StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

MARCH 2002

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288 MARCH 3, 2002: Lepus, the Hare: Below the feet of Orion the Hunter lies an inconspicuous constellation named Lepus, the Hare. It is overlooked by nearly everyone, but it's special to me because I have a fondness for rabbits. I know that hares are different than bunnies, but not by much. A sky map locating Lepus can be found in the web version of this week's StarWatch. It seems that Orion was very fond of hunting hares, and on one occasion after spotting this animal, Orion sent his two hunting dogs, Canis Major and Canis Minor, out ahead to chase it. The rabbit, followed by the Hunter, ran up a hill with the dogs in pursuit. The chase led Orion to the discovery of the whereabouts of the Seven Sisters or Pleiades with whom Orion immediately fell in love. The Pleiades, however, wanted nothing to do with a 70-foot giant and a chase of another kind ensued. Orion, not being the smartest of guys, became embroiled in a conflict with Taurus, the Bull, upon whose shoulders the Seven Sisters eventually found refuge. Today, the Bull and the Hunter are poised in the sky ready to duke it out. But what happened to Lepus? The hare chose to find a place of refuge directly below the feet of the Hunter. Orion must forever keep his attention focused upon the eyes of the Bull, less the battle commence, and the dogs are much too busy begging for food from the Hunter to notice the lowly rabbit crouching beneath them. There are several morals to the story of why Lepus is situated right where he is. The first is simply that the best place to often hide something of value is right up front where it can be easily found. Most people wouldn't look in such an obvious location. Secondly, if you believe that rabbits are dumb, well guess again. Just witness the latest Blockbuster ads on TV.
CHACO LOVES LEPUS: Any rabbit like my Chaco will tell you that their champion among the stars is Lepus, the Hare. Now in the Southwest at 9:00 p.m., Lepus can be found underneath the feet of Orion, the Hunter. Map and photo by Gary A. Becker...
289 MARCH 10, 2002: New Surprise Comet Now Visible: There is a new comet on the loose, and it will be visible to those observers who are willing to find a relatively dark location with a low horizon facing west and spend a little time scanning the heavens with binoculars. Kaoru Ikeya of Shizuoka, Japan was the first to report the comet on February 1. About 30 minutes after Ikeya saw it, Daqing Zhang near Kaifeng, Henan province, China reported it. About 12 hours later Paulo M. Raymundo of Salvador, Brazil spotted it, but he was already too late to have his name attached to the new interloper. At the end of February under optimum conditions, Ikeya-Zhang became a naked eye object sprouting a tail of several degrees. On March 4 when I first tried to find it, I latched onto the wrong reference objects, Mars and a star named Hamal, and swept the heavens about 15 degrees to the west of its actual location. That's a mistake I would not have made under a New Mexican sky, but it was a sobering reminder of just how light polluted our heavens are. The next evening, March 5, I used Mars and Hamal to successfully find the comet. Ikeya-Zhang had a condensed almost stellar head, but with averted vision, I could see a tail about a degree and a half long. Download a map showing Ikeya-Zhang's location in five-day intervals at the web version of this week's StarWatch. To see it, you should be outside as soon as it's dark, 7:15 p.m., and at a location with a good dark western horizon. Find the planet Mars and the star Hamal, low in the west. Mars is brighter and it will appear distinctly red though binoculars. Use the Mars-Hamal separation as a yardstick to locate Ikeya-Zhang directly below these two objects. I will be posting my observations at the web address below. E-mail me if you see it!
APPROXIMATE LOCATIONS FOR COMET IKEYA-ZHANG can be found on the map. Use the relative separation of Mars and Hamal to judge the location of the comet. Look west using binoculars around 7:15 p.m. in a dark location without any direct streetlights. Be patient. The comet may appear star like at first, but as your eyes adjust to the dark, a tail should be seen using averted (side) vision. In other words to see the tail, don't stare directly at the comet, but view another star in the field and sneak a peek at the comet with your side vision. The tail should become distinctly visible. The comet symbol on the map only indicates the location of Ikeya-Zhang, not its brightness or tail length. Graphics by Gary A. Becker using TheSky software...: Monday, March 4: Scouted out several observering locations in the afternoon, but eventually settled on a spot about two blocks NW of my residence as the darkest area. Spent about an hour and a half searching for Comet Ikeya-Zhang only to discover that I had mistaken my target stars and was observing about 15 degrees to the west of the comet's actual location. I decided to use these same objects, Mars and Hamal, as reference targets on the next clear night. Conditions: Clear, winds 15 MPH, T=20 deg. F., limiting mag. +5.0.
