IWCA II
1999 August 14-16
New Hall, Cambridge

After months of planning and much hard work the participants 
for the second International Workshop on Cometary Astronomy 
began to assemble at New Hall, Cambridge on the afternoon 
and evening of Friday, August 13th.  New Hall is one of the 
more recent Cambridge colleges and includes a centre built 
for Japanese students as well as accommodation for the 
graduate and undergraduate students.  It is a women's 
college and a few participants were later disturbed by the 
night porter doing his rounds and making sure that all 
ground floor windows were closed.  A hearty dinner was 
provided, but afterwards I had to leave to continue last 
minute preparations for the morning.

On Saturday morning, Dan Green and Jon Shanklin made a few 
opening announcements.  We had nine comet discoverers 
present and five continents were represented.  The next 
meeting would take place in 4 - 5 years time, possibly in 
America.  For most of the day the British Astronomical 
Association had a sales desk in the entrance foyer to New 
Hall, with a range of eclipse memorabilia on offer, as well 
as copies of cometary publications. 

Don Machholz gave the opening talk about comet hunting.  He 
used to live in a light polluted site and drove out to Lomo 
Prieta for comet searching.  In 1990 he moved 180 miles to 
the small town of Colfax (pop 1000) and has since discovered 
five comets.  He had searched 1000 hours since 1994 without 
a discovery.  If the Edgar Wilson award had been in 
operation he would have netted an average of $4000 a year, 
though some years would be more rewarding and others less.  
His search technique is to scan east/west and move down in 
the morning sky.  There are three conditions for success - 
you must look, the comet must be bright enough and you must 
find it first.  His first three comets were closer to the 
sun than those previously discovered by amateurs in the 
previous 25 years.  Type 1 comets are 30 - 60 deg from the 
Sun in the morning sky, bright, few in number and have small 
q.  Type 2 lie in the evening sky 60 - 120 deg from the Sun, 
are dim, common and have large q.  Most discoveries were 
from Japan, USA and Australia.  Southern Hemisphere 
observers only discover southern declination comets, however 
northern hemisphere observers find them in both hemispheres.  
There is no significant trend in discovery declination.  The 
average elongation is 70 deg.  Most are 20 to 60 altitude 
and average 9.4 mag.  They are slightly brighter closer to 
the sun, but not much.  Some bright comets (6th mag) have 
been found far from the Sun.  Amateurs average 3.3 per year, 
with an average of 368 hours per comet and a median of 177 
[NH 433/228, SH 165/113].  Average q is 0.9.

Kesao Takimizawa addressed the meeting on Japanese comet 
discoverers.  He had become interested in astronomy in 1966 
aged 14, and had observed Ikeya-Seki.  He had searched for 
33 years and discovered 5 comets.  The first Japanese comet 
discovery occurred in 1928.  Honda had been very successful 
with 14 comets, followed by Ikeya and Seki.  Several 
Japanese discoveries were made simultaneously by three or 
more observers.  57 visual Japanese discoverers have found 
comets, with 72 in total (14 photographic and one CCD).  
Most used reflectors or binoculars, and 113 different 
instruments had been used.  He has used large binoculars for 
30 years.  A plot of discoveries showed that they were 
mostly morning, followed by evening and opposition, with 
gaps between opposition and quadrature, particularly in the 
evening sky.  He showed prints of Japanese discoverers and 
mentioned a medal for Japanese discoverers.

After a break for refreshments came a panel discussion on 
hunting for comets, however I missed most of these whilst 
carrying out administrative duties.  LINEAR doesn't search 
within 90 deg of the sun, and there is no move to set up a 
Southern Hemisphere equivalent.  The Edgar Wilson award was 
discussed, most panellists didn't think it would make much 
difference, but it was nice to have the money.  One negative 
aspect is the feeling of financial loss when someone else 
discovers a comet.

Michael Jager had made accidental discoveries as a result of 
photographing other comets.  He had found a fragment of 
Machholz 2 (what should this be called if it turned out to 
be the main fragment?) and P/1998 U3 whilst photographing 
Harrington-Abel.  He uses Schmidt cameras, the smaller 
reaching 14m and the larger 15m and has photographed over 
150 comets.  He thanked the discoverers for providing him 
with opportunities for photographing new comets.  He began 
photographic work in 1982 and had failed to see comet 
Kohoutek.

