Firmware Versions on the NexStar GPS Series
NexStar GPS scopes have two sets of processors. There are processors in
the hand control (HC) and there are processors in the base of the scope in a
section known as the motor control (MC). The MC firmware can be updated by
the owner (read
There have been three versions of hand control available for the NexStar
control 1.2, 1.6 and 2.2. Hand controls prior to version 4 can NOT be updated.
- Hand control version 4.X. This hand control can be updated by the
owner and was available for purchase from January 2006 through summer 2012.
for info on purchasing the upgradeable hand control and
for step by step instructions on upgrading the firmware.
- The NexStar+ hand control. This hand control can be updated by the
owner and is available for purchase since February 2012. Read
for info on this new hand control and
for step by step instructions on upgrading the firmware.
For additional details about features on newer versions, check the
Manuals section of this web site.
NexStar+ Hand Control
Celestron has posted an official document detailing all firmware versions
for the NexStar+ hand control:
Check back periodically for updates.
Version 4 Hand Control (firmware files are named NXS)
- 4.21 - Fixed the RS-232 negative declination bug found in 4.20.
- 4.20 - This version has a bug - if you connect a computer/PDA/smart
phone to the RS-232 port and direct a GoTo to an object with negative
declination, the scope will instead point to +90 declination. It
is recommended you upgrade to 4.21 or higher. Fixed an error in the GoTo RA-Dec menu item. Hand Control now
reports immediately if the are communication ("No Response") difficulties at
start up. No Response errors now give a "Press UNDO to continue"
option. For mounts with a GPS module in use, changed the messages
displayed to clarify when the GPS was still attempting a link and when it
- 4.18 - An important upgrade with many new features and fixes. The
hand control now calculates positions with respect to precession - in other
words, previously all coordinates were J2000 while this version uses JNow.
Polar alignment routine is now under the Align menu and allows alignments on
stars other than Polaris. Additionally, after polar alignment, the
scope no longer requires a new alignment. Fixes problems with Southern
Hemisphere alignments. Pressing ALIGN while in the Named Stars menu
now takes you to the Align menu. Sets slew rate to 5 upon waking from
hibernation. The Factory Settings menu item now resets all motor
control settings (as well as the hand control settings) and will force the
user to restart the system. The hand control is now locked when
performing a motor control upgrade via the port on the bottom of the hand
control. Added two PC control commands: one to undo any current
"Sync", the other to retrieve the local sidereal time from the hand control.
Fixed error when using SAO stars (selected from the STAR button) as
alignment objects. Fixes a bug which changes rate if a direction
button is pressed after the RATE button. Fixes a rare problem updating the motor control through
the hand control. Corrects Abell objects with negative magnitudes.
- 4.13 - This version allows the motor control (MC) firmware to be upgraded
via the port on the bottom of the hand control.
- 4.12 - The most significant change in this version is variable brightness
control for the display and buttons - values are from 0 (off) to 8 (full
brightness). There is also a fix that reduces (but does not eliminate)
the chance that the display comes up blank the first time you power up, a
problem much more prevalent in cold weather. The fix on those occasions
when it does still come up blank remains the same - turn off the power, wait a
couple of seconds and turn on the power again. The Version menu item has
been changed - it now displays the mount model after displaying the HC and MC
versions. This version is also the first to support the new NexStar SE
- 4.10 - The most significant change in this version is Sync. Sync is
available both via the hand control and via PC software (TheSky, Starry Night,
etc.). This provides very accurate GoTo pointing in the area of
the sky where the Sync is performed and it allows the PC software to match
with the actual position the scope is pointed to. Other new features:
Calibrate Goto (help to improve GoTo accuracy), general pointing accuracy
improvement, a display of the polar alignment error (when EQ mounted on a
wedge) and the ability to start PEC playback and proceed with normal use of
the hand control.
- 4.03 - Minor change from 4.02. GPS scopes manufactured from October
2005 forward where supplied with the user-upgradeable hand control and this
firmware version. Owners of older GPS scopes can take advantage of this
new firmware by using
NexRemote or by purchasing the user-upgradeable hand control separately
(owners of older versions read
here for more details on the features in version 4 of the hand control.
- 4.02 - First available for use
on NexStar GPS series through use of
NexRemote. This version provides several new features. First, the physical 4.02 hand control is the first version that can be upgraded
to new firmware by the user. It also introduced the new alignment
methods - SkyAlign, Solar System Align and One Star Align. Also added
are Precise GoTo, Identify, Constellation Tour and few other new features.
here for more details on version 4 of the hand control.
Non-upgradeable Hand Control
- 2.2 - A minor upgrade that includes support for the NexStar 5i/8i and a
slightly more accurate Wedge Align routine.
- 1.6 - The updated hand control with all features described in
- 1.3 - This version has been seen on at least one NexStar GPS scope - it
was not officially released by Celestron and the features seem to be
virtually the same as version 1.2.
- 1.2 - Shipped with original NexStar 8 GPS and 11 GPS scopes. Several
features have since been added and if you have this version, you should
definitely upgrade. To upgrade, purchase the user-upgradeable hand
for more information) but be sure you have motor control 3 or higher.
- SA 4.00 - Prior to being discontinued, the NexStar GPS was sold in a
SkyAlign version - the GPS-SA. The MC version on this scope was SA 4.00.
This version is the same as 4.06 with two exceptions. First, it will not
function with hand control firmware below 4.02. Second, it is not
possible to load older versions of MC firmware (all those listed below) over
- 4.06 (hand control 2.2 or earlier will display this as 4.6) - In addition to the fixes introduced in
40.40, this newer version also improves autoguider performance, fixes a
runaway that occurred when at rate 1 or 2 and using the "double key press" for
rate 9, fixes PEC issues and is the first version to support Celestron's free
- 40.40 - This is a beta (test) version but was released to the public.
Fixed autoguider problems including runaway slew when autoguiding.
Finally fixed the hop in Alt-Az mode.
- 4.5 - Fixed a minor problem with manual slewing at rates 5 and 6.
- 4.4 - That pesky hop was still present on some scopes and this version
attempted to address that problem, though it turns out that a some scopes still have the problem
when running this version.
- 4.3 - Incorporates a slightly improved tracking algorithm that attempted
a slight hop seen in some scopes when used in Alt-Az mode.
- 4.1 - This version features silent, accurate tracking and support for all
the latest NexStar features. It also improves the encoder resolution to 0.112
arcsecond. Unfortunately, it introduced a slight hop seen in many scopes when
used in Alt-Az mode.
- 3.0 - This version is
characterized by the 'bee in a can' tracking sound that solved the vibration
issue. It does not support some of the newest features such as cordwrap
prevention and advanced control via a Personal Computer. This is also
the first version that allowed user upgrades to the MC firmware.
- 2.0 - Shipped for a short while in both the NexStar 8 GPS and 11 GPS. This
version overcame problems with tracking, but there were still some problems
with vibration in some telescopes. If you have this version, read
- 1.0 - Shipped only in the original NexStar 11 GPS. This version had some
problems with smooth tracking and should definitely be upgraded. The most
detrimental problem is a vibration that affects high magnification views and
astrophotography. If you have this version, read
With hand control version 1.6 or higher, you will find a Version
option on the Utility menu. If you don't find a Version option on the
Utility menu, you have hand control version 1.2 and motor control version 1.0 or