Magnitude/brightness and degree's?

[mikemasey]

Hi all,
I should know this but keep getting lost.
Is magnitude the same as brightness?
I have worked out that a 0.1 star is actualy brighter than a 0.55 star !
So '0' is the bench mark, is that corect and what is the mark. Not the moon as that is far to bright?

If uranus is 'x' degrees right of Jupiter, how do I work that out??
If I put Jupeter in the centre of my telrad will the small blue/green disk of uranus be inside or the outer retical?


tx

[mithrandir]

Try this page (http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_magnitude.html) for an explanation.
Tonight Uranus is about 1deg 49' westward along the ecliptic from Jupiter
I don't have a Telrad but the circles are supposed to have diameters 0.5, 2.0 and 4.0 deg. If you center Jupiter, Uranus will be between the 2 and 4 deg circles.

[Blue Skies]

Yes, although it is an open-ended scale. If you read the article that Andrew links to above it mentions Vega as the benchmark star - it was considered as such about 150 years ago or so when they decided on this scale but in our modern times Vega is considered a little bit off 0.0 I wouldn't use the Moon, it varies too much!

[mental4astro]

Finding both Uranus and Neptune helps if you have a map. Unless you know what you are looking for it can be near impossible to identify them as their disks are so small, particularly Neptune's really just stellar.

This link will take you to the Sky and Telescope current Uranus/Neptune locator map. I used the corresponding map for last year to find them for the first time:

http://media.skyandtelescope.com/documents/Uranus_Neptune_2010.pdf

A little tip with finding them, Uranus has a distinct greenish/blue colour to it, and high magnification will begin to define its disk which surrounding stars don't have. You can see this bugger through binoculars, even from Sydney.

Neptune is a very special character. The only way to identify it is with its striking blue colour. 'Blue stars' appear almost white, and very bright for their colour saturation. Neptune's colour is very blue, and 'not bright enough' to be a star for its colour intensity. You really won't make out a disk on it, unless you have access to special gear and very, very particular atmospheric conditions. Just keep in mind that you will need to look carefully and patiently for it. It isn't an immediate standout feature.

[Suzy]

Thanks Alex, that was great info. I'm about to go seeking Uranus for the first time on the next clear night- so what you said will help me a lot! :thumbsup: