Right ascension-declination

[lockyerlad (Brian)]

I am a vey keen newby at ASTRONOMY, with a 10" dob. reflector. Have downloaded lists of items of interest to examine with the RA and Dec details and have looked at numerous articles on the subject, but have a problem with understanding RA, Dec is OK.
I understand the comparison with longitude and RA, but how do I find a listed object e.g. NGC104 47 Tucanae at RA 00 24.1 and Dec -72.05.
The 0 point is where the vernal equinox occures and you move east by hourly intervals, 1 x hour = 15o but unless you know the exact vernal equinox point how do you know where to look, especially when it all changes by the hour.
Is this navigation system only for equatorial mounted scopes.

[Miaplacidus (Brian)]

G'day Brian.

Ahem, you might want to quickly change the spelling of astronomy before someone has a go at you.

Cheers,

Brian.

[mithrandir (Andrew)]

Originally Posted by lockyerlad

I am a vey keen newby at astrology, with a 10" dob. reflector. Have downloaded lists of items of interest to examine with the RA and Dec details and have looked at numerous articles on the subject, but have a problem with understanding RA, Dec is OK.
I understand the comparison with longitude and RA, but how do I find a listed object e.g. NGC104 47 Tucanae at RA 00 24.1 and Dec -72.05.
The 0 point is where the vernal equinox occures and you move east by hourly intervals, 1 x hour = 15o but unless you know the exact vernal equinox point how do you know where to look, especially when it all changes by the hour.
Is this navigation system only for equatorial mounted scopes.

Brian, with your dob it is easier to work in altitude and azimuth. You are right that to work out where a given RA is you need to make allowance for the time, but then the alt/az changes with latitude, and through the night and day by day too.
Free programs like Stellarium, Cartes du Ceil, C2A and Halo Northern Sky will convert RA/Dec to Alt/Az for you. For instance, now and here, for NGC104 CdC gives:
Visibility for your observatory:
Castle Hill 2012-10-29 22h01m56s ( AEDT )
Universal Time: 2012-10-29T11:01:56 JD=2456229.95968
Local sidereal time:23h38m38s
Hour angle: 23h13m 55s
Azimuth:+174?20' 47"
Altitude:+51?15'07"
Circumpolar
Culmination: 22h54m +51?44'

[barx1963 (Malcolm)]

Hi Brian
First off, be very careful with using the that Ast***gy word . This is an astronomy site, and most members are very careful to distance themselves from mumbo jumbo. Please take this advice in the spirit it is intended, many newcomers may not be aware of the significant difference between astronomy and that other stuff.
That said, welcome to IIS!!!
RA and Dec can be a little confusing at first. And whether or not you need to worry about it really depends on what type of gear you have. If it is a manual equatorially mounted scope, then yes it can be important as the setting circles can be used to find objects.
If it is a fully go-to scope it is not so important. As you have a dob, it is probably nice to know but far from essential.

To answer your query with how do you locate the 0 point in RA, you do not need to. All you need to do is locate a bright star with a known RA, put that in the centre of yout field of view and then move your RA dial (assuming you have an EQ mount) to read the correct RA and voila! all set to go. Usually best to select a star a reasonable distance from the pole as that will give a more accurate result. Dec takes care of itself if you have done your polar alignment well enough.

Malcolm

[OICURMT]

Originally Posted by Miaplacidus

Ahem, you might want to quickly change the spelling of astronomy before someone has a go at you.

Agreed.... basic similarities between Astrology and Astronomy...
Both view the stars, both use your hands, both require thought...


Basic differences... one requires intelligence

oh dear me.. did I just have a go

Welcome to the forums Brian... and also, Apologies..

OIC!

[lockyerlad (Brian)]

Thanks for the help, not a good way to start with you guys with a slip up like that. For the record I think it is all crap too, astrology that is.

[GeoffW1 (Geoff)]

Originally Posted by lockyerlad

Thanks for the help, not a good way to start with you guys with a slip up like that. For the record I think it is all crap too, astrology that is.

Hi,

You can edit your posts for a while after putting them up. I find the best way is to change the typo as quickly as possible and then pretend it never happened at all

Cheers

[mithrandir (Andrew)]

Originally Posted by GeoffW1

Hi,

You can edit your posts for a while after putting them up. I find the best way is to change the typo as quickly as possible and then pretend it never happened at all

That works - if you ask the people who quoted you to fix the quotes.

[GeoffW1 (Geoff)]

Originally Posted by mithrandir

That works - if you ask the people who quoted you to fix the quotes.

No claim to being logical

[LewisM]

There is a significant, albeit diametrically opposed, similarity between astronomy and astrology (and I tell this to people who mix them up when I talk to them).

Astronomy sees in the past, astrology pretends to see into the future. The past has happened and is undeniable, the future is all guess work.