PLEASE NOTE:


*

CCNet DIGEST, 20 August 1998
----------------------------


(1) NEW SEARCH TOOLS ON WEBSITE MAKE CCNet MORE USER-FRIENDLY
    Benny J Peiser <b.j.peiser@livjm.ac.uk>

(2) I ENJOY THE MIX OF ITEMS
    Robert Burnham <rburnham@execpc.com>

(3) WHY NOT SPLIT CCNet INTO FOUR DIFFERENT LISTS?
    Mark Anderson <nospam@grelber.egh.csc.com>

(4) A CONVENIENT INDEX WOULD BE NICE
    Brian G. Marsden <bmarsden@cfa.harvard.edu>

(5) NEW SEARCH TOOLS ON CCNET WEBSITE
    Bob Kobres <bkobres@arches.uga.edu>

(6) METEOR BURST COMMUNICATIONS OLD HAT
    Duncan Steel <dis@a011.aone.net.au>

(7) THE NUCLEUS & INNER COMA OF COMET 46P/WIRTANEN
    P.L. Lamy et al., LAB ASTRON SPATIALE TRAVERSE SIPHON

(8) MID-ULTRVIOLET SPECTOSCOPY OF COMET 46P/WIRTANEN
    S.A. Stern et al., SW RESEARCH INSTITUTE

(9) SPECTOSCOPY OF COMET 46P/WIRTANEN
    U. Fink et al., UNIVERSITY OF ARIZONA

(10) ROSETTA TARGET COMET 46P/WIRTANEN
     R. Schulz et al., ESTEC, ESA SPACE SCI DEPT

(11) PHOTOMETRIC RESULTS FOR 46P/WIRTANEN
     T.L. Farnham & D.G. Schleicher, LOWELL OBSERVATORY

(12) WATER IONS, DUST AND CN IN COMET 46P/WIRTANEN
     K. Jockers et al., MAX PLANCK INST AERON

==============
(1) NEW SEARCH TOOLS ON WEBSITE MAKE CCNet MORE USER-FRIENDLY

From Benny J Peiser <b.j.peiser@livjm.ac.uk>

A couple of days ago, Iwan Williams posted a number of suggestions for
re-organising the CCNet format. So far, I have received a mixed
response by list members (see a selection of comments attached below).
The most important and most effective reaction came from Bob Kobres who
manages and up-dates the CCNet archive on a daily basis
(see http://abob.libs.uga.edu/bobk/cccmenu.html).

In response to Iwan's proposals, Bob has now installed new search tools
for the CCNet archive. Anyone in search of a particular abstract, news
item, author, or keyword (say: 1997 XF11) has now easy and quick access
to all CCNet Digests which have been posted since early 1997. Of all
proposals and ideas, Bob's new search facilities will make it much more
easy to access and use the electronic archive in this way.

List members, on the other hand, who wish to organise their own
archive (and thus prefer a more structured format of posted material),
may find Robert Burnham's advice useful:

"Most e-mail systems let you cut and paste text, either to rearrange
the material within the mailing text itself or at least to export it
into a document that can be read by any word processor. That is, it's
easy for most of us to collect and assemble the files that [Iwan] is
talking about using Word or Word Perfect or (in my case) Eudora's
text-file utility."

Obviously, the rather diverse postings, ranging from scientific
abstracts to news items, film reviews, individual comments to
football-related and cosmological commentaries, are a reflection of the
way I have been organising this electronic forum. The wide range of
scientific disciplines and topics which are covered on the CCNet (from
pure astronomy and geology to the impact of NEO-related research on
popular culture, religion & politics) are even more diverse. They
mirror my belief that we are currently in the midst of a prolonged
scientific revolution which has (and will have) major implications for
scientific thought and popular culture around the globe. As far as I am
concerned, it is the aim of the CCNet not just to critically observe
these developments. Instead, I would like us to be active participants
on our way to a planetary civilisation. Coming to grips with the new
awareness of our precarious place in space is one thing; findings an
adequate, effective and civilised response to this new world-view and
the challenges it incorporates, is another.

Yet most of all, I hope that this electronic network with is 350
list members from some 40 coutries will keep its openness and
thought-provoking features. This, I hope, should ensure that many list
members will feel encouraged to contribute to CCNet Digests and
CCNet Debates - and no-one will need to complain about a boring
forum.

Benny J Peiser

===========================
(2) I ENJOY THE MIX OF ITEMS

From Robert Burnham <rburnham@execpc.com>

Dear Benny,

I agree with Williams' comments and classification scheme and I suspect
my own practice would mirror his. But there's also the fact I enjoy
the mix of items that appear in the mailings.

