Comet C/2007 N3 Lulin is fading rapidly into the western sky. But it is still a
good target, with a 20 arc minute long tail, magnitude about 9.5, and fairly
high in Gemini. It also has an incredibly slow relative motion of only 0.01 arc
seconds/minute, so you can take long exposures without blurring the comet.

Last night I imaged it under terrible seeing, but fortunately one doesn't need
good seeing to image a comet. When I focus using AstroArt 3.0, a medium bright
(mag 8 star) lights up just one pixel in focus mode. Last night the focus image
was bouncing back and forth between 4 and 7 pixels! Probably 6 or 7 arc second
RMS seeing. But I got a reasonable image at 5.0 arc seconds per pixel (binned
2x2).

My sky brightness was 19.0 magnitudes/ square arc second (measured with a Sky
Quality Meter, as my 68 year old eyes aren't very sensitive any more). That
translates into an NELM (naked-eye limiting magnitude) of about 4.7. I live 40
miles west of Chicago.

Images, associated data, and imaging notes at
http://home.att.net/~dpersyk/new.htm

Thank you for visiting my site.

Clear skies,

Dennis Persyk
Igloo Observatory Home Page http://dpersyk.home.att.net
Hampshire, IL

Pier Design Paper: http://home.att.net/~dpersyk/Pier_Design.htm