Comets of the 1990's


The 1990's will be long remembered for the 2 great comets that appeared during this decade, Comet Hyakutake 1995 and comet Hale-Bopp 1995O1. However there were many other bright and interesting comets visible during the decade. The decade also saw considerable changes in amateur comet observations. The first was the introduction of CCD's at affordable prices which suddenly made very faint comets easily observable. The second was the introduction of several deep sky surveys for minor planets, which had the unfortunate by-product of collecting most of the comet discoveries! The name LINEAR soon became a curse amongst comet hunters!

From a personal viewpoint, although I still retained my love of comet observation, increasing demands of university studies, and problems with the Australian Comet Section forced me to curtail much of my own comet work and reduced my comet observing to largely enjoyment only. However once I was able to obtain my own CCD and complete my university studies, I was able to return to occassional comet observing.

Comet Wild 4 1990a
Comet Levy 1990c
Comet McNaught Russell
Comet Temple 1
Comet Shoemaker-Levy 9
Comet Nakamura-Nishimura-Macholtz 1994N1
Comet Borrelly
Comet 6P/ d'Arrest
Comet 122P/ de Vico
Comet Schwassmann-Wachmann 3
Comet Hyakutake 1995 Y2
Comet 103P/ Hartley 2
Comet 55P/ Temple-Tuttle
Comet SOHO 1998J1
Comet Lee 1999H1

Comet Wild 4 1990a

The first few comets of the 1990's were actually discoveries from 1989. The best of these was undoubtedly comet Austin 1989c1. This comet put on a very good display during the first half of 1990.

The first comet discovered/recovered in 1990 was the periodic comet Wild 4 1990a. I first observed this comet on February 15 when it was a very difficult object in a 10" telescope at magnitude 12.3. The comet brightened slightly, reaching magnitude 12.0 on February 25 before fading slowly. My final observation was on April 28 when it was visible in a 16" telescope at magnitude 13.3.

As comet Wild 4 faded from view another periodic comet became visible, comet Schwassmann-Wachmann 3 1989d1. I first observed this comet on April 28 when it was magnitude 10.3 and an easy object in a 10" telescope. The coma was diffuse and around 2' in diameter and a 35' long tail was visible.

Over the next few weeks the comet changed very little as it drifted through perihelion and past the Earth. My final observation was on June 4, when the comet was magnitude 10.6, still with a small, diffuse coma and a tail 20' long. A relatively uninspiring return and one that certainly gave no hint of the fireworks to come at the next perihelion passage.

Comet Levy 1990c

The first really bright discovery of 1990 came on May 20 when David Levy discovered 1990c. My first observation was on May 23 when the comet was magnitude 10.3 with a 3', moderately condensed coma and no tail. The comet brightened steadily becoming visible to the naked-eye by early August. The brightness peaked around the end of August at magnitude 3.9. During this time the comet was less than 0.5AU from the Earth and as a result, the coma became very large, reaching 20' on August 23.

During September, the comet was a wonderful sight in binoculars with a large coma and a tail of around 3 degrees. It continued to be visible to the naked eye until October and was still around magnitude 6.8 when it disappeared into the evening twilight.

Reappearing in the morning sky during December, comet Levy faded steadily with my final observations of it coming in April 1991. Other comets that became bright enough for visual observation during late 1990 were the periodic comets Honda-Mrkos-Pajdusakova 1990f, Wild 2 1989t and 97/P Metcalf-Brewington, and the non-periodic comet Tsuchia-Kiuchi 1990i. Of these comet Tsuchia-Kiuchi was the most interesting, reaching around magnitude 7.5 during mid-November before becoming very diffuse and fading.

