- This topic has 6 replies, 5 voices, and was last updated 9 years, 2 months ago by
.
-
Posts
-
A simple query – could anyone tell me, or point me towards the relevant reference, to work out the exact current position ( RA & Dec) of Polaris?
I’ve been using RA 2hr 31.8 but then I suddenly realised this is based on Epoch 2000 so it’s changed a bit in 15 yr! ( in 1950 for instance it was 1 hr 48.8).
How does one find out?
(As you can guess, I’ve been trying accurately to orientate the polar axis of my scope – using N/S transit times of Polaris for the Alt/Az correction, and drift method for Dec. But like the stars I seem to be going round in circles!)
Thank you
Oliver
It’s been many years since I’ve had to worry about Polar Alignment (thankfully), but I do know that Stellarium software gives the hour angle for Polaris as well as RA/Dec for J2000.0 and for the current date/time for your location. If you have Stellarium simply click on Polaris. If you don’t have it, then it’s free to download and isn’t a bad bit of software to have! There are other ways to get this information, but this seems to be a simple method to me.
Gary
Thank you Gary for your speedy reply – first time I’ve used this forum & it’s a good feeling to know there’re experts around who can give a bit of advice when needed! Thanks again.
Oliver
Just checked Cartes du Ciel (software similar to Stellarium). It reports for Polaris as of today
Apparent RA: 02h52m45.576s DE:+89°19’29.12″
Mean of the date RA: 02h51m08.460s DE:+89°19’50.32″
Astrometric J2000 RA: 02h31m52.656s DE:+89°15’50.60″Robin
Hi Oliver,
I’m not an expert on polar aligning (being mainly a visual alt-az user), but my understanding for drift alignment is that you should choose an alignment star near the celestial equator and your meridian, so this maximises the effect of the drift, which will be minimal if you choose Polaris(?).
Clear skies. Callum
- You must be logged in to reply to this topic.