Clear skies but rubbish seeing ?

[James]

I've got clear skies here in North Somerset tonight but rather frustrating seeing conditions - normally relatively easy double stars are proving a challenge in the 6" mak-newt (it's been cooling for 2 hours !) and Jupiter refuses to focus crisply for more than a fleeting moment even at relatively low magnification.

Pretty annoying as it all looked a bit good to the naked eye

Anyone else having these sorts of issues tonight ?.

Yep - same here but then I am only 30/40 miles away... seeing was pretty poor until about 11pm/midnight when it improved a little. Transparency was good so I got my 10" Newt out for the first time in a long time

James

[oldfruit]

Pretty awful in east Lincolnshire too. Jupiter seems to be swimming almost some of the time. Never seen it quite this bad to be honest though the sky is lovely and clear.

[earth titan]

Thanks all. Glad to see you are suffering the same. Just made oit the GRS last night but an early start this morning meant early bed. Very unstable skies - made me paranoid about colimation and scope so glad everyone else was suffering too.

[JohnR]

This thread is a bit of a relief for me as i too was thinking i must have botched my recent collimation.Last night was the first time i've had the scope out for a while and i just couldn't seem to get anything in focus

[russ]

This thread is a bit of a relief for me as i too was thinking i must have botched my recent collimation.Last night was the first time i've had the scope out for a while and i just couldn't seem to get anything in focus

I couldn't focus the 12" at all on Jupiter to start with, so pulled out the refractor and 6" newt to confirm it was the seeing and not my collimation. All three were equally bad. One of those nights that are so bad you start having doubts about the quality of the scope or your own collimation abilities.

[MartinB]

Seeing was certainly bad last night and the transparency not quite as good as I thought it was. My guiding graph was pretty jagged, all down to the seeing. There is something very special about the sky on a clear wintery night though

[John]

...... One of those nights that are so bad you start having doubts about the quality of the scope or your own collimation abilities.

Absolutely - I started to tweak the collimation of the mak-newt then common sense prevailed and I just stuck to low power views of some DSO's until retiring to warm up.

Funny how paranoid one difficult night can make you about equipment that has delivered great performance during numerous previous sessions

[russ]

There is something very special about the sky on a clear wintery night though

I'm hoping to see that 'something special' tonight from the depths of the New Forest. But appears the forecasters have made a hash of things. Supposed to be clear and sunny but wall to wall cloud instead.

Absolutely - I started to tweak the collimation of the mak-newt then common sense prevailed and I just stuck to low power views of some DSO's until retiring to warm up.

Funny how paranoid one difficult night can make you about equipment that has delivered great performance during numerous previous sessions

Unfortunately i started tweaking before common sense prevailed. Started playing with the secondary and then messed things bigtime.

[Mr Spock]

It's a relief to know it's not just me.

For a moment I thought it was the booze...

[SiriusB]

Beautiful clear blue skies here in Lincs yesterday, as twilight fell i donned my "extra warm gear" in expectation of a long session.

I rarely get "good" seeing at my location, but it seldom affects my 80mm below 100x. (even if larger apertures suffer.) It sure did last night!

Got to have been some of the worst seeing i've ever experienced, & tranparency mediocre too- i was expecting that at least, to be reasonably good.

Further confusion, as light pollution was better than normal for me.

So can anyone explain this. What exactly was going on up there?

[Mr Spock]

At the moment, the jet stream is running N to S across the UK. Makes for a very turbulent atmosphere right above us. Observing is a waste of time right now.

Grrr...

[John]

At the moment, the jet stream is running N to S across the UK. Makes for a very turbulent atmosphere right above us. Observing is a waste of time right now.

Grrr...

Oh dear - I've got the 10" newtonian cooling at the moment - sounds like it will be low power stuff again.

Still, it better than staring at the cloud base !.

[budski]

Everything tonight looks like it's behind a lace curtain. Ice is forming around the 'scope and I've given up. Can anyone with any meteorological knowledge tell us why, even though the sky looks clear to the naked eye, the seeing is so abysmal?

[russ]

Transparency and seeing were indeed pretty bad once again last night. Although the transparency improved later on. Jupiter was dire!

[mike.brightmore]

Hi Mike

I keep trying for the Crab but can't see it. M57 is clear as anything despite being in a direction with bad LP but I just can't find M1. What sort of magnification is best? Any tips?