1991 saw a number relatively faint periodic comets being visible. Amongst these were comet Arai 1991b, periodic comets Chernykh 1991o, Hartley 2 1991t, Shoemaker-Levy 1991b1, Faye 1991n and Wirtanen 1991s. Of these comet Hartly 2 was the brightest, briefly reaching 8th magnitude although not well placed for southern observers. Comet Faye had a very favourable return and briefly reached 10th magnitude. The others were generally below 10th magnitude. Two other comets that were visible were Zenotti-Brewington and Muller. Zenotti-Brewington was well placed for southern observers and reached magnitude 7.5, and remaining visible into early 1992. Muller was a little brighter at magnitude 7, however it was very close to the Sun and difficult to observe.

1992 and 1993 were the most barren years for southern hemisphere visual comet observing since the 1970's. There were no periodic comets expected to become brighter than 11th magnitude during 1992, and even the 2 brightest discoveries, Bradfield 1992B1 and Tanaka-Macholtz 1992F1 were poorly placed for southern observers! There was however one notable exception. At long last comet Swift-Tuttle returned. This celebrated parent comet of the Persid meteor shower had been waited for for several years. It was finally recovered on September 26, 1992. Unfortunately for southern observers, the comet's peak brightness of around 4.5 occurred when the comet was a northern hemisphere object only. I did managed to observe it twice however my records are lost.

In 1993 only faint comets were visible. 2 comets that did reach 10th magnitude were Mueller 1993A1 and Mueller 1993Q1. However both of these were northern hemisphere objects. The periodic comet Schaumasse did reach 9th magnitude during February and I did manage to observe it on several occasions, however as with Swift-Tuttle, my records are lost.

Comet McNaught Russell

1994 saw much more comet activity than the preceeding 2 years. In March comet McNaught Russell reached magnitude 8.6 and displayed a moderately condensed coma up to 7' across. On March 6 and 7, I suspected a very faint tail, but was never certain.

I only have records of observing the comet on 5 occasions during March of 1994. Possibly the main reason for this is that during 1994 I spent much of my observing time studying Jupiter, getting ready for the BIG event of that year (and possibly THE event of the century!) the impact of comet Shoemaker-Levy 9 with Jupiter in July.

Comet Temple 1

The periodic comet Temple 1 made another return during 1994, reaching 9th magnitude. I first observed it on April 30 as a 10.6 magnitude object with a 1.5' diameter coma that was moderately condensed.

From there, the comet brightened slowly until early June, when it peaked at around magnitude 9.6. It then faded steadily until late August when it became too faint for me to observe.

There were 2 other comets around at the same time. The first was Takamizawa-Levy 1994G1 which peaked at around magnitude 8.0 during June. Unfortunately at this time it was a northern hemisphere object only. The other comet was Takamizawa 1994J2 which reached magnitude 9.2 in late May. I only observed this object on a couple of occasions due to study and Jupiter observing. Both of these comets had a coma that was around 4' across and moderately diffuse. Neither displayed any visible tail.

Comet Shoemaker-Levy 9

Without a doubt, THE event of the 1990's was when comet Shoemaker-Levy 9 crashed into Jupiter. The first time in recorded history, a collision between a planet and another body had been observed. The fact that we also had over a year's warning, meant that during July, 1994, there was probably not a single operational telescope on Earth or in space that was not aimed at Jupiter. For my own part, I had been making detailed observations or Jupiter at every opportunity beginning in March. I even took an 8" telescope with me on a visit to Singapore and Malaysia during June. This also meant a severe neglect of other comets as the time of impact drew near. Before the impacts I did not have access to a telescope large enough to allow me to observe the comet. However the impacts more than made up for that! Since there are plenty of websites which discuss the comet and the impacts, all I will mention here are a few of my own observations.

My first opportunity to observe the results of the first impacts was on July 18. Waiting for the skies to become dark enough to observe was a frustrating time. I had seen messages posted on the internet that the results were impressive and when finally it was dark enough to observe Jupiter, it was very clear that the reports were not exaggerated! Two large whitish regions with dark spots near their centres in the South Temperate Belt were rotating into view, radically changing its appearance from the previous night.

