Spectrum of asteroid 2004 BL86

[David Boyd]

On January 26, this NEO passed about 3.1 lunar distances from the Earth. I recorded its spectrum with a C-11 + LISA spectrometer from 21.45 to 22.05 UT before clouds stopped observation. The asteroid was moving at 2.5"/sec and the autoguider was unable to track it so I had to continually relocate it manually onto the spectrometer slit. As the effective width of the slit was 2.2", light from the asteroid was probably only entering the spectrometer about 25% of the time. The SNR of the resulting spectrum was only ~20. The spectrum was wavelength calibrated and corrected for instrument response then deconvolved with the solar spectrum to remove the prominent H, Mg and Na absorption lines originating in the Sun. The telluric bands remain.

The spectrum appears to be consistent with that of a V-type asteroid made of basalt, as reported by the NASA Infrared Telescope Facility on Mauna Kea which also recorded a spectrum of the object. 2004 BL86 was probably created as the result of an ancient impact on the large main-belt asteroid (4) Vesta.

David