Results from UVCS and LASCO observation of the sungrazing comet C/2000 C6

During 2000 February 9-10, the Large Angle Spectrometric Coronagraph and Ul traviolet Coronal Spectrometer (UVCS) instruments aboard the Solar and Heli ospheric Observatory observed comet C/2000 C6, a member of the Kreutz famil y of sungrazing comets. A tail nearly 0.5 Ro in length was detected in Ly a lpha emission. UVCS was able to observe the comet at four heights as it app roached the Sun. A jump in the Ly alpha brightness between 5.71 and 4.56 R. suggests that the nucleus fragmented, exposing more area to solar illumina tion and increasing the outgassing rate. We interpret the Ly alpha luminosi ty in terms of the outgassing rate and use this to estimate the diameter of the nucleus. The Ly alpha emission fades as H I is ionized, providing esti mates of the density in the coronal streamer encountered by the comet.