Comet C/2002 T7 (LINEAR)

M. L. Sitko, University of Cincinnati; R. W. Russell and D. L. Kim, Aerospace Corporation; and S. M. Brafford, University of Dayton, report 3-13-micron spectrophotometry of comet C/2002 T7, obtained on May 31.1 UT with the 1.5-m University of Minnesota telescope (+ Aerospace Broadband Array Spectrograph System; 8".5 aperture; 49" chop throw; integration times 10 min on the comet and 20 min on the reference star, beta Gem) at Mt. Lemmon: "A virtually featureless comet continuum was seen to rise from 3.5 to 13 microns, with only a very weak possible silicate emission band superimposed. A blackbody with a temperature of about 300 +/- 10 K was fit to the underlying continuum flux at 5, 8.4, and 12 microns. This grain temperature is about 9 +/- 4 percent higher than that of an equilibrium blackbody at the heliocentric distance of the comet. The silicate-feature-to-continuum ratio, based on the underlying continuum fit, was about 1.03 +/- 0.02. With our aperture, the comet has the following narrowband (about 0.25 micron) magnitudes and combined random errors (due to calibration star and comet, as well as variations due to the presence of real spectral structure): [3.7 microns] = 7.63 +0.44/-0.31, [4.7 microns] = 5.58 +/- 0.09, [5 microns] = 4.79 +0.49/-0.33, [8 microns] = 1.43 +/- 0.16, [10.5 microns] = 0.06 +/- 0.32, and [12 microns] = -0.39 +/- 0.02 (the stated errors are standard deviations of the mean)."