C. E. Woodward and M. S. Kelley, University of Minnesota; and P. M. Hinz, M. A. Kenworthy, and W. F. Hoffman, Steward Observatory, University of Arizona, report the discovery, in 10.55-micron narrow- band (FWHM = 0.97 micron) images obtained with the 6.5-m MMT telescope (+ MIRAC4-BLINC) and adaptive optics (AO) secondary on Nov. 7.08 UT, of a detached-coma feature located 3".4 from the nuclear condensation of comet C/2006 M4 (corresponding to 2700 km at a geocentric distance of 1.10 AU) in p.a. approximately 43 deg. Aperture photometry, derived from images obtained through thin cirrus, with the AO system locked on the diffuse comet nucleus in a 3".1 circular beam, yields 10.55-micron fluxes of 9.5 +/- 0.5 Jy for the nuclear condensation and 4.1 +/- 0.4 Jy for the detached-coma feature. The detached-coma feature is elongated along the same position angle, with a spatial extent of approximately 3" by 1".5. The nucleus was unresolved in the diffraction-limited images (FWHM = 0".4) and appears to be embedded in a diffuse coma (FWHM = 0".7). Further mid-infrared observations are encouraged.
International Astronomical Union Circular
- Pub Date:
- November 2006