Free Access
Volume 550, February 2013
Article Number A83
Number of page(s) 22
Section Interstellar and circumstellar matter
Published online 30 January 2013

Online material

Appendix A: Data reduction

The SOFI and SIRIUS data were reduced in the same manner as in Paper I. IRAF3 and the external XDIMSUM package was utilised. For SOFI, each frame was corrected for cross talk. Then bad pixels were masked and cosmic rays removed in all frames. Sky-subtraction was done using the two temporally closest frames. An object mask was created for each frame to mask the field stars. Running sky-subtraction with the object masks also created hole masks for each frame. The flat field and illumination correction files available at the ESO SOFI website were used on the SOFI sky-subtracted images. Evening sky flats were used to flat-field the SIRIUS data. The bad pixel mask, cosmic ray masks, and hole masks were combined to create rejection masks, which were used when co-adding the images. The coordinates were tied to the 2MASS Point Source Catalog (PSC).

For each colour the objects were extracted from the registered frames using Source Extractor v. 2.5.0 (SE, Bertin & Arnouts 1996). SE fits an aperture to each object, and this is used to extract the flux information. The SIRIUS photometry was calibrated using 2MASS PSC. The SE photometry of each colour and field was calibrated using 10–14 2MASS PSC stars per field by linearly scaling the frames to the PSC star level. The difference in the magnitudes of the observed field and the PSC was  <  ± 0.01m in all colours. SOFI-magnitude zero points were fixed using standard star observations. The SOFI magnitudes

extracted by SE were converted into the Persson system (1998) and from there to 2MASS magnitudes, as described by Ascenso et al. (2007). The SOFI magnitude scale was checked using stars in common with the 2MASS PSC.

Several experimentally found selection rules were used to discard galaxies and stars with poor photometric data from the catalogues produced by SE. SE photometry of SIRIUS images were filtered as follows. Objects were removed if they were closer than 80 pixels to the frame border, SE flagged their flux data, their elongation was more than 1.3 or if any colour had a photometric error calculated by SE of larger than 0.m15. SE also provides keyword CLASS, which assigns a number between 0.0 and 1.0 to describe how star-like the object is (1.0 for stars, 0.0 for galaxies) in each colour. This was utilised so that objects that had a summed-up star index less than 1.6 were discarded. The selection rules to exclude non-stellar objects and stars with doubtful photometry in the SOFI SE photometry were the objects closer than 30 pixels (0 for CG 2) of the edge of the registered frame, those SE flagged to have bad flux data, objects with an elongation larger than 1.3 (1.25 for CG 2), or a magnitude error over 0.m15 in any of the three bands. Objects whose summed-up star indices were less than 2.70 were left out. After a visual inspection, any objects with two unresolved stars in the extraction aperture were removed. The OFF field SE photometry was filtered the same way. In practice the formal error of the remaining objects is less than 0.m1 in all colours.

Appendix B: Additional figures

thumbnail Fig. B.1

Colour-coded SIRIUS image of CG 1. The J , H , and Ks bands are coded in blue, green, and red.

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thumbnail Fig. B.2

SOFI Js, H , and Ks band images of CG 1.

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thumbnail Fig. B.3

Colour-coded SIRIUS images of CG 2. The J , H , and Ks bands are coded in blue, green, and red. The object CG 2 IRS 1 is indicated with a box.

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thumbnail Fig. B.4

Sirius J , H , and Ks images of CG 2.

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thumbnail Fig. B.5

SOFI Js, H , and Ks band images of CG 2.

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thumbnail Fig. B.6

IRAS HIRES-processed images of CG 2 in 12, 25, 60, and 100 μm.

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thumbnail Fig. B.7

IRAS 25 μm HIRES-processed image of CG 2. Overplotted are the IRAS HIRES-processed 60 μm (black) and 100 μm (red) contours.

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thumbnail Fig. B.8

Age and mass in the SED fits. The filled grey circles show the distribution of models in the model grid, and the black filled circles shows the distribution of the best-fitting models i.e. with per each data point.

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thumbnail Fig. B.9

Spitzer IRAC 3.6, 4.5, 5.8, and 8.0 μm images of CG 1.

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thumbnail Fig. B.10

Spitzer MIPS 24 (left) and 70 μm (right) image of CG 1.

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thumbnail Fig. B.11

WISE 3.4, 4.6, 12, and 22 μm images of CG 1.

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thumbnail Fig. B.12

Observed structures in the CG 1 head over-plotted on the false-colour SIRIUS image. The thin, solid arcs starting from the YSO denote the possible outflow cones. The dashed semi-circle below the brightest objects NX Puppis marks the reflection nebula. The solid circle marks the location of the molecular hydrogen object MHO 1411. The ellipse in the top right-hand corner denotes the location of the patch of surface brightness, and the extended ridge (solid line) in the bottom right-hand corner marks the bright WISE_SW streamer filament seen in the Spitzer images.

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thumbnail Fig. B.13

IRAC falsecolour image of CG 1. The 3.6 μm is coded in blue, 4.5 μm in green, and 8.0 μm in red.

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thumbnail Fig. B.14

IRAS HIRES-processed images of CG 1. Top left: 12 μm. Top right: 25 μm. Bottom left: 60 μm. Bottom right: 100 μm.

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thumbnail Fig. B.15

Js image of CG 1. Left: the WISE 3.4 μm contours have been overplotted. The dashed lines indicate the strongest NX Pup diffraction spikes. Right: the WISE 22 μm contours have been overplotted. The contour levels are arbitrary.

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thumbnail Fig. B.16

WISE CG 2 in 3.4, 4.6, 12, and 22 μm images. The strong artefact in the tail is caused by a nearby bright star.

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© ESO, 2013

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