We broke for a buffet lunch, which turned out to be another 
filling meal, with more than just bites on offer.  After 
lunch Charles Morris spoke to the title "Why you don't get 
your papers published in the ICQ and other rants".  He began 
by defining a rant as a heated one sided discussion.  His 
topic was on amateur research.  Many amateurs observe at a 
profesional level.  The ICQ would like to publish amateur 
papers, but their quality is often below the acceptable 
standard.  He gave as an example the Morris method of making 
magnitude estimates.  In a casual discussion he had 
mentioned that he used averted vision and one group had then 
published a paper discrediting the method.  He then asserted 
(Charles Morris personal communication!) that using the 
Sidgwick technique for DC3+ or Bobrovnikoff method for DC7- 
will give bias.  He noted that several groups want 
additional information to be published in the ICQ, however 
they must be able to prove that the information would be 
useful.  Statistics are important and you can't just assert 
a correlation.  There is a difference between precision and 
accuracy and you need to quote errors.  The delta effect may 
exist, but as r and delta are correlated its existence is 
not convincing.  Extrapolation also presents problems when 
observations only cover a limited magnitude range.  Adding 
extra parameters, eg coma diameter, doesn't necessarily 
improve estimates of M1, particularly if the parameter is 
poorly defined.  His advice was to listen to reviewers 
comments, they should help to improve the paper, though 
reasoned argument can convince an editor that the reviewer 
is incorrect.  In discussion Nick James pointed out that the 
assertion that the Morris method was not proven, Charles was 
not allowed to forget it for the rest of the meeting!  Joe 
Marcus commented that work by the Dutch comet section does 
demonstrate the delta effect.

The next item was a panel discussion between Charles Morris, 
Jonathan Shanklin, Guy Hurst, Dan Green and Andreas Kammerer 
on The World Wide Web, the Internet and the influence on 
comet observing.  Although there had been some feeling that 
the new media acted to bias observers, there was little 
demonstrable evidence.  Guy Hurst made the point that the 
scatter in variable star estimates was typically no more 
than �0.8 whilst the scatter in comet observations was often 
2 magnitudes.  When the extreme observations were queried 
the observers sometimes admitted that they were guestimates 
rather than actual observations.  There might be a case for 
always including the actual magnitude estimate in reported 
observations, as is done with variable stars.  Magnitude 
estimates of comet Hyakutake were quite discordant, with 
experienced and inexperienced observers making 
systematically different estimates.  Andreas Kammerer 
commented that the long tails reported for comet Hyakutake 
were physically impossible, however the moon prevented 
further observations as the tail shrank after closest 
approach.  It was pointed out that the telephone had existed 
before the internet and that it had always been possible to 
exchange information.  Charles Morris said that he regarded 
the Internet as an educational tool, and the beginner 
observers would eventually become experienced.

After the discussion, tea was a little delayed and we took 
the opportunity for the first group photograph.  Following 
the break Herman Mikuz explained his careful procedures for 
CCD photometry [I missed this talk whilst finding new 
supplies of poster pins and mains adaptors.]  Nicolas Biver 
spoke on his work on the outgassing of carbon monoxide from 
distant comets.  He concluded that there was a good 
correlation between visual magnitude and CO outgassing.  He 
suggested that any comet brighter than 14th magnitude should 
be observable if CO drives the activity, even out to 30 AU.

A panel discussion between Charles Morris, Dan Green, Herman 
Mikuz, Nicolas Biver and for the last few minutes Jonathan 
Shanklin followed.  One conclusion was that a group should 
be set up to discuss the issues of CCD photometry and set up 
standard procedures.  Jon Shanklin commented that current 
ICQ coding didn't include a code for the type of CCD chip 
being used in the photometry.

