Image Display

To start the data processing, press in the main NICMOSlook window. A separate small window will appear with directory names and the files in each of the directories. See Figure 6.2. Select the correct directory and the image file which you want to load into NICMOSlook. For example, you can click on subdirectories , a file ov10_dir.fits/TT>, then click . This will load the FITS format image ov10_dir.fitsthe IDL image display window.

In order to produce a quick spectrum extraction of a grism spectrum, you need to load both a grism spectrum and the corresponding direct image into NICMOSlook. This is because the direct image provides the information about the locations of your objects on the NICMOS detector, and NICMOSlook needs to know the precise positions of your objects before starting tracing and extracting the corresponding grism spectra.

 

Figure 6.1:   The NICMOSlook main window when you first start up nicmoslook.

 

Figure 6.2:   The window configuration when you start loading images to NICMOSlook.

You can load your direct image and grism spectrum in any order you want. NICMOSlook recognizes your image file from its FITS header. If it is a direct image, NICMOSlook puts it in the direct image buffer; if it is a grism spectrum, NICMOSlook puts it in the spectrum buffer. It should be pointed out that each of these buffers can hold only one image file at a time. If you do any processing to the image, it overwrites the original image in that buffer. If you need the original image, you have to reload the image from the disk again. If you want to save what you have done, you have to press in the main NICMOSlook window.

After you have loaded both the direct image and the grism spectrum, you can click the exclusive menu button labelled Display (on the main NICMOSlook window) to choose which image you wish to display in the main IDL image window. Select to display the grism image, or to display the direct image.

If you wish to examine your image in detail, put the cursor at the position you want in the big IDL image display window, then click the left mouse button. A section of your image centered around the cursor position will appear in the small image display window in the main NICMOSlook window. You can then control the image expansion from this small window.

You can also examine your file header by pressing in the main NICMOSlook window. Again a separate window appears to show you the fits file header. To add any comments to the file header, you can press button, then a separate window will appear which says: Enter comment to be added to header. After you are done, press . You can check your newly added comment by using .

Using ,you can change some of the parameters used for the spectrum extraction. For example, if you click in the field , you can put in the appropriate gain factor, then press . This not only changes the values for the current session, but also saves the values in the calnicc.setup file. When you start a new session of NICMOSlook, these newly saved setup parameter values will be the default. Of course you could change the setup parameters in the file calnicc.setup in the $NICMOSLOOK_BASE/calib directory.

By pressing you can adjust the color table. Also in , you can choose one of the options for your image display.