Waiting for some more elaborate tools accessible from everywhere on the network, a simple tool is available for the CFH12K observers in a CFH12K observing session. It can be used to visualize the images, to measure the image quality, to determine the best focus from a focus exposure, to check the focus, and to set it. It can also be used to run the IRAF task imexam without opening an IRAF session (limited to commands not opening a graphics window).
It is designed for running with MEF (multi extension fits) files. You can also use it for non MEF files (see at the end of this page), but it's no as easy...
1. Launching the tool
- A display tool has to be running with the session.
- The tool itself has to be launched.
In a terminal window on Mahina, type the following
The support astronomer will check that no open session of a display
tool is running on Mahina at the beginning of a run.
2. Using the tool
- The default directory where the files are listed is /h/cfh12k/images . You can change it by typing the name of the needed directory in the corresponding text window (top left).
- You click the list image files (or list all directory) button to display or refresh the list of files which appears in the text window.
- To select the image file you want to use, you click twice on the image number (the number is then highlighted) with the left button of your mouse, and you click on the right button. The image number is then selected and displayed in the upper right corresponding text window.
- The program will recognize which format you se (mef or non mef...), and use directly the MEF file, or instead one of the chip files in the directory named as your image... The type of the image (mef on or mef off) will be displayed next to the image number.
- Select the last focus exposure
- Click on determine focus
- The chip 02 is automatically selected and displayed in the frame 1 of ximtool.
- The instructions are displayed in the lower text window. Hit the 'x' key when the cursor in on the top star of a focus sequence image, and again with the cursor on the bottom star of the same sequence. You can repeat the operation on more than one star if you want. When done, hit 'q', and the program will display the best focus.
- The value found goes in the focus text window (lower left). You can set the focus by pushing the set focus button. When the focus is set, done! will appear after the focus value in the focus text window.
- Select an image
- Select the chip you want to display. You have the option to display the whole mosaic if you have a MEF file, or a given chip.
- Push one of the four View buttons, according to the frame you want to use in ximtool. The image will be displayed in the requested frame.
- You can check the image quality of the image you already displayed.
- Push the check seeing button. The instructions are displayed in the lower text window. With the cursor on the star(s) you want to use for the image quality determination, hit the ',' key. When done, hit 'q', and the program will display the fwhm of each of the selected stars in pixels, and the mean (and rms if more than one star have been selected) in arc-seconds.
If you are familiar with IRAF, you can push the imexam button, and use the imexam commands from the display on the displayed image. You won't be able to ask for graphics, but you can use for example the 'a' command. The results are displayed in the lower text window. Don't forget to quit this mode through 'q'... You can also open your own IRAF session, which will share the running ximtool with checker.tcl .
Displaying the last binned 8x8 image
This binned image is automatically built by "12kcom", whatever the MEF status is...
Just click the button, and the mosaic will be displayed in frame 4 of ximtool.
- Checker.tcl is robust. You can get error messages, for example if the selected star in a focus determination is not suitable for a focus determination. Just push the ok button, and try again with another star.
- If you think you are lost in ximtool, or that the pipe between checker and ximtool has been corrupted, close both the programs and start them again. It is harmless and takes a few seconds...
Please send comments on this tool to Christian