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Applications Supported | Stellarium Mobile | Stellarium Desktop | Sky Safari Pro | Aiming Accuracy
The Alpaca Benro Polaris Driver supports both the Alpaca ASCOM and SynScan protocols. This opens up a wide range of Telescope Control applications now compatible with the Benro Polaris. Out of all those listed, we recommend Stellarium PLUS and Stellarium Desktop.
- Stellariium Mobile PLUS (IOS, Android) - paid, telescope control via SynScan protocol.
- Stellarium Desktop (Win) - free, telescope control via Alpaca ASCOM
- Stellarium Desktop (MacOS, Linux) - free, telescope control via a binary protocol
- Sky Safari 7 Plus and Pro - paid, telescope control via Alpaca
- Nina (Win) - free, telescope control via Alpaca
- CCDciel (MacOS) - free, telescope control via Alpaca
- Stellariium Web - free, no telescope control
- Stellarium Mobile (IOS, Android) - free, no telescope control
- Sky Safari 7 Basic - free, no telescope control
- Skyportal - Celestron’s free version of Skysafari
- SynScan App and SynScan Pro App - Not currently supported
You can view a demonstration of parts of this documentation in the following YouTube Video.
Stellarium Mobile PLUS is ideal for use on a tablet or mobile phone, either Android or IOS. It includes more features than the free Stellarium Web and the free Stellarium Mobile offerings.
Stellarium Plus connects to the driver over the network using SynScan protocol. It is the most straightforward setup; you only need to do this once. To connect Stellarium PLUS:
- Select the Hamburger menu from the top left
- Select Observing Tools > Telescope Control
- Toggle it off/ and on to bring up the popup at the bottom left
- In the Host field, enter the IP Address of the ABP Driver.
- In the Port field, leave a default of 10001.
- Click the Link toggle to start the connection.
- Stellarium will attempt to connect to the driver.
- Choose Sync Location (Stellarium site alt/az will be sent to the driver)
- Choose Sync Time (Stellariam will send its time to the driver)
A Yellow Not Aligned flag indicates that the driver has not completed initializing its communications with the Benro Polaris and may still be out of alignment.
Commanding the Benro Polaris to move is as simple as Selecting the Target Object and clicking the Goto Icon. The icon will flash red while the mount is slewing and re-establishing sidereal tracking.
As the telescope sweeps across the sky, you will see a reticule marking its path. You can tailor the size of the reticule to match your camera and lens setup, allowing you to visualize your framing easily.
If you lose sight of where the mount is pointing in Stellarium, simply click this second icon, and the view will immediately pan to your reticle.
The third icon on the Telescope Popup allows you to move the primary and secondary axes of the Benro Polaris. The Driver supports move commands on the third (Astro) axis of the Benro Polaris, but we have not found any applications that support the third axis at this stage.
Speeds 1 to 5 match the slow Move Axis speeds of the Polaris. Speeds 6 to 9 map to a variable faster speed ranging from 1 to 2000 units. The table below gives you an approximate speed for each value.
| Rate | Rotational Speed |
|---|---|
| 1 | 21.5 arcsec/s |
| 2 | 1.1 arcmin/s |
| 3 | 2.8 arcmin/s |
| 4 | 5.3 arcmin/s |
| 5 | 12.5 arcmin/s |
| 6 | 1.0 degree/s |
| 7 | 2.0 arcdeg/s |
| 8 | 3.6 degree/s |
| 9 | 5.5 degree/s |
Note that Move Axis in Nina allows you to enter fractional speeds. Due to Benro Polaris, these only have effect from 5.1 to 9.0 (i.e., for the Benro Polaris Fast Move commands).
The Driver also implements Equatorial rotation move around the RA and Dec Axes. By setting the Rate to a decimal value between 1 and 2, you can control how far the driver will rotate on the next axis move call. A rate of 1.30 on the primary axis will move the Right Ascention axis 30°. A rate of -1.15 on the secondary axis will move the Declination axis -15°.
You can help improve the aim of the Benro Polaris by Syncing with a known object in the sky.
- Using the Move Axis controls, aim the telescope with the known object in the center of the eyepiece or image.
- Find the known object in Stellarium and select it.
- Tap the Sync icon on the Telescope Control Popup.
- The Reticle should immediately shift to your selected target.
- This amount will now offset all RA/Dec coordinates sent and received from Polaris.
