[guide-user] Comet/Asteroid data

[Bernd Klemt]

Hello Rolf,

Am 9 Mar 2021 um 10:46 hat Rolf Stadelmaier geschrieben:

> Hello Bill,
> 
> recently by chance I was animated by Guide to have a telescopic look on
> P/Tempel-Swift-LINEAR (11P). Guide told me it would be a worthwhile object with
> 12.1 mag. But I found no hint of a moving object in the captured CCD frames.
> Next night I had a closer (longer exposure time) look at the predicted position,
> but again no indication of the comet.
> Searching the internet led me to the site
> _https://theskylive.com/how-bright-is-11p_ where I could see that I had no
> chance at all to capture such a faint object. 
> How can it be, that Guide claims a brightness so far beside reality (~8
> magnitudes)?
> BTW: On the occasion of the flyby of (99942) Apophis on March 5-6, 2021, I
> noticed that Guide claims Apophis not to be an asteroid. 
> 
> Yes, I had clicked to download updated comet/asteroid data and add it to Guide.
> Have I missed somthing essential?

yes. The elements Guide uses are from the Minot Planet Center (MPC). And in the 
past these data for comets are very unreliable (for some comets the orbital 
elements aren't updated as frequently as one wants they would be). Use these 
instead: <http://astro.vanbuitenen.nl/cometels> or look at 
<https://cobs.si/analysis>, choose your comet and click on "GetObs". It's listed 
between 14 and 18 mag in the last month....

> 
> Regards,
> Rolf Stadelmaier
> 

Clear skies
Bernd

Bernd Klemt
Sternwarte Herne (A18) and
Breitenweg Observatory (G11)

<http://www.sternwarte-herne.de>