Comet 73P/Schwassmann-Wachmann
Observations April 27

Dia 1 The course of the two fragments of Comet 73P/Schwassmann-Wachmann from April 26 to 16 May 2006.
Fig. 1 Fragment 73P/(C) imaged April 26 at 22h 43m UT. A 60 sec. exposure 160mm f/1.4 ISO 400. The bright star is iota Cor, Bor. magnitude 4.97. Stars to magnitude 15 are visible. Field: 2 arc degrees approx.
Fig. 2 Fragment 73P/(B) imaged April 26 at 22h 46m UT. A 60 sec. exposure 160mm f/1.4 ISO 400. The bright star is theta Cor, Bor. magnitude 4.16. Stars to magnitude 15 are visible. Field: 2 arc degrees approx.
Fig. 3 Corona Borealis imaged April 26 at 23h 16m UT. A 30 sec. exposure 75mm f/1.4 ISO 400. Refer to Dia. 1 for fragment locations. Field: 12 arc degrees approx.
Fig. 4 Corona Borealis imaged April 27 at 23h 17m UT. A 40 sec. exposure 75mm f/1.4 ISO 400. See text for fragment locations. Note the distortion on bright stars due to over exposure with this large aperture.

In contrast to the previous night that of April 27/28 proved to be fine and still with excellent transparency.

Fig 4 shows an image made with almost exactly the same exposure credentials as that of the previous night (Fig. 3). The two fragments are clearly seen a little above middle left [73P(C)] and top right of middle [73P(B)]. Moreover, both could readily be seen as diffuse nebulosities in 30x60 binoculars.

The movement of the two comets in the 24 hour interval was 86 arc minutes in position angle 60 degrees for 73P(B), and for 73P(C) 108 minutes in 72 degrees P.A.

JV 28/04/06

Comet 73P/Schwassmann-Wachmann

The two fragments of this comet (see recent archives) continue to show changes in form and brightness.

The fragment I initially denoted 'A' we shall now refer to by the generally recognized designation 73P/(C). This remains the brighter of the two.

Bad weather has hampered observation for the past week. Some short, clear spells on the night of 26/27 April gave reasonable conditions.

However, it was by no means easy to see either comet in anything less than 10x40 binoculars.

In 20x80s, 73P/(C) was seen to have a short tail but 73P/(B) was still more difficult, though generally more organized in structure than when previously seen.

The two images confirm the above observations (Figs. 1 & 2).

At the time of these observations the two fragments sat close to the cusps of the Northern Crown (Corona Borealis).

This was captured with a short exposure 75mm lens (Fig. 3) but neither fragment is easy since some light cloud intervened.

Dia 1 shows the course of the two fragments up to May 16.

The comets are expected to be at their brightest in mid-May by which time twilight will hamper observations from high northern latitudes.

JV 27/04/06