To reset the RA/Dec Offset, simply tap the disconnect and reconnect icons on the Telescope Control Popup in Stellarium. For a better understanding of how this works, refer to Section 3 below.
Stellarium Desktop has the broadest set of features of all versions of Stellarium. It is flexible, allowing you to customize what is shown (deep sky objects, satellites, meteor showers, planets, etc.) and how it is revealed (annotations, projections, landscapes, etc.), including numerous sky surveys.
It includes an extensive What's Up Tonight tool for planning imaging targets. It also includes an extensive library of plug-ins that add more functionality to the application. It's a very powerful platform.
Stellarium Desktop on MacOS and Linux does not support native Alpaca or ASCOM. We have implemented a simple External Software Binary Protocol that only allows GOTO functionality. You can add an External Software Telescope by using the following procedure:
- Select the
Plug-instab on the Configuration Dialog menu bar. - Scroll down the list of plugins and find the
Telescope Control plugin. - Check
Load at startupon the Telescope Control Dialog. - Close Stellarium and Restart Stellarium from the Desktop.
- Press
Ctrl+0(Windows) orCommand+0(MacOS) to open the Slew Telescope Dialog - Click the
Configure Telescopesbutton at the bottom of this dialog. - Click on the
Add Telescopebutton (3rd one at the bottom of the Telescope Control Configure dialog). - Choose Telescope controlled by
External software or a remote computerand enterBenro Polarisinto the Name field. - In the Host field, enter the IP Address of the ABP Driver.
- In the TCP Port field, leave a default of 10001.
- Click OK
Unfortunately, Stellarium Desktop does not include native Alpaca support. You must install the ASCOM Platform if you haven't already done so. After the ASCOM platform has been installed, you can add an ASCOM Telescope by using the following procedure:
- Select the
Plug-instab on the Configuration Dialog menu bar. - Scroll down the list of plugins and find the
Telescope Control plugin. - Optionally, if you want to always use the ABP telescope, check
Load at startupon the Telescope Control Dialog. To browse Stellarium without Polaris, leave it unchecked, and just connect on demand from theCtrl+0(Windows) orCommand+0(MacOS) dialog. - Close Stellarium and Restart Stellarium from the Desktop.
- Press
Ctrl+0(Windows) orCommand+0(MacOS) to open the Slew Telescope Dialog - Click the
Configure Telescopesbutton at the bottom of this dialog. - Click on the
Add Telescopebutton (3rd one at the bottom of the Telescope Control Configure dialog). - Choose Telescope controlled by
ASCOMand enterBenro Polarisinto the Name field. - Leave the Coordinate System as
J2000 (default), - Check
Start/Connect on Startup. - Scroll down to the ASCOM Settings.
- Click
Choose ASCOM Telescope - Click the
Alpacatab on the ASCOM Telescope Chooser dialog box. - Click
Enable Discoveryfrom the Alpaca tab - Click
Discover Nowfrom the Alpaca tab - For a local APB, Choose
Benro Polarisfrom the drop down-menu, then clickOK. - For a remote APB, Click
Create Alpaca Driver (Admin)from the drop-down. a. ClickYesfor User Account Control. b. Enter the nameBenro Polaris, then clickOK. c. ClickPropertieson the ASCOM Telescope Chooser dialog box. d. Change the Remote Device Host Name/IP address (127.0.0.1when running ABP on same machine as Stellarium, otherwise enter the IP address of the machine running ABP (dont use192.168.0.x). e. Change the Alpaca Port to5555. f. ClickOK. - Click
OKon ASCOM Telescope chooser dialog. - Click
OKon Add a New Telescope dialog. - Click
Connectand close the Telescopes dialog. - You have now added the Benro Polaris telescope and connected it.
Commanding the Benro Polaris to move is as simple as Selecting the Target Object and pressing Ctrl+1 (Windows) or Command+1 (MacOS).
You can also bring up the Slew Telescope To dialog by pressing Ctrl+0 (Windows) or Command+0 (MacOS). This dialog allows:
- Manually enter the co-ordinates
- Select the Current Object
- Select the Center of the Screen
- Select from a customisable list of Targets
- Initiate the Slew of the Benro Polaris.
On Windows, as the telescope sweeps across the sky, you will see a reticule marking its path. You can tailor the size of the reticule to match your camera and lens setup, allowing you to visualize your framing easily.
