Re: [guide-user] RE: comet 45P -- whats going on ?

P. Clay Sherrod Feb 12, 2017

Please note that nearly every comet that is uploaded via the Observable Comets list for Guide or any other planetarium program has a magnitude base on orbital parameters and you should not expect every comet to be right on target - or even close as you are discovering with 45P - to predicted.  Many are far brighter that given in the computed values and others are dimmer.
I suspect that all the incorrect hype over the media last week was due principally to just this fact - the comet's magnitude predicted by ephemeris elements and not the actual values that are being reported.
In my opinion this is a good thing, because it would give observers an improper bias toward magnitude estimates.  There are in fact a couple of individuals who are reporting magnitudes to MPC that appear to be right off of the lists and not actual computed or observed magnitudes.  Always report what you see and assume that the data is subject to considerable error.
Roger, I know that you are aware of this, but I am stating the above for the sake of those confused by the numbers.
Dr. Clay
Arkansas Sky Observatories
ASO Petit Jean Mountain /MPC H41
ASO Petit Jean Mountain South /MPC H45
ASO West Conway /MPC H43
.......serving astronomy since 1971
----- Original Message -----
From: 'Roger Pickard' roger.pickard@... [guide-user]
Sent: Sunday, February 12, 2017 3:13 PM
Subject: RE: [guide-user] RE: comet 45P -- whats going on ?

Oops, sorry, I thought I’d updated my comet info but I hadn’t.  Now, after I have done that, guess what I get?  Yes, 3.7!





From: []
Sent: 12 February 2017 20:56
Subject: RE: [guide-user] RE: comet 45P -- whats going on ?


well it's not 3.7 so i wonder How 2 of us get the wron result ?
roger --did you use update from MPC ?