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Astron. Astrophys. 339, 134-140 (1998)

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2. Observations

We obtained photometric imaging of HD 97300 on February 2nd, 1996 using the long wavelength array of ISOCAM. The morphology of the object has been studied by using multi-filter observing template (The ISOCAM Team 1996). We selected four narrow band filters: lw9 (14.0 - 16.0 µm), lw8 (10.7 - 12.0 µm), lw5 (6.5 - 7.0 µm) and lw4 (5.5 - 6.5 µm). For each filter we performed 4 [FORMULA] 4 micro-rasters with raster step size of [FORMULA]. We chose a pixel size of [FORMULA] and the small field mirror. The read-out time for each exposure was 2.1s. We took 75 stabilization frames in the first filter (lw9) and 30 stabilization frames in the other three. At each raster position 25 exposures have been taken. We use gain 1 for lw9 and 2 for lw8, lw5 and lw4.

Spectrophotometric images were taken on September 24th, 1997 with the circular variable filter (CVF). We used the [FORMULA] pixel scale, the small field mirror and performed a complete downward scan from 13.83 to 9.442 µm and from 9.535 to 5.807 µm. This gave us some overlap of the two CVF segments. At each CVF step position 20 read-outs were taken with 5.04 s read-out time at gain one (see The ISOCAM Team 1996 for more details).

The data were reduced within the CIA (v1.0) 1 environment. The basic data reduction steps are described in Siebenmorgen et al. (1997). The dark current was subtracted using the calibration dark exposure scaled by a factor which depends on the orbital position of the satellite and on the revolution number (Biviano et al., private communication). Cosmic ray hits were removed with a multi-median transform method (Starck et al. 1997a,b) and transients were corrected with the IAS model (cf. Abergel et al. 1996). Flat fielding was performed using the calibration library flats.

The narrow band images at each raster position were coadded and sky-projected to construct the final raster map, which has a pixel scale of [FORMULA]. For flux calibration we adopted the sensitivity given by Blommaert (1997).

After coadding the exposures in each CVF step we obtained CVF photometry using the spectral response function as given from in-orbit calibrations (Biviano et al. 1997)

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© European Southern Observatory (ESO) 1998

Online publication: September 30, 1998
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