Background
Because NIRC is sensitive to many infrared targets that the
visible guider for LWS cannot see, and because its field of
view is much wider than that of LWS, it can sometimes help to
use NIRC as an acquisition camera for acquiring LWS targets.
A NIRC script called
nirc2lws allows you to measure
the center of a target using NIRC and then center it up on
LWS.
Prerequisites
The following is assumed for this procedure:
- LWS has been started up
- The chopper is running
- NIRC has been started up
- NIRC has been set to the minimum exposure time by typing
tint 0 and coadd 1.
- Nodding has been enabled by typing nod 0 40.
Procedure
- Point telescope to target using any pointing origin.
- Set the filter appropriately:
- For bright targets (stars and such), use the
very narrow band filter by typing oii.
- For faint targets (nebulae and galaxies), use the K
filter by typing k.
- Run the LWS centering program by typing nirc2lws.
The script will halt the chopper, point the target to NIRC,
take a snapi image pair, and display it on FIGDISP.
- Move the cursor onto the FIGDISP window and adjust the
colormap by clicking and dragging RIGHT
MOUSE. You should see a target in white (not
black) near the center of the field. If too faint, interrupt
the script using CTRL-C, reset the integration time and/or
coadds using the tint and coadd commands
and run the nirc2lws script again.
- If target is visible, move cursor onto target and press
the keyboard key labeled Find to compute the
center of the target. A popup window will show you the X
and Y centers.
- The program will prompt you for the X center; enter the
value you just measured. It will then prompt for Y center;
enter the Y value you just measured.
- Program will point the target to the center of LWS,
restart the chopper, and beep to indicate completion.
Go to:
LWS Home Page -
Instruments Home Page -
Keck Home Page
Last modified: Fri Feb 18 17:21:28 HST 2000