As the weather looked a bit threatening (we had heard 
thunder rolling around and a gust front had thrown up dust 
outside the college), a fleet of taxis took the participants 
the short drive to the Cambridge University Press bookshop 
in the centre of Cambridge.  It should have been a short 
drive, but at least one taxi was sufficiently unfamiliar 
with Cambridge that they went to the Press Building on the 
other side of town.  Here we were treated to a generous 
reception from the Press, and were able to purchase books at 
20% of list price.  Most participants managed to walk back 
to New Hall for dinner.  By the end of dinner the storm 
clouds were retreating and Jon Shanklin took all those that 
were interested over to the University Observatory, a 20 
minute walk from New Hall.  Here we were able to use 20x80 
binoculars to observe comet Lynn, the Thorrowgood refractor 
to observe comet 10P/Tempel 2 and the Northumberland 
refractor for a variety of deep sky objects.  The two 
refractors are historic instruments, with the Northumberland 
first being used to observe comets over 150 years ago.  
Skies were very transparent and most observers spotted 
fragments of 109P/Swift-Tuttle blazing through our 
atmosphere.  Observing finished around midnight, though we 
managed to loose at least a couple of observers on the walk 
back to New Hall.  They were eventually retrieved and I 
stayed up till dawn at a dark sky site observing Perseid 
meteors and the other two comets visible in the morning sky.

On Sunday morning the participants were free to explore 
Cambridge and discussions resumed after lunch.  Kay Williams 
introduced the legendary British observer, George Alcock.  
By way of background she revealed that her son Gareth had 
wanted to be an astronomer from the age of seven and had 
eventually gone to Cambridge, MA to work with Brian Marsden.  
At a dinner party Nancy Marsden had suggested that her next 
work should be a biography of George Alcock.  She was a bit 
daunted by this as all her previous subjects had been dead!  
George's work speaks for itself and includes history, 
architecture, ornithology, meteorology and astronomy as well 
as a lifetime in teaching.  George is perhaps most famous 
for his comet and novae discoveries, but some of his comet 
drawings were also on display.  George said a few words in 
response and sat down to a standing ovation.

George was followed by another comet discoverer, Kesao 
Takamizawa, who had been observing comets, variable stars, 
novae, supernovae etc since the 1960s.  He now uses a 10-cm 
f4 astrograph, with limiting magnitude 15.5 (B) on T-Max 400 
and a 25-cm f2.8 Baker-Schmidt with limiting magnitude 17.  
He sometimes visits a 1500-m altitude site in the mountains.  
He searches in 720 areas and checks for variable stars and 
minor planets using a PC.  Over 5 years he has observed on 
367 occasions, taken 16530 shots and discovered two comets, 
two asteroids, 15 novae and 502 new variables.  He changed 
from visual to photographic search techniques in 1994.

Jean-Claude Merlin spoke about his work at Le Creusot, IAU 
station 504, which has a 40-cm f5 reflector and CCD, with 
more than 120 clear nights a year.  He averages 6 runs per 
month, taking two hours per run while observing two - five 
comets, with up to 30 second exposures.  He has measured 900 
positions since 1997, with an average accuracy of about 
0.5".  As a guide he suggested that Exposure time = pixel 
size/object speed.  As an example if pixel size was 2" and 
the object was moving 30" per hour it would require a total 
of 4 minutes exposure.  Looking at combined observations he 
had found systematic trends in the position residuals, for 
example 104P/Kowal 2 showed about a 160 day period.  
73P/Schwassmann-Wachmann 3 showed larger residuals than 
average and he thought there might be a 75 day period to 
them.  Questions suggested that these might be related to 
poor orbital determinations, or that the non gravitational 
parameters didn't quite match reality.

Bob Neville gave a very enthusiastic talk about the need to 
use CCD equipment to make positional measurements.  His own 
set-up at 967 Greens Norton was entirely homemade.  He used 
a 30-cm guide scope to a 22-cm reflector with a Starlight 
Xpress SX CCD.  The system allowed for offset guidance to 
about 1 degree.  The telescope had a roller drive in RA, 
which was very smooth and gave symmetrical star images.  For 
reduction he used Astrometrica and the USNO catalogue which 
gives dense coverage, with Guide 6 or Megastar for finder 
charts.  ACLOCK (share/freeware) provided LST.  Observers 
need to use short exposures to avoid saturation.  Sometimes 
poor seeing can actually help as it fuzzes out images; it is 
possible to make worthwhile observations even in poor 
environments.  Nicolas Biver commented that speedy 
astrometry to provide good orbits is essential to help 
professionals target radio telescopes.

