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Re: Plato's challenge new [Re: Asbytec]
      #6353142 - 02/03/14 12:15 PM

Keeping this thread on Plato is a good idea.

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Asbytec
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Re: Plato's challenge new [Re: star drop]
      #6354487 - 02/03/14 10:19 PM

Plato should be visible in a few days, I'm hoping the weather will allow someone to report on it. I plan to observe it again. Craterlet 'e' is of particular interest, but may be better seen during Plato's sunset a few weeks from now.

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Asbytec
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Re: Plato's challenge new [Re: Asbytec]
      #6363440 - 02/08/14 07:12 AM

Okay, first glance at Plato on 8 Feb 1200UT just emerged from the terminator. IMO, Plato's floor is still too dark with glancing sunlight.

I could see the big 4 as faint light arcs and maybe, just maybe darker pits. However, when I say the big 4, I mean the 'c' and 'd' were kind of seen together and not resolved individually.

Craterlet 'w' was a solid dark spot against the wall. Craterlet 'e' was difficult, but it showed itself a few times as a faint, fleeting light arc like the big 4.

It's too early, need another day (per edosaurusrex post), I think to see them better. But the seeing was good and it was clear...was clear, so I took a chance on it.


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nirvanix
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Re: Plato's challenge new [Re: Asbytec]
      #6363451 - 02/08/14 07:26 AM

Good work Norme. I had a quick peek at Plato last night through the clouds. Definitely the crater floor was too dark to make an attempt. Wishing us both good skies tonight.

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Asbytec
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Re: Plato's challenge new [Re: nirvanix]
      #6363454 - 02/08/14 07:29 AM

Thanks, Nirv.

Gotta check the skies. Not a cloud on weather radar, but it certainly closed in regardless...low stuff.


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Asbytec
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Re: Plato's challenge new [Re: Asbytec]
      #6365591 - 02/09/14 08:41 AM

Okay, add 'g' to the list of craters in crater form! Serious as I can be, confirmed with it showing nice floor and a crescent rim brightening twice in a half hour of viewing. No question about it, full on crater form with a dark pit and a sunlit crescent confirmed twice. (Edit: and again a third time at 1330UT while sketching.)

I also spotted 'h' for sure and I suspect 'i' and only /suspect/ having glimpsed each with a dark pit once or twice. Actually I did see a dark spot there only fleetingly, so it is way too uncertain to call with any confidence. These two were mostly brighter specks than rolled into and out of view with the relatively good seeing.

I held 'e' for long periods of time in crater form. No question about it, no tomfoolery. Plain as day. It was somewhat dimmer with a fainter floor and dimmer crescent shaped sunlit inner pit than the big four. I did not notice a thinner crescent outer rim. The thing about 'e' is it sits kind of in a darker albedo area, but seems to have a brighter albedo streak pushing across it.

The big four were in full crater form with 'A' showing not only a dark pit, but also a crescent shaped sunlit inner pit and a bright outer rim. Craterlet 'B' same description. Craterlets 'C' and 'D' were well resolved with a nice dark pit and sunlit crescent interior as well. However, their sunlit outer rim was less prominent.

Feb 9th at 1100UT, seeing was excellent (8/10 or better mostly.) Transparency was descent. I was at 320x with 6mm TMB II. The moon's distance is about 400,000Km (402,678 according the JPL sim and 398,086 according to Virtual moon Atlas.)

Man, I could not be happier to have such great nights to be thankful for. On such nights, if you'll forgive the religious reference, I just have to give a prayer of thanks. Serious, just as we do on Thanksgiving. WOW

Edited by Asbytec (02/09/14 08:42 AM)


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nirvanix
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Re: Plato's challenge new [Re: Asbytec]
      #6365863 - 02/09/14 11:47 AM

Hey, congrats Norme! Have to admit I'm a little jealous

What is your total Plato craterlet count? Are you at eight? That's a fine accomplishment for a 6 inch scope.

