The ICQ Comet Information Website
Primary and secondary information on comets and observing comets:
This is a key place to begin looking for
useful and accurate information regarding news, observations, orbital
data, designations and names, and good links regarding comets and related
topics [sponsored by the International Comet Quarterly (ICQ)].
(Quick aids: Site
map 1/Site map 2)
Special dated news items:
- Comet 17P/Holmes underwent a huge outburst of some 13-14 magnitudes
(the largest ever known for a comet in only a day or two)
around 2007 Oct. 24, attaining total visual mag 2.4 +/- 0.2 in the
last week of October. It is only slowly declining in brightness as
it moves slowly through the constellation Perseus, well placed for
northern-hemisphere observers into early 2008.
Additional
information is available here.
[11/10/07]
- NOTE: when comet is large in size (such as comet 17P/Holmes is in
Nov. 2007), normal binoculars cannot defocus enough to produce proper magnitude
estimates, leading to values that are too faint; special instruments
are needed for comets larger than about 10' or 15' in size (such instruments
can be binoculars with eyepieces detached, or 1x monoculars composed of
two binocular objective lenses, for example).
- The
Edgar Wilson Award
for comet discoveries in 2006-2007 has been
announced (see IAUC 8854),
with three recipients, for four different comets.
[Earlier Wilson Award
recipients.] [7/12/07]
- The
fourth International
Workshop on Cometary Astronomy (IWCA IV) was scheduled to be
held in the Osaka/Kobe area of Japan on the weekend of 2009 July 25-26,
after the July 22 total solar eclipse that will be visible from Asia,
but due to lack of international interest in travelling there, it has
been cancelled. We are currently investigating the possibility of
an IWCA around the same time in Shanghai, China (where the path of
totality will pass), and another one the following month in Rio de
Janeiro, Brazil (in conjunction with the IAU General Assembly there).
[4/23/08]
- In 2007 April, the CfA changed the first part of its URL from
cfa-www to cfa.www. In addition, on 2007 April 19, the Computation
Facility at the CfA deleted the unix subdirectory /ps, where all of
the ICQ/CBAT/MPC/NELPAG webpages were at one time located (and many
were still located at the time of the deletion). The files were
all moved to new subdirectories, and in the case of the ICQ webpages,
a /icq subdirectory was created so that there is now an /icq part to
most or all ICQ webpages. This creates great problems, because it
will take many hours (probably spread over many months, realistically,
given our other work-load issues) to fix all the broken links in
the ICQ webpages (and unfortunately, this goes for the other webpages
in our group, as well). If you get such a broken link, try to
manually delete out the /ps part of the URL in your web-browser
URL-address window and type in /icq instead (for ICQ pages, or
/iau for CBAT webpages).
Need help?
Try our search program.
- The only ground-based-observable comets currently known to be
brighter than total visual magnitude 12 are
C/2006
Q1 (near total visual mag 11.5),
C/2007
T1 (near total visual mag 10-10.5),
C/2008
C1 (near total visual mag 10-11),
8P
(near total visual mag 7.5),
17P
(near total visual mag 5, in outburst),
and 46P
(near total visual mag 9-9.5).
[3/10/08]
- After being visible in broad daylight for several days in the second week of
January 2007, comet
C/2006 P1
(McNaught) passed its perihelion and was visible to southern-hemisphere
observers (only) in the third and fourth weeks of January as a spectacular
evening object after sunset, low in the west. Brightness estimates
by many observers
show this to be
the brightest comet
observed in over forty years; see also the
nice
spacecraft images and
beautiful
southern-hemisphere photographs.
Among the very best photos of C/2006 P1 are those by
Rob McNaught and
Gordon Garradd.
- Comets in urgent
need of
photometric observation [new webpage added 10/10/05]
- We are gradually making various articles and data of past published issues
of the ICQ
available here on the
ICQ website.
