Zlender Images of Comet Hale-Bopp

Observer: Udo Zlender
Location: Bonn, Germany
Date: March 22, 1997 04:26 UT

These three ccd-images of comet Hale-Bopp were made at the prime focus of a Celestron C11 at 4:26 UT. Camera was OES LcCCD14 in 2x2 binning mode, exp. time was 3 seconds, no filters were used. The pictures are a combination of 9 images which were dark subtracted, flat fielded, log scaled, registered and median combined. To enhance details in the nuclear region the second image was further processed by an unsharp mask. As this technique also degrades the signal to noise ratio, outer layers of the coma become visible here. This a rare example where more noise brings out more information. The third emphasises details by false color.

See here for good explanation of the structure that you see in the images above.

Or see the discussion about structures in the coma from

Comet Hale-Bopp Update (Richard West - March 17, 1997) ...

Bill Matthews writes (March 12): I am an amateur astronomer, located in the central USA. I have been observing this comet for about 18 months. Observing the shells on March at 11.44 UT, in a 25-cm reflector at 110x, I was struck by the impression that I was viewing not three distinct shells, but a spiral (seen edge on). As if I was looking at part of an apple peel(peeled in spiral) held up and looked at from the side. I have not seen any discussion of such a hypothesis of the shell formation. Could it be possible, that the jet is at a latitude below the solar, or rotational axis, and ejecting material in a circle, that forms a spiral as it moves away from the coma? This would seem to explain the differing geometric centers (I think).

R. West answered: The described phenomenon is well documented in various images, e.g. from Observatoire de Haute Provence (message from Luc Arnold of March 12, who likens it with a spiral galaxy!).

23K 60K 67K

45K 47K

In the upper sequence I try to get some deeper insight into the dense nuclear surroundings. Starting with image 1, which is dark processed, flat fielded and presented in false color, a next image is obtained by the Larson-Sekanina algorithm (12 deg) showing complex radial details. The third image uses a negative grey scale of the same data. The last two pictures were obtained by superimposing image number 1 by a grey scaled version of number 2. Both have different false color palettes.

Back to Home Page