A question of seeing...

[ashenlight]

Hi everyone,

Very much a beginners question for you all. In almost all the reports I read from alot of you guys on here mentions the 'seeing conditions'. I take this to be how well you can literally 'see' the stars, if there is a high layer of cloud etc. Sometimes, particularly on photos or sketches, the 'seeing' seems to be graded, I remember it appearing something like 'II/I' or something like that.. I tried to look for an example but couldn't find it. How do you 'grade' seeing? Does anyone know of any good links on this subject? I seem to be under the impression that heat rising from the roofs of houses can affect 'seeing', making what you see appear 'hazy'? Have I got this right?

I would like to understand this as I'm getting a scope soon and would like to produce some observing reports with more detail, and would also like to have a go at sketching, I think it'd be handy to note the seeing conditions as I go along. I have done brief google searches on this topic but can't seem to find a definitive answer, would appreciate your help.

Amanda

[barkis]

This might explain it a bit for you Amanda. If not, I'm sure you will get other explanations.

Ron.

http://www.ayton.id.au/gary/Science/Astronomy/Ast_seeing.htm

[ashenlight]

Thankyou Ron, I'll have a look at that now. This forum is great, I never feel stupid asking questions like this, haha!

[Talitha]

Hi Amanda, here's an animated version of what things look like (telescopically) during various degrees of seeing. When making your notes using this scale, just say the seeing was "Pickering 4" or "Pickering 7" and other Amateurs will know what you mean, or you could just say 4/10 or 7/10. Ten is always implied to mean the best.

You mentioned 'haze'... that's what we call 'Transparency'. It's the visual appearance of the atmosphere we're looking through, and you'll see it mentioned in reports alongside the Seeing. Basically it's airborn particles. Mostly moisture, but it can also be smoke, smog, or even dust I suppose... anything which interferes with the clarity of what we're observing. For the most part, it's rated the same as the seeing.. #10 is Nirvana, and #1 is 'why bother?'.

[ashenlight]

Thankyou Talitha, I'll have a look at that now. I've recently been having a look at your lunar sketches and your tutorial, they really are fantastic, your tutorial has spurred me on to have a go!

Amanda

[Talitha]

:)Thanks Amanda, we're looking forward to seeing your work if you decide to post it. The best thing about sketching is that it makes you look at things harder, which in turn, makes you a better observer (but we still need adequate seeing, lol).

And thanks for starting this thread. For every member who posts a question, there's probably 10 readers out there who are helped by the answers.

[ashenlight]

That is what I thought Talitha, I have no shame, I will ask anything haha!

When I get round to doing some sketching I will post it, be nice to hear any suggestions for improvement. It is like any art isn't it, makes you see things in a different way. It's all very exciting Are you going to the star party?