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revans
scholastic sledgehammer
Reged: 09/26/05
Posts: 811
Loc: Fitchburg, MA
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Hi all,
Seeing was better than usual at my observing site in New England... about 1 arc second at the moon's declination on April 11, 2008 at 03:45 UT (I measured the FWHM of a nearby star). I tried a new DMK20 camera that just arrived and except for some unwanted learning experience with compression artifacts I managed to get a few detailed images. I've attached one of Fracastorius and I noticed that I managed to record the Y shaped rille on the floor. I'be been trying to read up on the various types of rilles... this one must be sinuous from its appearance. Does this imply a volcanic somewhere nearby or has the lava just extruded up through an irregular fissure in the crater floor? I thought someone would have a particular interest in rilles and might teach me something about this one...
Rick Evans
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Rick Evans
http://www.freewebs.com/revans_01420/
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Mare Nectaris
Pooh-Bah
Reged: 03/09/08
Posts: 1114
Loc: Toijala, Finland
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Congrats Rick for the excellent catch! Your DMK really seems to deliver magnificient results!
Charles A. Wood writes in his interesting book "The Modern Moon. A Personal View" (Sky Publishing Corp., Cambridge, Massachussetts 2003), at page 114 as follows:
"At Fracastorius ... is ... a rille that crosses the crater floor from east to west. This delicate feature, a mere 1 to 1.5 km wide, is only visible in good seeing. Second, as moderatly high lightning shows, the southern portion of Fracastorius ... are brighter and rougher than the adjacent mare. Spurr proposed in the 1940s that this border of light gray material was "surged over" by mare lava and then upwarped, like a raised beach on Earth. Most geologists today would say that the border material (including the grayish plains on the east side of the mare) represents an earlier fill of Nectaris otherwise covered by mare lavas."
Also Wood describes - as it is apparent from your pic too - why and how the tilting of the crater towards the lava basin happened as a result of an interplay of impact and volcanic activity.
I hope this sheds some light to the rille -thing in the firstplace! Let's - though - wait what the experts have to say, as this is just text I found looking at Woods wonderful book.
Thanks Rick for sharing this with us - keep 'em comin'!
Be well and clear skies!
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Share - and you shall have it all
Timo Keski-Petäjä
CtheMoon
Observation shelter KuuMaja (MoonHut)
TAL 250K*Celestron C8-N*SkyWatcher Skymax 150 Pro*TAL1(Mizar)*EQ6 Pro SynScan*Celestron Advanced GT (CG-5 GOTO)*Baader Hyperion Clickstop Zoom 8-24*17 mm UWA-70*TeleVue BIG 2x Barlow*Celestron 2x Barlow Ultima SV Series
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revans
scholastic sledgehammer
Reged: 09/26/05
Posts: 811
Loc: Fitchburg, MA
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Timo,
That is another book I really need to buy... Wood is brilliant and very clear in his writing.
I'm still learning this camera... I have trouble still with choosing the wrong codec in the software that comes with it... I'm trying to get rid of compression artifact and still have reasonable image file size... I ahd 1 arc second seeing when the image of Fracastorius was taken and that only happens infrequently at my site... usually I have around 2 to 4 arc second seeing  (
Rick
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Rick Evans
http://www.freewebs.com/revans_01420/
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larrytOMC200
sage
Reged: 07/05/07
Posts: 222
Loc: New Zealand
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hello Rick,
That is a good capture of one of my favorite sites on the moon, There is something about this area that always draws me to it whenever I see it. I cannot wait until the moon becomes a little more visible here in the southern hemisphere. Now that autumn is on the way, the moon will be gaining in elevation and I might be able to get some viewing/imaging in once again, that rill is something I have wanted to see for a while now. Be proud that you have gotten such a nice image, Anyway, keep well. Larry
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revans
scholastic sledgehammer
Reged: 09/26/05
Posts: 811
Loc: Fitchburg, MA
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Larry,
I wish I got seeing as good as 1 arc sec more often... usually I set the scope and camera up with little chance of capturing much detail.
PS - the OMC300 subaperture Mak was sent from my dealer in Germany back to England because of some glitches... I am waiting for another scope to be sent out and then Markus Ludes at APM can look it over and test the optics before it is sent out to me... so I am in for more delays... but at least I already have a decent working scope (if the weather ever improves again)...
PPS - I really envy you your southern stars.... someday I really want to visit the southern hemisphere and at least look at the Megallanic clouds etc. Since you have experience of both hemispheres, which do you prefer?
Rick
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Rick Evans
http://www.freewebs.com/revans_01420/
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larrytOMC200
sage
Reged: 07/05/07
Posts: 222
Loc: New Zealand
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Hi Rick,
Sorry to hear about the problem with the scope, I do hope it gets sorted soon. As to which hemisphere has the best overall 'view' of the stars, I would have to say the southern hemisphere has it. It may be because where I live (Dunedin) is no where near as light polluted as where I used to live (Cleveland, North Yorkshire) where one of the biggest petrochemical complexes in Europe as well as a steel complex was sited. However, the night sky has a lot to offer over here. Keep well. Larry
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revans
scholastic sledgehammer
Reged: 09/26/05
Posts: 811
Loc: Fitchburg, MA
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Larry,
Yes, from everything I've heard and read the Southern stars are spectacular... and I think the moon through binoculars has a different orientation as well... sort of "upside down" from my perspective... am I right?
Rick
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Rick Evans
http://www.freewebs.com/revans_01420/
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larrytOMC200
sage
Reged: 07/05/07
Posts: 222
Loc: New Zealand
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Hello Rick,
Yes you are right on all counts. The view took a while to get used to. It will always seem 'upside down' to me when I look at it, especially with my naked eye or through my binoculars. I think the view of a full moon through binoculars or a short tube rich field telescope gives the best view of a world floating in space that one is able to have. Anyway, keep well. Larry
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