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Position Editor Menu Bar

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The position editor menu bar is used to configure the image and overlay displays:

  • File - open, save and print images (see details below).
  • View - configure and examine the image properties (including cut levels, colour table and FITS header; see below); configure the offset and WFS displays (see details below).
  • Go - navigate the image history list
  • Graphics - annotate the image with text and graphics. These can be saved with the underlying image
  • Catalog - change internet proxy settings, pick an object, and access the catalog query tool. The overlays can be saved with the underlying image.

Further information about the highlighted functions see below.

Open, Save and Print Images

Any simple FITS image may be loaded into the position editor. If the image has multiple planes, a summary of the image extensions is reported and you can choose which extension to display.

The raw image can be saved to a FITS file or in one of several file formats (e.g. jpeg, tiff, bitmap) from the file save as menu. You can save any graphics (overlays, annotations) as an extension in the FITS file using the graphics save graphics with image menu. Likewise you can save catalogs in a FITS extension using the catalog overlays with image menu. This FITS file may be loaded into the position editor at a later time, the image displayed and extensions selected and displayed using the manipulation tools.

Alternatively, and more portably, you can save the overlays along with the image in jpeg or gif formats from the file save current view menu. This format is particularly useful if you have annotated the image e.g., as a finding chart.

The image with overlays can be printed, and previewed, directly from within the position editor or by printing an image saved to disk.

To close the position editor select file close or click on the X in the upper right corner.

Image Examination and Manipulation

You can interactively change the high and low cut levels either manually, by selecting the percentile range or the median clipped range from the view cut levels menu.

You can change the colour table, intensity transformation and mapping algorithm from and view colors menu.

The view fits extensions menu shows the various data structures contained in the FITS file. This may simply be the image plane or may include header and data extensions. If you have used the position editor to save an image with a catalog then select the appropriate FITS table extension name and click open. This opens the catalog navigator from which you can plot (or unplot) the catalogued objects.

The keywords, values and comments in the current FITS header are displayed with the view fits keywords menu.

Configure the Offset Display

The view base position offset display menu configures how the offset iterator sequence is displayed. You can toggle the tags (steps in the offset list) on/off, and display the science field of view at the selected, all or none of the offset positions.

Configure the OIWFS FOV Display

From the view OIWFS FOV display menu you can choose whether to display the on-instrument wavefront sensor vignetting region in outline or solid block of colour. If the OIWFS is not in the focal plane (e.g. NIRI) you can choose whether to include or exclude the partially vignetted region.

History List

The position editor maintains a history list of images displayed. You can navigate forwards or backwards through the list, jump to a particular image, or clear the history list from items in the Go menu.

Proxy Settings and Catalog Objects

If your computer is behind a firewall with a proxy server, then enter the server details in the Proxy Server dialog. This may be needed to access catalog and image servers on the internet.

The Pick Objects dialog is used for zooming in and selecting an individual object. The selected object will be added as a User target to the currently selected observation.

Pick object dialog

The Manual GS catalog menu option opens the Catalog Query Tool for querying guide star catalogs and manually selecting a star.

Gemini Observatory Participants