Comet Prospects for
2002
2002 sees a number of returns of periodic comets,
however none of them are particularly exciting. The brightest periodic comet of the year is predicted to be
P/Brewington, which is making its first predicted return early in 2003 and this
comet may reach 10th magnitude at the end of the year. Several long period comets discovered in
previous years are still visible.
Theories on the structure of comets suggest that any comet could
fragment at any time, so it is worth keeping an eye on some of the fainter
periodic comets, which are often ignored.
This would make a useful project for CCD observers. Ephemerides for new and currently observable
comets are published in the Circulars,
Comet Section Newsletters and on the Section, CBAT and Seiichi Yoshida's web
pages. Complete ephemerides and
magnitude parameters for all comets predicted to be brighter than about 18m
are given in the International Comet Quarterly Handbook; details of
subscription to the ICQ are available from the comet section Director. The section booklet on comet observing is
available from the BAA office or the Director; a new edition is at the
printers.
7P/Pons-Winnecke was discovered by Jean Louis Pons with a 0.12-m
refractor at Marseilles in 1819, but was then lost until rediscovered by
Friedrich August Theodor Winnecke with a 0.11-m refractor in Bonn in 1858. He demonstrated the identity and recovered
the comet in 1869. The perihelion
distance has slowly been increasing since the early 1800s. It can make close approaches to the Earth
and did so in 1927 (0.04 AU), 1939 (0.11), 1892 (0.12), 1819 (0.13) and 1921
(0.14). An outburst of the meteor
shower associated with the comet, the June Bootids, occurred on 1998 June 27.6.
It will be a morning object, becoming visible in
February and reaching 11th magnitude in May after which it is
unfavourably placed for observation from the UK. Observers at lower latitudes will be able to follow it until
September. It moves eastwards, being in
Serpens in February, Ophiuchus in March, Aquila in April and Aquarius in May.
Comet 19P/Borrelly reached perihelion in
September 2001 and begins the year at 11m moving northward in Canes
Venatici. It remains quite well placed
as it fades, passing into Ursa Major in late February when it is 12th
magnitude.
22P/Kopff was discovered
photographically by A Kopff at Konigstuhl Observatory in 1906, when it was
around 11m. The next return
was unfavourable, but it has been seen at every return since then. Following an encounter with Jupiter in
1942/43 its period was reduced and the perihelion distance decreased to 1.5
AU. The following return was one of its
best and it reached 8m. The
next return was unusual, in that it was 3m fainter than predicted
until perihelion, when it brightened by 2m. It suffered another encounter with Jupiter
in 1954, but this made significant changes only to the angular elements. 1964 was another good return and the comet
reached 9m.
UK observers may pick up the comet in March, when it is
at opposition and follow it as it retrogrades in Virgo until May, but the comet
is only 13th magnitude.
Although it continues to brighten, the solar elongation decreases and it
is poorly placed when at its brightest (11m) at the end of the year.
29P/Schwassmann-Wachmann
1 is an annual comet which has frequent outbursts
and seems to be more often active than not at the moment, though it rarely gets
brighter than 12m. It spends
the year in Capricornus reaching opposition in early August, fairly close to
Neptune. The comet is an ideal target
for those equipped with CCDs and it should be observed at every
opportunity. Unfortunately
opportunities for UK observers are limited, as its altitude will not exceed 20°
from this country.
Carl
A Wirtanen discovered 46P/Wirtanen at Lick in 1948. It is in a chaotic orbit, and its perihelion
distance was much reduced due to approaches to Jupiter in 1972 and 1984. It has been reported to outburst, but BAA
data suggests that it was just rejuvenated after the perihelion distance was
reduced. It is a target for the Rosetta
mission. A December perihelion would
give a close approach to the Earth, however the present period is exactly 5.5
years so that perihelia alternate between March and September.
The comet is also a morning object. More southerly placed observers may pick it
up in June, but UK observers will probably not find it until August, when it is
fading from its best magnitude of 11.
The solar elongation only increases from around 40º to 60º by the end of
the year, so it is never very well placed.
In June it is in Cetus, moving into Taurus in July, Gemini in August and
Virgo in November.
67P/Churyumov-Gerasimenko was
discovered in 1969 September, by Klim Churyumov and Svetlana Gerasimenko on a
plate taken for 32P/Comas Sola at Alma Ata observatory. It reached its present orbit after a very
close encounter (0.05 AU) with Jupiter in 1959, which reduced the perihelion
distance from 2.74 to 1.28 AU. At a good
apparition, such as in 1982, when it approached the Earth to 0.4 AU and was well
observed by the comet section, it can reach 9m.
The comet is
another morning object, and even at best it probably won’t exceed 12th
magnitude. Southern observers may pick
it up around the solstice, but from the UK we won’t pick it up before August, when
it will be fading. Again the elongation
is not good, increasing from around 50º to 100º at the end of the year. The comet’s track closely parallels that of
46P/Wirtanen, entering Gemini in August and ending the year on the border of
Leo and Virgo.
81P/Wild 2
is a new comet that made a very close (0.006 AU) approach to Jupiter in
September 1974. Prior to this it was in
a 40 year orbit that had perihelion at 5 AU and aphelion at 25 AU. The comet was discovered by Paul Wild with
the 40/60-cm Schmidt at Zimmerwald on 1978 January 6. The Stardust spacecraft is due to visit the comet in 2004 and
recover material for return to earth in 2006.
The comet is at
opposition in Taurus in December when it will be around magnitude 13.5. It will brighten into 2003, when it is at
perihelion, but is too close to the Sun for observation when at its brightest
(11m).
95P/Chiron is an unusual comet in that it is also asteroid
2060. It reaches 17m when at
opposition in June in Sagittarius. CCD
V magnitudes of Chiron would be of particular interest as observations show
that its absolute magnitude varies erratically. It was at perihelion in 1996 when it was 8.5 AU from the Sun and
will be nearly 19 AU from the Sun at aphelion in around 50 years time.
The orbit of 96P/Machholz
1. is very unusual, with the smallest perihelion distance of any short
period comet (0.13 AU), which is decreasing further with time, a high
eccentricity (0.96) and a high inclination (60°). Studies by Sekanina suggest it has only one active area, which is
situated close to the rotation pole and becomes active close to
perihelion. The comet may be the parent
of the Quadrantid meteor shower. It is
rarely sufficiently well placed to see visually and this return is no
exception. However, at perihelion on
2002 January 8 it is only a few degrees from the Sun and may be seen in the
SOHO LASCO coronagraphs from January 5 to 11.
116P/Wild 4 was discovered on 1990
January 21.98 by Paul Wild with the 0.40-m Schmidt at the Zimmerwald station of
the Berne Astronomical Institute at a photographic magnitude of 13.5. At its brightest the comet only reached 12m,
but it was surprisingly well observed.
The comet was perturbed into its present orbit after a close approach to
Jupiter in mid 1987.
The comet emerges
from the solar glare in November, moving south-eastwards in Virgo, but is
poorly placed for viewing from the UK.
It brightens from 13th magnitude near the end of the year to
12th magnitude in April as it nears opposition but is a long way
south and will be difficult to observe from the UK. It is at perihelion in January 2003.
P/Shoemaker 3 (1986 A1) is also making its first
return since discovery. It will be
quite faint, around 14-13th magnitude, when it is picked up in
November and does not get much brighter by the time it reaches opposition in
February 2003. It moves eastwards from
Cancer into Leo at the end of the year.
P/Brewington 2 (1992 Q1) makes its first return
since its discovery in 1992. It was
discovered by Howard J Brewington of
Cloudcroft, New Mexico, as a small diffuse 10m object on August
28.41 using a 0.40-m reflector x55.
This was his fourth discovery and his second periodic one. The comet is in a Jupiter crossing orbit,
but has not approached the planet for several revolutions. At a favourable return it could reach 7m.
It will be too
far south for viewing from the UK when it gets into visual range in June. It reaches opposition in August when it may
be 12th magnitude and continues to brighten. We may pick it up in November as it
brightens to 10th magnitude and we will be able to follow it into
the New Year as it continues to move north.