In any case, I fully agree that whatever system you use, it has to be
easy to administer.  Most e-mail systems let you cut and paste text,
either to rearrange the material within the mailing text itself or at
least to export it into a document that can be read by any word
processor. That is, it's easy for most of us to collect and assemble
the files that he's talking about using Word or Word Perfect or (in my
case) Eudora's text-file utility.

I also appreciate the timeliness of the postings, and I would hope that
any further division of the postings into categories would not hold any
of them up (by, for example, collecting all the abstracts for a week or
three before posting them in one big bundle).

So -- bottom line -- the current system is fine, and the proposed
changes are OK.  But I'm concerned that they may impose more work on
your end which could turn the list moderating job into something too
onerous to continue. And that would be a real loss --

Best regards, and thanks for doing a great job!

Robert Burnham

======================
(3) WHY NOT SPLIT CCNet INTO FOUR DIFFERENT LISTS?

From Mark Anderson <nospam@grelber.egh.csc.com>

I agree that breaking things up wouldn't hurt. Although Iwan may want 
to read all four of his categories, perhaps others may not want to read
them all. I would like to suggest separate lists to which a reader may
individually subscribe may be more flexible.

I'd like to bring your attention to another list that does something
similar. The VSNet in Japan manages four subscription lists. Two of
the criteria that they seem to be using are email volume and urgency.

    http://www.kusastro.kyoto-u.ac.jp/vsnet/information.html

This may or may not be more work for you, at least initially during
setup. However, there are several mailing list manager programs freely
available, one of which you may already be using. After setup, it
should require no additional work.

mark anderson

================
(4) A CONVENIENT INDEX WOULD BE NICE

From Brian G. Marsden <bmarsden@cfa.harvard.edu>

Dear Benny,

Iwan Williams has made some interesting suggestions about reorganizing
the CCNet. But your point about not involving yourself in more work as
a result is the most important consideration. The same thing comes up
from time to time in connection with a possible reorganization of the
IAU Circulars, and our answer is precisely the same as yours: to do so
should not involve more work on our part. Personally, I like the way
you arrange things. Each issue has a nice variety of different
features. Abstracts of published papers do not necessarily warrant
greater "longevity" than "opinions" and movie reviews! If more 
organization is considered desirable, I would suggest that that be done
in the version that is the WWW, i.e., by some more sophisticated method
of indexing, rather than just lumping the week's issues into a single
file. But YOU don't have to do this: it could be done by some
imaginative and enterprising computer whiz. We do have indexing like
this for the IAU Circulars in our "Computer Service", but to make a
quick scan through the daily (or hourly) e-mail, just to see what is
going on, is a totally different operation. (I still read the daily
newspaper while I am eating breakfast and don't need it to be excessively
organized for that purpose. But yes, days, weeks, months, years later,
it would be nice if there were a convenient index that would allow me
to recover a specific item I vaguely remember appeared...

Regards
Brian

====================
(5) NEW SEARCH TOOLS ON CCNET WEBSITE

From Bob Kobres <bkobres@arches.uga.edu>

Hi Benny. I've modified the CCC menu page to aid people in the use of
the search tool. Give it a try; perhaps it will suffice to allow
locating desired topics.

Later.
bobk


http://abob.libs.uga.edu/bobk/cccmenu.html
(You may need to 'reload')

Tips for Searching
From:
http://abob.libs.uga.edu/bobk/ixtiphlp.htm

=====================
(6) METEOR BURST COMMUNICATIONS OLD HAT

From Duncan Steel <dis@a011.aone.net.au>

Regarding 'Meteor Trails Are Being Used As Cheap Alternative To
Satellite Systems', it is clear that New Scientist is not always
terribly 'new'.

MBC have been around in the military sphere for decades, but MBC
systems have also been employed for commercial purposes for a long
time. For example, see:

Sky & Telescope, September 1989, pp.245-246

for a description of a truck-tracking MBC system in the US, with a
(another?) Washington state company also being involved.

Duncan Steel

=====================
(7) THE NUCLEUS & INNER COMA OF COMET 46P/WIRTANEN

P.L. Lamy*), I. Toth, L. Jorda, H.A. Weaver, M.A'Hearn: The nucleus and
inner coma of comet 46P/Wirtanen. ASTRONOMY AND ASTROPHYSICS, 1998,
Vol.335, No.2, pp.L25-L29

*) LAB ASTRON SPATIALE TRAVERSE SIPHON, BP 8, F-13376 MARSEILLE
   12, FRANCE

We report the detection of the nucleus of comet 46P/Wirtanen from
analysis of images taken with the Planetary Camera (WFPC2) of the
Hubble Space Telescope (HST) on 28 August 1996. The high spatial
resolution (a WFPC2 pixel projects to 50 km at the distance of the
comet) allowed us to separate the signal of the nucleus from that of
the coma and to determine the Landolt V and R magnitudes of the
nucleus. Assuming a spherical body with a geometric albedo of 0.04 and
a phase coefficient of 0.04 mag/deg, we derived a radius of 0.60 +/-
0.02 km. The color of the nucleus is moderately red with a gradient of
10% per 1000 Angstrom at optical wavelengths. From the lightcurve data
we derived a rotational period of 6.0 +/- 0.3 hr and find that the
ratio of the semi-axes of the assumed ellipsoidal body must satisfy a/b
greater than or equal to 1.2. From an analysis of the dust coma, we
derived that A f rho is 23 cm and that the dust production rate is 4 kg
sec(-1). Copyright 1998, Institute for Scientific Information Inc.

