User’s Manual FOR
GoTo & Tracking Systems
Ó
Original manual
text written by Wm. J. Wiegert.
Volume 1
Equatorial Mounts
User’s Manual FOR
GoTo & Tracking Systems
Ó
Original manual
text written by Wm. J. Wiegert.
Volume 1
Equatorial Mounts
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There are three (3) sets
of cables:
A.
One (1) "Telephone" cord.
Connects
the handpad to the control-box containing the
Printed
Circuit Board (PCB). It is Omni-directional.
NOTE: - This is NOT a standard phone cord.
It is a straight through
data cord.
B. Two
(2) Motor-Control cables with DB-9 connectors (9-pin).
One is
for the Right Ascension motor.
One is
for the Declination motor.
These are interchangeable.
However, each motor MUST be connected to its correct (corresponding) terminal
on the PCB, or Declination and Right Ascension functions will be reversed.
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There are two other red buttons
that control
functions such as the Grand Tour mode. (In Grand Tour,
Each time the switch is pressed in one direction, the telescope slews to
the next object in the Tour. Conversely, if the switch is pressed in the
opposite direction, the telescope slews back to the previous object).
For a typical user, the Grant Tour mode is all these buttons are needed
for.
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Brief description:
The software is event-driven by either keyboard or input by the handpad. If no events occur, then the scope remains at the current equatorial coordinates. If the coordinates remain unchanged the scope tracks. If new coordinates are entered, the scope slews. TRACKING can be turned ON and OFF easiest by pressing "t" on the keyboard.
NOTE: "t" is a Hot-Key. Hot-Keys are described later.
With user input, the software handles Backlash (Appendix-B) and Periodic Error Correction (PEC) for both axes. A 'Guide' function is also included so that guiding for a minute or two nulls occasional tiny residual drift.
Power-up the laptop computer
using the 12V marine battery. You will be presented with a start-up screen
that displays this message:
| Warning: to prevent overheating
motors & electronics,
turn off the motor power supply if program not running and stop tracking before hot-keying to another program. Please turn on the motors’ power supply now. Press any key to continue
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"Input" displays coordinates input by the user.
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You should now test movement of the telescope (assuming that the scope is mounted, and the computer is powered-up). Pick up the handpad, and hold it as shown here. Press one of the red buttons.
You should identify the cables as RA and DEC on their connectors, and on the PCB terminals as well.
Familiarize yourself with the functions of the handpad. Operate it through several sequences of Right Ascension and Declination swings. Become familiar with the scope’s behavior in Slewing and Slow Motion. Note that your particular setup and arrangement may offer unforeseen interference-points between the scope and mounting platform (tripod or pier).
NOTE: - The power supply will continue to provide torque to the motors despite any interference between the optical tube and the mounting platform. To prevent damage, check closely, and note any potential interference hazards. Use caution when approaching the Zenith! You must become familiar with the motion-limits of your system!
NOTE: - Slewing can be stopped in Grand Tour Mode by pressing ESCAPE on the computer keyboard.
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Look at the computer screen:
Left & Right arrow keys select the menu category. Up & Down arrow keys select the submenu items within a category. Just beneath the group of menu selections, a description of the submenu item is displayed.
The program opens with "FILE" highlighted at the upper left. Beneath it are listed several submenu functions that are accessible with the UP or DOWN arrow keys. As each submenu function is chosen, (highlighted) a description of that function appears below. Note that the first option highlighted under FILE is "Quit". If "Quit" is highlighted, a description of Quit is beneath the list of options. Note that it says: "Quit the program".
NOTE:
- Hot-Keys (The most used "Hot-Keys" are t, d, q, r, and 1).
There are several keyboard
"Hot-Keys" that perform all the necessary functions in the program. The
Hot-Key for "Quit" is the letter "q".
A complete list of Hot-Keys is in the program. It’s the last submenu item under FILE.
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You’ve aligned the telescope on a known star, and you’ve told the system where the telescope is pointing. The system is now ready to GOTO an object of your choice (west of the Meridian).
NOTE: - (REMEMBER) To view in the East, you must perform a "Meridian Flip". See Appendix-A for simple instructions on executing a Meridian Flip.
NOTE:
- If you are not familiar with the night sky, consult a planisphere, or
the "Guide to The Evening Sky" in a current issue of Sky & Telescope
or Astronomy magazine.
FIRST EXERCISE: - GOTO a Messier object.
