Brightest Comet Ever Observed by SOHO (Forwarded)

ESA News
http://www.esa.int

16 Jan 2007

Brightest Comet Ever Observed by SOHO

Comet C/2006 P1 (McNaught) has become the brightest comet that has been
observed by the SOHO instruments since the start of routine operations in
early 1996. In its own right, McNaught is the brightest comet observed in
the last 40 years.

The exact peak apparent magnitude of the comet is not yet determined, but it
is currently estimated at -5.5 (see also the related link to the
International Comet Quarterly's (ICQ) list of brightest comets). This makes
it several magnitudes brighter than SOHO's previously observed brightest
comet: C/2002 V1 (NEAT) at about -0.5 magnitude.

Comet C/2006 P1 (McNaught) is a single-apparition comet on an hyperbolic
orbit, inclined at ~78 deg to the ecliptic. It was discovered by Rob
McNaught on 7 August 2006, when the comet was still at ~3 AU from the Sun,
or nearly 450 million km. Over the past 5 months comet McNaught has been
steadily closing in on the Sun, eventually passing it at 0.17 AU as it
reached perihelion on 12 January 2007.

Around perihelion, the comet's proximity to the Sun prevented it from being
observable from the ground. SOHO, however, was able to observe the comet
during this period. The sequence on the right shows comet C/2006 P1 as it
passes the field of view of the LASCO C3 instrument between 12 and 16
January 2007. LASCO (Large Angle and Spectrometric Coronagraph Experiment)
is a coronograph dedicated to observing the Sun's corona and uses an
occulting disk to block out direct sunlight, covering the central ~2 deg of
the nearly 16 deg wide view.

Also visible in the sequence is Mercury, which is moving slowly from right
to left, in the central left part of this view. As the LASCO detector is
built to study the much fainter solar corona, the comet appears saturated,
with the characteristic horizontal spokes extending from the comet's
nucleus.

Having passed its perihelion, comet C/2006 P1 (McNaught) is moving away
again from the Sun and will become increasingly better visible for ground
observers, particularly in the southern hemisphere as its orbit now takes it
to higher southern declinations. With the increasing distance to the Sun,
however, the comets brightness will decline with time.

For further information please contact: SciTech.editorial @ esa.int

IMAGES AND VIDEOS

* Comet C/2006 P1 (McNaught)
http://sci.esa.int/science-e/www/obj...objectid=40532

RELATED LINKS

* ICQ list of brightest comets
http://cfa-www.harvard.edu/icq/brightest.html
* More on Comet C/2006 P1 at SOHO SOC
http://soho.esac.esa.int/hotshots/2007_01_08/
* Bright Comet C/2002 V1 (NEAT)
http://sci.esa.int/science-e/www/obj...objectid=32521