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Comets
Comet 2002C1 (IKEYA-ZHANG)

Discovered February 1, 2002

C1-grp.jpg

These images of the comet were taken early in the evening on February 17, 2002 UT and processed by a variety of techniques to illustrate diffrent features of the comet.

From                                                   Circular No. 7843
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
2002 March 6                   (7843)            Daniel W. E. Green
 
COMET C/2002 C1 (IKEYA-ZHANG)
     B. G. Marsden (cf. MPEC 2002-D36) and S. Nakano have noted the
similarity of the orbits of comets C/2002 C1 and C/1661 C1 and that
numerical integration of the 2002 orbit backward yields a previous
perihelion date within a couple of years of 1659, making the link
rather likely. 

From Space.com, 19 February 2002
http://www.space.com/spacewatch/anew_comet_020219.html

By Joe Rao

A newly discovered comet, now approaching the Sun and Earth, could develop
into a relatively bright naked-eye object in coming weeks, researchers say.
The best views of the comet may be reserved for those under dark skies far
from bright lights, but even city dwellers should be able to spot it.

Kaoru Ikeya of Japan and Daqing Zhang from China first sighted the comet in
the constellation Cetus, the Whale, on Feb. 1. Both described it as a weak,
condensed glow in their telescopes with no mention of a tail.

The comet is called Ikeya-Zhang. The latest orbit calculation indicates it
will pass closest to the Sun, a point called perihelion, on March 18 at a
distance of 47.1 million miles (75.8 million km). After rounding the Sun,
the comet will continue moving toward Earth, making its closest approach to
our planet, called perigee, on April 28, when it will be 37.6 million miles
(60.5 million km) away.

Ikeya-Zhang's expected path across the sky in the coming weeks will greatly
favor Northern Hemisphere observers. During most of March on into early
April, the comet will be visible near to the north-northwest horizon about
an hour after sundown. Bright moonlight may hinder observations during the
last week of March.

After the first week of April, with the Moon no longer a factor, the comet
will also be visible in the morning sky, rising earlier and getting
progressively higher above the northeast horizon each night.

Seen before?

Initially, it appeared that this comet would not get brighter than fourth
magnitude, which is similar to the brightness of a relatively dim star.
Magnitude is a measure of a celestial object's apparent brightness.

But John Bortle, a longtime comet consultant for Sky & Telescope magazine,
said it could get brighter.

Soon after Ikeya-Zhang's orbit was calculated, some orbital specialists
noticed a similarity to a pair of much earlier comets that appeared in 1532
and 1661, Bortle explained in an e-mail interview last week. The 1532 comet,
in particular, was apparently a bright comet according to Oriental records.

Brian Marsden of the Smithsonian Astrophysical Observatory in Cambridge,
Massachusetts, an orbital specialist, said last Thursday that "a revolution
period of 400-500 years (for Ikeya-Zhang) is likely," keeping alive
speculations that this may be a return of the 1532 comet.

The key to figuring out if the comets are the same may lie in Ikeya-Zhang's
orbital period -- how long it takes to go around the Sun.

"In recent days, several observers have made their own independent
calculations suggesting that Ikeya-Zhang might have an orbital period of
roughly 500 years, making for a strong argument that there may indeed be a
direct connection with the comet of 1532," Bortle said.

What to expect

How comet Ikeya-Zhang ultimately performs is anyone's guess. So far it is
brightening more rapidly than originally expected. As of late last week, it
had nearly doubled in brightness in just one week and was at magnitude 6.8
as of Feb. 15.

But Terry Lovejoy, an assiduous comet watcher from Australia, says it's a
bit early to get excited.

"We've seen this situation before," Lovejoy cautions. "At first a new comet
appears to brighten at a much faster than normal rate, but then as it gets
closer to the Sun it seems to run out of puff. My best guess is that this
comet will be no different and will peak somewhere at around magnitude 3.5."


Such a brightness is just slightly fainter than Megrez, the star in the Big
Dipper that joins the handle with the bowl.

"A peak of magnitude 3.0 would not be at all surprising to me," says Bortle,
adding that he expects Ikeya-Zhang to unfurl an impressive tail perhaps up
to 15 degrees in length as it sweeps by the Earth. For comparison, your fist
held at arm's length measures roughly 10 degrees. However, because this tail
is likely to be chiefly composed of gas and not dust, it will appear faint
and bluish and likely only be visible to those with access to dark skies
free of light pollution.

