[BAA Comets] 2014 Q2

[Shanklin, Jonathan D.]

I've updated the current magnitudes etc on the web page.

The issue of electronic observers reporting much fainter magnitudes (and smaller coma diameters) than visual observers appears to be very similar to the well known aperture effect, as the majority of electronic observers are using large apertures.  Solving the magnitude equation for 2014 Q2 to include aperture gives a coefficient of 0.029, which is very similar to the standard value of 0.033 that I normally use.  This means that an observer using a 40cm would report the comet as being about a magnitude fainter than an observer using 7x50B.  I routinely apply this correction when trying to estimate how bright comets may become, for example 2013 US10.

Overall for photometry it is more useful if electronic observers stick to the fainter comets that are in general less well covered.  For UK based visual observers there are only three that regularly report estimates of comets fainter than 8th magnitude.  We do need more of both types of observer.

Regards,

Jonathan Shanklin

This message (and any attachments) is for the recipient only. NERC is subject to the Freedom of Information Act 2000 and the contents of this email and any reply you make may be disclosed by NERC unless it is exempt from release under the Act. Any material supplied to NERC may be stored in an electronic records management system.