o The comet will look much better from a dark sky. This is particularly true for late March when the head of the comet will be very large.
o Let your eyes get dark adapted. This requires at least 20-30 minutes for most folks.
o Be kind to your eyes and your fellow observers...use a red flashlight. This won't hurt your dark adaptation (unless it is too bright)! Don't have a red flashlight? Put red paper or even a layer of brown paper bag over your white light flashlight. Another suggestion (from Bob Black) is to cover the light with a cut up red ballon. To get the correct brightness level, go into a dark room (without windows). You should be able to see the floor (or ground) in front of you, but not much more. If you see more, the light is too bright.
o Most importantly, contact your local astronomical society or planetarium. They will probably be having a "star party" to show folks the comet. You will get the most out of the experience this way.
o We strongly recommend that you take a simple star chart with you when you go to observe the comet.
Coma or Head of the Comet: The dust and gas that surrounds the comet's nucleus. This will typically look round or, if the tail is bright, parabolic in shape. The coma will usually appear fuzzy (like in March), but can be well-defined with sharp boundaries when the comet is close to the Sun (in mid- to late April). Often there is a bright central "star" in the coma. This is not the actual nucleus of the comet, but rather the material that surrounds the nucleus. We can't see the nucleus directly.
Tail: When the comet comes close to the Sun, the dust and gas is pushed away from the comet's head. This extension from the coma is called the tail. Tails typically point away from the Sun. They can be straight, curved, or fan-shaped. A comet can have more than one tail. Tails can be quite bright or rather faint.
Half a Degree in the Sky: The size of the full Moon.
One Degree in the Sky: Two full Moons or one finger held at arm's length.
Ten Degrees in the Sky: Width of one fists at arm's length.
Alpha, Beta, Gamma, etc.: Are (usually) the brightest, second brightest, and third brightest stars in a constellation.
The following Northern Hemisphere information is for California or the West Coast of the USA (8 hours earlier than Greenwich Mean Time). The positions will be close for all the USA and Canada. Times for Moonset are specific to Southern California, but will be close across North America. The information for May is for Australia, but can be used as a guide for other Southern Hemisphere locations.
Note: The brightness, size of the comet's coma, and tail length are all educated guesses based on the current (3/6/96) information concerning the comet. Comet's are unpredictable so this is only a guide as to what to expect. (If an error is found in this write-up, each author blames the other.)
March 14-15, 1996: The comet will be located about three degrees north and slightly east of the star Alpha Libra. The brightness of the coma should be only slightly fainter than Alpha Libra, but because that brightness will be spread over half a degree (about the same size as the full Moon), the comet will appear quite a bit less obvious than the star. A faint tail will be visible in binoculars pointing toward the west. The comet will be at its highest point in the sky (looking due south) at about 3 AM.
[What really happened? Comet was magnitude 3.1-3.3 (pretty close to the prediction). The coma size was 3/4ths of a degree, but most of the light was within a 1/3 degree. The tail was faint, as predicted, but quite long (> 5 deg. in binoculars). Experienced observers saw the tail with the naked eye from dark sites. So far, so good...- csm]
March 19-20, 1996: The comet will be located in eastern Virgo (about 1/3 of the way from Beta Libra to Arcturus [Alpha Bootes]). Over the past five days the comet has traveled north nearly 15 degrees and it has brightened significantly. The comet shines at magnitude ~1.5 (or just slightly brighter than the middle star in the Big Dipper's handle. As the comet approaches the Earth, the coma or head of the comet also grows in size, perhaps reaching a degree in diameter on this date. The comet's brightness is spread over that area. The comet, if observed from dark skies, should be display a tail faintly visible to the naked eye. In binoculars, the tail may reach 5-10 degrees in length. The best time to see the comet is still about 3 AM.
March 20-21, 1996: The comet has moved about six degrees north near the border of Virgo and Bootes (half the distance between Arcturus and Beta Libra). Its magnitude is now about 1.1 or slightly brighter than Deneb, the brightest star in Cygnus (or the Northern Cross), visible in the northeast sky at 3 AM. The comet's coma now covers over a degree of the sky making the comet much less obvious than Deneb, but still an impressive sight.
