Help understanding RA/DEC and ALT/AZ

[bcfcciderhead]

Ok, having added a set of setting circules to my dob i need to get my head around using ALT/AZ instead of RA/DEC which seems to be printed in everything i got.

I understand the basic's of the two and what the difference's are, but now i need to put this into using the dob as a "manual goto".

with me up to now.........

The list i got of the Messier objects have there co-ords in RA/DEC, no good to me now, i need them in ALT/AZ.

Ok i can use Stellairum which gives you the two but only have a desktop, no laptop, well not yet.

I could write down the co-ords of the targets i'm looking for before hand but unless i view these at the exact same time as i wrote them down (of stellarium) i will be off target, as they move quite quickly.

Also why dont the RA/DEC co-ords change? they are the same on my list as they are on stellarium:icon_confused:, and yet the ALT/AZ co-ords move about like mad!

Is there any way i can convert the RA/DEC for a given target to ALT/AZ? and use this? or will this keep changing all the time?

Hope you can follow this as i found this hard to put into words:iamwithstupid:

Be nice to hear from those using setting circules on a dob to see what they do.....

thanks

[acey]

I just posted this link in your other thread (http://stargazerslounge.com/diy-astronomer/129979-dob-setting-circules-azimuth-altitude.html)

Celestial coordinate system - Wikipedia, the free encyclopedia

[bcfcciderhead]

Thanks Acey, that helps to explain why ALT/AZ moves about, makes perfect sense now, cheers

[Nibor]

Acey,

Thank you for this wiki link - it will answer my questions as well.

This forum is amazingly helful!!

Robin