Seeing Alert SOuthern Vic and northern Tas

[§AB]

Looks like some promising seeing on hand tonight according to the 300mb wind charts. Almost no upper level winds. Time for a date with the moon and planets me thinks

http://weather.unisys.com/gfs/6panel...panel_aus.html

[Starkler (Geoff)]

thanks for the heads up . Im hoping for a decent view of Mars before it dissapears

[erick (Eric)]

How did it go? Monday night was yuck!

[Night Owl]

It wasn't / isn't a bad night. But here in the west of Victoria the day was very hazy, so I think it may still be.

I also picked up my 12" GSO Dobs today, the replacement one, quickly sent to me by Andrew's Communication last Fiday. Only problem was the scum sucking moluscs who drive trucks and delivered the replacement also managed to damage this one as well! They pushed in where the left bearing mounts the OTA. It still fits the cradle bearings, but its about 3 degrees wonky. I've got some time in a few weeks and I'll drop the mirror out and do some tube straightening. Its pretty minor, but it shouldn't happen. But what else can you expect from interstate amphetamine sponges.

All went together pretty easy, I even estapolled the bare chip board ends,and the screw holes, so it should also be more moisture proof. Also found out a way to make the teflon bearings a little less sticky. It's a product called Selly's Ezy Glide.

http://www.selleys.com.au/Selleys-Ez...e/default.aspx

It made a significant improvement.

I also had a runing battle performing my first laser collimation of the dobs. Seemed fine at first, went back to double check, and the batteries in the laser karked it. Tried to put the spare set in, but couldn't get the flat ones out, had to drill one and hook it out! Couldn't get the rest out and realised that the laser centering screws may have distorted the battery case of the laser, so a few outward turns of the grub screws and out they fell. Go to supermarket, no batteries! Go home, get 2 AAA batteries and a cell holder for another project, and jury rig them to supply the laser. Yay, back in business! Collimate scope, then while checking realise its all up the creek, and why. Grubscrews in laser collimator I loosened off to get batteries out also align laser in collimator! DOH! Have to re- lign laser. Once done, all set. Drag it out to back yard.

Moon was / is BIG and Bright, and first thing right off the bat I swing the tube around to Orion and shooting from the hip, direct hit! Didn't even have use the spotting scope with a 15mm Plossl! Yep, magnificent, can see the four in the trap, and some wispy nebula, which I thought was pretty good from the back yard with no time for eyes to adjust and close enough to the full cheese in the sky in its zenith! Soon realise though that can't see anything below 7.5 Mag. But, with my first scope I don't care!

I'm very impressed with the GSO Dobs build quality and the price. And the prompt service from Andrew's Communication. Needless to say I would like the tube to be a bit more robust, or the packaging. Maybe if they removed the 'Fragile do not drop' off the box things might get through unscatherd?!

The supplied 6, 9, 15, 25 and 32 mm eyepieces may not be in the no expense spared category, but from what I can tell from having previously gawked through an 10" Meade LX200 and assesories, and my slight astigmatism, they are more than good enough for a begining and beyond. I think I'll grab some more GSO eyepieces as well, then try a big name and $$$ to see what the hype is all about!

Might go and have another gawk.

[§AB]

Originally Posted by erick

How did it go? Monday night was yuck!

it was TERRIBLE. I couldnt focus stars 156x. Mars was unfocusable at ANY mag. Out of focus it was a torrid boiling blob. The E & F stars of the trap were barely visible at 250x. That's how washed out they were.

I decided I wasn't going to wait for Saturn so after 30 minutes I packed up. Pissed off and disillusioned.

[Starkler (Geoff)]

Originally Posted by §AB

it was TERRIBLE.

I could see just by looking up that it wasnt worth dragging any scope out.
Some of the fiercest and fastest twinkling I have seen!

How on earth are we meant to predict good seeing?

[§AB]

The twinkling here wasn't bad at all so it did actually look promising. Canopus was almost perfectly steady. So yer I agree, seeing cannot be predicted. Period. It's a hit or miss.

[Starkler (Geoff)]

I think I live in a location that is seeing challenged. If i head down mornington peninsula to the Briars I seem to get about a 50% chance of reasonable seeing compared to maybe less than 20% on any random night at my home.

[Terry B]

Originally Posted by §AB

it was TERRIBLE. I couldnt focus stars 156x. Mars was unfocusable at ANY mag. Out of focus it was a torrid boiling blob. The E & F stars of the trap were barely visible at 250x. That's how washed out they were..

Tis all relative. Seeing might have been good or bad here. Who knows? Hard to tell when you can't see ANY STARS AT ALL!!

[rumples riot]

I just want to clear something up here about the whole concept of seeing.

Actually the 300mb is not the only indicator of good seeing on any given night. In fact the absence of the jet stream from your skies almost never assures good seeing. Good seeing comes when all layers of the atmosphere are either still or travelling in the same direction.

Additionally the better chart to use during summer is the 200mb chart. during winter use the 300mb.

However even with or without the jet stream being present seeing can either be good or bad no matter what. The Jet only really affects the fine detail in an image ie tiny craters on the moon and tiny detail on the planets.

Where seeing is formed is the lower and middle layers of the atmosphere. You have to look at the what the middle level is doing more often than not. The middle layer can be going in the same direction as the Jet and you can still get good seeing even with the Jet stream present. However, if these are going in differing directions you can get what is known as fast seeing. That being the target looks really solid but cannot be focused correctly.

When you have local winds and high speed middle level this will also combine to make for very bad seeing. When seeing looks like the stars are smashed and wobbling, this is a result of all three levels travelling in totally different angles and directs.

The bottom line is that predicting seeing is a complicated affair and much attention needs to be paid to all the charts and satellite images. When the Jet is not there, check everything else.

Good luck next time.