The following night I observed something even more impressive. When fragment "G" impacted the planet, I saw a small plume of material rising off the limb of the planet. It was visible for about 3 minutes and looked very similar to a moon coming out from behind the planet. To have been visible from Earth with a 12" telescope, it must have been quite an impact. Several observing companions also saw the plume. (When they were able to drag me away from the scope!) About 20 minutes after the plume disappeared, the impact site rotated into view as a very dark spot. When the spot was on the limb, the limb appeared to have a bite taken out of it. About 40 minutes later, a dark ring was observed around the dark spot. Below are a couple of my sketchs of my observations.


Showmaker-Levy 9 fragment G impact result.
July1, 1994


Showmaker-Levy 9 fragment G impact result.
August 14, 1994

It was certainly exciting watching over the following few days as each new impact changed the appearance of the southern regions of Jupiter. By the end of July, some 9 impact sites were visible in the 12". As time progressed, these dark spots merged with one another to form a new dark band which was still visible the following year. Possibly one of the most amazing things of the whole week was that the weather co-operated! Despite July being the middle of winter and the wettest month for Perth!

Comet Nakamura-Nishimura-Macholtz 1994N1

Following the excitement of the comet impacts, it was difficult to return to normal comet observing. However there were several comets on display. The first was comet Nakamura-Nishimura-Macholtz 1994N1. I first observed this comet in August when it was a 9.6 magnitude object with a 4' coma that was fairly well condensed.

It changed very little over the next couple of months, peaking in brightness at around 8.3 during late August. After passing the Earth in late August, the comet faded rapidly, disappearing from view in mid-September.

Comet Borrelly

As comet Nakamura-Nishimura-Macholtz was fading away, its place in the sky was taken by another comet, the periodic comet 19/P Borrelly.

My first view of comet Borrelly was in early September when it was a 10.7 magnitude object with a 3', well condensed coma. On September 15 and 16, the comet passed between M42 and the Horsehead nebula, making an interesting sight and a challenging photographic target.

After passing the Horsehead, the comet brightened steadily, but unfortunately for southern observers, began to move rapidly northwards. My final observation was in early November, when it had brightened to around magnitude 8.4 and had a 6' coma. Northern hemisphere observers saw the comet peak at around magnitude 7.8 during early December.

The final comet of the year was comet Macholtz 1994T1. Although not particularly bright, I managed to observe it on a couple of occasions during December as a 10th magnitude object with a small moderately diffuse coma.

Comet 6P/ d'Arrest

1995 started very quietly for comets. The first comet I observed was the faint periodic comet 71P/ Clark.

I observed this comet on 5 occasions between April 25 and June 14. On April 25, it appeared as a magnitude 12.2 object with a very small (1') coma that was moderately diffuse. After that it brightened very slowly and was at magnitude 11.7 on my final observation.

The next comet I observed was very favourable return of the periodic comet 6P/ d'Arrest.

My first observation was on June 27, when the comet was a small, moderately condensed object of magnitude 9.8. From there the comet brightened steadily until it peaked at magnitude 7.3 on August 3. During late August and September, the coma became very large as the comet passed close to the Earth, reaching 14' on September 21. It also became quite diffuse. My final observation was on November 22, when the comet was still an easy object in a 17.5" telescope at magnitude 10.6

Comet 122P/ de Vico

As so often happens, a drought of comets is broken by a flood, with the second half of 1995 bringing a number of comet discoveries that were suitable for visual observation. While comet d'Arrest was visible, several other comets put in an appearance. Of these 2 were comet Bradfield 1995 Q1, and the periodic comet 122P/ de Vico. Although both comets were bright, they were both poorly placed for southern hemisphere observers. I managed to observe comet Bradfield on 2 occasions in late August, before it disappeared into the evening twilight. On August 20, the comet was magnitude 5.3 in 7 x 50 binoculars. On August 22 in an 8" telescope, the comet was slightly brighter at magnitude 5.2. The coma was only 3' across and well condensed, and a faint 10' tail was visible. Undoubtably it would have been a fine sight were it not very low in the twilight.