[What really happened? The comet is on-track to a wonderful performance. The brightness estimates range from 1.2-2.0. The coma is somewhat over a degree in diameter. The tail estimates in dark skies by experienced observers are over 20 degrees!]
March 21-22, 1996: As it continues its northward trek, the comet is located about 10 degrees southeast of Arcturus. The tail, which has grown, is now pointing toward the southwest. The comet is best seen at about 2:30 AM.
[What really happened? The comet is better than we expected! It had a flare in brightness! The brighness estimates range from 0.2 to about 1.2. The coma is somewhat over a degree in diameter. The tail...wow. The tail estimates in dark skies by experienced observers are up to 40 degrees! Most people at a dark site can see 15-20 degrees of tail.]
March 22-23, 1996: The comet will have moved another 11 degrees northward and will be situated near the star Epsilon in the constellation Bootes, about 10 degrees northest of Arcturus. In fact, the star Epsilon may be within the comet's coma. The comet's head is only slightly fainter than Vega in the constellation Lyra, which is high in the northeast sky above Deneb at 2:30 AM.
[What really happened? The comet's brightness remained stable brightness! The brighness estimates range from 0.0 to about 1.0. The tail in dark skies by experienced observers are up to 45-50 degrees!]
March 23-24, 1996: Hyakutake continues its rush toward the Earth and moves another 15 degrees north. Located about four degrees to the south-southeast of Gamma Bootes and six degrees southeast of Beta Bootes, the comet is now about as bright as Arcturus and about 17 degrees north of it. Its motion is obvious over a minute or two in binoculars. The comet's tail should be pointing southwest. The comet is highest in the sky at about 2 AM, but will be visible for much of the night.
[What really happened? The comet's brightness was as bright as or perhaps slightly brighter than Arcturus. In dark skies, even inexperienced observers are seeing tail lengths of 30-40 degrees! Some tail estimates are much greater than this.]
March 24-25, 1996: The night of Hyakutake's closest approach...the comet moves some 18 degrees or an average of 0.75 degrees an hour! Motion is obvious to the naked eye over several minutes. Through a small telescope, background stars seem to float past the comet. The comet's coma may be as much as two degrees or more in diameter. A faint tail will be visible in dark skies extending 10 - 20 degrees (or perhaps even more in binoculars). From the city, the comet appears like a large, strongly condensed (sharp brightening towards the center) fuzz ball. The comet starts the evening about 10 degrees from the end star of the Big Dipper's handle - above the handle. Over the night it moves six degrees further north. The comet should be at its brightest and largest during this night.
[What really happened? The comet reached its peak brightness (for now). The predicted tail length was much too short as the tail can be seen in dark skies for many tens of degrees. In a telescope, the comet displays a bright tailward jet coming from the intense central condensation (nucleus) in the coma.]
March 25-26, 1996: The comet will be located just off the Little Dipper's cup (or bowl) as it continues to move north and now to the west. Its brightness and size should remain near peak values.
[What really happened? The comet faded slightly. The tail remains very long when observed after the Moon sets.]
March 26-27, 1996: The comet is sitting next to Polaris, the North Star, which will appear faint in comparison. The comet is just past its most northerly point and is heading south and west. The tail has swung around and is now pointing toward the east. The first quarter Moon is beginning to interfere with observing the comet. The best observing is after Moon set (1:05 AM).
[What really happened? The comet continues to fade...it is now slightly fainter than Arcturus. The tail remains very long when observed after the Moon sets.]
March 27-28, 1996: The comet is now noticeably fainter and the tail has begun to shrink. The comet is situated about 15 degrees from Polaris, along the line from cup of the Little Dipper through Polaris. The Moon sets at 1:47 AM.
[What really happened? The comet continues to fade, but it is still visible to the naked eye as a fuzzball, even with the Moon. The tail remains very long when observed after the Moon sets.]
March 28-29, 1996: The comet is sitting on a line extended from Delta through Epsilon Cassiopeia (the two stars on the squashed end of Cassiopeia's W) about 10 degrees from east of Epsilon. The Moon sets at 2:47 AM.