During the break for tea we had a group photograph and 
managed to capture 11 discoverers on film, namely:  George 
Alcock, Doug Biesecker (SOHO), Kazimieris Cernis, Alan Hale, 
Michael Jager, Bill Liller, Don Machholz, David Seargent, 
Patrick Stonehouse, Kesao Takamizawa and Keith Tritton who 
between them had discovered 28 comets and many SOHO comets.  
Research in Sky & Tel showed that seven discoverers who at 
that time had discovered 15 comets had been present at an 
RTM meeting in 1990 [David Levy (6), Jean Mueller (1), Don 
Machholz (4), Clyde Tombaugh (1?), William Sorrels (1), Doug 
Berger (1) and Jeff Phinney (1)].

Before we resumed the formal sessions Charles Morris took 
centre stage and confessed that it was time to honour his 
bet with Alan Hale that his comet wouldn't become brighter 
than 0 mag.  It did, so Alan received 10 one dollar bills.  
Our first speaker after tea was Doug Biesecker, a member of 
the SOHO LASCO team, which has discovered a large number of 
sungrazing comet fragments.  They are all remains of a 
single progenitor which had a period of around 800 years, 
with a highly inclined orbit (and therefore not affected 
much by Jupiter).  The date of the original progenitor is 
not known and multiple fragmentation has occurred.  The most 
famous member of the familly is Ikeya-Seki.

SOHO orbits at the L1 Lagrangian point between the earth and 
sun.  The LASCO C2 camera has an orange filter with a 
bandwith of 100nm and views the region from 2.5 to 6 solar 
radii with a resolution of 13".  The C3 camera has an 
orange/clear filter with a bandwith of 300nm and views from 
4 to 30 solar radii with a resolution of 56".  They offer 
360 deg coverage round the sun, with C3 taking about 1 frame 
an hour and C2 2 frames an hour.  The camera support pylon 
hides the track of typical sungrazers between March and 
April.  Before LASCO about 10 sungrazers had been discovered 
from the ground between -371 and 1970.  Six were discovered 
by Solwind between 1979 and 1984 and 10 by SMM between 1980 
and 1989.  SOHO has now discovered 78 comets (updated to 79 
that evening); it finds about 1.9 comets a month, when 
corrected for the duty cycle.  Of a subset of 53 Kreutz 
group comets, 33 were seen in C2 and 52 in C3.  It has not 
been possible to compute an orbit for SOHO-45, though an 
mpeg loop shown later clearly showed the object.  There was 
some speculation as to whether the object was a sungrazer or 
earth approacher.  The team are getting better at visual 
detection, but are still running the automated search 
program.  This will only detect potential Kreutz group 
members, so there could be other faint comets being missed.  
The comets show fairly slow motion, and `disc' like ones are 
difficult to spot, and may only be seen in a few frames.

Most of the comets brighten as 10 log r, but after a certain 
point fade quickly.  Magnitude scales are not well 
calibrated on SOHO, partly because solar physicists require 
less accuracy than comet observers do.  There is a problem 
with vignetting and this makes reduction of the C2 and C3 
magnitudes uncertain.  At T-20 hours the median magnitude is 
around 8, with the brightest 1st magnitude and the faintest 
10th.  Most stop brightening 6 - 12 hours before perihelion, 
which implies a fairly narrow range of sizes.  No comets 
have shown tail features, and none have been observed closer 
than 3 solar radii.

The SOHO spectrometer had observed two comets.  Lyman alpha 
emissions give an outgassing velocity of 640 km/sec, which 
corresponds to a 20 kg/sec mass loss.  A body 6.7-m in 
diameter would weigh 120,000 kg and evaporate in about 5 
hours.

Brian G. Marsden, (Harvard-Smithonian Center for 
Astrophysics) provided a synopsis of his talk on 
'Discoveries, astrometry, catalogues and awards'.

