Deep sky from the City

[part timer]

As promised in another thread.

Many people seem to be obsessed with telling newcomers to astronomy that the only objects that can/should be observed from a light polluted location are the moon and planets.

I have moved a lot since leaving school and starting work have always been stuck in larger town/city locations.These locations have included, Blackpool, outer London, Reading (central and further out), Hull and Stockport. I have family commitments which mean that I use small scopes and never travel to a dark sky more than once or twice a year.

I spend about 80% of my observing on deep sky objects of the fainter varieties. I do not understand why anyone would say deep sky observing is not possible.

A dark sky makes a great difference to some very extended objects but is not nearly so important on more compact objects, and most objects are compact.

Star hopping is easier in moderate to badly light polluted areas as it is easier to trace constelation patterns tan in the countryside. London ans Stockport Were harder as only the brightest stars appear, but even there putting an umbrella up to block direct light made some more stars visible and i always had enough stars in the finder scope to navigate with.

Poor conditions are worse in the City as the smog is lit up from below but in those conditions deep sky objects are not great from any location.

Just to add, as mentioned in the other thread My vision is not particularly good so most others should get the same or better result's from their location.

So I ask, why not just try?

[zhgutas]

Completely agree. I've had some really nice observing sessions with my ST80 and ST102 from the balcony of my 12th floor flat back home, in the middle of a town. While it was not a "walk in the park" trying to spot some of the DSO's, I would certainly NOT call it impossible. IMHO, it's just a matter of proper selection of targets

Marius

[great_bear]

Many people seem to be obsessed with telling newcomers to astronomy that the only objects that can/should be observed from a light polluted location are the moon and planets.

No more than the number of people who say that scopes under 6" aren't worth having - or that refractors are the only serious option for planets or [insert recycled "knowledge" here]...

So I ask, why not just try?

Well, I think "trying" is the only way - no-one should be discouraged from doing that.

However, whilst I've seen lots of Messier objects in the countryside and know exactly for what (and where) I'm looking, most objects are simply not visible from my home location. Not even a trace. Nothing.

M31 is visible of course - but just as a mere lightening of tone in the middle of the eyepiece. Similar story for M13, M3 etc.

Other than being occasionally able to confirm the existence or location of something, what's the point? Every globular or galaxy is either missing or just looks like a slight lightening of the background sky - so why bother wasting time night after night? I couldn't honestly claim under such conditions that I've really "seen" those things - especially when - using the same scopes in the countryside, M13 looks like a wonderful little snow blizzard.

Acey's post here summed it up nicely.

Most people's skies will lie somewhere inbetween my inpenetrable sky and the deepest, darkest countryside. But just because some city skies turn out to be not so bad, doesn't mean that all city skies are viable observation points. For many city people whose lives aren't dominated by astronomy, having just one small GoTo scope that they can use for stars and planets in town and take to the country for DSOs is a neater and more elegant solution than carting a big dob about.

I'm sure we've all seen For Sale adverts from people getting rid of big dobs for "something a bit more portable"

In my case, I'm a considerably happier bunny looking at double-stars and planets, than looking sideways and asking myself "do I see a faint lightening of tone in that area there? Hmmm... Maybe I do...."

The fact that small, high quality telescopes continue to sell in large numbers proves that they're genuinely useful to a significant number of people.

- and I'm sure that they can't all be being used for autoguiding

[Capricorn]

Saw this in the other thread. You have to be realistic. DSO's are going to be either a problem or impossible in light polluted places. I will settle for a problem.

Double stars and other main stars of constellations are less of a challenge but also can still be difficult. Especially if looking for coloured ones.

However there must be some nights in cities when seeing is improved and when that occurs it will be good to point the scope at some of the brighter DSO's and take the chance. Also good to know where they are even if they cannot be seen many nights.

I wonder how much of the problem is light pollution and how much is atmospheric pollution. The description of M31 reads of atmospheric pollution being the greater problem.

[GuillermoBarrancos]

Saw this in the other thread. You have to be realistic. DSO's are going to be either a problem or impossible in light polluted places. I will settle for a problem.

Double stars and other main stars of constellations are less of a challenge but also can still be difficult. Especially if looking for coloured ones.

However there must be some nights in cities when seeing is improved and when that occurs it will be good to point the scope at some of the brighter DSO's and take the chance. Also good to know where they are even if they cannot be seen many nights.

I wonder how much of the problem is light pollution and how much is atmospheric pollution. The description of M31 reads of atmospheric pollution being the greater problem.

Those nights exist... during the colder late autumn and winter nights.

Late spring and summer are bad astronomy days. At least on the northern hemisphere, wich is where we are. Very short nights. And the sky is more hazy and the smog / polution is a lot more noticable.

That's why you see people taking the best pictures during the winter months. When you have long cold, crisp clear nights.

The only clear summer nights I have ever witnessed, was during a holiday deep and high up into the French Alpes. With no big light poluting city around. But that's on 1000 meters above see level in a valley, causing very spooky pitch black nights. It was the first time I was actually able to see the whole Milky way in full detailed glory with the naked eye.

I would be able to do that here in Norway too. But then I have to go high up on the mountains and/or deep into the forests... away from Oslo. And ofcourse not during summer. That would be pointless.

[PeterW]

Dark adaption is also nigh on impossible to maintain in the city, especially with lights visible from an observing location. I am currently wondering about video astronomy as a way of getting the advantages of the visual observing, but with some electronic help (filters and improved NIR sensitivity)?! I lack the patience and insomniac nature that is required for imaging.

