How dark is your not dark site?

[domstar]

With winter being too cold to stray far from HQ, I wondered what was considered good darkness for a garden. From my balcony I can see beta Monocerotis directly, which is magnitude 4.60 according to stellarium. This is only when it is in the south as my town glows to the east (I assume snow does the darkness no favours) I could maybe do a little better on a good night but perhaps understandably I don't know many dim stars.

Anyway, what is good or poor darkness without getting in a car?

[John]

From my back garden I can see stars down to magnitude 5 on a good night, mag 5.5 on the best nights. I can see a good portion the Milky Way and M31, the Andromeda Galaxy and the double cluster in Perseus with the naked eye.

If I look towards the NW and NE the glow from a couple of cities intrudes though so I wait for object to rise fairly well up into the sky before observing.

[Stu]

For me it is between 4.5 and 4.8 generally although it may just reach 5 at the zenith on good nights.

Anywhere away from the zenith worsens rapidly so I guess it is around 4 ish for many observations. North and north west are awful due to Heathrow (meaning mag 2.5 or 3 at best), South is not too bad.

No chance of the Milky Way unfortunately, occasionally I can glimpse M31 or the Double Cluster naked eye with averted vision.

[acey]

33 minutes ago, domstar said:

With winter being too cold to stray far from HQ, I wondered what was considered good darkness for a garden. From my balcony I can see beta Monocerotis directly, which is magnitude 4.60 according to stellarium. This is only when it is in the south as my town glows to the east (I assume snow does the darkness no favours) I could maybe do a little better on a good night but perhaps understandably I don't know many dim stars.

Anyway, what is good or poor darkness without getting in a car?

Your conditions are fairly typical for a suburban location. You should be able to see some of the most conspicuous DSOs (e.g. M42, M31, M13, M81/82, Double Cluster...), but less conspicuous Messiers (e.g. M1) will be a struggle while ones of low surface brightness (e.g. M33, M101) will most likely be impossible. To see M31 as anything more than a little fuzzy blob you'll need to get in your car. If you can get to a place where the Milky Way is easily visible with the naked eye then you can be confident of getting good views. That usually means a naked-eye limit of about 5.5 or better.

[Starlight 1]

If I can go out the front door with out stoping its not dark.

[swag72]

I use an SQM reading and my obs is 20.29 at best........  Everyone thinks I live in massively dark skies..... I don't know how that reading equates to a bortle scale or what not.... and I don't know what I can see as I don't know what I'm looking at  

[Nova2000]

The faintest I've seen from my place is mag 4. @swag72. What's a sqm? 

[swag72]

1 minute ago, Nova2000 said:

The faintest I've seen from my place is mag 4. @swag72. What's a sqm? 

It's a reading obtained with one of these

[Stu]

28 minutes ago, swag72 said:

I use an SQM reading and my obs is 20.29 at best........  Everyone thinks I live in massively dark skies..... I don't know how that reading equates to a bortle scale or what not.... and I don't know what I can see as I don't know what I'm looking at  

20.3 is reasonable, but not particularly dark. I would say anything over 21 is a dark sky?

Plenty of info here

http://www.unihedron.com/projects/sqm-l/

EDIT Actually an NELM of 6 translates to 20.8 mpsas which is what the SQM measures.

http://www.unihedron.com/projects/darksky/NELM2BCalc.html

[Bart]

I'm confused folks.  My sky is reasonably dark I thought. The Milky Way is visible from about 10-15 degrees up quite clearly and shows mottling across the sky yet I think the NELM is about 5.5. This differs greatly from some description above. Any suggestions why that might be?

thanks

barry

[xtreemchaos]

I'm lucky to live in a darksite in south wales which is fantastic, but I used to live in hull where DS targets where near impossible, even the moon was orange due to the amount of light from the city, I'm very happy here, its heaven for skywatchers even the bats use headlamps . clear skys charl.

[SilverAstro]

1 hour ago, Starlight 1 said:

If I can go out the front door with out stoping its not dark.

