Planetarium Comets gripe...

[StuTodd]

My predicament is this.

I write the Dunedin Astro Society newsletter and like to give the members accurate info regarding cometary magnitudes, in particular.

I use C2A for my charts and data but (noted recently with comet 252P/LINEAR), the real life data is nowhere near that of the software, even with fresh updates fetched from the MPC!
My C2A was so bad, it noted a magnitude of 11.2 for the comet, but it is reportedly visible by naked eye :(

Am I doing anything wrong? Surely the MPC updates its ephemerides day by day. Positionally, C2A is spot on but the mag is hit and miss.

Any thoughts??

Stu

[Merlin66]

Stu,
Don't know the answer to your planetarium question, but I would recommend the Comet Chasing website for current comet info:
http://cometchasing.skyhound.com/

[SteveInNZ]

I use Seiichi Yoshida's pages (http://www.aerith.net/comet/future-s.html). Click on the comet of interest and you'll get the elements, a simple path plot and brightness predictions with real observed brightness points included. His predictions are usually spot on.

Having said that, 252P/Linear is unusual in that it's brightened much more than was predicted.

Steve.

[StuTodd]

Thanks Ken and Steve.

I will use those links you provided, nice to get some accurate data!
It is frustrating when the data from MPC etc are wrong though.

Stu