User's Guide to ShARCS

Table of Contents

Summary Table
Detector Characteristics
Filters, Grisms, Apertures, Polarimeter
Software Overview
Data Taker GUI
Filter & Aperture Wheel GUI
Image Display GUI
Sound server
Temperature Monitor
Observing Procedures and Tips
FITS Header Keywords

Data Archive
Mt. Hamilton Homepage

Scripts for Observing and Calibrations

ShARCS dithering and calibration scripts are run using ScriptProc. It is started on the computer covert with the command scriptproc.tcl. This brings up the GUI shown in Figure 1.

Figure 1: Script GUI, scriptproc.tcl

The basic scriptproc GUI allows one to take multiple exposures with the current exposure settings in sharcs_fe. To do this, set NExpose to the number of desired exposures. The new setting will not be used (and will display a yellow background), until the Set button is pressed (at which time the background will revert back to the default white color). To start the exposure sequence, press the Go button. As the exposures progress the Exposure # will increment indicating how many exposures have been completed and Exposure will display the image in progress sequence number.

AO mode displays which mode the ShaneAO system is operating in, either NGS, Natural Guide Star, or LGS, Laser Guide Star.

The check boxes in the GUI are shown with their default settings. If one wants to test a new script, check the Test Mode box and no commands to either ShARCS or ShaneAO will be sent. This is useful for checking syntax and logic when the instrument is either not available or otherwise being used.

The other four checkboxes determine which actions are performed during scripts. All four should be checked for normal dithering script operation. When Nod-Telescope is checked, the telescope move commands from scripts will be performed. When checked, Nod-WFS moves the appropriate motors for NGS or LGS mode in the ShaneAO system to keep the guide star (natural or laser) on the wavefront sensor so AO corrections can be done. AutoOpenLoops will open the adaptive optics control loops on the guide star before performing and telescope or motor moves. AutoCloseLoops will automatically close loops once all telescope and motor moves associated with a dither have been completed. The AO operator will advise if any of these checkboxes needs to be unchecked due to special cases or problems with the AO system operation.

The File menu has two options Source... and Quit and will also list the currently loaded scripts (see Figure 2 for example). Quit is self-explanatory. Source... allows one to load a script for use. By default no scripts are loaded when scriptproc.tcl is started. When one clicks on Source... a file selection window will appear showing the names of all available scripts. The currently available scripts are bxy.tcl, rbxy.tcl, sky4.tcl, and imagesharpen.tcl. Each script is described in detail below. If none of the available scripts suits the needs of the science program, consult with a support astronomer who may be able to create an appropriate script.

Figure 2: File Menu showing two loaded scripts, imagesharpen and bxy.

Available Scripts

Bxy | rbxy | sky4 | imagesharpen

BXY Dither Script

Figure 3: Bxy Dither script GUI

The Bxy dither script is the most commonly used dithering script. The script will do NExpose number of exposures (as configured in sharcs_fe) at each position of the script. Positions are determined by the Object Dither Scale (in arcseconds). The dither script will put the science target at the corners of a box two times the Object Dither Scale in width, starting with moving the telescope NE. If the Expose at starting positon? checkbox is checked, the script will start with taking NExpose exposures at the starting position before executing the initial telescope dither move. At the end of the script, the telescope will be returned to the starting position. In NGS mode a maximum dither scale of 4 arcseconds is recommended.

RBXY Dither Script

Figure 4: RBxy Dither script GUI

The rbxy dither script functions similarly to the bxy script. The primary difference is the dither scale in the North/South (NS) direction can be different than in the East/West direction (EW).

SKY4 Dither Script

Figure 5: Sky Dither script GUI

The sky4 dither script is designed to make getting a set of sky background frames and functions similarly to the bxy. The primary difference is that the ShaneAO system will expect that there is no star (natural or artificial) to close loops on, so will not move any field steering motors nor close loops after each telescope move.


Figure 6: Image Sharpening Calibration script GUI

The imagesharpen script is used to assist calibration of the ShaneAO system by iteratively adjusting the selected Zernike modes on the woofer deformable mirror to improve the Strehl ratio. This script is normally used by the technical staff at Lick Observatory during the afternoon configuration of the instrument to ensure peak performance of the system. It is sometimes used on sky (when conditions are stable enough) to improve Strehl if there is a static aberration apparent in the images that needs to be corrected.

NExpose is the number of exposures to take at each mode value. Recommended value is 1. Press the Set button to make sure the new value for NExpose is accepted for use.

Image Sharpening Step Size is amount of change of each mode for each iteration of the script. Recommended value is 0.15 (allowed range is 0 to 1.0).

Each Zernike mode has a checkbox next to it and will only be adjusted during the script if checked. By default only Focus, Astigmatism, and Astigmatism45 are checked, as those are the primary modes that usually need ajustment. The value of each mode during the script is displayed to its right so the progress of the script can be monitored as well as displaying the set value. Note that all modes are actually offsets from the current reference centroids loaded into the ShaneAO real-time control system.

The Zero Modes button will set all the modes back to zero. Generally this button should be pressed after any new modes are saved (either when Auto Save Modes is checked or when Save File is clicked.

When Auto Save Modes is checked, a new reference centroid file will be saved using an appropriate file name set from the state of system. If the script needs to be re-run with different modes checked, the modes should be zeroed first by pressing the Zero Modes button, otherwise the offsets just saved will be applied a second time, degrading the image.

If the modes were not auto saved, a file name base can be entered in the entry box left of the Save File button. The subaperture mode (_16xLGS or _8xLGS) and .fits extention will be automatically added to the entered file name. When Save File is pressed, the new reference centroid file will be saved and loaded into the ShaneAO real-time code with the specified file name.

To adjust each mode manually, the imageSharpen GUI can be run on shade (gavel@shade:local/bin/imageSharpen).

Figure 7: imageSharpen GUI for manually adjusting Zernike modes.
Last modified: Mon Jan 4 09:58:38 PST 2016