Linux, Talon and Astronomy

A new open-source application lets professional and amateur astronomers explore space from their desktops.
Configuration

Configuration files are critical to the operation of Talon. They provide the means by which the software communicates with both the user and the hardware installed in the telescope. In the Linux tradition, these files are simple text files, commented heavily for the clarification of the user. The configuration files for all elements of Talon can be found in /usr/local/telescope/archive/config. Using the default tcsh shell, the simple command cd config moves the user into the configuration directory.

The operation of the telescope can be viewed as two discrete elements, each of which is addressed by a specific configuration file type. First, the internal motion control boards must communicate with the motors and encoders. Configuration files intended to serve this function utilize a .cmc extension. I've always viewed this extension as delineating files that configure motion controllers, cmc for short. The .cmc files establish the operating parameters for the controller boards, which, in turn, send signals to and receive feedback from the encoders and electromechanical components.

The other element of telescope operation is the interface between the user and the software. In simple terms, all user-controlled operations utilize configuration files with a more traditional .cfg extension. Whereas the .cmc files operate behind the scenes to communicate directly with the hardware, the user interface must communicate with the .cfg files.

Critical Configuration Files

Although every configuration file plays a role in the operation of Talon, some in both the .cmc class and the .cfg class bear special attention. These .cmc files include:

  • basic.cmc: establishes the basic communication between the motion control boards and the motors driving the telescope axes.

  • find.cmc: establishes the routines for finding objects based on encoder counts.

  • nodeDec.cmc: establishes the hardware parameters for the Dec axis of the telescope.

  • nodeRA.cmc: establishes the hardware parameters for the RA axis of the telescope.

  • nodeFocus.cmc: establishes the hardware parameters for the telescope focus control.

The .cfg files are:

  • boot.cfg: allows the user to script Talon startup routines. These may include starting GPS monitoring, weather station monitoring and opening the Talon main interface when the computer boots.

  • home.cfg: provides an initial set of constants to allow the telescope to find the home position of each encoder. These constants represent a spatial sense for the telescope prior to working through the initial calibration routines. Once these routines are completed, the actual encoder counts and axis travel are updated automatically.

  • telescoped.cfg: provides constants regarding the telescope axes, establishes the position of physical travel limit switches in relation to the encoders and establishes the maximum rotational velocity of each axis as well as the rotational acceleration rates.

Critical Configuration Settings

The settings in each of the individual .cmc and .cfg files utilize a naming convention that makes their function easily recognizable, but some critical settings within these files deserve special attention. These settings can be modified with any familiar text editor:

  • boot.cfg: establishes the overall parameters of the Talon software at boot.

  • setTelUser: creates the telescope user, the telescope user group and sets the appropriate permissions. By default, the initial telescope user and group are named talon. This can be changed for subsequent use by modifying the setTelUser constant in boot.cfg, provided the new user and group already exist on the system.

  • setTelDaemons: initializes the telescope dæmon (telescoped), camera dæmon (camerad), weather station dæmon (wxd) and global positioning system dæmon (gpsd).

  • home.cfg: provides the following four constants for encoder counts, home position, limit switches and rotational velocity and acceleration:

  • HSTEP: the number of encoder counts in the full rotation of the HA axis encoder.

  • DSTEP: the number of encoder counts in the full rotation of the Dec axis encoder.

  • HSIGN: the physical location of the HA encoder on the telescope. When viewed from the north, the HA encoder will increment clockwise if placed at the back of the polar shaft (the shaft upon which the telescope moves from east to west) or decrement when placed at the front. Another way to view this is, if the marked encoder surface points to the south in the final telescope configuration, it will increment when rotating clockwise. If it points to the north, the encoder will decrement with clockwise rotation. This configuration is a simple constant: 1 if the encoder increments, -1 if it decrements.

  • DSIGN: the physical location of the Dec encoder on the telescope. Much like the HA encoder, the increment/decrement of the encoder varies depending on the method used to mount the encoder. If the encoder is installed with the encoded surface toward the outside of the fork, it decrements when rotated clockwise, or toward the north. This requires a setting of 1. If the encoder is mounted with the encoded surface to the inside of the fork, it increments when rotated clockwise. This requires a setting of -1.

  • telescoped.cfg: provides the following constants for initial operation:

  • HAXIS: the telescope network node from which the HA axis is controlled.

  • DAXIS: the telescope network node from which the Dec axis is controlled.

  • HESTEP: the raw encoder counts per revolution for the HA axis.

  • DESTEP: the raw encoder counts per revolution for the Dec axis.

  • HMAXVEL: the maximum slewing velocity of the HA axis.

  • DMAXVEL: the maximum slewing velocity of the Dec axis.

  • HMAXACC: the maximum slewing acceleration of the HA axis.

  • DMAXACC: the maximum slewing acceleration of the Dec axis.

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Re: Linux, Talon and Astronomy

Anonymous's picture

I bought this issue on the news stand specifically for this article. What a disappointment to find the article was written a year ago and the software is no longer supported! I don't think I'll be buying this magazine again.

-Tom

Re: Linux, Talon and Astronomy

Anonymous's picture

So do I.

Thierry

KStars can control popular telescopes

Anonymous's picture

Most amateur astronomers use telescope from Meade and Celestron, the latest version of KStars (to be released in KDE 3.2 http://edu.kde.org/kstars) includes a support for such telescopes.

It seems that Talon is really great and professional, albeit it is limited to the Optical Mechanics and Oregen motion controllers.