So how might Ikeya-Zhang stack up against other popular comets?

The 1986 appearance of Halley's comet, considered disappointing by many,
also peaked at around magnitude 3.0. In contrast, comet Hale-Bopp, which put
on a memorable show in April 1997, attained a brightness close to magnitude
-1, or about 60 times brighter than Halley.

Binoculars or a small telescope should allow most skywatchers a view of
Ikeya-Zhang's fuzzy head, called a coma, and of the tail.

Editor's Note: Viewing tips and more information about comet Ikeya-Zhang
will be provided in our Spacewatch section in March.

Copyright 2002, Space.com

488-3n.jpg


From INTERNATIONAL ASTRONOMICAL UNION
Circular No. 7812
February 1, 2002

COMET 2002 C1
Word has been received of the independent visual discovery of
a comet by Kaoru Ikeya (Mori, Shuchi, Shizuoka, Japan; 0.25-m
reflector, 39x; communicated by S. Nakano, Sumoto, Japan; coma
diameter 2' with weak condensation; motion about 5' northeastward
in 30 min) and by Daqing Zhang (near Kaifeng, Henan province,
China; 0.2-m reflector; communicated by J. Zhu, Peking University;
coma diameter 3').

2002 UT R.A. (2000) Decl. m1 Observer
Feb. 1.408 0 08.9 -17 42 9.0 Ikeya
1.47 0 09 -17 30 8.5 Zhang

Sunflower imaged the comet on February 2, 2002 in 64 images starting at 00:41:03UT and ending at 01:09:39UT. These were 15 second exposures. All 64 images were combined to make the image displayed above. The bright trail and accomapnying brigtht spots were the result of an airplane flying through one of the fields. It improved the overall signal to noise ration so it was left in the combination. A faint tail is apparent in the image. This may be the first report of a tail on this comet. Originally it was reported with coma only and no tail. The tail is probably not visible visually.

The following position report was made to the Minor Planet Center:

COD 739
CON Sunflower Observatory 14680 W 144th St Olathe, KS 66062
CON [lrobinsn@ix.netcom.com]
OBS L Robinson
MEA L Robinson
TEL 0.30-m Schmidt-Cassegrain + CCD
NET USNO SA2
ACK 02-01-2002 18:55:59 (UT-5)
CK02C010 C2002 02 02.02859 00 09 58.56 -17 20 41.2 11.5 R 739
CK02C010 C2002 02 02.03488 00 09 59.23 -17 20 28.9 739
CK02C010 C2002 02 02.03708 00 09 59.32 -17 20 25.7 11.7 R 739

M.P.E.C. 2002-C03 Issued 2002 Feb. 2, 18:14 UT

The Minor Planet Electronic Circulars contain information on unusual
minor planets and routine data on comets. They are published
on behalf of Commission 20 of the International Astronomical Union by the
Minor Planet Center, Smithsonian Astrophysical Observatory,
Cambridge, MA 02138, U.S.A.

Prepared using the Tamkin Foundation Computer Network

MPC@CFA.HARVARD.EDU
URL http://cfa-www.harvard.edu/iau/mpc.html ISSN 1523-6714

COMET C/2002 C1 (IKEYA-ZHANG)

