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C/1996 B2 (Hyakutake)

Date:28.3.1996 Time:2:00 UT Exposure:B:15m, V:9m, R:6m
Field of View:15o x 9o Receiver: 20482 CCD Filter:B, V, R
Instrument: f=100mm, 1/2.8 Observatory: Hoher List Observer:T. Credner, J. Schmoll

© Copyright by the observers

Astronomical Institutes of the University of Bonn

From Colors to Astrophysics:

The image is a three color composite consisting of Johnson R, V, and B exposures and represented in red, green, and blue respectively. This almost natural color image separates the three cometary components ions, dust and neutral gas.

Blue mainly shows the plasma-tail with several tail-rays. The blue color is due to the high abundance of CO+ ions, which show line emission at about 426nm. Yellow (a mixture of red and green) shows the dust-tail. The large and neutral dust particles scatter the sunlight, so that the color of the dust tail appears similar to the solar spectrum. The blue-green almost spherical shape around the nucleus is the neutral gas coma. It is dominated by resonance fluorescense of the CN and C2 molecules mainly at the wavelengths of 390nm and 516nm, respectively.

The Instrument:

The DWARF (Deep sensing Wide Angle Recording Facility).
For the purpose of widefield imaging of cometary tail structures, a nitrogen cooled CCD-Camera with 2048 x 2048 Pixels was used. It was developed and buildt by the CCD-Group of the Astronomische Institute Bonn (Klaus Reif: Vier Millionen Bildelemente, SuW 31, 300 [3/1992]). Sometimes used for the 1.23m-telescope at Calar Alto, now the imaging optics was a small f=100mm f/2.0 Zeiss Planar camera lens. With this optics and the 3 x 3 cm2 sized chip a large field of 17 x 17 degrees2 can be covered. See also the DWARF page.