For most of us amateur astronomers out there who own a Meade or a Celestron, KStars allow us to easily control the telescope.

Re: KStars can control popular telescopes

Anonymous's picture


Most amateur astronomers use telescope from Meade and Celestron

and what makes you think that?
I know a lot of amateur astronomers, and not a single one owns a meade or celestron telescope... because they just suck.
Way too pricey for what those things offer.

Re: KStars can control popular telescopes

Anonymous's picture

You're right, but the whole article is about Software Telescope Control. So maybe most amateur astronomers have Dobs or refractors, but the majority of those who have _computerized_ mounts that can be used along with a control software has Meade/Celestron.

Re: Linux, Talon and Astronomy

Anonymous's picture

Kstars, included in KDEGames, contains telescope control software.

http://edu.kde.org/kstars/

And the telescope control documentation:

http://docs.kde.org/en/HEAD/kdeedu/kstars/indi.html

KStars is being actively developed.

Derek

Re: Linux, Talon and Astronomy

Anonymous's picture

A small correction, KStars in included in the KDE Eduntainment package.

Maybe Linux Journal can review KStars when KDE 3.2 is out?

Re: Linux, Talon and Astronomy

Anonymous's picture

Interesting story, this.
The article was written nearly a year ago. Since that time the company, Optical Mechanics, Inc., has shifted its focus to high precision optics and away from telescopes. I, in the meatime, have gone to work for a presidential campaign in Little Rock, AR. The Talon project on sourceforge has, to say the least, languished.
As the result of the article, I've had several offers to help rebuild the project page and continue development on Talon. You can expect to see a new project page within the next week or so (as of December 7), and an initial release of Talon shortly thereafter. The software is available now via CVS on sourceforge.
It started strong, faded, and looks to soon be revived by the open source community. Keep an eye open.
Tony Steidler-Dennison

Re: Linux, Talon and Astronomy

Anonymous's picture

I'm in the proccess of building my observatory to house my 10" Meade. I would really like to use all of the capabilities of this software.

Another good piece of software is "The Sky" for Linux and "Satalite tracker". Both are easily found threw a "google" search.

Re: Linux, Talon and Astronomy

zedkatuf's picture

Hi Tony

I've just downloaded your first source release from the Sourceforge site...Like others on this list, the setup I'm using is an LX200, (with a Robodome arriving in the Fall, hopefully).

I'm interested in seeing something like Talon being used for my setup, as I'd like to run it all under Linux....I'll email you to chat further.

Regards,

Dez Futak.
zedkatuf@hotmail.com

Re: Linux, Talon and Astronomy

Anonymous's picture

Thanks for the info, Tony. I was able to find a page
for Talon on sourceforge at:

http://sourceforge.net/projects/observatory/

I too am very interested in seeing this project move
forward. I am building a robotic telescope and plan
on contributing to the community both the mechanical design of my mount and my coding efforts on a resurrected Talon project.

Tom Bartol

Talon Development

Fabian Lim's picture

Hi Tom,

Myself and my partner are currently working on compiling the Latest Talon Software and porting it at the University of Toronto's Observatory. We are both students from the University of Toronto and we are trying to standardize the code so that it would work on all LX200 telescopes on Linux Enterprise 3.0. We are currently facing problems compiling, and we would like to know how far you have gone with this code. Please let us know if you would be interested in working together.

Thanks,

Fabian Lim

Re: Linux, Talon and Astronomy

Anonymous's picture

Ilooked for this software, too. Not only is it missing from the claimed spot, it is not available from the optical company, nor is it even mentioned on the author's website. So, what gives? if it is a product, that fact should have been stated in the article. If it is freeware or shareware, that too should have been stated. I'm seriously disappointed, as I have a potenitial use for Talon. Too bad.
Don Latham

Re: Linux, Talon and Astronomy

Anonymous's picture

The source code for Tolon is located at "www.sourceforge.net". Just type Talon into there search window. I've downloaded it, unpacked it, and now trying to install it

Re: Linux, Talon and Astronomy

Anonymous's picture

The source code for Tolon is located at "www.sourceforge.net". I've downloaded it, unpacked it, and now trying to install it

Re: Linux, Talon and Astronomy

Anonymous's picture

Has anyone successfully downloaded this code? I was curious
enough to want to poke around at it a bit, but http://observatory.sourceforge.net/ is an empty directory, and the
sourceforge project at http://sourceforge.net/projects/observatory/
claims not to have released any files. Am I missing something?

Re: Linux, Talon and Astronomy

Anonymous's picture

The project is still there, and indeed the latest version is 0.85, Dec 29 2003. But it has moved - observatory.sourceforge.com is now an empty directory. The new URL is:

http://sourceforge.net/projects/observatory/

Re: Linux, Talon and Astronomy

Anonymous's picture

Interesting story, this.

The article was written nearly a year ago. Since that time the company, Optical Mechanics, Inc., has shifted its focus to high precision optics and away from telescopes. I, in the meatime, have gone to work for a presidential campaign in Little Rock, AR. The Talon project on sourceforge has, to say the least, languished.

As the result of the article, I've had several offers to help rebuild the project page and continue development on Talon. You can expect to see a new project page within the next week or so (as of December 7), and an initial release of Talon shortly thereafter. The software is available now via CVS on sourceforge.

It started strong, faded, and looks to soon be revived by the open source community. Keep an eye open.

Tony Steidler-Dennison

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