Darn moon. Just can’t depend on it. Pity it’s moved far from Comet C/2011 L4 PANSTARRS. Does that mean you shouldn’t bother with the comet anymore? No! With PANSTARRS higher up in the sky compared to a week ago, don’t throw in the towel yet.
The moon’s proximity made finding the comet relatively easy on March 12-13. Now you’ll need to rely on your compass points while using the map above to return to it. The map shows the comet’s position every 3 days now through March 31 from mid-northern latitudes, specially 42 degrees north (Chicago, Ill.)
If you live in the northern U.S., the comet will be in approximately the same positions but slightly higher in the sky; in the southern U.S. it will be a little lower. Bottom line: you can use it across much of the U.S., southern Canada and a fair share of Europe, northern Africa, the Middle East, southern Russia and China.
Notice the “15 degree” altitude line. If you set the bottom of your fist flat on the horizon, the 15 degree line is a fist and a half above that level.
The map compensates for the sun rising later each night as we approach the spring season and shows the comet’s height above the horizon when the sun is 7.5 degrees below the horizon. 7.5 degrees corresponds to about 30 minutes after sunset. Notice that the sun moves northward (to the right) just like the comet does over the next couple weeks but more slowly.
See those yellow numbers along the map’s horizon? Those are compass bearings called azimuths. If you have a compass, dig it out and give it a look. Every compass is marked in degrees of azimuth. 270 degrees is due west, 285 degrees is a fist and a half to the right of due west, 315 degrees is exactly halfway between due west and due north. North can be either 360 degrees or 0 degrees. Azimuths are simple way to subdivide directions to make them more precise.
So the next time it’s clear, bring your binoculars and a compass (if needed) and find a location with a great view of the western sky preferably down to the horizon. Use the map along with the compass bearings to guide your eyes in the right direction. You can also use the sun’s position below the horizon to point you to the comet by angling up from the lingering glow at the sunset point.
As twilight deepens, the comet will drop slowly toward the horizon, remaining visible for a total time of approximately 40-50 minutes. Not a big window of opportunity but enough for a fine view. One final tip: before seeking PANSTARRS, don’t forget to focus your binoculars on “infinity”. Do this by focusing it on the moon, a cloud or bright star. There’s nothing more frustrating than sweeping for a fuzzy comet with an out-of-focus instrument.
Once again, good luck in your quest.