Yes that is a good way of describing proper dark    I need to carry a torch,  or wait to get dark-adapted, or slowly edge forwards with foot feeling the way.

[Charic]

3 hours ago, domstar said:

I wondered what was considered good darkness for a garden

The only real solution I have for the garden is to hide inside a darkened tent! Completely dark, as dark as I can get it, using extra ground sheet covers ( I still have to get in and out, and the scope is almost limited to one direction due to the light seal? )  I have everything in order,  locating my eyepieces by touch, I don't read, write anything, just look and enjoy. My visible sky boundary is fairly limited due to the glare and obstructions, so the tent option works for me, so anything within the path that Ursa Major scribes overhead is good enough for me, from the present site.

Having the car does afford some benefits, if the  possibilities allow when away from  your HQ.  Many of us have less then perfect skies under which to observe!
 
During (my normal) winter observations, when time and  the weather allow me to observe, I have to endure glare from local street lights shining though my garden from the North, West and South, and sky glow further South above the tree line! and during the Summer Months, almost permanent twilight, where the telescope is of no use to me, it hibernates?  I can just make out with my eyes, six Stars of Ursa Major, excluding Megrez.

For me, the only consideration I seek for a dark site, is when I cannot  visually see any man-made light in any direction, and I have free  access to such areas, but need to drive away in the car for about 50+ mins, to reach the darker sites. The further the  distance traveled ( to a limit)  the  further  away from any sky glow, but even a  0.5 mile drive provides a massive improvement  when looking straight up, but the city sky glow is still visible.

However, its still far from perfect?  Until you have experienced viewing from a darker site, you just can't imagine how bright Starlight  can get? Under these conditions, it can be too bright, losing the ability to quickly locate the  major constellations, as their absorbed into a Sea of Stars, not normally visual from the home observatory, just like looking at Stellarium with atmosphere turned off? 

I have in the past,  left my scope in the car, in favour of just sitting, using wide field binoculars for the show!
 

[SilverAstro]

Another way of judging proper dark is when one puts one's camera on a tripod with shutter locked open. Crawl ( cant switch the torch on) back to house for coffee whilst waiting. Then hands&knees back to approx location trying to see a silhouette against the milky way to re-locate where you put your camera & tripod !
 T-shirt.

 

[JOC]

You all sound sooooo dedicated.  I fully appreciate that dark-skies are best and the more dark adapted your eyes are the better you see, but I don't know that I will ever become that dedicated.  I know at home that I get on better if I turn off the porch light, and I do stop the security light from switching on (that's about 2000 lumens of pure spot-light), but at the moment I am still happy observing what I can easily see in my 'garden' set-up and when I look up I suspect it will be a good few years before I exhaust what I can easily find.  I know that my best 'looking' is to the East and the South, the west I get an orange glow from a small town about 8 miles away and North I get a larger glow from a town about 3 miles away, but I reckon I'm pretty well set to the East and the South and there seem plenty of targets in that direction that I reckon will sort me out for a while.  I am in awe of the lengths many of you go to find your 'dark' spots, I wonder if my viewpoint will change as I do more observing?

[SilverAstro]

4 minutes ago, JOC said:

 the security light from switching on

Sharp intake of breath ! A WHAT !!

[JOC]

SilverAstro LOL!  2000+ lumens of pure white light that my parents installed that will flood the area I stand the telescope in if I so much as 'twitch' - I make that one of the first switches I turn off!  What I need are one of those need baby observatory domes plonked down in the middle of my 10 acre field and an electricity supply run in to it.  Then I'd be fine!

[Charic]

JOC, that's basically it, just accept what we have.

Its no fun getting all my gear ready, heading out on a good weather report only to find, viewing becomes impossible for one reason or another.
 

[SilverAstro]

4 minutes ago, JOC said:

SilverAstro LOL!  2000+ lumens of pure white light that my parents installed

eeek, yes parents are often difficult to control. But talk of security lights on an astro forum , , I had visions of everyone running to look for their cloves of garlic to clutch and penning letters to the inquisition

[Charic]

2 minutes ago, JOC said:

What I need are one of those need baby observatory domes [sic]

I considered modifying a butyl rubber pond liner to drape over my  heavy duty rotary clothes dryer, which would allow me to rotate the 'dome'  and my  limit of view would probably be ok up-to about 80°
The rotary has been used in Summer's past  as an effective parasol.