Stu

Sent from my GT-I9000 using Tapatalk

Hi Stu

Keep trying. I find the Crab fascinating as the supernova that caused it was recorded by the Chinese nearly a thousand years ago. It is easily washed out by light pollution, Moonlight or poor transparancy. Sometimes I can't see it, other times I can. Often its better with the 25x100 binos. It needs maximum aperture and minimum magnification. I use a 40mm EP in my f10, 2800 mm F.L. tube so giving a magnification of 70x. SCTs are a bit long in the focal length department for faint fuzzies so a focal reducer does help. I haven't tried using any filters for M1 but there might be some improvement to be had. One way I can always see it is to replace the EP with a video camera and feed the AV signal into a TV monitor. This works on many faint DSOs that I just cannot see visually.

Mike

[Stu]

Thanks Mike, that's very helpful. I think my scope is a bit too extreme for the crab at f20! It's fine on smaller and brighter dso's but I guess the brightness of m1 is spread over a larger area so it's not detectable. Even my 41mm panoptic gives x97. Might try a focal reducer or give the binoculars a go somewhere dark

Cheers

Stu

Sent from my GT-I9000 using Tapatalk

[SiriusB]

At the moment, the jet stream is running N to S across the UK. Makes for a very turbulent atmosphere right above us. Observing is a waste of time right now.

Grrr...

Thanks Spock- i like to know why!

How did you know that?- guess maybe its down to your Vulcan powers.?

[sbooder]

I was out the other night, very clear but the only thing to look OK was M42. Jupiter was rubbish.

[Mr Spock]

Thanks Spock- i like to know why!

How did you know that?- guess maybe its down to your Vulcan powers.?

As Science Officer I know about these things

Plus, as a hobby, I've been keeping weather records since Jan 1976. I check the weather sites more often than anything else!

[budski]

Mr Spock said: Plus, as a hobby, I've been keeping weather records since Jan 1976. I check the weather sites more often than anything else!

I'm glad we've got a Vulcan aboard Star(ship)GL. I'd like to think that anyone possessing the Vulcan Death Grip is a friend of mine. Very logical.

[PeterM]

Except for a couple of occasions transparency's been really bad here (north Essex) for the last two or three months. Humidity has been so high that the light pollution is spreading almost to the zenith and I'm getting worse views through my dob & apo than I used to get through my old 60mm starter scope. Fingers crossed it clears up soon.

[sbooder]

Nothing against our Mr Spock, but I was always more of an Avon from Blake's 7 fan myself.

[cathalferris]

For me, I've had nights of great transparency, nights of poor transparency and nights of freezing fog. Every time I've been out with a scope, I've had seeing disks of 3-6 arcseconds. It's been brutal!

There are a couple of factors in play as I see it,

1) Local conditions (1-10m altitude)

2) High altitude shenanigans

3) Ground conditions.

Where I currently observe from, in the backyard of the house on the suburb outskirts of Galway where I'm renting at the moment, I have no artificial lights to the east at all and I have Galway to the southwest. There's an industrial estate to the north and northwest as well. As it's blumming cold, most of the nearby detached houses are much warmer than ambient when compared to a normal +5 winter day, so they are much more powerful heaters of the local air. This is rising quite strongly until it reaches an inversion layer that appears to be less than a thousand feet up. There's good mixing under this layer, giving one reason for pretty **** seeing.

Also, as the Siberian airmass is streaming gently from the NE across the North Sea and the Irish sea, the effect of those large warm water bodies is to create great convection plumes that move across the island of Ireland. Those plumes may haev dropped all of the moisture that they can on the east coast of Ireland, but there's a good deal of heat still contained in that rising airmass and this is the main reason for the poor seeing.

I can focus quite easily on the mixing interface when looking at Jupiter or the Moon, and I can see that the distance to the interface is somewhere between 1 and 3 miles up and the direction that the shimmers are moving is consistent with the upper-level airflows.

The local ground conditions with some cleared roads and snow/frost covered fields means that there are wide variations in the local temperatures on the ground, and gentle breezes push the slight thermal plumes from the warmer cleared areas around, making intermittent wobbliness.

It is probably great weather on the whole for widefield photography as long as the seeing disks are small enough that they are not problems.