Observations:
CK02C010 C2002 02 01.81453 00 09 37.57 -17 26 56.5 8.7 T 620
CK02C010 C2002 02 01.81874 00 09 38.00 -17 26 48.7 620
CK02C010 C2002 02 01.82516 00 09 38.63 -17 26 35.8 620
CK02C010 C2002 02 01.82715 00 09 38.82 -17 26 32.6 620
CK02C010 C2002 02 02.02859 00 09 58.56 -17 20 41.2 11.5 T 739
CK02C010 C2002 02 02.03488 00 09 59.23 -17 20 28.9 739
CK02C010 C2002 02 02.03708 00 09 59.32 -17 20 25.7 11.7 T 739
CK02C010 C2002 02 02.06968 00 10 02.67 -17 19 28.5 11.4 T 734
CK02C010 C2002 02 02.07131 00 10 02.92 -17 19 24.9 10.9 T 734
CK02C010 C2002 02 02.08148 00 10 03.88 -17 19 07.0 10.8 T 734
CK02C010 C2002 02 02.45552 00 10 40.75 -17 08 05.2 327
CK02C010 C2002 02 02.46337 00 10 41.52 -17 07 51.5 327
CK02C010 C2002 02 02.47553 00 10 42.69 -17 07 29.1 327
CK02C010 C2002 02 02.72046 00 11 07.03 -17 00 14.6 046
CK02C010 C2002 02 02.72363 00 11 07.27 -17 00 10.0 046
CK02C010 C2002 02 02.72448 00 11 07.43 -17 00 07.3 046
CK02C010 C2002 02 02.72529 00 11 07.48 -17 00 06.4 046
CK02C010 C2002 02 02.72609 00 11 07.53 -17 00 06.1 046
CK02C010 C2002 02 02.72778 00 11 07.75 -17 00 01.7 046
CK02C010 C2002 02 02.73185 00 11 08.21 -16 59 53.5 636
CK02C010 C2002 02 02.73338 00 11 08.35 -16 59 51.4 636
CK02C010 C2002 02 02.73459 00 11 08.26 -16 59 49.6 9.7 T 151
CK02C010 C2002 02 02.73484 00 11 08.45 -16 59 49.5 636
CK02C010 C2002 02 02.73589 00 11 08.45 -16 59 45.9 9.4 T 151
CK02C010 C2002 02 02.73721 00 11 08.78 -16 59 44.0 636
CK02C010 C2002 02 02.73965 00 11 08.74 -16 59 40.2 9.4 T 151
CK02C010 C2002 02 02.74193 00 11 09.09 -16 59 36.0 9.2 T 151

Observer details:
046 Klet. Observers J. Ticha, M. Tichy. Measurer M. Tichy. 0.57-m f/5.2
reflector + CCD.
151 Eschenberg Observatory, Winterthur. Observer M. Griesser. 0.40-m f/5.9
Hypergraph + CCD.
327 Peking Observatory, Xinglong Station. Observers J. Zhu, H. Wu, R. Wang,
C. H. Liu, S. L. Kong. Measurer J. Zhu. 0.6-m Schmidt + CCD.
620 Observatorio Astronomico de Mallorca. Observer S. Sanchez. 0.30-m
f/8.8 Schmidt-Cassegrain + CCD.
636 Essen. Observer T. Payer. 0.32-m f/5.7 reflector + CCD.
734 Farpoint Observatory. Observer G. Hug. 0.30-m Schmidt-Cassegrain + CCD.
739 Sunflower Observatory, Olathe. Observer L. Robinson. 0.30-m
Schmidt-Cassegrain + CCD.

Orbital elements:
C/2002 C1 (Ikeya-Zhang)
T 2002 Mar. 8.912 TT MPC
q 0.49127 (2000.0) P Q
Peri. 19.237 -0.623647 -0.664184
Node 111.715 +0.646398 -0.734707
e 1.0 Incl. 26.341 +0.439584 +0.138076
From 24 observations 2002 Feb. 1-2.

