AstroHopper (formerly known as skyhopper) is a free and open source progressive web application developed Artyom Beilis a software developer and amateur astronomer based in Israel. The application helps users find objects across the night sky. Simply attach a smartphone to a telescope and the setup becomes a “push to” system. The application has been released in version 1.0.6 and includes a number of enhancements
AstroHopper works by allowing an accurate hop from a well-known and easily identifiable star to other fainter stars or DSO by measuring changes in angles of the cell phone using the built in gyroscope and gravity sensors. It is similar to having digital setting circles implemented in a smart phone (The smart phone has to have gyro, gravity sensors and preferably a compass).
To use the application, attach the cellphone to the telescope such that the physical top part of the phone points towards the viewing direction. Note this is different from sky observing apps that simulate camera view of the sky. For this application the screen is parallel to the viewing direction.
Before you attach the smartphone, open AstroHopper and calibrate the compass using “8” like movements. The calibration will significantly improve compass direction accuracy. Then attach the phone to the telescope and follow these steps:
– Align your telescope with an easily identifiable star or a planet near the object you want to observe
– Tap on Align button
– Tap on the star or the planet you selected. 3s timer is started to make sure there is no shaking. After 3 seconds the application is aligned on the selected object. “Aligned” message is shown and a cross that represents the direction your telescope is looking to is shown in the center of the screen.
– Tap on an object you want to observe and you get a line showing a direction you need to move the telescope to and the changes in altitude and azimuth are shown at the right and bottom part of the screen
– Move the telescope till these numbers are close to zero – at this point your telescope should point to the requested object
– In order to move to next object – repeat the alignment process from the step 1 since the built-in cellphone gyros don’t keep the accuracy for a long time/multiple movements
Here you can find a demonstration and tutorial video created by Nir Zonshine: https://youtu.be/AtArqBLWWJ8
Notes for iOS Users
You need to provide some permissions to Safari in order to run AstroHopper properly as follows.
Device Orientation Sensors:
– For iOS 13.0 and above you need to allow access to device orientation information by pressing Enable Device Orientation button once application loads
– For iOS 12.2 and before 13 you need to allow access via: Settings > Safari > Motion and Orientation access
Geolocation (watch for No Geolocation message on screen):
– Settings > Privacy > Location Services ON. Then scroll down to “Safari Web…” and check mark “While Using the App”. For iOS 14.0 and above both precise and approximate location should work.
AstroHopper is a progressive web Application. It can be installed as regular application on your smart phone. Once it is installed it is fully accessible offline.
In order to install the application, open the URL https://artyom-beilis.github.io/astrohopper.html and install it:
– Android/Chrome – tap on “…” near the URL, and select “Install App” or “Add to Home Screen”
– Samsung Browser – tap on ↓ symbol near URL
– Android/Firefox – tap on “…” near the URL, and select “Install”
– Android/Edge – tap on “…” at the bottom and select “Add to Phone”
– iPhone/Safari – tap the “Share” button scroll down and select “Add to Home Screen”
The application will be installed on the home screen or in an applications screen – depending on browser.
To test if it works offline:
– Close all applications/browsers
– Put your phone to “Flight/Airplane” mode, make sure WiFi is closed
– Tap on application icon and make sure it works properly
You can usually update the installed version of AstroHopper by refreshing the page. If this does not work for your browser, uninstall it and install from the scratch.
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