[BAA Comets] Comet C/2014 Q2 (Lovejoy)

[Shanklin, Jonathan D.]

Hi Roger,

I think as noted in The Comet's Tale, the electronic observations are not capturing the entire coma and hence will report magnitudes that are too faint.  This is one reason why it is important to use the ICQ format, which includes an estimate of the coma diameter.  Although I haven't done it yet, it would be possible in theory to correct for under-estimates of the coma size, just as it is possible to correct for aperture (which probably has the same effect of reducing the apparent coma size).

Regards,

Jonathan Shanklin
________________________________________
From: Roger Dymock [roger.dymock at ntlworld.com]
Sent: 15 January 2015 14:48
To: comets-disc at britastro.org
Subject: [BAA Comets] Comet C/2014 Q2 (Lovejoy)

Good afternoon all,

It would appear that this comet is not playing ball as far as equivalency of visual equivalent
magnitudes from CCD images and visual magnitudes are concerned. The magnitude chart on COBS
indicates that these started to diverge when the comet brightened past mag 8 and are now somewhere
between 1.5 and 2 mags different - the visual mags being the brighter.

The same tends to be true for the coma diameter. These are widely spread for both visual and CCD obs
- 10 to 40 arc mins in diameter - with the CCD obs being at the lower end.

I doubt all those who submit observations to COBS are using our method so at least there is some
consistency. Thoughts anyone?

Regards

Roger Dymock
Email: roger.dymock at ntlworld.com
Tel: 023 92647986
Skype: rogerdymock67 or
Skype: rjvdymock
Project Alcock http://www.britastro.org/projectalcock/



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