Easy method on working on Magnitutude and Surface Brightness

[m11]

Hi All,

I am just starting off and loving getting out with the binoculars and dob.

Just wondering when looking at charts that show magnitude and surface brightness how to determine what is viewable, especilly from urban skies. I understand the arch degrees and minutes plays a major part as the brightness is spread over a wider area.

From my place, i can see Tarantula and Eta Carina.

Thank you for any assistance.

Mel

[Somnium]

Hi Mel

in normal conditions, Mag 6 is about the limit of the Naked eye with Mag 8 possible under extremely good conditions. after that it all depends on your optics, mainly the size of the aperture. the eyepiece used, any filters and the focal length also come into play.

[m11]

Hi Aidan,

Thanks for the reply. Its always difficuly to work what is viewable from the urban backyard.

I am still working things out. Is there a easy method to see what type of magnitude skies you have?

Thanks,

Mel

[Somnium]

you might want to use a star map and work down from the brightest to the dimmest and see at what point you are unable to see any more. that is the simplest way i can think of

[m11]

Hi Aidan,

Yah will do that. Thanks for suggestion as I havent thought to do that. Good idea.
I have been focused on dso in which it is hard to work out what you can see. I am getting a astronomik UHC filter which i hope will help with viewing some the nebula.

Thanks again for your help. :)

Mel

[ausastronomer]

Hi Aiden,

Where might be some dark sites you could get down to mag 8 naked eye?

I think I need to go there :)

Cheers
John B

[Somnium]

http://darksitefinder.com/map/

Best to look at something like the above. Kiama is not bad ... My observatory is in berry. Not exactly a perfectly dark site but not bad and a heck of a lot better then Sydney

[Somnium]

Ummm central Australia, Atacama desert , you need ideal conditions. Not likely to find these conditions on the east coast of Australia.

[AEAJR]

I took a print out from Stellarium and compared it to the sky at my viewing site. I marked off the dimmest stars that I could see taking note of the ones on the paper that I could not see.

The dimmest star I could see was about mag 3.5 so I consider the Naked Eye limit at my location to be mag 4.

You might try doing something like this at your location.

[m11]

Hi Ed,

Thanks for that. Will try that next time there are clear skies.


Thanks,

Mel

[AEAJR]

This is something I prepared for someone else that you might find helpful.

==============
When you are planning an observing session there are a variety of way to
proceed.

* You can set up your scope and just wander around the sky. I sometimes do that.

* You can scan with binoculars or the finder scope and when you see
something interesting, zero in on it with the telescope.

* You can start to organize you observation sessions with a target list
using "Tonight's Sky", a free web site that will allow you to run a report
of what is in your sky tonight. It will let you select the difficulty of
the targets and will provide a printed, PDF or HTML report that you can use
when you are at your telescope.

The default sort is by difficulty, from brightest to dimmest. That is
great but you could end up all over the sky trying to work the list. I
normally sort it by constellation. Then I can mark the constellations that
are in my best part of the sky and focus on them. You could spend an
entire evening working on small part of the sky finding all sorts of cool
stuff.

Aside from making it easier to observe, you get to know a specific region of
the sky. You can focus on Orion, for example. See all that is in Orion
up to the capability of your telescope and your local sky.

Then move on to Taurus or Cassiopeia or whatever constellations are in the best
areas for you to observe.

Not sure which constellations are in your best viewing area? I use
Stellarium to help me see which constellations are in my best viewing area.
For me that is East and directly overhead. But you could use a Planisphere,
a star chart, "Turn Left at Orion, or an app on your phone or tablet.

Here is how I do it.


Tonight's Sky Web site
http://www.tonightssky.com/MainPage.php


Put in your location and time settings and click the box to remember them

Select the difficulty level - If you are using binoculars then select that.
If you are in a highly light polluted area work naked eye and binoculars
first, maybe small telescope. If you can find all of those then on the next
report raise the difficulty level.

Select what types of targets you want to see - Planets, clusters, whatever
you want. Note that nebulae can be tricky from light polluted skies so those
might not be the best first targets. Galaxies can also be challenging as you run
into surface brightness rather than magnitude.

Run the report - the standard sort that will be displayed is by increasing
magnitude number, that is to say brightest to dimmest

Choose which ones you want in the printed report, or select all.

Select Print or right click and select print. If you want a PDF select
"save as"

I change default print out sort to "by constellation"

Run the report and it will be sorted by constellation. This is how I
normally sort it.

You can print it or save it as a PDF or a web page. Try all three.


Just another resource.