It is an evening object, but its solar elongation decreases from 80º in
November to 50º at the end of the year.
It will not reach perihelion until 2003. By October it is moving north-eastwards in Capricornus and ends
the year in Aquarius.
Several recently
discovered parabolic comets will be visible during 2002. 2000 SV74 (LINEAR) will be fading from 13th
magnitude and may remain visible until December. 2000 WM1 (LINEAR) begins the year too far south to be visible
from the UK, but it is well placed for Southern Hemisphere observers and may be
a binocular object. In March it will
have moved far enough north for UK observation and should still be a binocular
object as it emerges into the morning sky in Sagittarius. It continues to move rapidly north and will
probably be best for northern viewers in mid month when the moon is out of the
sky. It passes from Aquila into
Hercules in April and will probably be too faint for easy observation by
June. 2001 N2 (LINEAR) may reach 13th
magnitude between May and August. 2001
HT50 (LINEAR) will become visible towards the end of the year as it brightens
towards its perihelion in mid 2003.
2001 MD7 (P/LINEAR) may be visible to Southern Hemisphere observers at
the beginning of the year fading from around 13th magnitude.
Several other comets return to perihelion during 2002, however they are unlikely to become bright enough to observe visually or are poorly placed. 6P/d’Arrest, 15P/Finlay, 26P/Grigg-Skjellerup and 28P/Neujmin 2 have unfavourable returns. 30P/Reinmuth 1, 31P/Schwassmann-Wachmann 2, 39P/Oterma, 54P/de Vico-Swift, 57P/du Toit-Neujmin-Delporte, 77P/Longmore, 89P/Russell 2, 90P/Gehrels 1, 92P/Sanguin, 115P/Maury, 124P/Mrkos, 125P/Spacewatch, 1999 F1 (Catalina), 2001 C2 (LINEAR), 2001 K5 (LINEAR) and 2001 R1 (P/LONEOS) are intrinsically faint or distant comets. Ephemerides for these can be found on the CBAT WWW pages. 18D/Perrine-Mrkos has not been seen since 1968.
Looking ahead, 2003 has a good return of 2P/Encke, which might be observable
from September until the end of the year, when it could be 6th
magnitude. This may however be
optimistic as observations from the SOHO spacecraft in 2000 showed that it
suddenly brightened after perihelion, which does not occur until late December
2003.
Comet |
T |
q |
P |
N |
H1 |
K1 |
|
96P/Machholz 1 |
Jan
8.6 |
0.12 |
5.23 |
3 |
13.0 |
12.0 |
|
2001 X1
(LINEAR) |
Jan
9.0 |
1.69 |
|
|
11.0 |
10.0 |
|
31P/Schwassmann-Wachmann 2 |
Jan 18.4 |
3.41 |
8.72 |
11 |
6.7 |
11.3 |
|
2000 WM1
(LINEAR) |
Jan 22.7 |
0.56 |
|
|
7.5 |
10.0 |
|
125P/Spacewatch |
Jan 28.1 |
1.53 |
5.54 |
2 |
15.5 |
10.0 |
|
2001 T3