If you lose site of your selected target, press SPACE, and the window will immediately pan to your selected object.
Stellarium Desktop allows you to create a custom Landscape to match your own observation site, including the image of the horizon overlaid into Stellarium.
To create your own custom Landscape:
- Create a 4096 x 2048 pixel image of your location's 360 degree horizon
- If you have an Insta360 X3 camera, take a 360 Photo from your tripod, with the screen facing. Open the image in Insta360Studio, change to a 2:1 FOV Ratio, and export the image.
- Take multiple images with a wide angle lens. Use Photoshop to merge the images into a 2:1 ratio image with the horizon in the middle and the 360 degrees spanning the width of the image.
- Use Photoshop to edit the 4096 x 2048 pixel image and convert the background into a single layer. Select the Sky, modify the selection shrinking it 15 pixels, feathering it 15 pixels, then deleting the sky selection. Save the image as a transparent png called
horizon.png. - Create a file called
location.iniwith the following contents, setting the name, latitude, longitude, altitude and timezone correctly.[landscape] name = Your Sites Observation Location type = spherical maptex = horizon.png angle_rotatez = 0.0 [location] planet = Earth latitude = -33.000 longitude = 151.000 altitude = 39 timezone = Australia/Sydney - Using Windows Explorer, select both files
location.iniandhorizon.png, then Right Click and select Compress To... Zip File. - Using Stellarium, open the 'Sky and viewing options' window by clicking F4, select the Landscape tab, click the Add/remote Landscapes button, then install the zip file you just created.
- Check the orientation of the image in Stellarium. You may need to fine tune the
angle_rotatezvalue to correctly align the image with reality. - You can now align your Benro Polaris during the day by syncing with a known spot in the horizon image.
You can use the Stellarium Desktop Remote Control Plug-in to further integrate Stellarium with Nina. Using this plug-in, Nina can pull any selected Stellarium Target into the Framing Tab on Nina.
To setup this integration:
- Using Stellarium
- Press
F2to callup the Configuration Dialog and navigate to the Plug-ins tab - Scroll down to Remote Control Plug-in and enable Load at startup.
- Restart Stellarium navigate back to its Configuration Dialog.
- Enable the Server and Enable the Server on Startup.
- Restart Stellarium
- Press
- Using Nina
- Navigate to the Options/Equipment tab
- Under the Planetarium, select Stellarium
- Enter the Host IP address of
localhostor its remote IP address.
Now on the Framing tab you can click on a small pin icon next to the Coordinates Heading and Nina will ask Stellarium for the currently selected Target Co-ordinates. Much better than Nina's Sky Atlas.
On Windows, you can help improve the aim of the Benro Polaris by Syncing with a known object in the sky.
- Using the Benro Polaris App, aim the telescope with the known object in the center of the eyepiece or image
- Find the know object in Stellarium Desktop and select it.
- Press
Ctrl+0(Windows) orCommand+0(MacOS) to bring up theSlew Telescope Todialog and clickSync. - The Reticle should imediately shift to your selected target
- This amount will now offset all RA/Dec coordinates sent and received from Polaris.
To reset the RA/Dec Offset, restart the driver. Refer to Section 3 below for a better understanding of how this works.
This section is optional and only provided to give you insight into the design and inner workings of the Alpaca Benro Polaris Driver.
The Benro Polaris is primarily an Altitude/Azimuth mount as opposed to an Equatorial mount. Although the third axis does help with sidereal tracking, the primary axis is Azimuth, and the secondary axis is Altitude.
The Driver must convert RA/Dec coordinates to Alt/Az when it commands Polaris. To do this accurately, it must have your correct time and location. It retrieves the time from the system clock, and the initial location is retrieved from config.toml, with the option to sync it from Stellarium or Nina later.
config.toml
site_latitude = -33.8598874 # Site latitude (degrees, positive North)
site_longitude = 151.2021771 # Site longitude (degrees, positive East)
site_elevation = 39 # The elevation above sea level (meters)
During testing, we noticed the Benro Polaris consistently misaligns it's aiming position due to the time taken to re-engage sidereal tracking. To compensate for this, the Driver calculates where the Alt/Az position of the coordinates will be a few seconds into the future. This can also be tuned in config.toml.
config.toml
aiming_adjustment_time = 20 # Aiming time (in seconds) in the future.