[Stu]

59 minutes ago, Charic said:

The only real solution I have for the garden is to hide inside a darkened tent! Completely dark, as dark as I can get it, using extra ground sheet covers ( I still have to get in and out, and the scope is almost limited to one direction due to the light seal? )  I have everything in order,  locating my eyepieces by touch, I don't read, write anything, just look and enjoy. My visible sky boundary is fairly limited due to the glare and obstructions, so the tent option works for me, so anything within the path that Ursa Major scribes overhead is good enough for me, from the present site.

Having the car does afford some benefits, if the  possibilities allow when away from  your HQ.  Many of us have less then perfect skies under which to observe!
 
During (my normal) winter observations, when time and  the weather allow me to observe, I have to endure glare from local street lights shining though my garden from the North, West and South, and sky glow further South above the tree line! and during the Summer Months, almost permanent twilight, where the telescope is of no use to me, it hibernates?  I can just make out with my eyes, six Stars of Ursa Major, excluding Megrez.

For me, the only consideration I seek for a dark site, is when I cannot  visually see any man-made light in any direction, and I have free  access to such areas, but need to drive away in the car for about 50+ mins, to reach the darker sites. The further the  distance traveled ( to a limit)  the  further  away from any sky glow, but even a  0.5 mile drive provides a massive improvement  when looking straight up, but the city sky glow is still visible.

However, its still far from perfect?  Until you have experienced viewing from a darker site, you just can't imagine how bright Starlight  can get? Under these conditions, it can be too bright, losing the ability to quickly locate the  major constellations, as their absorbed into a Sea of Stars, not normally visual from the home observatory, just like looking at Stellarium with atmosphere turned off? 

I have in the past,  left my scope in the car, in favour of just sitting, using wide field binoculars for the show!
 

What is your NELM at home and at your dark site Charic?

[Stu]

1 hour ago, Bart said:

I'm confused folks.  My sky is reasonably dark I thought. The Milky Way is visible from about 10-15 degrees up quite clearly and shows mottling across the sky yet I think the NELM is about 5.5. This differs greatly from some description above. Any suggestions why that might be?

thanks

barry

Why confused Barry? 5.5 is pretty good, and I would expect to be able to see the Milky Way quite well at that level?

[scarp15]

Perhaps your recreational lifestyle might indicate how you best approach indulging in this preoccupation. I live in a city and besides attending occasionally my local Saturday morning Park run event, or occasionally meeting up with friends in a local pub on the high street, my preference in my free-time is to get out of the city boundary, cycling or going walking and camping for example. Therefore this easily translates into venturing on dark sky trips, which is no different than for example being into course or sea fishing and going to a quality stretch of river or sea loch for an evening session. If the weather turns out to be poor then so be it, at least you'd tried and there can still be tranquillity in being for a time in a remote countryside location. Determined very much by where you live of course, in my own circumstance, the transformation from a fairly poor sky to reach a location with an approx.  21.4 -  21.5 SQM reading in approx. 45 to 50 minutes is the difference between continued fascination with this hobby and gradual disinterest if restricted to only being at home. 

[vlaiv]

On a good night I can get an order of 18 mag (SQM equivalent) sky in my back yard - measured by sky levels in astrophotos I take. I did not use SQM meter to verify this but it does agree both with satellite info about sky quality (red zone) and visual Bortle / NELM. On best of the summer nights I can say that there is a hint of Milky way at zenith.

[Charic]

Stu, not too scientific, and not sure during which Month I checked?  but from memory, Polaris is (always) visible and can just make out Kochab and  Pherkad, so that suggests about NELM magnitude 4 - 4.5 from the garden. I would need to re-asses the darkest site, but from the footy pitch when the tree foliage is present, providing some extra screening from the street light, its nearer 5.5 - 6.