View Single Post
  #6  
Old 08-02-2011, 02:53 PM
gary
Registered User

gary is offline
 
Join Date: Apr 2005
Location: Mt. Kuring-Gai
Posts: 5,999
Quote:
Originally Posted by Outbackmanyep View Post
The discrepancies in the co-ords wouldn't make that much difference in finding the object would it? Not visually at low power, surely.
Hi Chris,

As Rob pointed out, it comes as a surprise to many enthusiasts how significant
the rate of precession is.

It shifts at about 50.3 arc seconds a year - about the diameter of Jupiter.

So going between the B1950.0 Epoch to J2000.0 is about 2515 arc seconds,
which is equivalent to 41.9 arc minutes. Depending upon how extended the
target object is, that can make quite a difference in reliably
locating and identifying it through 'blind pointing', if one relies
on the B1950.0 RA/Dec co-ordinates alone.

Best Regards

Gary
Reply With Quote