Quote:
Originally Posted by leinad
I have a Dobsonian scope, so Im limited(I think) to Alt/Az for lcoating objects in the sky.
However it seems that RA/Dec coordinates is how every star/object is located.
What is the most common way that Dob owners to their viewing?
Is it more so starhopping, or do we use coordinates prior to starhopping using starcharts.
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Hi Leinad,
Looks like you made a good start with the Collins Guide and the Atlas of the Southern Night Sky.
The important thing to understand is that RA/Dec coordinates are a (more or less) absolute reference grid, independent of the position of the observer, whereas Alt/Az coords are relative to the position of the observer in the universe as well as to time - so they change continuously.
In order to locate things, RA/Dec is only of use if you have instruments that can measure them from a fixed reference point (i.e. alignment of the scope with the Celestial South Pole). In parallel with Eric's comparison above ("I have a sense that its a bit like terrestrial maps and directions") no one goes around his neigbourhood navigating by latitude and longitude (the terrestrial equivalent of RA/Dec), and even if you would want to you would need a GPS or something.
Most entry-level dobs do not come with setting circles or the like, so measuring RA/Dec is not possible - and not necessary in the beginning.
In star hopping you will learn to recognise familiar patterns in the sky, like constellations or parts of them, asterisms - just like you recognise the streets in your neighbourhood by all sorts of clues like buidlings, trees, traffic signs and the like. A good way to get started is to take seasonal sky maps for each cardinal direction (as found in most astro-magazines and Astronomy Australia 2008 for example), and match the maps with what you see in the sky, naked eye - to learn how to recognise the patterns. I'm sure Starry Night can print them for you too, exactly for your location and time.
Many people recognise Orion's Belt, and you will learn for example that M42 is just a few degrees 'above' it - likewise you can locate the Southern Cross as an 'anchor-point' and find eta Car from there (which except in inner cities is a naked eye object anyway), as well as the Jewel Box Cluster and much more...
On p18 of the ASNS is a handy tip on how to use your hands to roughly estimate distances in the sky - use it! For now I suggest you don't worry too much about RA/Dec etc... try to recognise the patterns first...
good luck!
