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.