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яЛП Iowa Robotic Telescope Facilities
Introduction Observing Statistics Curriculum Research Technology Sample Images Links

Both the IRT and Rigel telescopes utilize the Talon software suite for Observatory scheduling, telescope control and image analysis tasks. Talon is an integrated suite of Linux-based software which includes telescope scheduling algorithms, observatory instrument control, and image analysis. It is written primarily in classic ?C?, with some components in Perl and csh script. Most user-level applications in have a Motif-style GUI interface. Talon is based on OCAAS, a software suite developed by software engineer Elwood Downey (Clear Sky Institute) for use at the University of Iowa?s first remote facility (the ATF, or Automated Telescope Facility). Significant enhancements were made to OCAAS (renamed Talon), especially extending Talon to a web-based interface, by Steve Ohmert at OMI. A block diagram of the telescope control for Talon is shown below.

  1. Telescope Scheduler (Telsched)

The telescope schedule accepts schedule requests from the web-based observing schedule request interface and sorts them in an optimal manner based on request time and priority level. The user interface is shown below.

Talon's Telescope Scheduler

  1. XObservatory: Telescope Control Interface

The program Xobservatory provides a real-time display and control of the observatory. The telescope can be operated in one of two modes: real-time or batch (remote scheduling). In real-time mode, the observer may specify the source to be observed by catalog name or coordinates. There are also tools for auto-focussing, re-homing all axes, and control of filer wheel. Xobservatory also display time and weather information, current telescope position, and current status of filter wheel, roof, focus position, and camera. The user interface is shown below.

Xobservatory

  1. Camera

Camera is a powerful FITS image analysis program that also provides real-time CCD camera control. It has a large number of analysis tools, including absolute and differential photometry, a WCS (world coordinate system) solver, a image ?movie? tool, in addition to the usual analysis tools, such as magnifying lens, histogram adjuster, image arithmetic, and FITS header editor. The user interface is shown below with several tools illustrated..

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Camera: Image Analysis and Camera Control

The table below describes the Talon system is more detail  Layered atop this are the components of the remote access Internet solution, including user management, scheduling, remote monitoring, direct remote control, remote maintenance, and basic user data management.

Specification

Description

Observatory Control System (OCS)

The Observatory Control System of Talon consists primarily of Xobs, the Linux X-Windows based observatory control program.  This program calls upon and coordinates much of the interrelated portions of the Talon architecture, and forms the primary control panel for the telescope, dome, and peripheral systems when used locally. 

Remote users accessing the system will be presented with a web-browser display, incorporating much of the same information as is found in Xobs, but presented in a somewhat different style more appropriate to the medium.   This functionality is provided by Claw.

Logging of critical system functions is performed by Talon for diagnostic and technical review purposes.  This information chronicles the operation of the observatory subsystems at a component and driver level.

Telescope Control System (TCS)

The telescope control software of Talon supports the controlled, properly accelerated and damped slewing of the telescope to target (manually or automatically) and subsequent tracking of the target.  Tracking is supported by a pointing mesh (calibration) that is created by preparing a survey of the sky and performing precise WCS solutions at each of these sampled locations.  The encoder-to-actual error is recorded for each position and is then used as interpolation points for any subsequent pointing operation.  This results in a very good and very repeatable pointing accuracy

Instrument Control System (ICS)

The Instrument Control System controls the primary CCD camera, filter wheel, guide camera and focus mechanism. 

Access to the controls for the Instrument Control System is through Xobs as implemented by Talon, and by similar interfaces in Claw, as well as the scheduling options available via Claw.  Locally, images captured by the system may be viewed using Camera, a comprehensive CCD camera controller, image viewer, and analysis tool.  Web based users have the option of downloading their images for offline processing, or for simple viewing in web-delivery format.

Both standard and H-compressed FITS files are supported.  All relevant FITS fields are noted for each exposure, including location, time, exposure, image scale, object, and WCS solution, among others.

Dome Control System (DCS)

Documentation for interface and configuration options to the dome enclosure are provided with Talon.  The control system for the dome is governed by a CSIMC controller, which runs a script that handles basic dome operational commands.  These CSIMC functions can be easily adapted to control nearly any type of switch interface to a dome control system.

The Dome Control Software handles all aspects of the dome function including rotation, shutter open/close, and rotation to shutter power.  Optical Mechanics has adapted Talon for use with domes from a variety of manufacturers.

Environmental Control System (ECS)

Weather station monitors for barometric pressure, temperature, humidity, precipitation, wind speed and direction are standard in Talon.  The Davis Instruments EZ Mount Weather Monitor II or equivalent is provided.

Scheduler Manager System (SMS)

Development of the Claw product includes creation of a scheduling solution that addresses most common user needs. 

The scheduler as delivered accepts observing requests from users.   The basic components of an observation request consist of naming the object or coordinates to view, the equipment to be used including filter choice, and the exposure time.  Other specialized options, such as scheduling a fixed location (non tracking) exposure, or shutter ?flashing? (used in determining streak direction) may also be selected.

Direct Internet Control System

Users with appropriate privileges can request direct control sessions and are entered into the scheduler as fixed blocks of time.  The user for whom the direct control session has become active is allowed to sign into the system for remote control at any time during this session block.  As with any observation, the system will prohibit the use of the telescope equipment during unfavorable weather conditions.  Administrators may override a direct session, in the same way that they might override a scheduled request.

 

Contact: rigel@phobos.physics.uiowa.edu

Last updated December 2, 2003