Comet de Vico also was much better placed for northern hemisphere observers, and put on a fine display there during October and November. From the southern hemisphere it was briefly visible in the dawn twilight at the beginning of October. I managed to observe it on 3 occasions, October 1 - 3. On each occasion it was around magnitude 5.3, with a moderately condensed 4' coma and a faint, 10' tail.

Amongst the rush of discoveries during the middle of 1995 were 2 comets that were destined to become considered great. These were comet Hyakutake 1996B2 and comet Hale-Bopp 1995O1. Since both of these were major comets, a discussion of each is separate. A discussion of Hyakutake is here, while a discussion of comet Hale-Bopp is here.

Comet Schwassmann-Wachmann 3

One comet that put on a very unexpected display was the periodic comet 73P/ Schwassmann-Wachmann 3. Expected to reach only about 9th magnitude, the comet's nucleus underwent disruption, splitting into several fragments. This resulted in a flare in brightness, with the comet becoming visible to the naked eye during October. The comet also showed a good tail around 2 degrees in length.

On October 22, the comet passed close to the bright globular cluster M62 making a fine sight. It also had close conjunctions with M6 on October 27, M69 on November 5, M70 on November 7, and M55 on November 18.

On November 22, the comet displayed a very prominent anti-tail, and made one of the most unusual comet sights I have seen in over 30 years of comet observing. The main tail and the anti-tail were similar in brightness and similar in length, with a bright central condensation in the middle. It gave the comet a very strange appearance!

There were several other comets visible during the latter half of 1995. These included Szczepanski 1996 B1, Hyakutake 1995 Y1, and the asteroid-come-comet Chiron. Add to that comet Schwassmann-Wachmann 1 which could have outbursts at any time. At one stage during October there were 8 comets visible in a 17.5" telescope. Many of these carried over into 1996, helping to make 1996 a very busy year for comet observers. During February I managed to visually observe 11 comets with the 17.5" scope!

Comet Hyakutake 1995 Y2

The first of Hyakutake's discoveries, comet Hyakutake 1995 Y2, was visible in small telescopes until March, 1996 when it disappeared into the dawn twilight from the southern hemisphere. My observations have it peaking at magnitude 8.3 on February 24, 1996. It had a moderately condensed coma, 5' across and no tail.

Comet Szczepanski became visible from the southern hemisphere in early 1996 as a magnitude 8.7 object with a 5', diffuse coma and no tail. The comet peaked in brightness at magnitude 8.5 on February 18 and then faded steadily, reaching magnitude 9.4 on March 20. My final observation was on April 22 when it was a faint 10.7 magnitude object with a 3', diffuse coma.

February 18 was a busy night for comet observing. On that night there was a possibility of observing 12 comets with a 17.5" telescope. The first of these was the periodic comet 67P/ Churyumov-Gerasimenko. It was a very faint and diffuse object of magnitude 13.2. The second comet on my list was another periodic comet, 58P/ Jackson-Neujmin. Unfortunately this one was a little to close to the moon and so could not be found. 3 more periodic comet came next. These were 29P/ Schwassmann-Wachmann 1, which was in outburst at magnitude 12.1. It was surprising to find Schwassmann-Wachmann 1 visible, as there had been no sign of it the previous night! 116P/ Wild 4 was easy at magnitude 12.9 with a small, well condensed coma, while 45P/ Honda-Mrkos-Pajdusakova was faint at magnitude 9.9 due to its 10', very diffuse coma. The coma was noticeably parabolic, possibly hinting at a very faint dust tail. Then came comet Szczepanski at magnitude 8.6, and comet Hyakutake 1996B2 at magnitude 7.9. For Hyakutake, the coma was diffuse with some central condensation and about 7' across. It also displayed a faint, broad tail 1 degree long.