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A Grand Tour is the ‘automated’ viewing of successive objects in a database. The user merely ‘flicks’ a toggle switch on the handpad, and the telescope slews to the next object on the Tour. The scope tracks each object until the switch is activated again. Pressing the switch in the opposite direction causes the scope to slew back to the previous object. You can advance or step back in the Tour as far as you wish.
Any data file can be used for a Tour. For instance, if you were to select one of the constellations in the program’s database, you could do a Grand Tour through the entire list of objects in that constellation (the list of objects in some constellations is enormous!). The tour can contain an infinite number of objects, or just a few. There is no minimum or maximum.
The quick-and-easy way to experience a Grand Tour is to select a constellation from the database. There are however, two disadvantages with that approach: First, many objects in the database are beyond the capability of medium-sized telescopes, i.e. – thousands of galaxies that are fainter than 10th magnitude. Second, many of the objects listed are not likely to be your favorites. For these reasons, it is pleasing and popular to have custom Grand Tour files that are tailored to your telescope, and to your particular preferences.
We will start out with the easy/simple method, and then briefly discuss a custom tour. To build a Custom Grand Tour you must first assemble a list of objects in Windows Notepad (or a similar utility) and then convert it to a ‘dat’ file.
Grand Tour, using existing program files
This section assumes that you are correctly polar aligned, and that you are currently tracking on a known object.
Assembling a Grand Tour file requires familiarity with the program, and knowledge of a utility like Windows Notepad (or any utility that allows you to save your work as a data-file (i.e. – .dat file-extension). Only files that end with a "dat" extension will work in the program.
NOTE: - Making custom Grand Tour files is recommended for experienced users only! Therefore, it is highly recommended that you contact GOTO & Tracking Systems for assistance when a custom Grand Tour file is needed.
The following is a brief
description of a custom Grand Tour file. It is intended for demonstration
purposes only.
Here’s what a short Custom
Grand Tour might look like for October-November. Next to the coordinates
you can type a short description which will appear on the screen. There
are only 25 objects shown here, but the list can be as lengthy as you like.
NOTE:
- For this Tour, a convenient alignment star would be Vega.
18 44 20 39 40 12 Epsilon Lyrae
18 53 36 33 02 00 Ring Nebula [M-57]
19 16 29 30 10 00 GC [M-56]
19 16 36 30 11 00 NGC-6779 GC 08.3
19 41 51 50 31 03 16 Cygni A/B Xtra-Solar
19 53 41 18 46 59 GC [M-71]
19 59 36 22 43 00 NGC-6853 PN [M-27] 07.3
20 13 36 46 42 00 Omicron Cygni [Triple]
20 23 59 38 31 00 OC [M-29]
20 34 12 07 24 00 NGC-6934 GC 08.9
20 45 42 30 43 00 WEST VEIL NGC-6960
20 46 13 33 58 13 52 Cygni in WestVEIL
20 56 24 31 43 00 EAST VEIL NGC-6992/95
21 04 12 –11 22 00 NGC-7009 Saturn Nebula
21 06 54 38 45 00 61 Cygni Double
21 07 00 42 14 00 NGC-7027 PN 08.5
21 30 00 12 10 00 NGC-7078 GC [M-15] 06.0
21 33 30 –00 49 00 NGC-7089 GC [M-2] 06.4
21 39 06 57 30 00 IC-1396 OC+Nebula 03.5
22 37 06 34 25 00 NGC-7331 GXY 09.5
23 25 36 42 32 00 NGC-7662 PN 08.3
23 57 00 56 44 00 NGC-7789 OC 06.7
00 42 42 41 16 00 NGC-224 GXY [M-31]
01 05 05 54 00 40 SN-CAS 1995 09.2
01 33 05 30 38 59 GXY [M-33]
NOTE: - Each line must start with a space.
The utility used to organize
the data files for your system is a program called "SkyTools" from CapellaSoft.
Their current web address
is http://www.skyhound.com/cs.html.
The best way to obtain Grand Tour files of your favorite objects is to contact GOTO & TRACKING SYSTEMS, either through their website, (gototelescopes.com) or by e-mail (lenord@gototelescopes.com). Custom files are free of charge.
The system contains files for observers of all levels, and for a wide range of equipment. Besides the highly popular Messier and Caldwell subjects, there are listings of nearly every type of deep space object, including those difficult challenges which inhabit the far-reaching domains of larger apertures, darker skies, etc. Conversely, there are some files dedicated to urban sites where light pollution might be a factor. And for users of medium telescopes, there is a file labeled "6-inch Newt".