Ephemeris:
C/2002 C1 (Ikeya-Zhang)
Date TT R. A. (2000) Decl. Delta r Elong. Phase m1 m2
2002 01 26 23 58.97 -20 32.2 1.410 1.055 48.4 44.2 9.5
2002 01 28 00 01.99 -19 40.4 1.386 1.020 47.3 45.2 9.3
2002 01 30 00 05.11 -18 46.6 1.361 0.986 46.3 46.3 9.1
2002 02 01 00 08.31 -17 50.4 1.335 0.951 45.4 47.5 8.9
2002 02 03 00 11.58 -16 51.8 1.307 0.916 44.4 48.8 8.7
2002 02 05 00 14.93 -15 50.5 1.279 0.882 43.5 50.3 8.5
2002 02 07 00 18.33 -14 46.2 1.249 0.847 42.5 51.9 8.3
2002 02 09 00 21.77 -13 38.8 1.218 0.813 41.6 53.7 8.0
2002 02 11 00 25.24 -12 27.7 1.186 0.779 40.7 55.7 7.8
2002 02 13 00 28.71 -11 12.8 1.153 0.746 39.9 58.0 7.5
2002 02 15 00 32.14 -09 53.6 1.119 0.714 39.0 60.5 7.3
2002 02 17 00 35.50 -08 29.7 1.083 0.682 38.1 63.4 7.0
2002 02 19 00 38.73 -07 00.7 1.046 0.651 37.2 66.6 6.7
2002 02 21 00 41.77 -05 26.0 1.008 0.622 36.3 70.2 6.5
2002 02 23 00 44.52 -03 45.2 0.969 0.595 35.4 74.2 6.2
2002 02 25 00 46.89 -01 57.6 0.929 0.570 34.4 78.7 5.9
2002 02 27 00 48.74 -00 03.0 0.888 0.547 33.3 83.6 5.6
2002 03 01 00 49.92 +01 59.1 0.847 0.528 32.2 89.1 5.4
2002 03 03 00 50.24 +04 08.9 0.806 0.512 31.0 94.9 5.1
2002 03 05 00 49.52 +06 26.2 0.766 0.501 29.7 101.0 4.9
2002 03 07 00 47.54 +08 50.5 0.727 0.494 28.4 107.3 4.7
2002 03 09 00 44.11 +11 20.9 0.690 0.491 27.0 113.4 4.6
2002 03 11 00 39.08 +13 55.7 0.655 0.494 25.8 119.1 4.5
2002 03 13 00 32.34 +16 32.7 0.623 0.501 24.7 123.9 4.5
2002 03 15 00 23.83 +19 09.2 0.594 0.513 24.2 127.6 4.5
2002 03 17 00 13.60 +21 42.3 0.570 0.529 24.2 129.7 4.5
2002 03 19 00 01.76 +24 08.7 0.549 0.549 24.9 130.1 4.6
2002 03 21 23 48.49 +26 25.4 0.532 0.572 26.5 128.9 4.7
2002 03 23 23 34.02 +28 30.0 0.518 0.597 28.8 126.5 4.8
2002 03 25 23 18.63 +30 20.7 0.508 0.625 31.7 123.0 5.0
2002 03 27 23 02.61 +31 56.3 0.501 0.654 35.0 119.0 5.2
2002 03 29 22 46.23 +33 16.8 0.496 0.685 38.6 114.6 5.3
2002 03 31 22 29.73 +34 22.6 0.493 0.716 42.4 110.0 5.5
2002 04 02 22 13.34 +35 14.5 0.492 0.749 46.3 105.4 5.7
2002 04 04 21 57.20 +35 53.9 0.493 0.782 50.2 100.9 5.9
2002 04 06 21 41.41 +36 22.2 0.494 0.816 54.1 96.5 6.1
2002 04 08 21 26.05 +36 40.6 0.497 0.850 58.0 92.2 6.3
2002 04 10 21 11.15 +36 50.4 0.501 0.885 61.9 88.1 6.5
2002 04 12 20 56.70 +36 52.7 0.505 0.919 65.8 84.1 6.6
2002 04 14 20 42.69 +36 48.4 0.510 0.954 69.6 80.3 6.8
2002 04 16 20 29.11 +36 38.2 0.516 0.988 73.4 76.6 7.0
2002 04 18 20 15.93 +36 22.6 0.522 1.023 77.1 73.1 7.2
2002 04 20 20 03.13 +36 02.1 0.528 1.058 80.8 69.6 7.4
2002 04 22 19 50.68 +35 37.0 0.535 1.092 84.5 66.3 7.5
2002 04 24 19 38.59 +35 07.7 0.543 1.127 88.1 63.1 7.7
2002 04 26 19 26.82 +34 34.4 0.551 1.161 91.7 60.0 7.9
2002 04 28 19 15.38 +33 57.3 0.560 1.195 95.2 57.0 8.0
2002 04 30 19 04.27 +33 16.6 0.569 1.230 98.7 54.1 8.2
2002 05 02 18 53.49 +32 32.5 0.579 1.263 102.1 51.2 8.3
2002 05 04 18 43.04 +31 45.2 0.590 1.297 105.5 48.5 8.5
2002 05 06 18 32.93 +30 55.0 0.602 1.331 108.8 45.9 8.6

Brian G. Marsden (C) Copyright 2002 MPC M.P.E.C. 2002-C03

Circular No. 7813

COMET C/2002 C1 (IKEYA-ZHANG)
Precise astrometry (Feb. 1-2) and the preliminary parabolic
orbital elements given below appear on MPEC 2002-C03. Visual m_1
and coma-diameter estimates: Feb. 1.910 UT, 7.5:, 5' (P. M.
Raymundo, Salvador, Brazil, 0.25-m reflector; independent
discovery); 2.081, 9.5:, 3' (A. Hale, Cloudcroft, NM, 0.41-m
reflector; thin clouds); 2.43, 8.8, about 4' (K. Yoshimoto,
Yamaguchi, Japan, 20x100 binoculars); 2.47, 8.8, 3' (D. Zhang,
Kaifeng, Henan, China, 0.20-m f/4.4 reflector, 28x, as used for the
discovery on Feb. 1.47; comet more condensed than on previous day);
2.53, 9.1, 3' (A. Pearce, Nedlands, W. Australia, 0.2-m reflector);
2.53, 8.5, 5' (N. Brown, Quinns Rocks, W. Australia, 0.15-m
refractor).