(P/NEAT) |
Feb
1.1 |
2.51 |
16.59 |
0 |
12.0 |
10.0 |
|
6P/d'Arrest |
Feb
3.6 |
1.35 |
6.53 |
17 |
10.0 |
20.0 |
|
15P/Finlay |
Feb
7.2 |
1.03 |
6.75 |
12 |
12.0 |
10.0 |
|
1999 F1
(Catalina) |
Feb 13.7 |
5.79 |
|
|
5.0 |
7.5 |
|
2001 R1
(P/LONEOS) |
Feb 17.6 |
1.36 |
6.48 |
0 |
14.0 |
10.0 |
|
2001 OG108
(A/LONEOS) |
Mar 15.2 |
0.99 |
48.47 |
0 |
13.0 |
5.0 |
|
89P/Russell 2 |
Mar 23.0 |
2.29 |
7.42 |
3 |
10.0 |
15.0 |
|
2001 C1
(LINEAR) |
Mar 28.3 |
5.10 |
|
|
6.0 |
10.0 |
|
2000 SV7
(LINEAR) |
Apr 30.5 |
3.54 |
|
|
5.0 |
10.0 |
|
7P/Pons-Winnecke |
May 15.7 |
1.26 |
6.38 |
21 |
10.0 |
15.0 |
|
2001 T4
(NEAT) |
May 15.8 |
8.57 |
51.89 |
0 |
5.5 |
10.0 |
|
90P/Gehrels 1 |
Jun 23.0 |
2.97 |
14.8 |
2 |
8.5 |
15.0 |
|
124P/Mrkos |
Jul 27.0 |
1.47 |
5.74 |
2 |
13.1 |
15.0 |
|
57P/du Toit-Neujmin-Delporte |
Jul 31.2 |
1.73 |
6.42 |
5 |
12.5 |
15.0 |
|
54P/de Vico-Swift |
Aug
7.5 |
2.15 |
7.32 |
3 |
10.0 |
15.0 |
|
2001 U6
(LINEAR) |
Aug
8.5 |
4.41 |
|
|
7.5 |
10.0 |
|
2001 X2
(P/Scotti) |
Aug 10.3 |
1.95 |
7.21 |
0 |
13.5 |
10.0 |
|
67P/Churymov-Gerasimenko |
Aug 18.3 |
1.29 |
6.57 |
5 |
9.5 |
10.0 |
|
2001 N2
(LINEAR) |
Aug 19.6 |
2.67 |
|
|
7.5 |
10.0 |
|
46P/Wirtanen |
Aug 27.0 |
1.06 |
5.44 |
8 |
9.0 |
15.0 |
|
77P/Longmore |
Sep
4.7 |
2.31 |
6.83 |
4 |
7.0 |
20.0 |
|
18D/Perrine-Mrkos |
Sep 10 |
1.29 |
6.76 |
5 |
11.5 |
20.0 |
|
92P/Sanguin |
Sep 23.1 |
1.81 |
12.4 |
2 |
12.0 |
15.0 |
|
2001 K5
(LINEAR) |
Oct 11.9 |
5.18 |
|
|
2.5 |
10.0 |
|
26P/Grigg-Skjellerup |
Nov 29.7 |
1.12 |
5.31 |
18 |
12.0 |
40.0 |
|
22P/Kopff |
Dec 12.1 |
1.58 |
6.46 |
14 |
6.6 |
12.5 |
|
P/Shoemaker 3 |
Dec 15.0 |
1.81 |
17.1 |
1 |
10.5 |
10.0 |
|
39P/Oterma |
Dec 22.2 |
5.47 |
19.5 |
3 |
5.0 |
15.0 |
|
P/Helin-Lawrence |
Dec 22.4 |
3.11 |
9.52 |
1 |
10.0 |
10.0 |
|
115P/Maury |
Dec 23.9 |
2.04 |
8.79 |
2 |
11.5 |
15.0 |
|
30P/Reinmuth 1 |
Dec 24.4 |
1.88 |
7.32 |
9 |
9.5 |
15.0 |
|
28P/Neujmin 1 |
Dec 27.4 |
1.55 |
18.2 |
5 |
8.5 |
15.0 |
The date of perihelion (T),
perihelion distance (q), period (P), the number of previously observed returns
(N) and the magnitude parameters H1 and K1 are given for each comet.
Note: m1 = H1 + 5.0 * log(d) + K1 * log(r)
References and sources
Nakano, S. and Green D. W. E., Eds, International Comet Quarterly 2002 Comet Handbook, (2001).
Shanklin, J. D.,
Observing Guide to Comets, 2nd
edition (2001)
Marsden, B. G. Catalogue of Cometary Orbits, 13th
edition, IAU CBAT, (1999).
Kronk, G. W., Cometographia,
Cambridge University Press, (1999).
Belyaev, N. A., Kresak, L., Pittich, E. M. and
Pushkarev, A. N., Catalogue of short
Period Comets, Bratislava (1986).
Jonathan
Shanklin