User manual

pixels for the peak below. This method is useful for example to make a quick

approximation for the width at half maximum of a star.

On top of this, for an image in real colours (see 8.2 – supported data types), the levels

for the three components Red/Green/Blue will be shown simultaneously.

Depth cut associated with the “Tag” tool

The location and selection of a tag (with the “Tag" tool) in an image cube will generate

also a cutting plot. However, this time it is along the depth of the cube. In the plot

thereby obtained, the vertical red line corresponds to the location of the current image in

the cube (in Aladin, a cube is seen as a sequence of images). The value mentioned at the

bottom of this mark gives the physical scale corresponding to the current image in the

cube (e.g. the speed). As for the distance tool, moving the tag with the mouse leads to the

automatic scaling of the plot. Furthermore, going over the plot with the mouse pointer

gives the value of the corresponding pixel (coordinates in the plot). A horizontal click

and drag will move the red line out of the current image and hence will change the image

in the current view.

Photometry measurements associated with “Tag ” and "Draw"

If "Tag” and "Draw" tools are used for drawing an area (click-and-drag with the "Tag”

defining a circle, closed poly-line with "draw" tool) throws the computation of 5

statistical measurements for the embedded pixels: the sum, the average, the median, the

sigma and the surface. These values are displayed directly on the view when the object is

selected. Zooming on this area will highlight the concerned pixels with small squares.