View Full Version : C/2007 N3 (Lulin) has emered into the morning sky

2009-Jan-04, 05:34 PM
Comet C/2007 N3 (Lulin) just emerged from morning twilight as predicted at the end of December 2008. Comet observers who can see that low to the eastern horizon have begun again to submit astrometric observations. Observers are reporting total magnitudes of this comet which are right enough to be seen with a modest telescope.

Its still very low in the sky when morning twilight starts. It will slowly rise to become easier for everyone to see in the coming weeks.

You can see comet orbital elements and an ephemeris at:

Look at the Elong. or Elongation column of data on the ephemerides and you can see how it is rising earlier each day. Elongation is the sky angle of the object from the sun.

Look at the r column of data on the ephemerides and you can see how r, its distance from the sun, is getting smaller.

You can see the time of perihelion in the line which says:
T 2009 Jan. 10.6418 TT
which means that perihelion is calculated to occur on January 10, 2009 which is next week.

Look at the delta column of data on the ephemerides and you can see how delta, its distance from earth, is also getting smaller and is smallest on about February 23, 2009

Look at the m1 for the calculated total magnitude and you will see that it reaches peak brightness about the same day. Apparent magnitude changes with both solar and earth distance.

A glossary of the terms is given at:

I would also highly recommend Seiichi Yoshida's comet web page at:


He has the very best overview of current comets anywhere on the internet, next the Minor Planet Center. He has light curves based on comet observations and provides magnitude estimates and comet positions and dates that he personally updates routinely. He is a very experienced and dedicated comet astronomer. I personally use his web page when I am making comet observations. I have this page called up on my laptop, and use it to decide on my next target to observe during the night.

If you want to see images of comets:

Francois Kugel has his own web page on comet C/2007 N3 Lulin at:

Recent images within the past week show it now has two tails.

Charles Bell
H47 Vicksburg

2009-Jan-07, 11:31 PM
Thanks, Charles. Very instructive.

2009-Jan-08, 04:20 PM
Recent images from the last few days posted by the Lulin Observatory (the discoverers of this comet) and others show the ion tail is composed of several radial components. This comet should put on a good show for all of us.

2009-Jan-08, 11:58 PM
Personally I am hoping it will brighten considerably more than the predicted mag 5. I would like to be able to see it while flying at night and mag 5 is a wee bit too faint with cockpit glare and reflections considered. Perhaps it will out-gas more as it rounds the sun and give us a great show!