We also noticed that whenever the Benro Polaris is commanded to slew to an Alt/Az coordinate, the final position it tells us it has arrived at after sidereal tracking is re-enabled can be consistently off.
The Driver compares the final Alt/Az with the aimed Alt/Az for every GOTO command. It uses an Adaptive Integrative algorithm (hence the AI) to determine an Alt/Az offset to correct for any consistent error it notices. You can see this in the log after each GOTO command is complete. See below.
If you notice that the Alt/Az offset is consistently the same, you can set the initial Alt/Az offset to prevent the Driver from relearning on every startup. Copy the offset from the log to the settings in config.toml. The driver does not refine the Alt/Az offset if the error is too large. This can also be set in config.toml.
And finally, you can disable the time, Alt, and Az aiming adjustments using config.toml. When disabled, any RA/Dec coordinates are converted to Alt/Az and sent straight to Polaris without any fine-tuning adjustments.
config.toml
aiming_adjustment_enabled = true # Allow time, Alt and Az fine aiming adjustments
aiming_adjustment_az = 0 # The initial az aiming adjustment (in decimal degrees)
aiming_adjustment_alt = 0 # The initial alt aiming adjustment (in decimal degrees)
aim_max_error_correction = 0.5 # Ignore errors over this maximum angle (decimal degrees)
Telescope synchronization, or ‘syncing,’ aligns your telescope with the night sky. Syncing helps the Driver understand where the telescope is pointing compared to where Polaris thinks it is.
After identifying the actual center of view (from visual observation or plate-solving), you will notice that both Stellarium and Polaris may have it wrong. Syncing will help correct anything upstream of the Driver.
As soon as you select the actual object at the center of view and press Sync, you will notice Stellarium immediately corrects itself and positions the reticule over the target you have synced with.
The Driver remembers a Sync Offset to add to all coordinates sent to Polaris. It subtracts this Sync Offset whenever Polaris tells the Driver where it thinks it is pointing. You will see this Sync Offset in the logs when the Driver converts from ASCOM coordinates to Polaris coordinates.
The Driver supports two pointing Models depending on the sync_pointing_model setting in config.toml. Pointing model 1 uses an RA/Dec Sync Offset, and pointing model 0 uses an Alt/Az Sync Offset. We recommend pointing model 0, as it is more independent of the Polaris orientation.
By default, the Driver also performs a Polaris Star Alignment whenever a Sync function is performed. This tells the Polaris to update its alignment based on the current known coordinates of the Sync function. If the alignment is successful then the SyncOffset in the driver is reset back to zero, as the Polaris no longer needs correction.
The Polaris will also update its understanding of where the polar axis is based on the sync coordinates given and its understanding of its lat/lon position. Polar alignment is vital for sidereal tracking and minimizing the movement of stars during longer exposures.
You can change sync_N_point_alignment in config.toml to false if you do not want to align the Polaris on sync functions. When this is set to false, nothing is sent to Polaris, as the sync is purely within the Driver.
The following screen capture shows the log file of a successful GOTO command from Stellarium. The aiming ajustments are appled at (1) The SyncOffset RA/Dec, (2) The AimOffset for Time offset, (3) The AimOffset Alt/Az, and (4) Refining the AimOffset AltAz.
The process is as follows:
- Stellarium requests a SynScan GOTO RA/Dec command.
- The Driver turns this into an ASCOM GOTO RA/Dec command.
- The Driver calculates Polaris GOTO RA/Dec command, (1) adding any RA/Dec SyncOffset.
- The Driver calculates the Polaris Alt/Az co-ordinates, incorporating (2) the AimOffset time (where it will be 20s in the future) and (3) the AimOffset Alt/Az correction. The Driver issues the Goto Alt/Az Command to Polaris.
- Tracking is turned off
- Goto Slew startsd.
- Goto Slew ends.
- Tracking is turned on and backlash removed.
- Goto slew is marked as complete.
- The Driver calculates the Alt/Az error in Arc Seconds, (4) refining the AimOffset's Alt/Az values to improve Aiming Accuracy.
And finally plate solving is a game changer. I guarantee you will have a smile on your face the first time Nina successfully plate solves and automatically moves the Benro Polaris to point at what you asked it to point at in the first place. With spot on accuracy and validity.
Refer Using Nina for more on Plate Solving.