NexStar Resource Site

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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 this).

There have been three versions of hand control available for the NexStar GPS:

  • Hand 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.  Read this for info on purchasing the upgradeable hand control and this 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 this for info on this new hand control and this 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.

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NexStar+ Hand Control

Celestron has posted an official page detailing all firmware versions for the NexStar+ hand control:
Check back periodically for updates or click the link to sign up for notifications.

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Version 4 Hand Control
(firmware files are named NXS)

  • 4.22 - Fixes the date when the internal GPS returns a date 20 years in the past.
  • 98.22 - Only for use from May 2019 through Aug 17, 2019; fixes the date when the internal GPS returns a date 17.5 years in the past.  After Aug 17, 2019, switch to version 4.22.
  • 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 was successful.
  • 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 mounts. 
  • 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 this).  Click 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.  Click here for more details on version 4 of the hand control.

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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 this review.
  • 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 control (read this for more information) but be sure you have motor control 3 or higher.

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MC Versions

  • 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 this version.
  • 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 PECTool utility.
  • 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 to eliminate 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 this.
  • 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 this.

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Determining Versions

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 2.0. 

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Michael Swanson
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