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Comet Hale-Bopp - When And Where To Watch

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COMET HALE-BOPP - WHEN AND WHERE TO WATCH

All dates are for 1997

March 1-10. The comet is up before the first light of dawn. Set your alarm clock for about an hour and 45 minutes before sunrise (look up your local sunrise time in a local newspaper). Step outdoors and look east-northeast. Comet Hale-Bopp is shining there moderately high. It's about as bright as the brightest stars, with a hazy head and a dimmer, filmy tail extending to the upper left.

March 10-19. The comet remains fairly high in the predawn sky. It is shifting a little left toward the northeast and gradually brightening. But by now the comet is also becoming visible low in the evening sky too! Look low in the northwest just as the last glow of twilight is fading out. Again, look for a hazy star with a dim tail. When the comet is seen in the evening sky, its tail extends to the upper right. Each night Comet Hale-Bopp gains altitude and becomes a little easier to find after dusk. Moonlight starts flooding the evening sky around March 16th, compromising the view of the dim outer parts of the tail. But the comet's increasing height and brightness may just about make up for the worsening effect of moonlight. If you want a moonless view as late as the night of March 19-20, continue looking just before dawn.

March 20-22. The ever-brightening comet is now easy to spot fairly high in the northwest after dusk. Meanwhile before the first light of dawn, it has started to sink a bit lower in the northeast -- so that it's now balanced equally high at both times. A bright Moon is in the sky at both times as well.

March 23. This is a big night for skywatchers! The full Moon undergoes a deep partial eclipse that will be visible throughout most of the Americas (and western Europe on the morning of the 24th). Above or to the upper right of the eclipsed Moon will be the bright orange planet Mars, separated from the Moon by a little more than the width of your fist at arm's length. For more on this spectacular lunar eclipse, including a timetable of events, see the March issue of Sky & Telescope, page 82. Comet watchers on the West Coast, especially the Pacific Northwest, get an added bonus. The eclipse will cleanse the sky of most moonlight from about 8:15 to 9:00 p.m. Pacific Standard Time, right in prime comet-watching time.

March 24 - April 10. This is the peak of Comet Hale-Bopp's performance. Look well up in the northwestern sky after the end of evening twilight. The Moon is low in the east at the end of twilight on March 24th and is just rising on the 25th. Then the sky is moonless for the next two weeks. During this time Comet Hale-Bopp is high enough that it will remain in good view for well over an hour after the end of twilight -- though the earlier you look after twilight, the higher it will be. (In fact the comet doesn't actually set until almost three hours after twilight ends as seen from near 40 degrees north latitude.)

The comet's head may shine at about magnitude 0, as bright as the star Capella (which is sparkling much higher in the west-northwestern sky). Anyone able to get away from glary city lights should be treated to an awe-inspiring spectacle: the comet's brilliant, starlike pseudo-nucleus in a hood-shaped head or coma trailed by a thin, bluish ion (gas) tail and a broad, curved, yellowish dust tail, both extending upward.

April 11-15. The comet has moved a little to the left; look west-northwest now after the end of twilight. The waxing crescent Moon returns to the western evening sky during this period, growing thicker and brightening each night. At first its light has little or no effect. But as the days go by the moonlight will increasingly brighten the sky.

April 16 - 23. Comet Hale-Bopp is fading now and getting somewhat lower in the west-northwest, and moonlight fills the evening sky, washing out our view of celestial objects. Even so, the comet should still be plainly visible to the naked eye.

April 24 - May 7. The comet continues to fade and sink lower in the west-northwest at the end of twilight, but now the Moon is gone. How late into the spring can you follow the comet with the naked eye? With binoculars?

May 8. The last hurrah. This evening the thin crescent Moon could form a dramatic tableau with Comet Hale-Bopp -- which, however, may have become increasingly difficult to see low in the fading glow of sunset. First spot the Moon in the western sky in late twilight. The comet is 4 or 5 degrees to the Moon's upper right -- about as far from the Moon as the width of three fingers held at arm's length. Both objects will fit into a typical binocular's field of view (appearing on opposite sides of the view).

During the next week or two, try following the fading comet right down into the sunset with the naked eye or binoculars.

THE VIEW FROM THE SOUTHERN HEMISPHERE

While Comet Hale-Bopp is sinking out of good view from northern latitudes, observers in South America, South Africa, Australia, and New Zealand -- who have not seen the comet since last November -- begin to have their turn to witness the show.

By about the end of April, viewers there should be able to catch sight of the comet very low in the northwest in early evening hours. As April progresses into May, the comet climbs higher into far-southerners' evening skies. By late May, when their northern counterparts are losing sight of it, Southern Hemisphere watchers will still find the comet fairly high above the horizon well after dusk's end. Although Hale-Bopp will have faded substantially from its peak brightness, a fairly long tail may still be visible.

Thus, there is a possibility that observers below the equator will be treated to a decent display after all. And Southern Hemisphere viewers with telescopes will be well placed to follow the comet's slow recession into the distant outer solar system for the next couple of years.

James Musser
UCLA Astronomy


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