Comet Brorsen-Metcalf in the 3.5 Micron Region

We observed comet Brorsen-Metcalf on UT August 21-24 1989, using the CRSP spectrometer and the 1.3m telescope at Kitt Peak National Observatory. The cometary continuum was detected on all nights. The data are very noisy, due to the short observation window and the untried nature of the instrument. Low resolution (0.0227 micron) spectra show the 3.4 micron C-H stretch feature having a contrast of at most a factor of two to the neighboring continuum. High resolution (0.00331 micron) spectra between 3.4 and 3.6 microns some 1 sigma features that might be attributed to the nu5 band of formaldehyde (H2CO). Similar spectra of the region between 3.2 and 3.4 microns show one 3-sigma line at 3.34 microns, which is as yet unidentified. Although the cometary spectra were more spatially extended than the spectra of standard stars, no extension of the line emission beyond the continuum was observed.