Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.astro.louisville.edu/software/xmtel/archive/xmtel-3.1/DOCUMENTATION Дата изменения: Sat Oct 14 23:24:45 2006 Дата индексирования: Mon Oct 1 21:09:06 2012 Кодировка: Поисковые слова: winter solstice

XmTel
-----

XmTel is a Motif-based program including a command line utility cmdtel
developed by John Kielkopf (kielkopf@louisville.edu) to operate
a telescope connected to a Linux computer system. The most recent version
should be available from

http://www.astro.louisville.edu/moore/software

XmTel is offered with the GNU General Public License without warranty of any
kind. See the files LICENSE and COPYRIGHT for the details. Because unattended
operation of a telescope could inadvertently damage it, we urge you to be very
careful when you use this software. Check the protocol.h file for the altitude
limit settings and modify them in accordance with your facility. Exercise the
software thoroughly before trying to use it in the dark, or from the warm
comfort of your computer console when the telescope cannot be directly
observed.


The default installation will use /dev/ttyS0 for LX200 and NexStar telescopes.
In the present version, you have to change this at compilation time.
See INSTALL for more information about insuring the permissions for the
serial device driver are set properly.

If your telescope is connected to the computer you are using as a console, simply
start xmtel on the command line, followed by xephem:

xmtel &
xephem

If you are running on a remote telescope computer, then first connect using
secure shell with a request to transport the X11 display:

ssh -Y user@remote.telescope.edu

and then start xmtel and xephem as above.

You may need to delay briefly starting XEphem so that XmTel can communicate
with it through fifos. See INSTALL to be sure your computer has the
directories and files needed for this. They are not installed by default in
Suse Linux, although the public version of XEphem is there.

When xmtel is launched you will see a control panel with the following
functions:

"File" offers the option of new Log and Queue files, and the usual Exit.

"Edit" enables editing Log and Queue files with your favorite editor (selected
at compile time).

"Control" at present offers only the option of communicating with a telescope
attached to your console computer.

"Pointing" has radio button selections to enable pointing corrections. Only the
first one (Refraction), and the last one (Reference) actually do anything at
this time. If Refraction is ticked, then the commands sent to the telescope are
automatically corrected for atmospheric refraction. This is to say that the
telescope will be pointed at the apparent position of the object. The
coordinates that are displayed will be the true coordinates, not the apparent
coordinates. If Reference is ticked, then the reference position previously
stored will be used. Both features may be turned on or off at your discretion.
As an operational note, if you are looking for something faint or difficult to
identify, it is a good idea to point first at a nearby bright star. Then
select "Reference" from the menu (see below) and Sync to Target. With a German
Equatorial Mounting if you switch from one side of the pier to the other you
will have to turn off the Pointing -> Reference selection, find a bright star,
and Sync to it. The direction of backlash and loading changes and the
manufacturer's telescope controller may, or may not, take this into account.

"Reference" allows you to set the offsets based on the present Target coordinate
set. In other words, slew to a bright or easily recognized target, center it in
the field, and click Reference -> Target. Enable Pointing->Reference and the
telescope will be directed to take into account the error between where its
controller "thinks" it is and where it actually is pointed. You may also
reference to Zenith which is useful in some telescopes with an internal
leveling system.

"Telescope" is a menu system for control of telescope functions. If the
functions of interest to you are accessible through the same controller that
runs the mounting, then they may be included here at compile time. "Focus"
would be the most useful of these, but you may prefer to control the focus from
the same program that runs the camera in order to implement autofocusing.

*Guide *Center *Find *Slew radio buttons select the move speed. Slewing
operations will always be at slew speed.

NSEW buttons move the telescope as long as the button is depressed. The
coordinate display will update when the button is released, after a
delay for motion to stop.

Telescope and Target RA and Dec display the coordinates of the telescope and
the most recently selected target. Click on the "Telescope" or "Target" label
to have XEphem show you where these objects are. A click on the telescope's RA
or Dec entry will force an update of telescope coordinates. A click on the
Epoch entry will toggle it from "Now" to "2000". This is for display purposes
only and does not affect the actual pointing. You may enter a target from the
keyboard by clicking on the entries for RA or Dec for the Target field.

Target entries may be more conveniently handled from the GUI by using XEphem.
Right click on the object of interest, select Telescope GoTo, and the target
field will be filled in for you. (This does not work for orbital objects
because XEphem only transmits the object name in that case, and not its
coordinates. For planets, comets and asteroids click on the closest GSC star.)

Target entries may be filled in from a queue file. If a new queue is selected
the names of its entries will appear in the scrollable display panel at the center of
XmTel. Just click on one and its coordinate entry will be transferred to the
Target field. If you then "Mark->Target" XEphem will show you where this object
is. A convenient way to make a queue list is to copy the information from the
catalog entry for XEphem, using XEphem's format. (But, see note about orbital
objects above.)


Below the queue field there are eight buttons that control telescope functions:

Save puts the contents of the telescopes current location in a log file and
pushes into a memory buffer. You can use this to return to a particular
position.

Recall will take values from the memory buffer and put them in the target field.

Meridian will load the target field with the coordinates of the meridian at the
present declination.

Zenith will load the target field with the coordinates of the zenith.

Pole will load the target field with the coordinates of the pole at the present
hour angle.

Track will start tracking if, for some reason, it has been disabled.

Stop will stop sidereal rate tracking. It may also stop a slew in progress, but
this is not guaranteed. (See the main README for cautions.) A master stop or
power switch near the keyboard is recommended, just in case.

A comment field appears at the bottom of the control panel that may contain
messages regarding the operation of the telescope.


About Epoch
-----------

XmTel assumes that the telescope is set to "Epoch of Date", which means that it
is using ideal celestial coordinates precisely aligned today. The
correction routines in pointing.c makes adjustments for refraction, flexure,
and mechanical misalignments of the telescope. The protocols which are provided
here for use with XmTel operate on this principle. The LX200 and NexStar
telescope operating systems use an approximate Epoch of Date. The differences
between the two systems should be far less than the pointing error after
corrections are applied.

Coordinates which are displayed on the console may be in an Epoch of your
choice, selected from Epoch toggles. XmTel assumes that target coordinates
entered from the keyboard are in the Epoch that the telescope coordinates are
currently displayed in.

Coordinates which are transferred from XEphem may be in another Epoch, depending
on the catalog selected and the internal operation of XEphem. XEphem provides
this information to XmTel, and the target epoch may change depending on the
source of the target coordinates.

About Time
----------

XmTel requires an accurate system time. It is advisable to either set the
system clock using the NIST website, or to use NTP services to maintain an
accurate system clock.