Target Information and Using the Position Editor

To use the position editor :

Move the yellow highlight to target list and double click, enter a coordinate for your source. To see the display click on plot at the bottom left. Alternatively you can start the display by selecting the display tool icon at the top right of the program display tool bar. The Position Editor, a graphical display tool for visualising the observation will open at first with an empty (black) display window, with the centre of the field (base position) marked by a yellow "Earth" symbol. The (RA, dec) co-ordinates of the field centre are shown and the current mouse position within the main window will update.

A view of the field can be generated by connecting to a digital sky survey server (provided the machine you are using is connected to the Internet at the time). Download an image from one of the servers (via the Image menu) and repeat for the guide star catalogue (via the Catalog menu). On-line catalogues local to UKIRT can be added here.  In Europe the ESO catalogues are usually fastest, in Hawaii connecting to UKIRT or CADC.

The upper-right right window displays a region of sky 15 arcmin on a side, centred on the base co-ordinates. The yellow box within it indicates the region displayed in the main window. Click and drag anywhere within the yellow box to pan. The lower-right box shows a magnified view centred on the current mouse position. The main and magnified windows can both be scaled using the magnification drop-down list (or the zoom, Z or z, buttons, or by typing a magnification factor in the box). Setting the magnification of the main window at 0.6 allows virtually the full field to be displayed.

The view buttons along the top of the main window allow different aspects of the configuration information to be displayed. For example, selecting "Guide" and "xhead range" shows which star will be used for guiding and whether the xhead can reach it. Selecting "Catalog" shows the stars identified in the Guide Star Catalogue as potentially usable guide stars. Try this now.

Here is an example of the position editor showing target, guide stars, the instrument fov, the area covered by the dichroic etc.

To change a previously selected guide star if it is unsuitable (it's a binary, say) : the buttons to the left of the main window allow selection, deletion and movement of several items. To select a different guide star click on GUIDE; note the "browse" button is de-selected and the cursor changed to a crosshair. Now select one of the other suggested guide stars (one with a pink box around it) by clicking near it in the image. Provided the cursor is sufficientlyclose, within the pink box, the software will "snap" to the nearest catalogued object and the relevant entry in the catalog text box will be highlighted blue.

If you look back at the Telescope Targets window you will see that the specified guide star has changed. If the Position Editor gets in the way of other component displays you can iconify it by clicking in the [x] box on its top line.

Note that selection of guide stars is not restricted to those in the catalogue. In this case, the ID in the Telescope Targets list is left blank (as there can be no translation of the position into a catalogue name). the tool does not centroid on stars without a catalogue position, so if you do this it is as well the zoom the image first

Use the "drag" tool to move an object around. For example, click and hold on a guide star box or the base position to move it around. Note how its position in the Telescope Targets list is updated.

Use the "erase" tool to remove an object. The cursor changes to an "I" and you can use it to 'wipe out' the unwanted object.

What the "view" buttons at the top show :

Base  - displays the telescope base position  i.e. where the telescope will slew to and  where offsets will start from .

Catalogue - displays the positions of sources in the most recently fetched catalogue

Xhead  - displays the range of motion of the UKIRT crosshead, centred on the base position. The area between the two circles is where there is some vignetting.

Guide  - shows the location of the specified guide star

Science Area  - the field of view of the instrument.

Acq Cam - the field of view of the  acquisition camera

Dichroic - the area of the dichroic.  This rotates according to which port the instrument is mounted on.  (Currently the implementation of this is hard-wired, e.g. the code assumes that CGS4 is always on the south port, but the intention is for it to be controlled through the instrument's configuration file). The thick green areas indicate the edge of the glass and its supports (where stars cannot be found/used) and the thin lines delimit the region of the dichroic coating.

Note that a button to display the region vignetted by the IRPOL  mount will be added when we have a method of drawing the complicated shape

Under tools (on the left)  the GUIDE button allows the selection of a guide star by clicking on the image.   The other tools function

Under tools (on the left)  the GUIDE button allows the selection of a guide star by clicking on the image.   The other tools function as they do on the Gemini version of the position editor.