I was out last night but my sky was as lumpy as oatmeal. Looked over to Plato and the alpine valley, and did spot the three biggest 'lets', but no chance for gravy and glory.


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Asbytec
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Re: Plato's challenge new [Re: nirvanix]
      #6366040 - 02/09/14 12:56 PM

I am at 7 in crater form: A through D, e, and w makes 6 then g tonight makes 7. I think you are, too, yea? Specks were pretty hard to see tonight. I am not calling 'h' or 'i' as crater form sightings, wish I could.

Yea, Nirv, seeing is totally everything. Please excuse me admitting I just love that 6" Mak under nice skies. It never ceases to amaze. Never. I'm simply awestruck.

Were you able to observe this evening?


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edosaurusrex
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Re: Plato's challenge new [Re: Asbytec]
      #6366177 - 02/09/14 01:56 PM

Hi Norme,

Was your first sighting of "g" at 1100UT? If not, tell me when it was so I can update the prediction table.

Thanks,

Ed


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Rutilus
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Re: Plato's challenge new [Re: edosaurusrex]
      #6366687 - 02/09/14 05:37 PM

Been following this thread with interest, last month I had cloudy skies, and so far this month it has been one storm after another.
However, tonight is clear, and while the seeing conditions are not the best I had a go with my 6 inch f/15 refractor at 180x power.
A,B,C, and D seen as crater form. G was glimpsed in better seeing moments as a bright spot. E was observed, but was difficult,
appearing as a bright spot during moments of better seeing..


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nirvanix
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Re: Plato's challenge new [Re: Asbytec]
      #6366884 - 02/09/14 06:54 PM

Quote:

I am at 7 in crater form: A through D, e, and w makes 6 then g tonight makes 7. I think you are, too, yea? Specks were pretty hard to see tonight. I am not calling 'h' or 'i' as crater form sightings, wish I could.

Yea, Nirv, seeing is totally everything. Please excuse me admitting I just love that 6" Mak under nice skies. It never ceases to amaze. Never. I'm simply awestruck.

Were you able to observe this evening?




I've got clear skies tonight so will be trying again. Last year I got 7 plus an albedo feature.

You should enjoy and be proud of your Mak! Did you try for the alpine rille? I will look for it tonight also.


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Asbytec
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Re: Plato's challenge new [Re: edosaurusrex]
      #6367166 - 02/09/14 08:54 PM

Quote:

Hi Norme,

Was your first sighting of "g" at 1100UT? If not, tell me when it was so I can update the prediction table.

Thanks,

Ed




Hi Ed, do you need accurate time for that? I began observing at 1110UT through 1145UT, my first sightings were between those times. Both were within a few minutes of each other, I would estimate about halfway though pretty near 1125UT.

Having observed on the 8th, the big 4 were more difficult as faint arcs seen against Plato's darker floor. The improvement tonight was spot on according to your predictions earlier in this thread.

Quote:

...and while the seeing conditions are not the best I had a go with my 6 inch f/15 refractor at 180x power.
A,B,C, and D seen as crater form. G was glimpsed in better seeing moments as a bright spot. E was observed, but was difficult,appearing as a bright spot during moments of better seeing.




Rich, I bet you could have nailed e if seeing settled into a perfect moment. In such seeing, I was able to hold it for long periods, I am fully confident you would have done likewise.

I got the feeling it was slightly elongated, but not sure why. Maybe it is, maybe they all are to some degree due to the angle we view Plato, but it was just more obvious with e than the others. There were some brighter spots or albedo nearby toward Plato's center and toward w.

I was literally stunned to notice g, however. It did roll in and out most of the time as a faint white something. I would not call it a bright speck, just kind of a faint indistinct faint and fleeting smudge. About twice as I noticed it and once again a bit later (taking a break from sketching as seeing had improved again), it just settled into a very tiny, dark gray shadow with a lit rim crescent for a third time.

What's interesting is h is apparently two craters or at least an elongated one. In sum, but maybe not individually, it is much larger than e or g, yet I never managed to resolve it. It was the same faint and fleeting white smudge and maybe once viewed as a dark spot. I (I believe) was the same.

