An ESO spectrum of Comet Hyakutake (March 28)
A low-dispersion spectrum of Comet Hyakutake was recorded from the European Southern Observatory during the night of March 27 - 28, 1996, at a time when the declination of this object was about +78 degrees.
The latitude of the ESO La Silla Observatory is -29.5 degrees and the northernmost sky position (theoretically) observable from that site is therefore at a declination of about +60 degrees!
So how was this observation made?
It is not usual that astronomical observations are made from the ESO Headquarters in Garching, just north of Munich, capital of Bavaria. But this spectrum represents such an exception.
It was obtained by Gerardo Avila (ESO Optical Instrumentation Group), Juan M. Alcala (Max-Planck-Institute for Extraterrestrial Physics), Carlos Guirao (ESO Data Management Division) and Jesus Rodriguez (ESO Electronics Group) with a home-made spectrograph, linked to an amateur telescope with a fibre optics cable. The exposure time was 20 minutes. The spectrum has been wavelength calibrated by means of a He-Ar standard lamp. Here are some details about the equipment:
Telescope: · diameter 10cm; F/10 Maksutov objective mounted in a Zeiss equatorial mount; Fibre optics: 0.2 mm core diameter (40 arcsec sky aperture) and 3 metres long.
Spectrograph: · Collimator Doublet with diameter 50mm F/6; · Grating: 600 grooves/mm blazed at 500 nm, 50x50 mm; · Camera optics: Photographic objective f=100mm and F/2.2.
CCD Camera: · Hale Research equipped with a Tektronix CCD 512x512, 27mm pixel; · TE cooling system; · 12 bits.
Hardware and Software: · Lap-top 486/33MHz, 16Mb RAM, 500Mb Hard disc; · Linux 1.2.13 with MS/DOS emulator; · Data reduction system: ESO - MIDAS release 95NOVpl2.0.
The spectrum [GIF,5k] shows the strongest lines usually seen in a comet at Hyakutake's current heliocentric distance (0.985 AU, or 147 million kilometres), in particular the strong C2 bands.
This photo may be reproduced, if credit is given to the European Southern Observatory and the observers.