How to observe Comet PANSTARRS in April

Throughout March, Comet PANSTARRS (C/2011 L4) shone low in the western sky after sunset. Many observers glimpsed its coma (the gaseous envelope that surrounds the comet’s head) with just naked eyes. Many more saw it through binoculars and telescopes. In April, the comet gets higher each evening, even as it fades in brightness while receding from the Sun.

So far, Comet PANSTARRS has hit every prediction related to its brightness. It arrived at perihelion (its closest approach to the Sun), on the evening of March 9 in North America. It appeared most brilliant — with a total magnitude of –1.0 — at that point, when it stood approximately 28 million miles (45 million kilometers) from our daytime star.

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For complete coverage of Comet PANSTARRS, visit www.astronomy.com/panstarrs.

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On April 1, Comet PANSTARRS lies 33° north of the Sun and 4° north-northeast of the Andromeda Galaxy (M31). And the separation between the two objects decreases to 2.5° on April 4. Amateur astronomers who image should consider this a great photo opportunity. And visual observers should take this opportunity to compare the relatively nearby comet to M31, a vast spiral galaxy 2.5 million light-years away. Use binoculars to get an overall view, but a 4-inch or larger telescope with an eyepiece that provides a wide field of view will deliver the best results.

By April 19, Comet PANSTARRS has put 49° between itself and the Sun. The comet shines a bit fainter than 5th magnitude — still bright for a comet but a shadow of its former glory — having lost a full magnitude approximately every week since perihelion. Although the Moon will be a day past First Quarter, you’ll easily find the comet through binoculars in the early morning hours (after moonset) located between magnitude 2.2 Schedar (Alpha [α] Cassiopeiae) and magnitude 2.3 Caph (Beta [β] Cassiopeiae).

By month’s end, on April 30, Comet PANSTARRS will stand 57° north-northwest of the Sun. You’ll find it in Cepheus, less than 1° east of the large emission nebula NGC 7822, also known as Cederblad 214. Because of its position, high in the northern sky, the comet will remain above the horizon all night for observers north of latitude 23° north.

During May and June, Comet PANSTARRS continues to diminish in brightness, but it also never sets during this time for most locations in the United States. By July 1, it glows at magnitude 11 in the constellation Ursa Minor, but its dark-sky presence will be better because its distance from the Sun will have increased to nearly 80°. You’ll need a medium-size telescope and an eyepiece that magnifies about 50x to track the comet down. When you do find the small, faint smudge, take some time to smile and remember its former glory.

Expand your observing with these online tools from Astronomy magazine

• Special Coverage: Find everything you need to know about Comet PANSTARRS in Astronomy.com's Year of the Comet section.
• Video: Get ready for Comet PANSTARRS, with Senior Editor Richard Talcott
  
• StarDome: Locate Comet C/2011 L4 (PANSTARRS) in your night sky with our interactive star chart. To ensure the comet is displayed, click on the "Display..." drop-down menu under Options (lower right) and make sure "Comets" has a check mark next to it. Then click the "Show Names..." drop-down menu and make sure "Comets" is checked there, too.
• Images: Check out our special Comet PANSTARRS photo gallery or submit images of Comet PANSTARRS to our Online Reader Gallery.
• Discussion: Ask questions and share your observations in our Reader Forums.
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