T = 2002 Mar. 8.912 TT Peri. = 19.237
Node = 111.715 2000.0
q = 0.49127 AU Incl. = 26.341

2002 TT R. A. (2000) Decl. Delta r Elong. Phase m1
Jan. 26 23 58.97 -20 32.2 1.410 1.055 48.4 44.2 9.5
28 0 01.99 -19 40.4 1.386 1.020 47.3 45.2 9.3
30 0 05.11 -18 46.6 1.361 0.986 46.3 46.3 9.1
Feb. 1 0 08.31 -17 50.4 1.335 0.951 45.4 47.5 8.9
3 0 11.58 -16 51.8 1.307 0.916 44.4 48.8 8.7
5 0 14.93 -15 50.5 1.279 0.882 43.5 50.3 8.5
7 0 18.33 -14 46.2 1.249 0.847 42.5 51.9 8.3
9 0 21.77 -13 38.8 1.218 0.813 41.6 53.7 8.0
11 0 25.24 -12 27.7 1.186 0.779 40.7 55.7 7.8
13 0 28.71 -11 12.8 1.153 0.746 39.9 58.0 7.5
15 0 32.14 - 9 53.6 1.119 0.714 39.0 60.5 7.3

(C) Copyright 2002 CBAT
2002 February 2 (7813) Daniel W. E. Green

COMET IKEYA-ZHANG, C/2002 C1

The 9th-magnitude comet spotted last week in the constellation
Cetus should continue to brighten as it approaches the Sun.
In early March, Comet Ikeya-Zhang could be 5th or even 4th
magnitude, but it will then be very low in the western evening
sky after sunset and difficult to locate. After mid-March the
comet skirts north of the Sun and enters the predawn sky,
where strong moonlight will hamper observations. Prospects
get better during April as it draws away from the Sun and
makes its way across Cygnus, but by then the comet will have
started to fade.

That's the upshot of the preliminary orbital elements
calculated by Brian G. Marsden and published on IAU
Circular 7813. The comet is expected to reach perihelion
on March 8th at 0.49 astronomical unit from the Sun, which
puts it midway between the orbits of Venus and Mercury. (For
further details, and for information on how to subscribe to
the International Astronomical Union's telegram service,
visit http://cfa-www.harvard.edu/iau/cbat.html )

The ephemeris below, based on Marsden's elements, gives the
comet's coordinates at 0h Universal Time on selected dates
along with its distance from the Earth (Delta) and Sun (r)
in astronomical units, elongation from the Sun, predicted
magnitude, and constellation. Since these computations are
based on a very short observation interval, don't be surprised
if the comet drifts off a bit after a few weeks. But the
ephemeris should still give a fair idea of how the apparition
will unfold.

Be sure to check the observing section of SkyandTelescope.com
in coming weeks for more about this object.

As we reported in last Friday's AstroAlert, this comet was
picked up visually on February 1st by Kaoru Ikeya of Shizuoka
prefecture, Japan, and by Daqing Zhang in Henan province, China.
Both observers described it as a small glow about 2' or 3'
across, with no mention of a tail. Ikeya was using a 25-cm
(10-inch) reflector, Zhang a 20-cm.

If the name "Ikeya" rings a bell, it should. During the 1960s,
Kaoru Ikeya discovered or codiscovered no less than five comets.
One of them, Comet Ikeya-Seki, became the famous naked-eye
sungrazer of 1965. But little had been heard from Ikeya, at least
outside Japan, until he made his sixth comet discovery last week.

"He is the phoenix!" says astrophotographer Shigemi Numazawa
of Niigata, who adds that Ikeya, now age 58, is manager of the
Ikeya Optical Lab, supplier of telescope mirrors to Japan's
discriminating observers.


Roger W. Sinnott

Senior Editor
Sky & Telescope

Sunflower Observatory 739 Olathe, KS