2 faint periodic comets were next. Comet 22P/Kopff was difficult at magnitude 12.9 with a 2', diffuse with some central condensation, coma. Comet 65P/ Gunn was the most difficult. I could not be certail of observing it. With averted vision I could see something in the correct position, but not continuously. If it was the comet, it was fainter than magnitude 13. Comet 95P/Chiron was easy at magnitude 14.9 as it appeared as a star-like point. Then came comet Hale-Bopp at magnitude 8.7 with a well condensed coma 4' across and a 0.5 degree tail. The final comet of the night was shortly before dawn. This was comet Hyakutake 1995 Y1. It was magnitude 8.3 with a moderately diffuse coma about 7' across.

After this night, attention was increasingly directed towards the fantastic display of comet Hyakutake 1996B2, however many of these comets were still visible in April, after Hyakutake disappeared into the northern sky. Later on in the year, comet Hale-Bopp began to draw all the attention although there were numerous other comets visible.

One of the best comets of late 1996 was comet Tabur. This comet peaked at around magnitude 5.5 during mid-October and displayed a tail up to 1.5 degrees long. Unfortunately for southern observers, Tabur, along with almost all of the bright comets since comet Halley, was best observed from the northern hemisphere. Southerners might have seen the best of comet Halley, but we sure were paying for it ever since!!!!

Comet 103P/ Hartley 2

1997 was totally dominated by comet Hale-Bopp. Reaching around magnitude -1.5 and displaying 2 long tails, the comet was visible to the naked eye virtually for the entire year! However there were a few other interesting happenings on the comet front that year. One of these was a fantastic increase in the number of comets discovered! The main source of these discoveries was the SOHO spacecraft. Continuously monitoring the Sun, a very surprisingly large number of very faint comets sungrazing were observed. However few of these mini-comets survived perihelion. Another source contributing to the large number of comet discoveries gave an ominous signal to amateur comet hunters:- the ever increasing number of comets labeled LINEAR! As more deep asteroid surveys were coming online, more and more comets were being discovered when they were well beyond visual observation.

Visually, there were several comets visible during the year apart from comet Hale-Bopp. Comet 46P/ Wirtanen reached magnitude 10.5 during February and March although it remained quite close to the Sun, making observation very difficult. Comet 2P/ Encke was briefly visible duning late June/early July, initally as bright as magnitude 7, but fading quickly. The asteroid-come-comet Chiron continude to be visible as a star-like point around magnitude 15. Comet Tilbrook 1997O1 was around magnitude 10 at discovery in late July and was visible for a number of weeks as it faded slowly. Another 10th magnitude Australian discovery in July was comet Tabur 1997N1. **** Comet Meunier-Depouy 1997J2 remained visible as an 11th magnitude object during much of the second half of 1997, as did comet 1997D1 Mueller.

Probably the most interesting of the fainter comets during 1997 was the periodic comet 103P/ Hartley 2. At the beginning of November, this comet was around magnitude 10.5. It brightened steadily, reaching magnitude 8.6 at the beginning of December. My final observation of this comet came on February 2, 1998, when the comet was still at magnitude 9.2. On February 1, the comet drifted past the famous variable star Mira, which at the time was near maximum brightness. The result was an interesting photograph.

Comet 55P/ Temple-Tuttle

1998 was again a fairly busy year for visual comet observers. There were several returning periodic comets visible, along with a number of the new discoveries. One interesting returning periodic comet was 55P/ Temple-Tuttle, the parent comet of the November Leonids. This became visible in the southern hemisphere during January as a 9th magnitude object without tail, low to the north. In subsiquent weeks, is moved south, fading steadily, falling below 10th magnitude 10.5 by the end of March. During late January, I was able to spend a week comet observing at the Chrio observatory, and on January 27, 28 and 29 I was able to observe 11 comets each night. Comet Hale-Bopp was the brightest at magnitude 8.3 with a 2.5 degree tail. Hartley 2 and Temple-Tuttle were 9th magnitude, while Chiron was the faintest at magnitude 15.8. Comet Schwassmann-Wachmann 1 was in outburst at magnitude 12.4 and the periodic comet 59P/ Taylor was magnitude 12.6. 4 comets were 13th magnitude, these were Wolf-Harrington, Kowal 2, Mueller, and Geherls 2. The most difficult object was the periodic comet 128P/ Shoemaker-Holt 1. At magnitude 14.7, it was only visible because it was small and condensed.

