Astroblog: How Bright is ISON? Comparing Comet ISON to Lovejoy

Thursday, November 28, 2013

How Bright is ISON? Comparing Comet ISON to Lovejoy

How bright is comet C/2012 S1 ISON now? It's pretty hard to tell with the images we have, as we don't really have high resolution images with good comparison stars at the moment. So I've compared ISON as it looks now to C/2011 W3 Lovejoy as it looked when it just entered the SOHO LASCO C3 imager and STEREO COR2B imager.

Both comets look roughly the same in the SOHO images, but Lovejoy looks brighter in the COR2B images. Unfortunately I don't know where Lovejoy was with respect to COr2B, so I don't know if this is due to the comet being closer to the camera.ISON looks around the same brightness as ~~Aldebaran~~ Antares (bright object bottom left in top SOHO image, hat tip to Les Dalrymple for picking up the typo), so it is probably around magnitude 1, just a bit under perhaps.

Still, overall it is looking similar to Lovejoy at the moment, perhaps it will perform like Lovejoy?

Labels: C/2012 S1 ISON, comet lovejoy, Soho, Stereo Satellite