Plato Craterlets

[rl]

10 March 2014, 2100:2130

12" Newtonian, *150, 250

Went out tonight with the intention of observing galaxy NGC2903 in Leo but was frustrated by a broken Telrad, very light cloud and a gibbous moon. Turned the scope on the moon and was dazzled and gobsmacked by the clarity of the view. Dropped in a 13% moon filter which allowed a more painless view and tidied up the image considerably leaving a really black sky against the limb. I was seeing some serious detail down the Apennines, and in Clavius and Archimedes. I looked at the floor of Plato more in hope than expectation and saw nothing except the usual grey featureless surface. Cranked up the mag to *250 and took out the filter (wrong format for the other eyepiece) and looked again; sure enough there were 3 little bright patches in the middle of the crater floor going in and out with the seeing. Well chuffed! That's a first for me.

RL

[Pig]

Its great to see the craterlets inside Plato, I didn't even know they existed until John mentioned them in a post a short time ago   I now make a point of looking for them.

[John]

Nice one RL ! 

I expect one of the ones you saw was actually two close together so you can claim to have seen 4 of them

I managed to see 9 of the little blighters a few weeks back on a night of really good seeing.

Heres a Lunar Orbiter photo of Plato with the size in KM of the craterlets to help you ID the ones you saw:

[Pig]

LoL@ little blighters

[MoonNut]

Ah!  Nebula..... sounds to me like you are ready to start the Lunar100, you have already seen one of the more difficult items (L83 Plato Craterlets)

http://www.skyandtelescope.com/observing/objects/moon/3308811.html?page=1

There are many sites with resources to help you, it is a great observing project.

[Mike73]

I managed to see 9 of the little blighters a few weeks back on a night of really good seeing.

That really is quite an achievement John, well done!!

I presume you used your 12" OOUK? I've always stood up for the quality of Chinese optics and thats partly because I've never really read any reports that ultra high grade optics users actually seeing more than standard 1/4Pv optics but I'm pretty sure that 9 craterlets is well out of the realm of 12" GSO or Skywatcher.

Great optics, perfect seeing conditions and experienced eyes. Once again well done, I bet you felt quite happy after that night out!? 

[rl]

Thanks John...9 sets a challenge! I guess like most of these things it gets easier once you know what you're looking for. I''ve read reports of people seeing the biggest of them with a 3" refractor which is a bit humbling....

Mike73...I'm using OO optics ultra grade as well and I can vouch for their quality on the few occasions the atmosphere allows you to see the difference. It's rare for any scope to resolve better than an arcsecond where I live regardless of aperture but last night was one such occasion...

RL

[rl]

Moonnut..thanks for the S+T reference...I've just printed it out in works time and I'll have a go. I've been observing for 40 years and have always struggled with the moon simply because there is so much to remember feature-wise. It's like learning another language remembering all the names even though the features are visually familiar. This might be a motivation to get to grips with it as an observing project.

RL

[Mike73]

I think the key to having high grade optics is actually knowing enough about an object to be able to recognise when you may see the advantage, being realistic I think its all to easy to claim your getting better views from high grade optics when in reality because of seeing conditions your actually seeing the same as everyone else.

I do hope I'm wrong though as I have a VX10L on order! 

[rl]

True..there is virtually never the opportunity to do a side-by-side comparison on the same oblect under the same conditions...

what is measureable though is the improved quality of OO optics since they started Zygo testing them. My 12" was bought secondhand ..it's an old one (1999 vintage) and the original "1/4 wave" optics were real rubbish....I took then up to Crewe to be checked ...results were 0.62 wavelengths P-V with a Strehl ratio of 0.52 for the primary alone. Take off another 0.3 for the secondary and its support and the Strehl for the whole instrument was probably down at 0.2....They were embarassed enough to offer me a discount on a new set (which I gratefully accepted..) but it wasn't as simple as that..the new mirror was twice as thick as the old one . I ended up modding the old cell and shifting the focuser further up the tube but he work was worth it.

I don't think you will be disappointed with the new optics but the focuser might need some attention, althoiugh I hear rumors they are fitting baader as standard now.

Anyway... I digress..

RL

[michael.h.f.wilkinson]

Congrats on spotting these craterlets, not an easy target at all.

[rl]

Went out again tonight (11th) and bagged 6. As John said, the original 3 were in fact 4, and I managed to see 2 extra. Referring to the thumbnail, they are:

2.09, 2.44, 2.22+1.98 pair, and 1.21 and 1.30.

I was disappointed not to get the one near the eastern limb..might be a shadow effect. It's amazing what a difference a day makes; the 3 big ones were seen quite easily tonight as proper craters with an indentation and shadow rather than just white blobs.

I'm starting to feel Patrick's ghost looking over y shoulder every time I go to the eyepiece now,,,

RL