These spectra of the comet C/1996 B2 (Hyakutake) have been obtained in the morning of Feb 9th. The horizontal axis denotes wavelength and the vertical one is flux (in units of ergs/cm2/sec/A).

The upper spectrum is the tracing of a long 2 arc sec slit centered on the comet nucleus. The reflected Sun spectrum accounts for the vast majority of the flux as can be seen by checking the red tracing which is a scaled spectrum of a normal G0 type star (HD 128852). In addition moderate cometary emission lines of CN at 388 nm, and bands of C2 and C3 can be seen.

The lower spectrum is the tracing of 2 arc sec slit further in the forming tail. The fluxes have been multiplied by 10 to bring the emission lines to the intensities of the upper spectrum. It is clear however that the solar continuum is missing because no solar light is reflected here.

Authors: T. Zwitter, H. Mikuz (University of Ljubljana, Slovenia), U. Munari, M. Rejkuba (Asiago Observatory, Italy).