[What really happened? The comet continues to fade, but it is still visible to the naked eye as a fuzzball, even with the Moon. ]
March 29-30, 1996: The comet is now 10 degrees due east of Cassiopeia's W on the line from Gamma (the middle star in the W) to Epsilon Cassiopeia (the end star on the squashed end of the W). The comet is now a factor of six fainter than just five days ago. The comet's coma has also shrunk by a factor of two. The Moon sets at 3:03 AM.
[What really happened? The comet has faded significantly in the last 24 hours (more than expected). It is just visible to the naked eye with the Moon in the sky.]
March 30-31, 1996: This is the last night that the comet is circumpolar, never setting below a flat horizon, for Southern California. The only time to see the comet in a dark sky is to catch it at the beginning of morning twilight when the comet is less than seven degrees above the north-northeast horizon. The Moon sets at 3:39 AM.
[What really happened? The comet's brightness has stabilized. It is slightly brighter than Polaris, the North Star, and just visible to the naked eye with the Moon in the sky.]
The comet will be visible in the northwest sky (starting about 30 degrees off the horizon at the end of twilight) as a fuzzy star with a tail. The comet's motion across the sky will be much slower than in March...if you find it one night, the comet will be very close to the same location several days later. The comet should fade at first, but by April 10th it will be brightening each night. The comet may be easier to pick out than in late March because the head will be smaller and the tail should be brighter. As it sinks lower towards the northwest horizon each night, the tail should grow brighter and longer. It is possible that the comet's head will equal the brightness of Sirius (low in the southwest after dark, the brightest star in the sky) by the 26th, and the tail could stretch 15 - 30 degrees in length. On the 26th, the comet will set at the end of astronomical twilight and thus, will not be visible in a totally dark sky. However, the tail may be visible after the comet's head has disappeared below the horizon. The comet will remain visible for two or three more days in bright twilight before disappearing for good (for the Northern Hemisphere) in the Sun's glow.
More detailed information is given below...hopefully, the comet will be obvious so "star hopping" will not be necessary to find the comet:
April 1-4, 1996: The Moon interferes with viewing the comet. It should be noted that early in the evening of April 3rd, a lunar eclipse will be visible from the Eastern US. This will provide an opportunity to observe the comet in a darker sky. The Western US will not see the total phase of the eclipse and thus, it will not gain any advantage in viewing the comet. On April 2-3, the comet passes just below Alpha Perseus (Mirfak) and is about the same elevation as Venus, which is located about 25 degrees to the left of the comet.
[What really happened? The comet's brightness appeared to fade reaching an average brightness of 2.5 (obviously fainter than Polaris). This significant fading is perhaps the result of the bright Moon. In binoculars the comet became quite small and displayed a tail at least five degrees long, despite the Moon. ]
April 7-13, 1996: The comet passes close to Beta Perseus (Algol). On the 9th, the comet passes about one degree from Algol. During much of this time the comet should be between magnitude 2.0-2.5. It will look like a fuzzy twin to Algol as it passes by the star.. The tail, now that the Moon is out of the sky, should be easily visible to the naked eye from a dark site. It may stretch several tens of degrees, but it is still faint.
[What really happened? After the Moon left the sky, the comet's brightness remained stable or perhaps faded a bit. At the beginning of the period, the comet was close to Algol in brightness, although some observers did report the comet one magnitude fainter. What was amazing was the long tail that continued to grace the skies from a dark site. Tail length estimates of 60+ degrees were reported. However, much of the tail was extremely faint. Most observers reported much less...10-20 degrees.]
April 16-21, 1996: Hyakutake is found by going on a line from Alpha Perseus past Beta Perseus (Algol); the comet is slightly below that line. Each day the comet moves further away from Algol. On the 21st, distance between the comet and Algol is about the same as the distance between Algol and Alpha Perseus. By the end of the period, the comet has brightened so that it is distinctly brighter than Polaris. Algol and Alpha Perseus. The gas tail has also brightened, but has grown shorter due to foreshortening. The dust tail will have brightened so that it is obvious, but remains short. The gas tail is no longer directly superimposed on the dust tail.
