Sydney observing & urban filters

[lacad01 (Adam)]

Gday, my first post and a long one at that . Shame about the cloudy weather lately but hope the rain is getting to the bush. My lovely family bought for my 40th b'day a Bintel 200mm dob but because of time constraints, etc have only managed in the past week to "break it in" but I must say it was a lot of fun constructing the base assembly, bit like Ikea furniture ...anyhow, last Sunday night I finally got it outdoors in the backyard and started on the moon. All I can say is "amazing", akin to the excited toddler as they take their first baby steps. Prior to getting my "eye to glass" for the first time, I'd been reading all I could on the subject, websites, etc but nothing compares to actually getting amongst it. So now I can't wait for the holiday season and clear skies, which leads to one of two questions I have:
(1) Can anyone recommend a site not far from Sydney that's reasonably clear, say 1 hour drive at most that would provide good observing? Living 6km from Sydney CBD I have the tyranny of light pollution from the CBD & surrounding suburbs but also my backyard is fairly small so have a limited field of view of the northern sky.
(2) Can anyone comment on the effectiveness of Urban light pollution filters.
thanks & regards
AL

[ving (David)]

hiya, we at macarthur astro society go to the oaks which is near camden... not too far for you

http://macastro.org.au

while the sky isnt completely dark its pretty darn good
and the company is even better

welcome aboard!

[wavelandscott (Scott)]

Another option although a bit farther than 1 hour would be to got to one of the Central Coast get together (nearish Gosford) at either Paintball or Pony Club. There will be posts in another thread when a night "is on" (in Star Parties and Observing Nights section).

The NSAS (Northern Sydney Astronomical Society) were doing observing at the Turramurra Golf Course on some weekend evenings...you can check out their website for the details there.

With respect to Light Pollution Filters let me say first up that there is no "magic bullet" and nothing will ever replace a dark site. (full stop)

Having said that, there are a couple of ways to attack the problem...

Flocking the inside of your scope will help add contrast, as will building/buying a dew shield/light shield. There are some commercially available ones or you can make your own pretty easily from things like camping mats to stiff plastic.

Light pollution filters...

There are a couple of different types...

There are filters targeted to the light from sodium/mecury street lights...they do reduce the impact and can improve the view a bit...I have the Astronomics CLS...it is okay but pretty broad in its filtering.

The next step would be a narrow pass band filter (UHC)...there are several different ones available I have the DGM Optics NPB (narrow pass band) but have also owned the Astronomics UHC. There are some differences but they will generally all imrpove the view.

One of the really difficult problems with light pollution (in my mind at least equal to the impact of the light on the scope) is the stray light not allowing your eyes to ever really dark sky adapt...Some people use eyepatches or I've even heard red goggles...

Again, all of these things will help but getting out to darkness is very much better than these other solutions...

Clear Dark Skies...

[rmcpb (Rob)]

You already have good suggestions for observing places but for those times you cannot get away and have to use the scope in the light pollution here are a few ways to improve the situation.

Flocking the tube and baffling the rear end to stop any light getting in from behind the mirror and a tube extension/dew shield that projects 1.5 time your mirror diameter in front of the focuser will help dramatically. This will go a long way to cutting down off axis light from getting into your light path and improve the contrast but the baffling will make it pretty important to have a fan for cooling your primary.

Another, often overlooked, consequence of light pollution is that you never really dark adapt. How to fix this is quite simple, use an eyepatch over your observing eye when not looking through the scope and fit an observing hood to your scope (some black cloth) and only take your eyepatch off when under the hood. This will let your observing eye fully dark adapt and take advantage of what light you have available.

Cheers

[koputai (Jason)]

Originally Posted by rmcpb

use an eyepatch over your observing eye......
This will let your observing eye fully dark adapt and take advantage of what light you have available.

So, do our eyes dark adapt independantly?

Cheers,
Jason.

[erick (Eric)]

Originally Posted by koputai

So, do our eyes dark adapt independantly?

Cheers,
Jason.

It seems so. Mythbusters last Monday night tested whether pirates of old wore a patch over one eye so they could move quickly from bright sunlight above decks to dark conditions below deck (eg. in an attack on a ship), by uncovering the eye with the patch and using that dark adapted eye below decks. Testing verified this proposal, most emphatically.

[norm]

G'day Al,

One site is Waterfall Oval at the Entrance of the Royal National Park in Sutherland ~ 45mins from city.

Its currently out of commission due to some key issues with the gates, but thats where the Sutherland Astro Society have viewing sessions. Visit the website www.sasi.net.au

I'm a member, but admittedly haven't been there for a while. I'm sure if you drop them an email, you'd be welcome to come along. Its generally for members, but I'm sure they don't mind just to try it out.

Norm

[lacad01 (Adam)]

Thanks a lot for the advice and tips, that's been really helpful.
AL