BAA Circular

2003 December 13

Dust storm activity

A significant dust storm has broken out on Mars. Dr Donald Parker (USA) writes of his CCD images taken on December 13 (Ls = 315 degrees): ‘A significant dust storm has arisen to cover Chryse, Erythraeum M., Aurorae Sinus, Candor, with smaller clouds in northern Argyre and possibly Aram.’ On December 9–10, Chryse and Candor were bright, especially in Parker’s red-light images, but no definite obscurations were present. Typically, storms in this region break out in eastern Valles Marineris or in southwest Chryse (classical SW Xanthe).

Bad weather has plagued observational work in the UK throughout December to date, but it can stated that CCD images by Michael Foulkes on December 5 show the region to have been normal then, whilst images by Damian Peach on December 9 show the longitude of Hellas to be normal too. Visual work by Gianluigi Adamoli (Italy) on December 3 provides further confirmation, as do drawings by Gerard Teichert (France) on December 7–9. (This shows the value of routine work, which far too many observers have already abandoned!)

The seasonally latest planet-encircling dust storm known began at Ls = 311 in 1924 December, suggesting that the present event will not exceed large regional status. The December 13 images resemble those taken during similar events in 1990 October and November.

Mars is well-placed for northern temperate observers, although good seeing will be needed to identify features upon the small disk. From the UK, only the eastern end of the dust-affected region can be seen at the morning terminator with the planet well past the meridian, but it will be better placed for viewing later.

Richard McKim, Director

2003 December 13