[What really happened? The comet failed to brighten. Most observers estimated the comet to be between 2.0 and 3.0 magnitude. A long (> 20 degree) faint tail was reported by some observers. The comet was star-like even in large telescopes.]
April 22, 1996: The comet is located about 13 degrees to the right of Mercury and should be at least as bright as Mercury. (Note: There are no bright stars to use as reference points. The comet should be the brightest object in that part of the sky.) At the end of evening twilight, the comet will be only 10 degrees above the west-northwest horizon. The tail might be obvious to the naked eye, even in twilight. Binoculars should pick-up the comet quickly.
[What really happened? Most observers continue to estimate the comet to be between 2.0 and 3.0 magnitude. The moon has begun to interfere with the observing, partcularly the faint tail.]
April 25, 1996: The comet is located about 13 degrees below and to the right of Mercury. It is only 10 degrees off of the horizon at the end of twilight. It should appear as a bright star with an obvious tail. A good horizon, with not trees, buildings, etc., will be necessary to spot the comet. Over the next few nights, the comet will be swallowed up by the twilight sky as Hyakutake moves toward perihelion. The tails should be obvious, but will be short (~10 -15 degrees).
[What really happened? While a few observers suggest that the comet is brighter than magnitude 2.0, most observers continue to estimate the brightness between 2.0 and 3.0 magnitude. The comet is in twilight for most observers and naked eye observations have become rare...binoculars are needed to locate the comet.]
The comet will only be visible from the Southern Hemisphere. This summary was made for Australia (latitude of 35 degrees south), but should be close for other locations, as the comet is moving slowly. Dates are local to Australia. I will update this as more is known about the light curve.
May 7, 1996: The first thing that should be visible is the tail rising about 10 degrees north of due east. The head of the comet, perhaps 2nd magnitude will rise during bright twilight. Hyakutake will be about four degrees below and to the right of Mars. The comet should be significantly fainter than Mars and have two short (<10 degrees) tails, that are distinctly separated. The dust tail, which should be curved, will be pointing toward the north while the gas tail will be directed toward the west (pointing almost straight-up from the horizon). There will be a bright Moon in the west.
[What really happened? So far no positive observations have been reported. A negative observation by Terry Lovejoy (Australia) is consistent with the comet being no brighter than 2nd magnitude.]
May 11, 1996:The comet rises at the beginning of astronomical twilight and is located 30 degrees below and to the right of Saturn. The comet has faded about one magnitude. The tails are still distinctly separated with the dust tail curving to the north-northwest and the gas tail pointed towards the southwest. The Moon may still be bright enough to interfere with the tails.
May 15, 1996:The comet has faded yet another magnitude (to 3.5-5.0). It is located 13.5 degrees to the right of (and slightly above) the thin crescent Moon. The gas tail has doubled in length, but the dust tail is getting shorter. The tails are now much closer together...both pointing towards the southwest.
May 20, 1996:The comet has faded to magnitude 4.0-5.5. It rises due east and is about 10 degrees up at the beginning of astronomical twilight. The gas tail reaches its peak length at about 20 degrees.
May 25, 1996:The comet has faded to magnitude 4.5-6.0. It is about 14 degrees up at the beginning of astronomical twilight. The gas tail has begun to shrink and the dust tail is very short...just a few degrees.
May 31, 1996:The comet has faded to magnitude 5.0-7.0. It is about 21 degrees up at the beginning of astronomical twilight and rises 10 degrees to the right (south) of due east. The gas tail is now much shorter than just 11 days ago.
Sky and Telescope's
Excellent C/1996 B2 Viewing Guide
Charles Boley's Comets On-Line
has plots to help you find the comet.
Finder charts for Comet Hyakutake
from Dennis Willnitz (Univ. of Md-College Park) that can be downloaded.
A. G. K. Smith provides information on
observing the comet from Australia and New Zealand
Comets Currently
Visible
C/1996 B2 Main
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Charles S. Morris / csm@encke.jpl.nasa.gov