900GTO GERMAN EQUATORIAL
You asked …. We responded …
A number of improvements have
been incorporated into the 2005 version of the 900GTO.
Some are small; others are more significant. Here is
a sample of the changes that we feel are most noteworthy.
Many of them can be retrofit to earlier versions of
- Declination Axis. Complete redesign of the declination axis with new thrust bearings and preloaded shaft bearings. This allows the mount to operate with excellent guiding precision when the telescope is upside down for imaging many hours past the meridian.
A special upgrade (part # 900DU) will be available for existing 900 mounts that will incorporate improved bearings, the new spring-action motor bracket, and other changes.
- Azimuth adjustors. This one-piece assembly makes azimuth adjustment easier and more accurate for precise polar alignment in your observatory or in the field. The heavy-duty construction and integrated one-piece design results in smooth control of the azimuth axis. Large left and right adjuster knobs are graduated for precise control of azimuth position angle. The small graduations are 1.3 arc minutes per graduation; long graduations are 6.5 arc minutes per graduation. The size of the knobs makes them easy to turn with very little torque required, even with the mount fully loaded.
Available to upgrade previous mounts. Refer to 900
Upgrades and Spare Parts for photos and detailed
description of the Azimuth Adjuster .
- Polar forks. Height was increased to allow tightening of the rear knob. Eliminated the sharp corners to prevent cords from catching.
Available to upgrade previous mounts. Refer to 900
Upgrades and Spare Parts for photos and detailed
description of the Polar Fork .
- Gearbox. Improved the gear profiles of the motor gearbox, so slewing is noticeably quieter. Amount of backlash delay in the motor gearbox has been reduced so that declination reversal occurs almost instantly. The gears are made by the same company that supplied NASA with the drive gears on the Spirit and Opportunity Mars Rovers. They have also produced components for the space station.
Not available for previous mounts at this time.
- Motor bracket.
Has built-in spring-action to keep the worms loaded
at the proper setting. Available only as part of the 900 Declination Upgrade (part # 900DU) due to the way the bracket attaches. It is not available as a separate upgrade item.
- Additional internal enhancements that enhance the overall performance.
Pier Adapter Options
In the past, the Standard Pier Adapter was provided as part of the mount. However, we now offer two choices, which are purchased as options for the mount. Please read the descriptions below to decide which adapter is most appropriate for your needs.
Pier Adapter with Azimuth Bearing (900RPA).
Not included with mount, purchased separately.
Rotates on a bearing surface. This allows
you to lock the mount down with no need to loosen
the base during azimuth adjustment. Especially
recommended for use in the field. Will be available
to upgrade previous mounts. Refer to 900
Upgrades and Spare Parts for a more
Pier Adapter (900SPA). Not included with
mount, purchased separately. This pier
adapter is essentially the same as the adapter
that we have offered standard with the 900 in
the past, however it has a slightly taller (1.2",
rather than 1.1") azimuth adjuster block
to accommodate the new azimuth adjuster assembly.
Note: If you just want to upgrade your present
pier adapter with the new block, order part #M12020-A,
which you can install easily yourself.
Refer to 900
Upgrades and Spare Parts for photos and more detailed description.
GTOCP3 Servo Motor Control
Although the GTOCP3 control box looks the same on the outside as the prior GTOCP2 model, the internal circuit boards have been redesigned to allow expanded functionality and provide additional protection of the circuit. The command language has been expanded to allow additional functions. As always, our command language is available to write your own program.
These functions cannot be added
to the earlier GTOCP1 and GTOCP2 control boxes; they
are available only in this new version. However a
complete GTOCP3 control box can be purchased as an upgrade for all prior GTO mounts - 400GTO, 600EGTO,
900GTO and 1200GTO.
- All new electronics.
All input lines are protected against heavy static
discharge with transorbs. Larger internal chip to
allow additional functions. FCC and CE certified.
- Drainage holes.
Two threaded drainage holes are drilled into the
lower part of the control box housing so that excess
moisture can drain easily. This may prove useful
if you live in an area with high humidity.
- Timed Move.
If the “:Me#" or “:Mw#"
or “:Mn#" or “:Ms#" commands
are issued with an integer between 1 and 999, the
controller will move in the specified direction
for the number of milliseconds specified. No respective
quit command is necessary. The total displacement
will be determined by the current guide/center rate
setting. This allows PC based programs to introduce
precise motion without the complication of providing
accurate time separation between the move and quit
- Continuous variation
of both RA and Dec tracking rates. The tracking
rate in either RA or DEC can be set to any arbitrary
value using the “:RR sxxx.xxxx#" or
“:RD sxxx.xxxx#" commands. “s"
is the sign “+" or “-“.
