Wanted to see if what I was seeing was....erm...seeing?

[Beagleboy]

The last couple of evenings that I've had the telescope out (Thursday and last night), the sky has been completely clear of clouds where I am just to the south of Stirling. I reckon I'm on the cusp of a transition between urban and rural light pollution as on clear nights I can clearly see the hazy band of the Milky Way overhead). These last two nights though, have seen me struggling to get as good a view of some of the DSO's that I've previously spotted in my very amateurish, newbie way! 

On a previous night, I'm sure I spotted a hint of the shape of the Whirlpool galaxy, but last night I could barely make out the two cores with just a suggestion of a haze linking them. Certainly, to the SE over towards Grangemouth and Edinburgh, the sky has seemed to carry a much 'milkier' hue than usual these last couple of viewing nights.  Although there wasn't any real hint of a shimmer in the atmosphere, as I went on to look at the globular cluster in Hercules as well, and even though I couldn't see a great deal of detail at x48...I still reckon I was getting a pretty clear and stable view and even managed to up the power to x240, although at that magnification it was really, very dim!

So I was wondering, could there have been a lot of vapour in the air that was maybe making the sky a bit more translucent than normal and thus harder to see the fainter Whirlpool. Is this what you're talking about when you refer to 'seeing conditions'? Or am I just expecting a wee bit too much from Dobby, my 200p?

Cheers again,

Craig

[Charic]

The 200P is a great scope but conditions will often dictate what you see, despite how good the collimation, or how premium the eyepiece?

I've hardly been out this Year due to the poorest of weather conditions, usually overcast, and now,  as the leaves are almost of the  trees, I have to contend with the full  street light pollution again. If I can shield my eyes from the glare by sitting inside my Dob tent, or having a cape/blanket over my head, and a foam underlay extension on the OTA, the views are ok from my garden, but away from home, just stunning, weather and seeing conditions permitting.

Jupiter is the only Planet so far, from my garden,  that I have seen successfully, and on, what for me, was just another  perfectly normal night, then Bam! something changed,  Jupiter was totally detailed, small but detailed, with the shadow from the Moon Io (eye-oh) clearly visible, so what happened? The conditions above me improved, and sometimes for only a few fleeting moments.

I will see more, and more often,  if I venture away from the house to darker sites, guaranteed, its just the effort and planning involved.

Each night will be different, keep a diary maybe, noting the stats for the weather, and see if there are any clues to how and why certain nights were better than others, then plan to associate viewing with just those nights maybe. Having said that, some folk just look up whenever  there is a break in the clouds, and somehow, have the best viewing session EVER!

Just keep at it and enjoy what ever you see.

[Astro Imp]

A great post by Charic above. Yes that's pretty much it, your viewing experience does vary night to night.

There are basically two sky conditions to consider.

i) Seeing, if the stars are steady as opposed to twinkling the seeing is good which is the ideal for planetary and luna viewing. Later in the winter look at Sirius on a poor night with bins or a low power eyepiece and you will see a great light show.

ii) Transparency, describes how transparent (obviously) the sky is. You need good transparency to view DSOs. As an aside at this time of year I get the bins (8x42) on M31. If all I see is a very slight smudge then I know the transparency is poor but on a good night the glow of the centre is very obvious.

[Stu]

The last couple of evenings that I've had the telescope out (Thursday and last night), the sky has been completely clear of clouds where I am just to the south of Stirling. I reckon I'm on the cusp of a transition between urban and rural light pollution as on clear nights I can clearly see the hazy band of the Milky Way overhead). These last two nights though, have seen me struggling to get as good a view of some of the DSO's that I've previously spotted in my very amateurish, newbie way!

On a previous night, I'm sure I spotted a hint of the shape of the Whirlpool galaxy, but last night I could barely make out the two cores with just a suggestion of a haze linking them. Certainly, to the SE over towards Grangemouth and Edinburgh, the sky has seemed to carry a much 'milkier' hue than usual these last couple of viewing nights. Although there wasn't any real hint of a shimmer in the atmosphere, as I went on to look at the globular cluster in Hercules as well, and even though I couldn't see a great deal of detail at x48...I still reckon I was getting a pretty clear and stable view and even managed to up the power to x240, although at that magnification it was really, very dim!

So I was wondering, could there have been a lot of vapour in the air that was maybe making the sky a bit more translucent than normal and thus harder to see the fainter Whirlpool. Is this what you're talking about when you refer to 'seeing conditions'? Or am I just expecting a wee bit too much from Dobby, my 200p?

Cheers again,

Craig

Craig, outside light pollution, there are two main aspects to sky conditions which are normally referred to. The first is seeing, and the other transparency.

What you are referring to I would class as transparency. The sky can be very transparent, or it can be clear, but with a milky/hazy appearance to it. Seeing objects like M51 well requires dark and transparent skies, so I would keep trying on a few more nights, it does make a real difference.

Seeing conditions are related to the stability of the atmosphere. It is often poor after a hot summer's day or when the jet stream is passing overhead for example. The sky might be very clear, but if the stars are twinkling then it gives a hint that seeing conditions will be poor. This mainly affects mid to high power views for lunar/planetary and double star observing, whereas good transparency is more important when viewing faint nebulae or galaxies.

Fortunately, often you get one or the other so this can tend to dictate what sort of session you end up having.

[Beagleboy]

Thanks again for the very helpful info. I've had a wee bit of a read and it does sound like I was trying to view some faint objects on a night where the Transparency wasn't ideal. Now that I have a name for it, I can shake my fist in the air and curse, "Damn you Transparency!!", which'll make me feel much better.

Every day's a school day, brilliant innit!

Cheers,

Craig xx

[Stu]

Thanks again for the very helpful info. I've had a wee bit of a read and it does sound like I was trying to view some faint objects on a night where the Transparency wasn't ideal. Now that I have a name for it, I can shake my fist in the air and curse, "Damn you Transparency!!", which'll make me feel much better.

Every day's a school day, brilliant innit!

Cheers,

Craig xx

Great stuff.

You'll soon get used to replacing transparency with any one of the following:

Seeing

Wind

Cloud

Rain

Snow

Hail

Etc etc [emoji6][emoji6]

[triton1]

I often use Ursa Minor as a guide,Polaris generally can be found easy enough but if I can,t see the other 6 stars in the constellation I often Don,t bother setting up.This is what is leaning me towards a goto mount life's to short to be faffing around with our weather.When seeing condition have been good I have been known to do a 10 hr shift of which a third was hunting the objects down.