Re: [guide-user] Comets mag, how true?

P. Clay Sherrod Oct 27 8:19 AM

One more helpful link that may be of use to you is the Date of Last Observations of Comets published each day by the MPC:
http://www.minorplanetcenter.net/iau/lists/LastCometObs.html
 
Although I strongly urge observers to never rely on other observers' estimates, this can be used as a guide to determine which comets are indeed visible and which may be in error in terms of expected magnitude.
Typically this list is updated each morning.  It will give you an excellent idea of which comets to pursue for your particular equipment and limiting magnitude, etc.
 
Dr. Clay
_____
Arkansas Sky Observatories
MPC H45 - Petit Jean Mountain South
MPC H41 - Petit Jean Mountain
MPC H43 - Conway West
http://www.arksky.org/
----- Original Message -----
From: Rolf Stadelmaier
To: guide-user@yahoogroups.com
Sent: Sunday, October 27, 2013 10:14 AM
Subject: Re: [guide-user] Comets mag, how true?

Aha, I see there are most regrettable uncertainties in play.
At least the informations about position are utmost close.
BTW, despite the comet is almost lost in noise in my pictures,
the program astrometrica (H. Raab) could find out a magnitude
for the comet between V = 13.9 and V = 14.1, very faint so far
but seems relativly correct.
 
Thank you very much for your enlightening explanations and
good wishes Mr. Sherrod.
 
CS,
Rolf Stadelmaier
 
Sent: Sunday, October 27, 2013 2:30 PM
Subject: Re: [guide-user] Comets mag, how true?
 
 

You are correct that the magnitudes given are far, far from actual magnitudes.
These are magnitudes that were derived from the basic sets of orbital elements that
Guide (and other programs, including the MPCORB) uses to extrapolate the magnitude
given the parameters of the orbit.
Rarely are the comets anywhere close to what these provide; there are many comets
listed that are not even visible, much less as bright as given and others are
somewhat brighter than the prediction suggests.

On comets, never go by what is listed by others. Always determine for yourself using
comparison stars, either visually or photometrically via CCD.
An excellent article that sums up all of the methods that are accepted is given at:
http://www.skyandtelescope.com/observing/objects/comets/3304211.html

Best of luck on your comet observing.

Dr. Clay
_____
Arkansas Sky Observatories
MPC H45 - Petit Jean Mountain South
MPC H41 - Petit Jean Mountain
MPC H43 - Conway West
http://www.arksky.org/