: Tuesday, March 5: Ikeya-Zhang was spotted with a minimum of difficulties using 7x42B Leitz Trinovid binoculars. The relative separation of Mars and Hamal was utilized as a relative yardstick (see map above). The comet was due west about 15 degrees off the horizon with a tail of about 1.5 degrees in length. Its magnitude, using the defocusing technique, was estimated at +5.0, using +5.21 magnitude Zeta Piscium and +4.26 magnitude Epsilon Piscium as reference stars. The coma was very condensed, almost star like in appearance. A tail of about 1.5 degrees in the antisolar direction could be seen distinctly with averted vision. Conditions: Clear, calm, T=24 deg. F., limiting mag. +4.5.
: Wednesday, March 6: This is the third clear evening in a row. The comet was easily found using the Trinovids from just up the street where I live and from my standard haunt. The magnitude was still holding at +5.0, maybe a tad brighter. The tail length was about 1.5 degrees. Conditions: Clear, breezy, T=48 deg. F., limiting mag. +4.5.
: Thursday, March 14: Under hazy and less than optimum sky conditions Ikeya-Zhang could be seen and compared with +3.62 magnitude Eta Piscium. Seven by 42mm Trinovid binoculars were used. Estimated magnitude, +3.8-+4.0 with a tail length of about 1.5 degrees. Conditions: Hazy, calm, Temp. approx. 50 deg. F., limiting magnitude about +2.5.
: Saturday, March 16: After a long hiatus of cloudy/hazy weather, this evening was crisp with no haze in the west. Comet Ikeya-Zhang exceeded all expectations--brighter than +4.0 magnitude (+3.8) through my Trinovid binoculars, and a tail that was at least four degrees in length. I'm pretty sure I saw it naked eye, but the comet is nothing that would have caught my attention had I not known where it was. Still this has got to make Ikeya-Zhang the best comet since Hale-Bopp, seen during the spring of 1997. Conditions: Clear, calm, T=35 deg F., limiting magnitude +4.5. A definite WOW object, but really still binocular...
: Saturday, March 16: Peter J. Brown of Mount Desert, Maine writes, "I had ideal conditions here on Mount Desert Island Saturday night, and as you reported, Ikeya-Zhang was an exceptionally bright comet. My observations were made after 8 p.m. when the comet was quite low on the horizon. It far exceeded my expectations."
: Friday, March 22: Finally, tonight provided another all to brief peak at Ikeya-Zhang after five cloudy or rainy/snowy nights. The view under a moonlit, hazy to partly cloudy sky was not at all disappointing. The comet's brightness was estimated at +3.5 using +3.42 Alpha Trianguli, +3.00 Beta Trianguli, and +4.74 Upsilon Piscium as calibrating stars. The tail was measured 4 degrees using averted vision in my 7x42B Trinovid Binoculars. Conditions: Hazy clear to partly cloudy (toward horizon), slight breeze, T=24 deg F., limiting magnitude +3.5. Full moon is still six days away.

290a MARCH 17-19, 2002: View Vesta: This week, you'll have a good chance of viewing an asteroid as it lines up with Saturn. Asteroids, "little stars," also called minor planets, could simply be described as leftover debris from the early days of the formation of our solar system. About five billion years ago, Pennsylvania-sized boulders were assembling into the planets and moons that we know today. This may have been occurring between Mars and Jupiter, but something went wrong. The theory goes on to suggest that the gravitational tugs and pulls of giant Jupiter changed, gently colliding objects into missile-like projectiles that broke apart a larger mass. Huge county-sized rocks were sent on suicide missions, punching giant craters, hundreds of miles in diameter, into the planets and moons of our early solar family. The darker, waterless seas of our moon may have been the result of this asteroidal rampage about four billion years ago. Today asteroids are everywhere, from beyond Saturn sunward, but most reside as widely separated bodies between Mars and Jupiter. Several hundred thousand have been catalogued so far with thousands discovered each year. Occasionally, they hit the Earth to become meteorites. The most recent event for us occurred on July 23, 2001, NW of Williamsport, PA. This week, Vesta, the brightest and third largest of the minor planets passes very close to Saturn as seen from Earth. Tuesday and Wednesday are best. Follow the belt stars of Orion in the SW up to the bright star Aldebaran. Just beyond it is brighter Saturn. A map can be found at this week's web StarWatch detailing the position of Vesta each evening. Keep in mind that the moon passes close to Saturn on Wednesday making for a lovely view, even if you don't own a telescope. Clear skies! READ THE LASTEST ABOUT COMET IKEYA-ZHANG IMMEDIATELY ABOVE THIS ARTICLE.

