We’re in the final stretch! Time for updated maps of Comets ISON and Encke in the remaining days before perihelion or closest approach to the sun. And just for the heck of it, let’s throw in Comet Lovejoy, too. The latest brightness estimate for ISON comes to us from its co-discoverer Vitaly Nevski who estimated its magnitude at 3.7 on Nov. 19, a nice jump from Sunday-Monday. Amateur astronomer Neil Norman reports that southern hemisphere observers in his group report that ISON is a very easy binocular object now.
The first map shows the sky facing southeast an hour before sunrise for the central USA (latitude 39-40 degrees from Virginia through Illinois, Kansas, Nevada and central Cal.). If you live south of this belt, the comets will be slightly higher in the sky; if north, slightly lower. Notice that Mercury travels toward the sun just like Encke and ISON. That’s why you see dates along its path too. Click HERE to find your sunrise time.
Here are ISON altitudes on the following dates 1 hour before sunrise for the central U.S.:
* Nov. 20: 12 degrees
* Nov. 21: 9 degrees
* Nov. 22: 6 degrees
* Nov. 23: 4 degrees
Unless Comet ISON brightens sharply in the next few days, these next few mornings are likely the last time most of us will see it before perihelion. If the comet gets bright enough to attempt in the daytime sky at or near perihelion on Nov. 28, I’ll post another map with directions on how to safely see it without blinding your eyes.
Barring that, the best time to enjoy this icy visitor from the Oort Cloud will be during the first three weeks of December. Unfortunately, observers in the southern hemisphere will not have a good look at ISON after perihelion. It quickly leaves the sun behind headed north and sinks below the horizon from far southern locations. For northerners, the comet rapidly moves up and away from the sun into a dark morning sky.
I’ve also included a map for spotting Comet Lovejoy – still bright at around magnitude 5 – as it cruises alongside the Big Dipper in the morning sky. Nothing like having the easiest constellation (an asterism actually – the Big Dipper is part of the Great Bear Ursa Major) in the northern hemisphere to help you find a comet. Good fortune indeed!