Enhanced Commands for N8/9.25/11GPS, N5i/8i, CPC, LCM, SLT, CGE,
CGE Pro, CGEM and AS-GT Scopes
Celestron has included several new commands in the NexStar 8/9.25/11 GPS
(version 1.6 or higher), CPC, LCM, NexStar 5i/8i/8i Special Edition, CGE, CGE Pro, CGEM and AS-GT scopes. Some of these commands
are in the NexStar 5i/8i manual, the others will be included soon. The
commands are:
- Tracking rate. Allows control of the tracking rate in both axes
(independently) ranging from rates of a small fraction of sidereal up to 3
degrees/second. This command can be used to move the scope directly to a
set of coordinates (your responsibility to know what rate and how long you
need to apply it to get there) or to emulate the hand control's direction
buttons. Click
here
for an Excel spreadsheet that lists several useful rates.
- Tracking mode. Allows you to set the tracking mode to 'Off', 'Alt-Az',
'EQ North', 'EQ South'. It is required to set tracking mode to off prior
to issuing a tracking rate command otherwise sidereal rate will resume
automatically after a few seconds. To return to sidereal tracking you set
the correct mode: Alt-Az, EQ North, EQ South. There is no command to query
the mode prior to setting it to off, so you must provide a control for the
user to set the correct tracking mode in your application. See attached
application for example.
- 32 bit Goto and Get RA-Dec. Allows sub-arcsecond accuracy for
goto and get operations (1/12th arcsecond actually). This brings the
software precision in line with the encoder precision. Click
here
for a
spreadsheet (EncoderCalculations.xls) that calculates the correct values
for goto and get commands - you can use it to check the accuracy of a
program's algorithm. Note: the goto and get commands in the attached
Visual Basic application only uses the standard 16 bit commands - yielding
an accuracy of just 1/3 arcminute. The standard commands are sufficient
for most applications as the user will not be able to align the telescope
to an accuracy of better than a few arcminutes. However, programs that
provide advanced alignment accuracy by utilizing multiple alignment stars
(TPoint for example) can make good use of these commands.
- Version. Allows you to query the hand control for the
firmware version.
Download the actual commands
here. You can download
the entire source code for NexStar Control Pad (see the Downloads section
for details and the compiled program)
here
(requires that you have Visual Basic 6 to run, but you can open the files in
Notepad to view the code). This application shows how to
implement a program that emulates the hand control's direction buttons, sets
tracking mode and
more. All of these resources were created by me and you
will not violate any copyrights (nor my feelings) if you use them.
Additional Commands
Andre Paquette has investigated the internal communications protocol of the
NexStar 8/9.25/11 GPS and NexStar 5i/8i telescopes. Some of the more useful commands
control the motor control and GPS modules. He has published an excellent guide
of these commands for the technically inclined, which you will find available at
his web site:
http://www.paquettefamily.ca/nexstar/
Appropriate care must be used with any of these additional commands since a
few of them can render your telescope inoperable, requiring a return trip to
Celestron (most likely at your expense!) to remedy the situation.
|