290b MARCH 20-22, 2002: Comets are Like Cats!: The recent spat of cloudy weather has not dampened the anticipation of what Comet Ikeya-Zhang will look like once the Valley skies clear. Discovered on February 1 by Japanese (Kaoru Ikeya) and mainland Chinese (Daqing Zhang) amateur astronomers, it is amazing that the comet was not first detected by an automated sky patrol. However when it was finally seen, Ikeya and Zhang found it within 90 minutes of each other. The comet may have brightened suddenly making its discovery easier. Whatever happened, Ikeya-Zhang has continued to strengthen the motto that comets are very much like cats. They have tails, and they basically do whatever they want. But in this case, the unpredictability has been a decided bonus. Ikeya-Zhang has bettered the most optimistic brightness forecasts to become the most luminous comet since 1997, when the brightest, longest-seen Hale-Bopp rocked our skies. Naked eye sightings began filtering in on the very clear evening of Saturday, March 16. That was the last time the comet was visible from the Valley. Ikeya-Zhang was distinctive through binoculars on the 16th, sporting a "snazzy" four degree tail. That is the equivalent of eight full moons placed side by side. So how do I see this comet you say? Unless you are really in a rural location, make sure that you have binoculars handy. Download a copy of the map found with this StarWatch article and find a location with a good western horizon. Be there by 7:30 p.m. From the map use Mars, which will appear distinctly red through binoculars, and the stars, Hamal, and Mirach to proportion relative distances to the location of the comet. View with your binoculars to confirm the sighting. Moonlight will become more of an interference as the week progresses.
APPROXIMATE LOCATIONS AND TAIL LENGTHS FOR COMET IKEYA-ZHANG can be found on the map. Use the relative separation of Mars and Hamal, Hamal and Mirach to judge the location of the comet. Mars will appear distinctly red through binoculars. Look WNW using binoculars around 7:30 p.m. in a dark location without any direct streetlights. Be patient and allow your eyes to adjust to the darkening conditions for several minutes. The comet may appear star like at first, but by using binoculars you will be able to easily reveal its true nature. A tail several degrees in length should also be visilbe. Graphics by Gary A. Becker using TheSky software...

This impressive image of Ikeya-Zhang was photographed on March 11 by Michael Jäger of Stixendorf, Austria. Jäger used a Deltagraph 12"/F3.3, lens/camera and Kodak Ektachrome ASA 100/120 size, film for this seven minute exposure. Other wonderful images of Ikeya-Zhang by Jäger and Gerald Rhemann can be found by clicking on Rhemann's home page, Astro Studio. Copyright © 2002, Michael Jäger
291 MARCH 24, 2002: How Bright Will Ikeya-Zhang Become?: Comets that have brightened as extensively as Ikeya-Zhang basically come in two groups: those that reach their greatest brilliance at the point in their orbit when they are closest to the sun, known as perihelion, and those comets which just keep on getting brighter for several weeks after perihelion. Ikeya-Zhang reached perihelion on March 18, so the wait is on to see which brightness path it will take. Obviously, I am hoping for the latter because in the case of Ikeya-Zhang, this will place it under a new moon and back dropped against a much darker sky when the comet is at its brightest. I would predict that the comet could then be seen as a faint star-like object with a smudge of a tail even from urban Valley locales. The moon will burgeon in brightness this week making this assessment very difficult until after full moon on the 26th. Even if the comet has peaked, it should hold near its current brightness for several weeks and remain binocular or naked eye for the keen observer. By mid-April, I-Z will be high in the northeast by dawn. Actually by that time the comet will have become north circumpolar which means that it will be visible all night. However, it will spend most of that time low in the north, but still visible through binoculars. By 2 a.m. on IRS day, Ikeya-Zhang will begin its ascent in the northeast, hopefully gaining greater visibility as it moves into clearer skies and away from city lights which are always brightest near the horizon. Of course, Ikeya-Zhang is its own boss, and because comets are so fickle, it would be rash of me to speculate too far. However from my observations on March 22, I-Z is holding its own with a nice four-degree tail. Follow the daily comet postings at web StarWatch as well as download a new map for April. Good observing!
COMET IKEYA-ZHANG IN THE MORNING SKY: The locations of Comet Ikeya-Zhang are posted for April in the morning sky. Note the time of the observation, because we switch from Eastern Standard Time to Eastern Daylight Time on Sunday morning April 7th. By mid-April Ikeya Zhang will become visible all night, but spend most its time low in the north. Graphics by Gary A. Becker using TheSky software...
