[BAA Comets] CCD astrometry and photometry

[Roger Dymock]

Good afternoon all,

As those of you who use the Comet Section procedure at
http://www.britastro.org/projectalcock/CCD%20Astrometry%20and%20Photometry.htm will know we are
limited to using single images as FoCAs cannot handle stacks.

However there is a fairly simple way of arriving at the total visual equivalent magnitude (m1) where
stacked images are involved. As for bright comets;
- stack the images with Astrometrica and note the zero point
- open the stacked image with Iris and measure the coma diameter using View/Slice
- go to Analysis/Aperture photometry, enter the three radii (note - radii and not diameter),
magnitude constant and then OK
- place the resulting aperture over the comet, left click and the value appears in the output
window. 

Regards

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