This month we are celebrating the fortieth anniversary of 
George Alcock's discovery of what were announced on the IAU 
Circulars at the time as "Comet Alcock (1959e)" and "Comet 
Alcock (1959f)".  Following the tradition, the year/letter 
designations supplied in order of discovery announcement 
were later changed to 1959 IV and 1959 VI, showing the order 
of passage of the year's comets through perihelion.  In 
terms of the new system introduced in 1994 the announcements 
would have involved the single appellations "Comet C/1959 Q1 
(Alcock)" and "Comet C/1959 Q2 (Alcock)", the 1 and 2 
indicating the order of announcement of discoveries in half-
month "Q" of the year, i.e., the second half of August.  
Although we intended no disrespect, some astronomers have 
been condemning the IAU Circulars for this "new" procedure 
of placing the name of the discoverer, rather than the 
designation, in parentheses.  As it happens, this procedure 
is not new at all--early IAU Circulars speak of "Comet 1922c 
(Baade)", for example--and since "Comet Alcock" is not by 
itself a unique form of address, it is surely more logical 
to state the unique designator for the comet first, backing 
it up with the additional information identifying the 
discoverer.  The parenthetical use of the discoverer's name 
was for many decades also standard use in the Astronomische 
Nachrichten, the principal international source for 
information about discoveries, astrometry and orbits of 
comets prior to the first IAU Circular.  The discoverer's 
name, and sometimes also the date of discovery, were 
specified in this way, even in cases when the year/letter 
designations were not used and the Roman numeral 
designations had not yet been supplied.  "Comet 1889 ... 
(Barnard 1888 Sept. 2)", already recognizing the year in 
which the object would pass perihelion, uniquely defined the 
comet that later became 1889 I, that was from the start 
defined in some publications as 1888e, and that we now know 
as C/1888 R1 (Barnard). 

Since two earlier speakers have provided admirable accounts 
of their astrometric activities, there is little I need add, 
except perhaps to point out that it was not always this way.  
Modern CCD astrometry has turned out to be a much more 
automatic, accurate, reliable, rapid and straightforward 
process that the older astrometric processes involving 
photography and micrometry.

Although I am happy to announce that the thirteenth edition 
of the Central Bureau for Astronomical Telegrams/Minor 
Planet Center "Catalogue of Cometary Orbits" has just now 
become available, I again want to stress that by far the 
best and most detailed such catalogue ever published is that 
by Galle of 1894, which has the sole disadvantage that it is 
just very much out of date!  One feature of the 1894 
catalogue is that it defined the 15 multiple-apparition 
comets as (H) = Halley, (E) = Encke, ..., (Wo) = Wolf, (Fi) 
= Finlay.  Actually, these periodic comets are the only 
named objects in the catalogue.  Since there are now 140 
such comets, it might have been preferable if Galle had 
instead given them consecutive numbers.  The 1994 
designation system has taken care of this by calling them 
1P, 2P, etc.  As many as 55 comets were discovered during 
the twelve months preceding the end of July 1999.  Although 
22 and 14 of these were discovered by the very automated 
LINEAR and SOHO projects, respectively, even the remaining 
activity was prodigious in comparison with a year as recent 
as 1971, which yielded only a single discovery.  Cataloguing 
new discoveries has been complicated by the fact that, more 
often than not, LINEAR does not recognize its discoveries as 
cometary.  The same is also true of other CCD discovery 
programs, which often involve exposures sufficient only to 
detect moving objects.  Cometary status is often established 
only by careful scrutiny of objects that have orbits 
suggesting cometary nature.  Although some of these objects, 
like P/1999 DN3 (Korlevic-Juric), had already received 
designations as minor planets, the beauty of the new system 
is that such designations can be retained and combined with 
genuine cometary designations in a transparent manner.  
Again to complicate matters, June 1999 saw for the first 
time the discovery of an object (two objects, in fact) 
having a retrograde orbit but no trace of cometary activity! 

While monetary prizes and other awards specifically for the 
discoveries of comets date back to the year 1831, there was 
no such international award between the 1950s and this past 
year.  The Edgar Wilson Award, made possible by a bequest 
from a businessman in Kentucky, has recently been instituted 
for cometary discoveries by amateur astronomers (or 
individuals acting in an amateur capacity) for whom those 
comets are named and who are using for the discoveries 
amateur, privately-owned equipment.  The amount available 
each year, roughly $20 000, is shared according to the 
number of comets with eligible discoveries during the year, 
which for this purpose is taken as beginning at 0 hours UT 
on June 11.  The first year of operation has just ended, and 
there were six eligible comets, including the aforementioned 
P/1999 DN3 (with the two Croatian CCD discoverers having an 
equal share), a CCD discovery in Arizona, a photographic 
discovery in Austria and three visual discoveries in 
Australia.