The Lunar100 has been a help in stopping me get too depressed, but I've never had much luck with planets, partially as they are so small. A bit more aperture (currently 5") would likely help here. Maybe a car would be more use, but then I'd need to obtain 'permission' for going out (small people need putting to bed etc).

Sometimes it is hard to enthuse members of the public when the skies are so dire that even keen observers find it hard to see much. Maybe we ought to do light pollution lobbying rather than observing... make the skies better for everyone.

Cheers

PEter

[great_bear]

I wonder how much of the problem is light pollution and how much is atmospheric pollution. The description of M31 reads of atmospheric pollution being the greater problem.

I think one causes the other - i.e. ludicrously bright neighbourhood lighting probably lights up the Hackney rush-hour traffic-pollution.

[Deneb]

There is loads to see, even in very light polluted area of North London, but I do feel that lpr filters do have a big part to play as well. The stuff on my website was all taken in my backyard in a light polluted suburb of n. london.

Cheers

Nadeem.

[part timer]

However there must be some nights in cities when seeing is improved and when that occurs it will be good to point the scope at some of the brighter DSO's and take the chance. Also good to know where they are even if they cannot be seen many nights.

I wonder how much of the problem is light pollution and how much is atmospheric pollution. The description of M31 reads of atmospheric pollution being the greater problem. City skies can show a dramatic improvement by simply staying up late!

I find that by about midnight on any given clear night the seeing conditions do improve noticeably. This, I suppose, is due to a number of factors including less carp in the air and a slight reduction is lighting at that hour. Also the ground has cooled off by that time and so the air is steadier.

Filters do help, I find a UHC is nice with small scopes.

I think one causes the other - i.e. ludicrously bright neighbourhood lighting probably lights up the Hackney rush-hour traffic-pollution.

The only thing wrong with that statement is that you need to replace the word Hackney with Britain! As I say deep sky is much easier if you give all that smeg time to settle. Contrast can be surprisingly and even dramatically improved.

Also I have to say that, whilst Telrad's and some other zero power finders have their advantages, they aren't so good in LP. A decent optical finder scope cuts through to LP to show most of the stars in a cheap star map. You won't see many DSO's through the finder but you don't really need to as long as you can see some stars.

[acey]

Well, I'm one of those people who advise newcomers that deep-sky visual observing from a city is hard work, and may in some cases end with said newcomer putting their little-used 12-inch dob on the second-hand market. On the other hand, although nowadays I always drive well out of town to observe, I did start out by using an 8-inch in the back garden, limiting mag 4.5, and I did manage to see a reasonable number of DSOs. It's not impossible.

The thing is to be selective. Open star clusters and planetary nebulae are the best to go for (with a nebula filter on the latter to make things even easier). Bright globulars (M13 etc) should be visible and can be impressive, even if stars can't be resolved. As for galaxies, I made my first attempts at the Virgo Cluster and a number of Messier galaxies from the back garden. On the other hand, a single trip to a dark sky was enough to convert me. M31 with binos from a dark site will blow away any view you can get from an urban location.

I do plan to try some more deep-sky observing from my garden (simply because I can't make as many dark-sky trips as I'd like). My initial hit-list consists of planetary nebulae that I think I ought to be able to see with the 12-inch. First I intend to observe some clusters using a magnitude chart in order to determine what are the faintest stars I can see (I'll use a hood over my head to block light and improve my dark adaptation). Then I'll have an idea which stellar PNs should be feasible (as long as they rise high enough above other houses, trees, skyglow etc). In the past I had no trouble seeing bright PNs with the 8-inch or smaller (I saw M76 with an 80mm and UHC filter) and I plan to go for objects that are stellar or nearly so: in other words, small enough that they will have sufficient surface brightness to be visible in the lightened sky.

[great_bear]

There is loads to see, even in very light polluted area of North London.

But I think that this is the kind of generalisation that kicked off the debate in the first place. I think that local conditions have an important part to play in this.

For example, my father lives in a microclimate area of Poole, (Dorset), where the national weather can claim it is chucking it down with rain in his area, whilst he's actually basking in sunshine in his back garden! Similar differences must apply to Light Pollution I'd have thought. Whilst general statements can be made about light polution for a given area, the difference in smaller sub-districts I suspect may be rather large.

In my immediate area, the street lighting is at markedly strong levels - not just for my street but all the surrounding ones. If there is any low-lying mist it reflects all that light back at me I'm sure. There are areas not far from me with considerably less street lighting. I'm sure that accounts for some of the variances.

Once in a while - and extremely rarely - I can get dramatically clearer skies. No idea why.

I think this issue is far more complex than we imagine it to be...

[Demonperformer]

I am currently wondering about video astronomy as a way of getting the advantages of the visual observing, but with some electronic help (filters and improved NIR sensitivity)?! I lack the patience and insomniac nature that is required for imaging.

My easiest location is in my front garden surrounded by streetlights [the back has very little in the way of sky being surrounded by buildings on all sides]. On a good night limiting magnitude is about 3.3 (Megrez sort of floats in and out of visibility).

Since purchasing a mintron, I have managed to get quite a few DSOs. including globulars (M4 & M5) and M57. These are with 20min avis, with sensitivity maxed out, giving about 400-500 2.56second frames, stacked in Registax. Admittedly I haven't done much with galaxies yet.

I would have to say it has revolutionized my sessions. So I would definitely say, give it a go.

Now, if only I could find a capture program that would allow me to capture only 0.4 fps on the computer from the mintron ...