Joel W. Parker and S. Alan Stern (Southwest Research Institute) have
initiated a “Triton Watch” to study Neptuneís large moon over at least the
next two years. The effort will focus on detecting changes in the
brightness and color of the moonís surface using CCD observations.

Although professional astronomers will lead the Triton Watch, Parker is
encouraging qualified amateurs to contribute as well. The effort will
involve frequent observations taken by CCD cameras through a set of
standard (UBVR) filters. Once a variation in brightness or color has been
spotted, the Triton Watch staff will alert major observatories to make
follow-up observations.

In the 12 years since Voyager 2ís brief visit to Neptune, some curious
changes have occurred on both the planet and its big moon. During the late
1990s astronomers found that the temperature of Tritonís tenuous atmosphere
had climbed a couple of degrees to 40* Kelvin, probably because the
southern hemisphere is now enjoying its warmest summer in more than 350
years. This mild warming trend appears to be changing the character and
distribution of bright frosts on Tritonís surface, making it darker in
ultraviolet/blue light and brighter in red light. Its current color closely
matches a previous episode of “anomalous reddening” seen in 1977.

Parker notes that getting good measurements will be moderately challenging:
Triton gets no brighter than 13.5 in magnitude, and it never strays more
than about 17 arcseconds from Neptune. Even so, this should be well within
the capability of observers with 8-inch or larger telescopes and CCD
imagers — especially during the weeks surrounding Neptuneís opposition on
July 30th.

For more details, see the Triton Watch web site at