LWS
Acquiring LWS Targets with NIRC

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:

Procedure

  1. Point telescope to target using any pointing origin.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. Program will point the target to the center of LWS, restart the chopper, and beep to indicate completion.

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Last modified: Fri Feb 18 17:21:28 HST 2000