• The maps are coadds of large data sets from September 1997 (above) and December 1997 (below).
• The contour intervals are
  • 1, 2, 3, 4, 5, 10, 25, 50 and 75% of peak at 850um and
  • 2, 4, 6, 8, 10, 25, 50 and 75% of peak at 450um.

Click here for a PS figure that includes CRL618.

This source appears unresolved both at 850 and 450 micron. The September 1997 data give FWHM of 14.7"/8.1" at 850/450 micron, compared to HPBWs derived from Uranus of 14.8"/8.3". (Note that the CRL618 data appear to give a sharper beam size than Uranus, almost certainly because it is difficult to make an accurate Gaussian fit to the convolved beam of a Gaussian + cylinder, which is not really Gaussian in shape). The December 1997 data of CRL618 give a FWHM of 14.7"/7.9" to be compared with HPBWs from early evening data of Uranus of 14.8"/8.1". Both data sets are large (10, 18 maps, respectively), and therefore there is no doubt that CRL618 is unresolved. However, CRL618 can still be associated with faint extended emission at a level about or below the error beam. By comparing integrated intensities over 60" and 90" apertures of CRL618 to what we would expect from Uranus, we find an excess of 0.2 - 0.3 Jy within a 30" radius at 850 micron. At 450 micron this is even more difficult to assess, because of larger variations in the error beam level from night to night, but it is estimated that the amount of faint extended emission to be about 0.8 - 3 Jy in the same area. No extended emission is seen outside a 30" radius, and the excess seen is almost certainly much more compact.

There is no evidence of variability in the 850um data taken between 1997.6 and 2001.3.