====================
(8) MID-ULTRVIOLET SPECTOSCOPY OF COMET 46P/WIRTANEN

S.A. Stern*), J.W. Parker, M.C. Festou, M.F.. A'Hearn, P.D. Feldman,
G. Schwehm, R. Schulz, J.L. Bertaux, D.C. Slater: HST mid-ultraviolet
spectroscopy of comet 46P/Wirtanen during its approach to perihelion in
1996-1997. ASTRONOMY AND ASTROPHYSICS, 1998, Vol.335, No.2, pp.L30-L36

*) SW RESEARCH INSTITUTE, 1050 WALNUT ST, SUITE 426, BOULDER,CO,80302

We have used the Hubble Space Telescope Faint Object Spectrograph to
observe the mid-UV spectrum of the ROSETTA mission target comet,
46P/Wirtanen, on three dates during the comet's apparition in 1996 and
early 1997. During this time the comet moved inward from a heliocentric
distance near 2.7 AU to 1.3 AU. The first measurement (22.7 July 1996)
detected only reflected solar continuum; based on these measurements,
we set an upper limit on the nuclear radius of 1.45 km. A second
measurement (25.9 Aug 1996) detected this reflected continuum, as well
as weak OH (0-0) emission; the third measurement (15.2 Jan 1997)
detected three OH bands at high signal-to-noise (the 0-0, the 1-0, and
the 1-1), along with emission features from the CS radical and the CO2+
ion; upper limits on their emission brightness and production rate of
C-2 was set. Our key findings are as follows: The data indicate that
Q(H2O) varies like R-4.9 +/- 0.25 inside 2.5 AU, and that the CS2/H2O
production ratio at 1.3 AU is close to 3 x 10(-4). We also found that
the 2600-3200 Angstrom mid-UV coma color slope is more neutral (similar
to 25%/1000 Angstrom) than typical comets (similar to 40-70%/1000
Angstrom, but is steeper than Wirtanen's own visible-wavelength color
slope. Wirtanen's CS2/H2O production ratio is near the low end of the
range observed to date. A f rho was estimated from the data as a
measure of dust production; we found A f rho (2950 Angstrom) values of
15, 18, and 15 cm, respectively, for the three FOS datasets, after
correction for the estimated flux contribution of the nucleus.
Interestingly, we found that production of dust, to which the UV is
sensitive, did not appear to vary by more than a factor of about two
with heliocentric distance over the 2.7 to 1.3 AU range, despite a
factor of 50 variation in the production of H2O. Wirtanen appears to be
a small, but relatively normal comet. However, Wirtanen's ratio of dust
(i.e., A f rho) to H2O production is smaller than in > 90% of the 85
comets in A'Hearn et al.'s (1995) large sample. Copyright 1998,
Institute for Scientific Information Inc.

===================
(9) SPECTOSCOPY OF COMET 46P/WIRTANEN

U. Fink, M.D. Hicks, R.A. Fevig, J. Collins: Spectroscopy of
46P/Wirtanen during its 1997 apparition. ASTRONOMY AND ASTROPHYSICS,
1998, Vol.335, No.2, pp.L37-L45

*) UNIVERSITY OF ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ, 85721

Comet 46P/Wirtanen was observed during five observing runs around its
perihelion passage from 1997 January 28 to June 02. The spectra
acquired extend from 5200 to 10000 Angstrom at spectral resolutions of
12 Angstrom and 18 Angstrom. A total of 16 spectral averages, each
comprising about 30 minutes of integration time, were obtained. The
production rate of H2O near perihelion averaged 2.7 x 10(28)
molecules/sec. The continuum strength Af rho was 129 cm while the
production rates respectively of the parents of C-2, CN and NH2 were
5.7, 3.2 and 5.6 x 10(25) molecules/sec. Our estimated error for all
these quantities is 20%. The production rate ratios relative to water
can be compared to our larger sample of comets (Fink & Hicks 1996) with
the following results: the C-2 and CN abundance ratios are slightly
below average but the NH2 ratio is definitely enhanced putting
P/Wirtanen among the top few comets in that category. Its Af rho/H2O
ratio is very close but slightly below the median of our comet sample.
Reduced to 1 AU P/Wirtanen ranks near the 40% level of our ordered list
of the H2O production rates of 20 comets. If the production rate of
water is combined with P/Wirtanen's estimated radius of 0.6 km, it
implies that virtually the whole surface area of the comet is active.
Our measured Af rho values combined with those obtained by photometry
yield a fairly tight heliocentric activity dependence of r(-3.8) with
no pre-post perihelion asymmetry. This agrees well with the general
heliocentric brightness dependence of Jupiter family comets. Taking all
this data together, P/Wirtanen appears to be a rather typical member
of the Jupiter family of comets. Copyright 1998, Institute for
Scientific Information Inc.