I am wondering if 'f' can be seen, I didn't notice it. But then again I didn't think to look up there that close to the wall with shadow cast along the floor. It may have been in shadow, dunno. I do not remember seeing the east wall pit.


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Asbytec
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Re: Plato's challenge new [Re: nirvanix]
      #6367226 - 02/09/14 09:33 PM

Quote:

Thanks Norme. I've seen A-E and g,h. Will have to try for i,j. There is no l,n, o ?




Ah, okay, Nirv, reading back I see you nailed g and h. You don't list w, which is pretty easy when the west wall is not in shadow. You can pick that one nicely for a total of 8, no problem.

Again, h is interesting in that combined it is fairly large. Yet I could not resolve it as a combined or elongated form. Maybe just gonna have to try harder next time.

Good luck with the smaller ones, I'm pulling for you. You have a nice ten inch aperture, right? It'll be interesting to see if conditions will allow it, if so I'm betting you can.


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azure1961p
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Re: Plato's challenge new [Re: Asbytec]
      #6367230 - 02/09/14 09:40 PM

At this point can you provide a notated image of Plato Norme? I'm very happy for every one here .


Pete


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Asbytec
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Re: Plato's challenge new [Re: azure1961p]
      #6367290 - 02/09/14 10:14 PM Attachment (13 downloads)

Sure, was thinking the same. Something like this.

The one in the north was kind of hard to place, it was about there. The spot just above 'e', not sure what that was. But, it was persistent. Maybe albedo? It was too close to 'e' to be 'p.' I do not think I saw 'l.'

Over by 'n' was a small string of albedo or specks not well defined, one of them was likely 'n', that bright spot was in the right place.



Edited by Asbytec (02/09/14 10:32 PM)


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nirvanix
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Re: Plato's challenge new [Re: Asbytec]
      #6367380 - 02/09/14 11:07 PM

Well how do all? I spent another two hours out this evening in -25C, but it was fine until the wind picked up and drove me inside. My nose felt like it was being bit off.

The first half on my time was spent watching a lovely transit on Jupiter, but then turned attention to Plato mostly, and a few minutes on the Alpine Rille, with a brief stop prior to my moon landing to split out the e and f from the trap. It was straight forward task.

My sky was cycling with short (1-3 secs) bursts of very good seeing between the continuing bubbles. I'm starting to be bold now as the seeing improves and going straight for the gusto of high mags. Started out on Jove with 400x and stayed at that power for the duration of the night.

I was able to spot sections of the Alpine Rille, but never the whole length in one go. As for Plato, A-E, W easy, and I would say that during a few really good cycles I noted g and h as more than just albedo features - they looked structural. Try as I might couldn't make out much for k,p,q,m,i,j. Maybe a speckle for k and m. Perhaps the illumination isn't quite right, but I'm too cold and stiff to go back out! Kind regards and happy hunting.


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Asbytec
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Re: Plato's challenge new [Re: Asbytec]
      #6367396 - 02/09/14 11:15 PM

Okay, here's what I know to be true having seen g with a crater pit and a faint crescent. Apparently g is about 1.5km in diameter and the moon's distance is about 400,000km or close enough for both measurements.

Using the small angle formula (which I think is an approximation itself) then g subtends an angle of ~0.77" arc. Yes, that's the Dawes limit for a 150mm aperture. But, here's the kicker, my aperture is obstructed and that has diffraction effects altering the diameter of the Airy disc by an approximate factor of 1 - co^2. Actual Raleigh type resolution falls from 138.4/150 = 0.92" arc to about 0.83" arc. The Dawes equivalent falls to closer to 0.69" arc.

So, seeing g and maybe f in an obstructed aperture is actually is not that mysterious of an observation so long as seeing is diffraction limited at 8/10 Pickering or better. It falls within what would be the Raleigh and Dawes limits for an obstructed aperture.

