[guide-user] Comet/Asteroid data

[Maik Meyer]

Rolf,

> 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?

comets are notorious for not being predictable in their brightness evolution. Especially 
this comet (11P) is an extreme example: It was discovered three times, mostly during 
outbursts: 1869, 1880 and 2001. There are more missed perihelion passages than observed 
ones. Prior any observing attempt for comet it is advisable to check current observations 
either at the MPC or at cobs.si.

Regards

Maik
-- 
"One cannot discover comets lying in bed." * Lewis Swift
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