Scope Setup

Use these settings to specify what kind of telescope hardware you have, and how SkySafari should communicate with your telescope.

In order to communicate with your telescope, you will need either:

You can also use our SkySafari software, running on a macOS computer with Wi-Fi and a serial port, as a Wi-Fi-to-serial server. See Simulation Curriculum's web site at for more details.

Equipment Selection

Scope Type - selects the type of telescope you want to control. SkySafari can control any of the telescopes in the list. SkySafari supports many encoder systems that can read out the telescope position but not actually move the telescope. The Celestron AstroMaster and JMI NGC-MAX are examples of such encoder systems.

Mount Type - selects your telescope's type of mounting:

If your telescope mount has encoders which provide a digital readout of the scope's position, additional text fields will appear here. These let you specify the encoder resolution.

RA/Azm - The number of steps per revolution for the encoder attached to the telescope's Right Ascension axis (or Azimuth axis, if you have an alt-azimuth mount).

Dec/Alt - The number of steps per revolution for the encoder attached to the telescope's Declination axis (or Altitude axis, if you have an alt-azimuth mount).

Get Automatically - If turned on, SkySafari will attempt to read these values from your encoders when it connects to the telescope controller. If turned off, you can enter the encoder steps per revolution manually; then SkySafari will send the values you entered to the encoders when connecting to the telescope. You can do this if (for example) your mount is using gears or pulleys to increase the effective encoder resolution.

Depending how your encoders are installed, their position readouts may increase when they are turned clockwise, or increase when they are turned counterclockwise. If the encoder position readouts increase when they are turned counterclockwise, enter a negative value for the number of steps per revolution. You may need to determine the correct + or - sign by trial-and-error. If you push your telescope left (or up), but the telescope field-of-view indicator on the sky char moves right (or down), the sign is probably wrong.

Communication Settings

If you are using SkySafari with SkyWire connected to your iPhone, iPad, or iPad Touch, then SkySafari will use SkyWire (rather than Wi-Fi) to communicate with your telescope.

If you are using SkySafari for Android, then the first two settings below determine how SkySafari communicates with your telescope - either via Bluetooth or Wi-Fi. These settings are not present in the iOS version of SkySafari.

Connect via Bluetooth - If selected, SkySafari will only attempt to communicate with your telescope using a bluetooth serial adapter. The adapter must be turned on, physically connected to your telescope's serial port, and paired with your Android device.

Connect via Wi-Fi - If selected, SkySafari will only attempt to communicate with your telescope using a Wi-Fi adapter like SkyFi. The adapter must be turned on, and physically connected to your telescope's serial port.

If you are using Wi-Fi, then the following settings must be correct. These are only used with Wi-Fi telescope communication. They will be disabled if you are communicating via bluetooth, and ignored if you are using SkyWire with an iOS device.

Celestron WiFi Telescope Settings

If you have chosen Celestron WiFi as your telescope type, the Communications Settings section described above will not be present. Instead you will see choices for Setup and Control and for Communication. The Setup and Control screen will have options that vary depending upon the exact Celestron WiFi scope you are connected to. The Communication screen will allow you to change whether you connect to the WiFi directly or by using access point mode where the WiFi scope has joined your local network.

Additional Settings

Set Time and Location - If turned on, SkySafari will send the time and location from your mobile device to the telescope when establishing a connection. This will overwrite your telescope's previously-set time and location. For some telescopes, this may invalidate your alignment. For older Meade LX-200 telescopes, this may also cause a delay of up to 15 seconds when connecting.

Note: This option is disabled with Celestron WiFi scopes. The time and location is always sent in this case.

Readout Rate - The readout rate is how often SkySafari requests the telescope's position from the mount. If you set this rate to "4 per second", then SkySafari will request the telescope's position (and update it on screen) four times every second.

If the telescope communication drops often, the rate of position requests may be too high for the telescope to respond properly. Setting a lower rate of 1 or 2 readouts per second may improve reliability. The best readout rate may require some trial and error to find. A lower readout rate will update the telescope's position in the sky chart less frequently, and may make SkySafari's telescope controls feel sluggish.

Save Log File - If turned on, SkySafari saves a log of its communication with the telescope on your mobile device. SkySafari creates a new log file every time you connect to the telescope. The log file records every command that SkySafari sends to the telescope, and every response from the telescope. The log file name contains the date and time you began the telescope session, for example:


This log file can be emailed to Simulation Curriculum for troubleshooting telescope communication problems. You can transfer the telescope communication log from your iOS or Android device using iTunes file sharing (iOS) or SD file card transfer (Android).