=================
(10) ROSETTA TARGET COMET 46P/WIRTANEN

R. Schulz*), C. Arpigny, J. Manfroid, J.A. Stuwe, G.P. Tozzi, K.
Rembor, G. Cremonese, S. Peschke: Spectral evolution of ROSETTA target
comet 46P/Wirtanen. ASTRONOMY AND ASTROPHYSICS, 1998, Vol.335, No.2,
pp.L46-L49

*) ESTEC, ESA SPACE SCI DEPT, POSTBUS 299, NL-2200 AC NOORDWIJK,
   NETHERLANDS

The compositional evolution of the coma of ROSETTA target comet
46P/Wirtanen was studied along its pre-perihelion orbit. At 2.34 AU the
first gaseous species, CN and C-3, were detected. C-2 and NH2 arose at
2.0 AU. The production rate curves of gas and dust show a steep
increase between 1.8 AU and 1.6 AU indicating a distinct change of the
outgassing conditions. The Ca production increases more rapidly with
decreasing solar distance than CN. As one consequence the C-2/CN ratio
strongly varies with heliocentric distance. Due to this variation a
classification of 46P/Wirtanen by the taxonomy introduced by A'Hearn et
al. (1995) distinguishing comets with typical abundance ratios from
carbon-chain depleted comets, is impossible. It would be classified as
depleted beyond about 1.6 AU whereas it would be designated typical at
smaller distances. The knowledge of the unexpected changes in the
activity curves of 46P/Wirtanen will help to optimize the ROSETTA
mission scenario in particular with regard to science operations.
Copyright 1998, Institute for Scientific Information Inc.

===================
(11) PHOTOMETRIC RESULTS FOR 46P/WIRTANEN

T.L. Farnham*), D.G. Schleicher: Narrowband photometric results for
comet 46P/Wirtanen. ASTRONOMY AND ASTROPHYSICS, 1998, Vol.335, No.2,
pp.L50-L55

*) LOWELL OBSERVATORY, 1400 W MARS HILL RD, FLAGSTAFF, AZ, 86001

Narrowband filter photometry was performed on the ROSETTA spacecraft
target, comet 46P/Wirtanen, at Lowell Observatory in 1991 and 1997.
Production rates were determined for OH, NH, CN, C-3, and C-2, along
with a measure of the dust production, A(theta) f rho. Relative
abundances were computed, and a comparison to other comets indicates
that this comet has a 'typical' composition and a very low dust-to-gas
ratio. The peak value of A(theta) f rho was 138 cm, while the OH
production rates, used in conjunction with a standard water production
model, yield a peak water production of similar to 1.0 x 10(28) mol
s(-1) at perihelion and suggest a minimum active surface area of
similar to 1.8 km(2) Finally, a comparison to comet Halley puts
Wirtanen into context with previous in situ comet measurements.
Copyright 1998, Institute for Scientific Information Inc.

==================
(12) WATER IONS, DUST AND CN IN COMET 46P/WIRTANEN

K. Jockers*), T. Credner, T. Bonev: Water ions, dust and CN in comet
46P/Wirtanen. ASTRONOMY AND ASTROPHYSICS, 1998, Vol.335, No.2,
pp.L56-L59

*) MAX PLANCK INST AERON, MAX PLANCK STR 2, D-37191 KATLENBURG
   DUHM, GERMANY

Comet 46P/Wirtanen was observed at Pik Terskol (Northern Caucasus) with
the 2m-Zeiss-Telescope of the International Centre for Astronomical and
Medico-Ecological Investigations, Kiev, on March 10 and 11, 1997. The
two-channel focal reducer of the MPAe was used. It allows observations
of comets simultaneously in a red and a blue filter passband. The comet
was observed with interference filters centered at 615 nm (H2O+) and
388 nm (CN) and with a wide-band red continuum filter. From the March
11 data we have derived an H2O+ image and an upper limit of the H2O+
production rate, the CN production rate and the ''A f rho'' value,
indicative of the dust production. The gas to dust ratio is about 2-3
times higher than in comet 1P/Halley. Copyright 1998, Institute for
Scientific Information Inc.


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CCCMENU CCC for 1998

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