The sky is forecast to be clear tomorrow morning affording a last chance to see comet C/2012 S1 (ISON) before it disappears behind the sun. It will return a couple of weeks later, also in the pre-dawn sky.
On Nov 20th (2013) comet ISON will be low in the per-dawn sky and possibly visible about an hour or so before sunrise (7:09 EST). It’s reported to be magnitude 5, which is just bright enough to see unaided under dark skies. At 5:20 EST the sun will be 18° below the horizon which is the end of “night” and the start of astronomical twilight. At this time ISON will only be about 6° above the horizon bearing 114° (a little east of SE). So a magnitude 5 object won’t likely be visible through the thick dusty air near the horizon – even with a telescope.
Over the next 40 minutes, ISON will climb to an altitude of 12° (bearing 122°). 6:00am is the start of nautical twilight so the sky will be fairly light at that time. Only the brighter stars – those used for navigation – are usually visible to the naked eye during nautical twilight. But with binoculars or a small telescope, it might be possible to see the magnitude 5 comet.