- The ICQ got behind its publication schedule during 2007, but we
hope to be caught up by mid-2008. The April 2008 quarterly issue
of the ICQ is in preparation. The 2008 Comet Handbook is
nearing completion and should be printed in May. The 60-page Jan. 2008
quarterly issue of the ICQ was mailed to paying subscribers on
2008 May 8.
The 36-page October 2007 quarterly issue of the ICQ was mailed to
subscribers on 2008 Jan. 25 and 28.
The 28-page July 2007 quarterly issue of
the ICQ was mailed on 2007 Dec. 18 and 19.
The 52-page Apr. 2007 quarterly issue of the ICQ, which is a special
issue for comet C/2006 P1 (printed in color) and which also has a lengthy
review paper on forward scattering of light by cometary dust, was
mailed on 2007 Aug. 8.
The 118-page 2007 Comet Handbook was mailed on 2007 March 28.
[Other recent ICQ
mailing dates.]
- ALERT! We have introduced additional screening software to
block spam e-mail, due to its prolific increase; it is strongly recommended
that those sending e-mail to the ICQ or the CBAT remove ALL html-encoded
text, as we cannot read such text easily (we do not use web browsers for
reading e-mail) and such text may be deleted by our anti-spam software. (This
means: send plain ASCII text *only*, *not* plain ASCII text plus html-encoded
text in same message. The vast majority of ICQ contributors have no problem
sending ASCII-only e-mail with contributed observations, so HTML-encoding is
a natural place to attack SPAM e-mail since the vast majority of SPAM has
html-encoding.)
[11/14/03]. Due to excessive spam-e-mailing, our Computation Facility
took drastic measures on 1998 August 14 to block e-mail from many e-mail
extensions. Contributors of cometary observations to the ICQ, the CBAT,
and the MPC need to be aware of this: if you do not have a .edu,
.gov, or .org extension (chiefly, if your e-mail address
has a .com extension), your e-mail may not reach us
(and therefore
please read this)
[8/17/98].
- Special ICQ
observing project.
- There was a computer crash on 2004 June 24 involving the main ICQ
disk. While copies of most data are available on other computers,
there was a loss of some unpublished (pending) ICQ-formatted data
and of some unposted (pending) IAUC/comet-magnitudes-webpage-format
data.
- What is The International Comet
Quarterly?
- Currently-observable comets:
ephemerides,
elements, and links to magnitude estimates
- Recent comet magnitude estimates
- The
most recent observation of each recently observed comet, as
reported to the Minor Planet Center (astrometric data, about half of
which have magnitudes). Important note: this is compiled from our
astrometric archives; listed observations do not mean that they are real -- sometimes
bad observations get past the software checks -- and the magnitudes are often off by
several magnitudes. Further, the last observation does not mean that the specific comet
either does or does not need observation urgently. At any rate, it is suggested that --
for most comets -- observations be made of each comet by each observer once
or twice a week, 3-4 observations per night, if possible; more frequent observation
by a single observer usually is not warranted or even encouraged -- being better to
observe more objects in need of observation. And quality is always better than quantity!
- The
ICQ Comet Handbook, a special annual publication giving
orbital elements, ephemerides, predicted brightnesses, and (starting
with the 2007 edition) observability/elongation diagrams for comets.
- The 1997 edition of the ICQ Guide to Observing Comets is now
out of print, but we hope to have a revised edition
available soon. We have had a great
many requests for this popular item.
Additional information on comets (and related phenomena):
About This Service
Here are credits and a
user-feedback form.
These pages are light on inline images -- we are considerate of users
who may be accessing these pages over slow (modem) connections! They are
also intended to be text-browser friendly. We are
committed to keeping our pages accessible to as many browsers as possible
(a courtesy that we'd like
to see many other webmasters imitate!).
Further information is available via e-mail from
icq@cfa.harvard.edu
Index to the CBAT/MPC/ICQ pages.
New England
Light Pollution Advisory Group (NELPAG)
SAO
CfA
CBAT
MPC
