[meteorite-list] Newfound Comet Set for Winter Display (Comet C/2004 Q2 Maccholz)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri Sep 17 12:36:05 2004
Message-ID: <200409171634.JAA29450_at_zagami.jpl.nasa.gov>

http://space.com/spacewatch/comet_winter_040917.html

Newfound Comet Set for Winter Display
By Joe Rao
space.com
September 17, 2004

Donald Machholz of Colfax, California, an optician who has been
interested in astronomy since age eight, discovered nine comet from 1978
through 1994. He has since spent 1,457 hours scanning the skies for
other comets, without any luck.

But his luck changed on the morning of Aug. 27, when he swept up his
tenth comet.

Machholz's latest discovery could become the third fourth this year to
excite backyard astronomers.

After a treat of three comets in the spring -- NEAT, LINEAR and
Bradfield -- the first indications suggest Machholz's discovery will
become easily visible in binoculars and small telescopes this winter and
possibly to the unaided eye.

Comets brightness is notoriously difficult to predict, however, and it
is too early to know whether this one will put on a memorable show.

The discovery

When Machholz first picked up the comet - officially designated c/2004
Q2 - it was a fuzzy 11th-magnitude object in the constellation Eridanus
and drifting slowly southeast in the direction of the constellation
Lepus. On this astronomer scale, larger numbers represent dimmer
objects. Under the darkest skies, the typical observer can spot with the
unaided eye objects of magnitude 6.5 and brighter.

Machholz spotted the comet through the 30X eyepiece of his 6-inch f/8
Criterion Dynascope Newtonian reflector; a vintage telescope that was a
mainstay among amateur astronomers during the 1960s and 70's. Machholz
had purchased his back in 1968. Several hours later, Australian
observers Gordon Garradd and Robert McNaught confirmed the discovery,
capturing the comet in photographs using telescopes from Siding Spring
Mountain.

These CCD ("Charged Coupled Devices") images also showed a short, faint
tail.

>From 38 observations over a four-day period, Brian Marsden at the Minor
Planet Center in Cambridge, Mass. calculated an orbit for the new Comet
Machholz. It is on its way toward the vicinity of the Earth and the Sun,
and during October and November, its projected path will appear to
describe a small loop taking it into the constellations Lepus, Columba
and Caelum. Since it will still be relatively far from both the Sun and
Earth, its apparent motion -- in relation to the stars from night to
night -- will be quite slow.

At the beginning of December it will return to Eridanus, at which point
the comet's motion across the sky will abruptly turn northward and
rapidly increase, making the comet well placed for Northern Hemisphere
observers by the last week of December.

How bright?

According to Marsden's calculations, Comet Machholz could become as
bright as fourth magnitude, and possibly hovering around at this
brightness for about a month beginning right after Christmas. During
this interval, the comet will move north of the celestial equator,
tracking from southern Taurus on up into the constellation Perseus.

Fourth magnitude means that the comet should at be at least dimly
visible to the naked eye in dark skies, though better seen in binoculars
or telescopes. Urban skywatchers would not be able to see it without
optical aids.

That kind of brightness would still make Machholz a very fine comet from
the viewpoint of an amateur astronomer, especially in early January,
when it will be approaching the Earth and will be well placed for
viewing -- high in a dark sky. Given current information, it doesn't
appear that this comet will become the kind of spectacle that Comet
Hale-Bopp was in grabbing the public's attention.

Hard to predict

And although the script is still being written for this comet's winter
performance, Machholz advised that comets are notoriously bad actors. As
an example, the first brightness estimates for Comet NEAT had it
possibly becoming as bright as first magnitude -- easily visible even
from cities. Ultimately it became only as bright as third magnitude at
best.

Comet Machholz could brighten up and give us a real surprise. Comets
have surprised on the bright side before. Yet few celestial events have
greater false-alarm potential than these interplanetary vagabonds.

The comet is predicted to come closest to Earth on the night of Jan.
5-6, 2005, when it will be just 32 million miles (51 million kilometers)
away. On the evening of Jan. 7, it will conveniently pass just a couple
of degrees to the west of the famous Pleiades star cluster.

Comet Machholz will reach perihelion -- its point closest to the Sun --
on Jan. 24, when it will be just under 112 million miles (179 million
kilometers) from that blazing furnace. The comet will be more-or-less
opposite the Sun all during this "flyby", and thus should be easily
visible in a dark sky from Earth.
Received on Fri 17 Sep 2004 12:34:28 PM PDT