User manual

Giving the target

The target can be either the identifier of an astronomical object recognized by the

Sesame process (query in SIMBAD + NED + some large catalogues), either astronomical

coordinates in sexagesimal format in the J2000 referential.

Some examples:

NGC2045

Galactic centre

2 31 59 +89 15 54

12:59:48.70 +27:58:50.0

Giving a radius

The query radius corresponds to the radius of the cone search on the sky. This value can

be followed by a unit (“°”, “' ““"“ or “deg”, “arcmin”, “arcsec”). The default unit is the arc

minute. It is also possible to indicate a rectangular zone by using the following syntax: W

x H where W is the width of the rectangle in right ascension and H is the height of the

rectangle in declination. Both values can be followed by a unit. In the case where the

queried server only receive cone search (on the contrary to a rectangle), Aladin will

always choose a region large enough to cover the designated field (enclosing circle, on

the contrary to a enclosing rectangle).

Some examples

9.14’

20arcmin

10’ x 12’

1°

Automatic selection

In the current form, the target and radius are automatically written as a function of the

previously loaded data, in order to cover the same region on the sky. It is also possible to

select explicitly a region on the sky from a loaded image by using the “grab” button that

appears after the location selection field. Doing so, Aladin will ask you to select the

region by click/drag and drop in the view.

When switching from one form to the other via the tabs, the values indicated in the first

form will be kept in the second one.

5.2.3Data list and data tree