Note the expanded scale for the u-band transformation, which is a bit complicated. The transmission model of the Wide-Field Corrector and the camera window is derived from combining all the transmission and diffusion effects of the various glass and coatings. In a forthcoming paper, the table will be completed by the shell equatorial coordinates, surface brightness estimates, and the shell azimuthal widths. It was found that the shell systems with a radial range higher than around 6 had to be made of multiple generations of shells see Sect. They are marked by S n.

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The shell is clearly detected. The method is demonstrated in Fig.

The three sets are shown below. It is caused by a strong megcam that blocks any charge transfer from pixels further up on the same raw. Typical non-linearity is close to 1 percent but a few CCDs have a slightly higher non linearity: MegaCam filter set transmission and average CCD quantum efficiency.

The distance of the galaxy from Earth is between The full manufacturer scans of the current filters are available here. Small Dithering Pattern disk diameter 20”: This prediction was based on the shell radii tabulated by Prieur and Sikkema et al. The method is used in Figs.

MegaPrime/MegaCam Home Page

Each CCD image has now x pixels with the imaging area found at [ The resulting signal black curve oscillates around zero outside the area indicated by the vertical lines. Starting A, Megacam has a new set of broad and narrow band filters with a larger foot print than the old broad band filters, therefore allowing to observe with all 40 CCDs see below.


The old filter mean transmissions as measured at CFHT are shown in dashed lines for comparison. Regions of image quality analysis. The image is then further processed to extract the edges. Note the wide gri filter in the 3rd generation. CCD characteristics per amplifier The following characteristics were derived from transfer curves obtained with the LED internal calibration sources at the back of the MegaCam shutter.

In the first series, the images were created as a sum of the shell image from the simulation and of the image of the body of the galaxy modeled by a de Vaucouleurs sphere.

The shells were more visible in the HST image because of its higher angular resolution and the absence of seeing.

The outermost shells are created first and the innermost shells later when the progenitor loses enough energy. As a general note, notice that the upper half of the mosaic is flipped degrees in regard to the lower half. Table 1 Mosaic tile centers. Jungwiert 1 and L. To suppress the effects of noise, we smoothed the original image by the median filter before applying the erosion filter. QE is in black, dot-dashed. We looked for mebacam via a visual inspection of images processed in one of the following ways:.


The median noise over the mosaic all 72 amplifiers is 4. The resulting image is the difference between the original image and the model.

Here the similarity with minimum masking ends. The original red curve is a step-like transition between two constant values with added noise. On the basis of the modified Newtonian dynamics MONDit has recently been predicted that a new shell lies in this region.

The MegaPipe image stacking pipeline

The width of this area is determined by the width of the transition in the original signal and the chosen width of the filter. We used a circular neighborhood. All of them are seen as very diffuse in the HST image.

Then the erosion minimum filter is applied blue.