Agrippa, Manilus and Godin will also be worth looking at once the terminator is closer to them.

31 Taruntius - Success

http://the-moon.wikispaces.com/Taruntius

Yet another target which is a little past its best but I like a challenge! The outer wall and central peak were just about discernible and the location of the main crater itself assisted by the small circular crater, Cameron. I have to say that my location of targets like this has been transformed by the purchased of a used copy of Moon Mars and Venus by Antonin Rukl. This was a snip at £5+ delivered and the detail is superb. The good thing about lunar observing is that the moon, being so bright, you can also use a white light torch which definitely makes the reading of the maps much easier.

83 Plato Craterlets – Success

http://the-moon.wikispaces.com/Plato

Inspired by Doc and Jahmanson’s tales of what can be seen of these tiny specks on the floor of this huge crater I decided to have a go at them despite the lighting having moved away from ideal. The seeing could have been better but was bearable and with prolonged viewing I could see four white specks on the basin floor. Taking Plato as being like an egg on its side and with the ‘bubble’ in the wall to the left, I could see one near the bubble, one centre bottom, one centrally and then one centre top (once the contrast had increased later on, I got the impression that this one was split into two with averted vision – BUT, reading the reports of others this seems to be a more difficult split than I imagined and maybe I was seeing things). I need to check this again with more acute lighting and perhaps this will improve the overall view. One thing’s for sure, I was seeing craterlets on the floor of Plato.

66 Hadley Rille – Unexpected success

http://the-moon.wikispaces.com/Hadley+Rille

This was a nice surprise as I had seen reports of this in the past and it seemed a very difficult target. I also thought the light would be a problem as the rille is well behind the terminator. As it happened I managed to get a view of the full rille which was very like a sinuous river bed between the small crater of Hadley and the beginnings of the Montes Apeninus. Even more exciting to me was the fact that I was looking at the site of the Apollo 15 mission off the corner of a square projection in the Hadley mountains. In July 1971, Scott and Irwin expeditions to this rille with drilling undertaken to a depth of 1.5m. Obviously there’s nothing to actually see of the landing but seeing the general area is quite incredible – almost giving a feeling of being a part of it – ridiculous, I know.

98 Imbrium lava flows – Success

http://the-moon.wikispaces.com/Mare+Imbrium

I am pretty sure I got this one right and the oblique lighting helped make these wave-like ripples really quite obvious. They are larger and more sparse in Mare Imbrium and smaller and closer together in Sinus Iridium. The most obvious of all passed straight through the middle of the crater C. Herschel. Can anyone confirm I was looking at the right features please?

78 Lambert R - Fail

Although I know from the other features present that I was in the right spot, I could not make out the ‘ghost’ crater of Lambert R. I read that this requires perfect lighting when the shadow of the terminator is close by. I’ll try again another time.

95 Procellarum basin - Fail

This was one of my ‘have a go but not really sure what I am looking for’ targets. This proved to be my failure as I could not locate anything obvious. I now know this is the whole area in which the craters Billy and Hansteen are situated. I’ll prepare a little better next time.

69 Copernicus secondary craters - Fail

Again, even with Rukl in hand it was not really possible to determine exactly which craters the list refers to. Can anyone please confirm where they are?

74 Copernicus H – Success

Could not find a good image of this one.

When I first looked for this I was really not sure what the description meant. I watched the crater that I was sure was correct for a couple of minutes and it suddenly hit me. The tiny crater had a Ring Nebula around it! So that’s what a dark halo crater is….obvious really once you know.

65 Hortensius domes – Success

http://the-moon.wikispaces.com/Hortensius

I really like volcanic domes on the moon (do you get them anywhere else???). Like a bad case of boils, these small lumps are in two lines near to the small but sharply defined crater, Hortensius. I could only clearly make out five but there are six in total. I suspect if you looked when the terminator is right on them then you would see all six of them well enough.

67 Fra Mauro formation - Fail

There is not much of a description on the list and I did not manage to translate this into seeing the feature concerned. I know now that it is the site of the Apollo 14 landing and can see this in Rukl so should get it next time out.

