The NIRIM (Near-Infrared Imager) GUI (graphical user interface) was designed to allow the user to easily offset the telescope using a predetermined pattern. See Figure 2 for a snapshot of the GUI. The GUI can be run in two operating modes. The first moves the telescope in a simple rectangular grid. The observer can choose the number of positions and the spacing between adjacent positions in the grid. The second is a custom mode that allows for patterns designed by the observer. In the custom mode, the program reads a text (ascii) file containing the offset pattern that the observer specifies. The program also includes a running logfile that keeps track of what commands the program is sending to the TCS computer through the routers. This logfile is a simple text (ascii) file which is written to a location specified by the observer and can therefore be modified, added to, or even destroyed by anyone with access to the observing computer.
Figure 2. Snapshot of the GUI window used for observing using dither patterns with NIRIM on WIYN.
To use the GUI in order to take a rectangular grid of exposures follow the steps below:
1. Input the name of the logfile (including full path, e.g. /data1/nirim/logfile.txt)
2. Enter the desired values into the Rectangular Grid Inputs portion of the GUI
3. Have the Observing Associate slew to the desired coordinates and confirm pointing
4. Click on the New Object button
5. Click the Forward button in the Grid portion of the GUI
6. Take an exposure
7. Repeat 5 and 6 as necessary.
To use the GUI in order to take a series of exposures on an extended object follow the steps outlined below:
1. Create an extended dither pattern input file
2. Input the name of the logfile (including full path, e.g. /data1/nirim/offsets.txt)
3. Load the desired dither pattern by setting the name of the Offset File and clicking on the Read File button.
4. Have the Observing Associate slew to the desired coordinates and confirm pointing
5. Click on the New Object button
6. Click the Forward button in the Extended Objects portion of the GUI
7. Take an exposure
To repeat a dither pattern on the same object click on the Home button at the bottom of the GUI and repeat steps starting with clicking the New Object button.
The Target Information or custom comments may be saved to the logfile at any point after the name of the logfile has been input.
At present, all offsets are assumed to be specified in arcseconds. Positive offsets to declination will move the telescope North and negative offsets South. Positive offsets to Right Ascension will move the telescope East and negative offsets West.
The grid mode of the GUI was included as a default and as a pattern that most observers would probably use when observing standard stars. This is a simple rectangular grid with the number of grid positions specified by the observer for each axis and the offsets between positions for both N-S and E-W offsets are observer inputs. Each position in the grid is moved to in a simple snake-like pattern.
The Extended dither pattern is for any other pattern that the observer wishes. This is useful if the observer wishes to have sky frames interspersed with data frames and if the interesting parts of the target are not easily accessible using a simple rectangular grid.