My notes show a few further asides, which Brian mentioned in 
passing.  The D/ designation for some periodic comets 
implies defunct or comets which JPL shouldn't send a mission 
to as they might not find it.  He would like to see the 
numeric sequence disappearing from the named periodic comets 
(eg S-L 1 to 9).  Orbital computations are now not quite 
good enough to fit all the available observations, even with 
the inclusion of non-gravitational forces, and an improved 
model is clearly needed.  July and August is the rainy 
season in New Mexico, so there are not many LINEAR 
observations at this time of year.  LINEAR doesn't follow 
objects from night to night, which gives the amateur the 
chance to do two night linkages.  By definition tailed 
asteroids are comets (eg 139P/Elst-Pizzarro).  The Edgar 
Wilson award begins on June 11th because his brother died on 
June 10th.  The original bequest included recoveries, however 
this was thought to be unfair for recoveries with well-known 
orbits, though accidental recoveries might count towards 
future awards.  

Responding to a question, Brian said that comets are not 
allocated a provisional designation until positions were 
available.  Several recent SOHO comets have yet to have 
their positions measured and so do not yet have 
designations, and one has positions but no derivable orbit, 
despite clearly existing.  Brian's talk continued into a 
panel discussion also including Doug Biesecker, Bill Liller 
and Alan Hale.  Kuiper belt objects are cometary objects.  
There might be some bright Kreutz group comets to come, but 
he wasn't sure about different sub-groups.  The IAU could 
decline to name a comet if this might cause aggravation.  
The first Solwind object had been named, and the team's 
intention had been to name each subsequent object with the 
next three team-member's names, however they were instead 
named after the instrument.  New spacecraft missions planned 
for the future include stereo solar imaging and all sky 
imaging down to 12th magnitude every 90 minutes.  The first 
named comet is 1760 A1 as this was the year the Messier 
first began deliberate comet hunting.

Guiseppe Canonaco commented that useful positional data had 
been found in the logbook of a Dutch ship, enabling an orbit 
to be computed for a comet for the first time.  Jon Shanklin 
noted that he had been forwarded recent meteorological 
logbook entries relating to comets Hyakutake and Hale-Bopp, 
which showed that mariners were generally unaware of the 
comets despite widespread information being available and 
that they only spotted them when they reached 2nd or 3rd 
magnitude.

The skies again cleared after dinner, giving another very 
transparent night (for Cambridge), with the Milky Way 
clearly visible from the University Observatory.  It was 
possible to observe comets Lynn and 10P/Tempel 2 and more 
fragments of 109P/Swift-Tuttle were seen.

Monday began with the final session, which was devoted to 
short presentations and posters.  Philippe Morel of the 
Societe Astronomique de France described the history of the 
comet section of the SAF.  L'Astronmie, the Journal of the 
SAF had published observations of comets since 1887.  The 
comet section was formed in 1970 and has held several camps.  
There are about 120 members and future projects include 
transcribing old observations from L'Astronomie.  The SAF 
web pages include a section on comets.  Stephane Garro went 
on to elaborate about the SAF comet database.  They had 
decided to use database software and set up a form input so 
that those not familiar with the ICQ codes could enter 
observations correctly.  The first observations were from 
1882, but there are few in the database prior to 1980.  
There were 713 observations between 1939 and 1959.  Many of 
the early observations are rough, lacking supporting data.  
Sometimes the date is imprecise, for example only quoting 
October 1901, others gave no instrument and often only the 
date and magnitude were quoted.

Gyula Szabo described his observations at Konkoly in 
northern Hungary.  The 0.60-m Schmidt is now equipped with a 
CCD camera which has a 29'x18' field of view, compared to 
the original plates which gave a 5�x5� field, however the 
CCD reaches 22 magnitude compared to 19 magnitude on film.  
He showed images of 1998 K5, which revealed a bright tail, 
but little coma.  Several comets showed features in the 
coma.  A short period light curve of P/1998 U3 over 2 hours 
showed variation in the nuclear brightness.  They had 
carried out surface photometry using varying apertures, 
calculating the magnitude in various rings.  Theoretically 
(d ln B)/(d ln P) = -1 where P is the radius of the annulus 
and B its width.  Some LINEAR comets, eg 1998 K5, show much 
greater slopes than this.  Solar activity, diffusivity in 
the coma or activity in the comet may explain the variation.  
Some of the data may show a trend, with minimum values 
occurring some 20 days after perihelion.