54 Hippalus Rilles – Success

http://the-moon.wikispaces.com/Rimae+Hippalus

This was my favourite feature of the night. I was not 100% sure it would be visible but it was pretty much right on the terminator and this helped show it in all of its glory. There were three sharply defined gouges which stretched for a massive distance and resembled a ‘tiger scratch’ across the lunar surface – superb! It really does look just as described and if you get the chance to view it then do so – it’s really an amazing sight.

60 Kies Pi – Success

http://the-moon.wikispaces.com/Kies

Kies is a strange looking crater, a bit like a half sunken diamond ring and with a well-filled basin. Oh, no….I am becoming simile man…….anyway Kies Pi is a large volcanic dome which is off to the west of the diamond if the ring is facing south – you’ll understand if you look at images. Another impressive and apparently large dome.

81 Hesiodus A – Success

http://the-moon.wikispaces.com/Hesiodus

Hesiodus A is a medium sized crater and which is very dished in shape. Its centre is interesting as it has obvious concentric rings within the walls, resembling a concave bull’s-eye. Very nice indeed and when seeing is better this would be interesting at a higher magnification.

84 Pitatus - Fail

Although I found the crater Pitatus, the seeing / illumination did not seem adequate to allow good definition of the concentric rilles. I actually think with hindsight that I did see them but am not going to count this one at this time as I was not satisfied with the views I got.

59 Schiller-Zucchius basin – Fail, 37 Bailly – Fail and 94 Drygalski – Fail

These were all on my ‘probably no chance’ list and they were not illuminated at all so it was not possible to see them.

With my list building nicely, I look forward to more lunacy (sorry) soon.

Cheers

Shane

[jgs001]

A good session Shane and a fair few more of the list.

[Talitha]

Excellent report Shane, you're a great tour guide.

To answer a few of your questions...

I'm sure you've seen the Procellarum Basin already. Everyone who's seen the Moon has, but probably doesn't realize it... it's absolutely massive. Here it is outlined by the very large circle.

To make sure you saw the Imbrium Lava Flows and not Wrinkle Ridges, take a look and see if these are what you saw. Here's a great mouseover image of them, and a closer look. The easy to see ridges look pushed up, whereas the more difficult lava flows look 'poured'. That's crater La Hire A sitting atop the Zirkel Ridge (Dorsum Zirkel) in the close-up.

Secondary craters are caused by impact debris falling back onto the lunar surface after the initial big impact. Here's some of Copernicus' secondary craters... looks like there was quite a lot of good sized ejecta.

Bailly and Drygalski were in hiding the night of your report, so you wouldn't have seen them even if the area were fully illuminated. They're affected by libration and slip around the limb when the NE area of Mare Humboltianum is heavily favored.

Best of luck with the rest of the list.

[Moonshane]

Brilliant cheers Carol. I reckon I'll look at the Procellarum Basin next time then. As you say it's huge - I didn't realise it was this big.

Unfortunately, I did not see the the Imbrium Lava Flows and instead it was indeed the Wrinkle Ridges I was looking at. A shame I didn't know what the flows looked like as the illumination was spot on when I was observing. That's one off the list

I probably saw the secondary craters too but again I'll see these again. I saw lots of little pock marks but was not sure I was looking at the right ones.

It's all a learning curve and something that takes a bit more effort is clearly worth more

As with all things Astro, the features of the moon ain't going anywhere so there's always time next time.

[Doc]

Fantastic report Shane, I really enjoyed reading it. As you have found certain objects need very good libration and perfect seeing.

keep up the good work.

[Moonshane]

thanks Mick - it's all a (steep) learning curve and a very enjoyable one too.

I have no problems with being shown the error of my ways too (as Carol so politely did) as generally I work on the basis of 1) yes, no doubt so count it, 2) possibly/probably but check and ask the question to confirm and 3) not really sure if I saw it or not/didn't see it so don't count it.

although I am keen to see everything as quickly as I can, I am not in any rush to miss detail and reduce enjoyment by rushing about too much - it'll all keep:)