And this is the realm of the MTF where obstructed apertures pull ahead of even perfect unobstructed apertures - at those highest spacial frequencies. Some will say that tiny bit of performance boost near the Dawes limit is not significant because it is so often swamped by seeing. That's true, but I'd argue otherwise when it allows me to observe 7 tiny craters on Plato's floor or split tighter nearly equal doubles when seeing does not swamp that realm of the very tiny.

It's these types of observations that make me a believer in theory. Theory seems to explain seeing 'g' and 'e'. Most of us (maybe most of us, at least I do) think of diffraction limited as kind of a bad optic, nothing special, kind of blah. When in truth, diffraction limited even in a 150mm aperture is quite stunning to behold. And that beauty very often rests nearly entirely with the observing conditions and not the optic. But when your scope hits that diffraction limited performance, I am sure you will agree how so much nicer it can be.

So, the point being, I hope conditions permit others to observe 'e', 'g' in a modest aperture, or whatever other craterlets your aperture can theoretically resolve. If conditions are right, I am sure Nirv's 10" can nail many of the much smaller ones. I wish him, et al, Godspeed because I know it can be done.

Good luck and may you succeed - I want 'f'!

Edited by Asbytec (02/09/14 11:18 PM)


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Asbytec
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Re: Plato's challenge [Re: nirvanix]
      #6367424 - 02/09/14 11:26 PM

Quote:

As for Plato, A-E, W easy, and I would say that during a few really good cycles I noted g and h as more than just albedo features - they looked structural.




So, that's 8 for you, well done. Yea, specks were not as evident for me either, you're probably correct saying the sun angle isn't optimum. I'd bet you can count a lot more in a week's time. Get out your clicker.

So, your nose was bit off and my jaw fell off. We need a new hobby.

What do you recon your seeing was? You have a 10" aperture, which is ideal as it tends to be right at the aperture for the best atmospheric seeing. What you might see as 7/10, I might see as 8/10 or better in a 6". Being that 8/10 or better is diffraction limited, I would think your seeing was a tad less at about 7/10. Would that be a safe guess?


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edosaurusrex
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Re: Plato's challenge [Re: Asbytec]
      #6367439 - 02/09/14 11:41 PM

Here are the predicted times for the Sun altitude to be 11.15 degrees rising, 12 degrees setting, at Plato's center to agree with Norme's sighting. Rising time plus a few days or setting time minus a few days should put viewing at the conditions stated in the earlier posts.

PLATO PREDICTIONS FOR 2014
MMM DD HHMM UT

FEB 09 1125 RISING *correlation*
FEB 21 1157 SETTING

MAR 11 0231 RISING
MAR 22 2356 SETTING

APR 09 1728 RISING
APR 21 1028 SETTING

MAY 09 0739 RISING
MAY 20 2013 SETTING

JUN 07 2042 RISING
JUN 19 0559 SETTING

JUL 07 0833 RISING
JUL 18 1629 SETTING

AUG 05 1923 RISING
AUG 17 0416 SETTING

SEP 04 0537 RISING
SEP 15 1733 SETTING

OCT 03 1553 RISING
OCT 15 0813 SETTING

NOV 02 0253 RISING
NOV 13 2345 SETTING

DEC 01 1509 RISING
DEC 13 1525 SETTING
DEC 31 0454 RISING


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nirvanix
Carpal Tunnel


Reged: 06/07/07

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Re: Plato's challenge [Re: Asbytec]
      #6367446 - 02/09/14 11:50 PM

You're spot on the money Norme. I'd say seeing was P 7 in the good moments. Transparency was a bit off tonight, but that may help in crater hunting.

This evening I collimated several times as the scope cooled after noticing a few days ago the collimation does go off as the scope drops from +20 to -25C. Have to keep that up from now on. With familiarity I'm enjoying using the Astrosystems Lightpipe and auto-collimator. The Lightpipe has a feature that I heretofore had not used but I feel makes it better than a run of the mill cheshire.


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