292 MARCH 31, 2002: Measuring Ikeya-Zhang's Brightness: Comet Ikeya-Zhang still remains elusive; not because it is faint, but because of the dismal weather that we have been experiencing here in the Lehigh Valley over the past couple of weeks. Its closeness to the northwestern horizon in the thickest area of haze and the greatest amount light pollution has not helped matters either. I was able to observe I-Z last Thursday with a full moon in the east and hazy skies all around. I-Z brightness has remained constant. Now that the moon is removed from the picture, a really clear night should help to cement what is really happening. If I had to guess, I'd say the comet's brightness, currently near or at its peak, will maintain itself over the next week or so as I-Z moves from the evening into the morning sky and the moon's brightness wanes. Happily the Earth will continue to approach Ikeya-Zhang until April 21 helping the comet to maintain its brightness. After that time the comet should fade steadily. A map provided with this web issue of StarWatch will help you to estimate the brightness or magnitude, as well as the tail length of I-Z. Binoculars will be needed. A standard method of determining a comet's brightness is to defocus your binoculars and compare the "comet blob" against "star blobs" of various magnitudes. The white numbers on the star chart represent stellar brightness. Keep in mind that the more negative the number, the brighter the star. As an example, two lies closer to the negative numbers than four. Measuring the tail length is simply comparing the angular separation between two known stars, shown in yellow on the web map, with the length of the comet's tail as seen through binoculars. If you use your side or averted vision to examine the tail, it will appear much longer. Clear skies!
MEASURE THE BRIGHTNESS AND TAIL LENGTH OF COMET IKEYA-ZHANG: A standard method of determining a comet's brightness is to defocus your binoculars and compare the "comet blob" against "star blobs" of various magnitudes. The white numbers on the star chart represent stellar brightness. Keep in mind that the more negative the number, the brighter the star. As an example, magnitude two lies closer to the negative numbers than magnitude four. Measuring the tail length is simply comparing the angular separation between two known stars, in yellow on the map, with the length of the comet's tail as seen through binoculars. If you use your side or averted vision to examine the tail, it will appear much longer. Moving the binoculars back and forth slightly and using averted vision will help to extend the tail even further. Graphics by Gary A. Becker using TheSky software...: Thursday, March 28: Under a full moon and hazy conditions, Ikeya-Zhang's brightness was estimated at +3.6 using Mu Andromedae (+3.86) and Alpha Trianguli (+3.42). The tail length was 2.5 degrees using averted vision and 7x42B Trinovid binoculars. Conditions: hazy, T=50 deg. F., limiting magnitude +3.5.
: Monday, April 1: Tonight provided a good view of Ikeya-Zhang in a clear sky without a moon. I-Z's brightness was estimated at +3.6 using +3.86 Mu Andromedae and +3.69 Zeta Cassiopeia as guides. I-Z's coma appeared larger. Its tail was estimated at 5 degrees using averted vision and 7x42B Trinovid binoculars. Conditions: clear, T=45 deg. F., limiting magnitude +4.5.
: Wednesday, April 3: A cold front pushed through this afternoon and it seemed for a while that the sky would clear. At 7:45 p.m. thin clouds and haze hung in the direction of the comet allowing Ikeya-Zhang to be seen along with its tail, but not well enough for any accurate measurement to be make. I don't believe, however, the comet had lost any brightness from Monday. Condition: mostly clear, T=37 deg. F., wind 10 mph, gusting to 15 mph, limiting magnitude +4.5.
: Thursday, April 4: Despite it being a beautiful cool spring day, but the comet is now so low that it seems to be always in the haze near the horizon and the muck of the Allentown's sky glow. At first I thought Ikeya-Zhang had faded, but when I compared it to +3.89 Mu Andromedae and +4.53 Nu Andromedae it was consistent with the night before, about +3.5. The tail was much shorter because of the haze, about two degrees. About one half dozen degrees above the comet, the sky appeared much clearer. Conditions: clear, T=37 deg., calm, limiting magnitude +4.
: April 5/6: The comet's brightness appears to be holding steady at about +3.5 magnitude in comparison to other stars in the vicinity. Its tail was at least 2 degrees despite looking into Allentown's sky glow. Ikeya-Zhang was only about seven degrees above the horizon. Conditions: clear, T=low 30s, for both evenings, slight breeze, limiting magnitude +4. Because of trees, I'll have to wait until about Wednesday before I can catch the comet in the morning sky from my property.