Within this file, you will find some interesting subjects:
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When using any Equatorial Mount as a motorized GOTO device, objects can be viewed on one side of the Meridian at a time. To view objects on the other side of the Meridian you must execute what’s called a "Meridian Flip" (sometimes referred to as a "GEM-Flip"). If this maneuver isn’t done, the system will confuse directional movement with the opposite side of the Meridian, and GOTO functions will not be possible.
Your system was preset at the factory to begin slewing to objects that are West of the Meridian. This is because objects in the west are setting, while those in the east are rising, and western setting objects are usually what observers want to catch first (you have more time to catch those rising in the east).
The procedure for executing a Meridian Flip is NOT DIFFICULT. In fact, the program does almost all of it FOR you. You merely have to type a HOT-KEY, and then follow a simple instruction on the screen.
The following procedure (if done correctly) will accurately reset the system, to enable pointing, finding, and tracking to be accurate and repeatable on the other side of the Meridian.
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"Without backlash compensation, prior to every change of direction for slewing, microstepping, and tracking, the motors will spin for awhile and the [program] will think the scope is moving (and thus will change the coordinates on the screen). However the scope [itself] is not yet moving. This creates errors in pointing accuracy.
"Backlash can cause serious slewing, finding and tracking errors, especially if the backlash is a significant portion of the field of view.
"Also, when tracking an object for CCD imaging, if backlash is not compensated for, the object will drift across the [field of view] before backlash is taken up. With backlash properly compensated for (as described below), everything is taken care of automatically. The [program] knows exactly where the scope is pointing during initialization, resets, and slews. When the scope slews to an object, [that] object will land on the CCD chip, and tracking will start immediately after the motors take out the slop, leaving the object in the same place within the field of view. It's important to have the scope balanced (alt axis) since any imbalance will tend to make the backlash appear only in one direction, which will [tend to spoil] the backlash compensation."
The following procedure (if done correctly) will accurately determine and compensate for backlash in each axis to within an arcminute or less.
SOFTWARE UPDATES
From time to time Mel Bartels
updates the scope.exe program. You can always look for the current version
of the program at his website
To update your software, it
is really easy to do. All of the current settings you have in the program,
backlash, microstepping speed etc., all stay with the program. This is
what you need to do:
Make a backup copy of the scope.exe program and the config.dat file on a separate floppy disk. Save these in case something goes wrong.
Download the zipped file to
your computer.
Unzip it into a directory.
Take ONLY the file called scope.exe
from the archive and put it on a floppy disk.
Take that file and overwrite
the current version of scope.exe on your scope computer.
Done.
For those of you that forgot how to do this in DOS, the instructions are below. I'll assume you can put a single file onto a floppy from a Win xx computer.
Insert the floppy
Open scope and exit until you
get the c:/scope prompt
Type this: copy a:/scope.exe
DOS will ask if you want to
overwrite the current version of scope.exe, press Y
Type scope at c:/scope
The new scope version will
open.
You can check to make sure this is the new version by looking at the top line of the program for the compiled date.
For those of you that change mounts or belts and pulley's, this is how you change the software to correct for your final gearing change.
Count the grooves on the pulley
on the stepper motor for both axis'.
Count the grooves on the pulley
on the worm shaft for each axis. This must be a higher number than what
is on the motor shaft. Some timing pulleys will have the number of grooves
stamped on them, if you are lucky.
The gear ratio of the timing
belts is the number of teeth of the larger pulley divided by the number
of teeth on the motor shaft. Typical ratio's are from 1:1 to 5:1 and all
decimals in between.
Some people have a gear box
attached to the stepper. Get the ratio of the gearbox in place of the above
value.
Determine the gear ratio of
wheel and worm gear on each axis. You can use your setting circles and
some simple math to figure this out. Remember, the gear ratio of the wheel
and worm gear is the number of turns of the worm shaft it takes to move
the gear one revolution. If you have setting circles, you can count the
number of turns it takes to move a certain amount on the setting circle
and then multiply appropriately. If you have no setting circles, it is
likely you can just count the grooves in the gear. Use a fine felt tip
to count in 10's of teeth, then count the marks on the gear you made.
Once you have all of the ratio's
determined, you also need to determine the number of full steps your motors
have per revolution. Typically 200 or 400 step steppers are used.
This is the math to figure
it out the value to put into the scope software:
timing pulley ratio X W/W gear ratio X 400 = a large number
Divide this number into 1,296,000
Example: 3x180x400=216,000 1,296,000/216,000 = 6
6 is the value to put into the
Motors/AZStepsizes menu item for an axis.