Astron. Astrophys. 360, L9-L12 (2000)

2. Observations

The Wide Field Camera (800x800 pixel² with a plate scale of /pixel) was used to image Frosty Leo through the wide-band filter F606W (=593.5 nm, =149.7 nm) without, and crossed with, the polarisation filter set POLQ. Since the image with no polariser has larger saturation in the bright central region, we have used a total intensity image computed from images at 3 polariser orientations [see Sahai et al. 1999a (SZBtL99)].

The mm-wave and lines of ¹²CO and ¹³CO were observed with the IRAM 30m radiotelescope (Pico de Veleta, Spain) during August and November 1998, using SIS receivers tuned in SSB mode, with typical system temperatures of 1000 K, at = 1.3 mm, and 500 K, at = 2.6 mm (in units of , see below). Weather conditions were good, with zenith opacities at 230 GHz in the range 0.3-0.8. Telescope pointing was verified frequently by observing continuum sources close to our target. The spatial resolution is about 12-13" at 1.3 mm and about 22" at 2.6 mm. The mm-wave spectra presented here are calibrated in units of the main beam Rayleigh-Jeans-equivalent antenna temperature, , using the chopper-wheel calibration method.

© European Southern Observatory (ESO) 2000

Online publication: August 17, 2000
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