They took place in January and February Typical non-linearity is close to 1 percent but a few CCDs have a slightly higher non linearity: It can be so strong for some of them that the flat-fielding will sort of work but the noise in that area will be much higher. After adding the footprint of the primary focus and the four spider branches supporting it, the final collecting area of the primary mirror is 80, square centimeters each spider branch is 5 cm wide, over the area of the primary mirror, 3 are No processing — Most of the reported shells are visible in the original FITS images without further processing, although many of them with difficulty. Hence, the readout image is composed of four stripes of 9 CCDs each.

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We state only mgacam image processing method allowing a reliable detection with the minimal effort order of difficulty: The plot below Figure 4 shows the mean measured transmission curves of the 5 new SDSS-like filters solid lines metacam measured by their respective manufactures, Asahi for u, Materion for the others. These variations are caused by the deviations of the real galaxy profile from the model. Pence reported that the most prominent cloud labeled DP in Fig.

The shells that have the radii with the plus signs in Table 2 lie on the northeastern half of the galaxy and those with minus signs on the southwestern half.

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Nearby off-field bright stars: MegaCam is not a great instrument to observe in the z band as the CCDs sensitivity is low at those megaca and the sky background is very high resulting in very strong fringing. MegaCam Raw Data Description.

References Publications referenced by this paper. After our observation, the galaxy becomes even more exceptional.

O ct 2 00 7 MegaPipe : the MegaCam image stacking pipeline at the Canadian Astronomical Data Centre

There have been three generations of filters broadband filters for MegaCam. The largest shells form first, while the inner shells form later when the secondary loses enough orbital energy by dynamical friction. The red rectangle marks the region displayed in Figs. Mosaic raw data features 4. Detailed transmission data are available here.

Technical considerations to prepare MegaCam observations

The western end of the hook is located near a triangular object C1 in the figures with a filamentary structure typical for cirri.

The observer in direction A sees the shell as a msgacam structure. The zero points advertised on the MegaPrime pages come from photometric frames processed by Elixir.

The curve is shown on figure 5 and the data used to generate that plot are available here. The half-light radius was chosen to be two times the radius of the reference shell.

Deep imaging of the shell elliptical galaxy NGC with MegaCam | Astronomy & Astrophysics (A&A)

This feature is properly corrected on the science frames by subtracting a bias frame. The first pixels read from the camera are actually the bright ones. We used a circular neighborhood. A hook-like structure H in Figs. CCD characteristics per amplifier 2. On the basis of the modified Newtonian dynamics MONDit has recently been predicted that a new shell lies in this region.

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The most extreme values are 7. Gwyn, see this page.

This proves that the dust lies in the galaxy and not in the foreground. Distribution of optimally dithered exposures. The old filter mean transmissions as measured at CFHT are shown in dashed lines for comparison. There was a concern that the exposed golden pads in the middle of the mosaic the part where the CCD signal are connected from the substrate to the connectors would cause some problem.

This helped us to further confirm the existence of the shell, see Fig. This is the most commonly found blemish on MegaCam raw data. By clicking accept or continuing to use the site, you agree to the terms outlined in our Privacy PolicyTerms of Serviceand Dataset License.