During May, the distant comet Meunier-Dupouy 1997J2 again became visible from the southern hemisphere as an 11th magnitude object, and remained visible in larger telescopes for several months.

Comet SOHO 1998J1

The first bright discovery of 1998 was one of the SOHO comets. Originally discovered in SOHO solar images, this comet made a brief, interesting display during late May when it was visible to the naked eye and passed between M42 and the Horsehead nebula.

Unfortunately, like most sungrazing comets, comet SOHO faded quickly and soon disappeared.

Another relatively bright comet discovery was comet Williams 1998P1. The comet peaked at around 7th magnitude at the beginning of September, before rapidly heading northwards and disappearing from the southern sky. Northern hemisphere observers were able to follow the comet well into 1999.

Comet 21P/Giacobini-Zinner made a favourable perihelion passage during November, reaching magnitude 8.2 and displaying a short tail. Following perhelion, the comet faded steadily, falling below 11th magnitude during February 1999.

Comet Lee 1999H1

1999 was a quiet year for visual comet observing, however it marked a major change in how amateurs observed comets. By 1998, moderately priced CCD's were on the market and more and more comet observers were obtaining them. I started experimenting with one in May 1998, and by early 1999 I obtained one of my own. Suddenly, even very faint comets were observable with small telescopes. Even 16th magnitude came to be considered "bright" for a 8" telescope! As a result, many observers, myself included, were switching from visual observation of comets to CCD imaging.

The first comet discovery of 1999 was comet Tilbrook 1999A1. Never a prominent object, it was only around 9.5 magnitude at its brightest and remained close to the Sun and difficult to observe. The brightest comet of 1999 was discovered in April. Comet Lee 1999H1 was around 9th magnitude at discovery, but brightened steadily as it approached perihelion. At its peak during June, the comet was around magnitude 6.7 and displayed a fine tail. During late June the comet was too close to the Sun to observe and following perihelion, the comet had moved into the northern sky.

The next bright discovery was comet Lynn 1999N2. Discovered as a 7th magnitude object during July, comet Lynn was already past perihelion and faded quickly as it headed northwards.

The final periodic comet of the 1990's that I observed visually was another return of the periodic comet 10P/ Temple 2. Although not a favourable as some past returns, the comet still reached magnitude 9.7 during September, and did not fall below 10th magnitude until early December.

The final comet I observed visually in 1999 was an unexpected one. While observing faint outlying globular clusters belonging to the Small Magellanic Cloud, I came across one object that was not on my charts. A careful study showed that the object was clearly a comet at around 11th magnitude! Was this a discovery!!???? Alas not! A phone call to the Perth Observatory showed that this was comet 1999J3 LINEAR, a comet that had been widely observed during October from the northern hemisphere. (mumble... mumble... mumble....)


Other Comets Imaged


1997 BA6
Spacewatch

1997 J2
Meunier-Dupouy

1998 M3
Larsen

1998 M5
LINEAR

1999 F1
Catalina

1999 H3
LINEAR

1999 J2
Skiff

1999 K5
LINEAR

1999 K8
LINEAR

1999 N4
LINEAR

1999 S2
McNaught-Watson

1999 T1
McNaught-Hartley

1999 T3
LINEAR

1999 U3
LINEAR

1999 XB69
LINEAR

1999 Y1
LINEAR

1999 WJ7
Korlevic