Bill Liller had followed comet Hale-Bopp with his 0.20-m 
f1.5 Schmidt with an ST5 CCD at the Newtonian focus on 338 
nights.  This gave a 27'x36' field at a scale of 7" per 
pixel.  He could get a photometric accuracy of �0.04 
magnitude using a broadband V filter (effectively minus IR).  
Looking at the inner coma only, there was a 20�5 day 
periodicity when the comet was inbound.  After perihelion 
there were ongoing recurrent outbursts about 100 days apart, 
which showed an outflow of 40 - 55 ms-1.  

After the tea break Bill Liller presented Jonathan Shanklin 
with a bottle of Chilean wine and thanked him for making all 
the local arrangements for what had been a very successful 
meeting.  Bernd Brinkmann gave a short talk on his CCD 
observations with an SX camera on a C8 and with the Askania 
0.34/0.50-m Schmidt camera and ST6 camera, which also has 
several smaller telescopes which are under used.  He 
processes the images, which are mostly 60-second exposures, 
with bias, dark and flat field frames and uses co-added 
frames for fainter objects.  He showed high quality images 
of several recent comets, which had been used for 
astrometry.  He concluded with some spectacular slides of 
Hale-Bopp.

The final speaker was Simona Nikolova who spoke about the 
endurance lifetime of meter sized cometary fragments.  Meter 
sized fragments were common in meteor streams [though the 
audience was a little sceptical that photographs had showed 
such objects prior to atmospheric entry] and fragmentation 
in comets was common.  She had developed a sublimation 
model, in collaboration with Martin Beech, using the 
interaction of solar radiation with water ice and several 
variable parameters.  She concluded that 2P/Encke looses 
0.65-m per revolution and a 10-meter sized fragment would 
last around 50 years; 55P/Tempel-Tuttle looses 0.18-m and a 
fragment would last 1900 years.

During the meeting several posters were on display, though 
I'm afraid I didn't have time to make detailed notes.  The 
BAA Comet Section and TA had light curves of recent comets 
on display, a selection of superb comet drawings by George 
Alcock and the discovery observations of comet 1980 Y2 by 
Roy Panther.  Comets Hyakutake and Hale-Bopp featured 
prominently in several posters.  Nicolas Biver presented 
work on the estimation of the rotation period of Hale-Bopp 
using visual drawings.  Bill Liller had illustrations from 
his talk on Hale-Bopp and the Belgian VVS showed many 
photographs.  Andreas Kammerer displayed a comprehensive 
analysis of observations of the two comets and this will 
also be displayed at the Meteor Section meeting at the end 
of October.  Simona Nikolova showed a synopsis of her talk 
on cometary fragment lifetimes.

After lunch we boarded an air-conditioned coach for the trip 
to Avebury and Stonehenge.  It is quite a long journey to 
Avebury and I kept everyone entertained with descriptions of 
the passing scenery and was persuaded to recount some tales 
from my other hobbies, which include church bell-ringing, 
ice hockey, natural history and cricket.  Although there was 
rain en route, it had stopped by the time we reached Avebury 
and there was time to look round the large complex and 
discover its history in the local museum.  After a light tea 
we continued on to Stonehenge, where we waited until the 
public had left before being ushered into the stone circle.  
We had an hour to ourselves and the lighting conditions 
provided a spectacular backdrop to the ancient monument, 
which is Britain's earliest astronomical observatory.  The 
trip back was much quicker than the outward journey and we 
arrived back before midnight.

Final goodbyes were said on Tuesday morning and the 
remaining participants departed from New Hall for further 
touring round the UK and their journeys home.  During the 
three days of the Workshop 65 astronomers and friends 
participated in what was a very rewarding meeting.  My 
thanks to all those that contributed to making it such a 
success and I look forward to the next one in a few years 
time.

Jonathan Shanklin