In the RA axis, the rate is superimposed on the
sidereal rate. The rate is normalized to 1x sidereal.
This simplifies the scheduling of the mount trajectory
for tracking planets, comets, satellites, etc. The
command “:RTx#" is retained. PulseGuide
, the software program by Ray Gralak of Sirius-Imaging,
takes advantage of this feature.
- Arbitrary centering
rate. By specifying the centering rate using
a lower case “c" rather than an upper
case “C", (“:Rc64#" rather
than “:RC1#") the centering rate becomes
equal to the value specified as a multiple of 1x.
The range is 1 to 999.
- PEM memory.
PEM memory is accessible to external software programs
in order to smooth out and modify the curve. PEMPro
by Sirius-Imaging supports directly reading from/writing
to the PE storage locations. This allows more accurate
programming of the mount's PEM (that is, the mount
does not have to interpret move or autoguider commands).
Also, programming is significantly quicker than
waiting for one worm cycle's worth of playback (6
min 24 seconds) as is the case for the GTOCP2. Also,
PEMPro reads parameters and calculates the mount's
worm period (useful if you have a non-Astro-Physics
mount with the GTO Control System, available only through OEM manufacturers).
- The Time-of-Day clock
overflows properly from 23:59:59 to 0:00:00.
On overflow, the date also advances. A read date
command was also added, “:GC#".
- Solid electronic
connection. The controller is no longer susceptible
to uncontrolled motion/"racing" resulting
from input power fluctuations, “bounces"
or glitches. In prior control boxes, this could occur when the power cord was plugged in and the connection was incomplete for a split second.
- Horizon check.
Bug is fixed. This only impacts people who write
their own programs. The keypad and planetariums
all have their own independent horizon check routine
which did not rely on this code in the control box
the GTOCP3 Control Box as an upgrade for your current
GTO mount. Link contains details that you need
GTO Keypad with Keypad Protector
Control Box - Features and Specifications.
The keypad has also evolved
in its construction and firmware features over the years
since its introduction in 1998. Refer to
GTOCP3 Control Box and Keypad for Servo Drive for
information regarding features and specification.
These improvements have been
phased in over the last couple of years. Many customers
already have the current model. New keypads can be purchased
as replacements and backups for all GTO mounts.
- Larger chip memory
capacity on new circuit board. Will allow
us to add more features to the firmware program
in the future. All keypads with serial # 1491 and
later numbers have this larger chip.
- LED fiber optic backlit
panel. Does not require a transformer as
did the prior EL backlit panel, so they will operate
more quietly. Keypads with this feature also have
the updated circuit board. All keypads with serial
# 1568 and higher have this backlit panel.
- Epoxy coated elastomeric
keys.The keypad graphics will retain their
appearance longer. All keypads with serial # 1568
and higher have elastomeric keys.
- Additional internal improvements that take advantage
of advancements in technology.
Firmware updates are available at no charge to all owners
of Astro-Physics GTO mounts through an internet download.
Please refer to the download area of the Technical Support
section of our website.
This latest release is now available
to all Astro-Physics GTO mount owners. Check out the list
of new features. Our thanks to Charles Sinsofsky
and our beta testers for working with us to develop
PulseGuide is a stand-alone
Windows (98, ME, 2000, NT4, XP only) utility that provides
complete remote control of all Astro-Physics GTO mounts.
It derives its name from its most distinctive feature,
pulse guiding, which can improve unguided tracking.
Specifically, it can help correct tracking errors caused
by polar misalignment and atmospheric refraction. Additional
PEMPro (Periodic Error Management
Professional) is a Windows software application that
makes it easy to characterize and reduce periodic error.
PEMProAP is a special version that can only be used with Astro-Physics mounts. While the periodic error of your 900GTO will be 7 arc
seconds or less, you can reduce it even further to maximize
performance without auto-guiding. PEMProAP is included
with 900GTO mounts that will ship in 2005 and 2006. Additional
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Copyright © 2005, Astro-Physics, Inc. - All Rights Reserved
This page was last modified:
March 30, 2006
11250 Forest Hills Road, Machesney Park, IL 61115, U.S.A.
Phone: 815-282-1513 Fax: 815-282-9847