by rgrokett @instructables:
Overview – Part 1 Alt/Az Pointer
Expanding on my Stepper Motor controller using Adafruit Huzzah ESP8266 WiFi module by adding a small Servo, I created a mechanical device that can move in Azimuth (using a Stepper) and Altitude (using a Servo). This makes for a compact and low-cost remotely controlled celestial pointer. In this case, it can be used to point at the International Space Station (ISS) as it flies overhead.
Because the ESP8266 is a bit short on memory to handle the celestial calculations, I have split this project into two parts. The first part builds a generic Azimuth and Altitude control with an LED at the end of a pointer. It is controlled by sending HTTP commands to move the Stepper and Servo and light the LED.
A separate project will add a Linux server, such as a Raspberry Pi, to do the ISS calculations and send the HTTP commands to this ESP8299 pointer. Note that you could use this to point at any object using its horizontal and vertical positioning commands, not just the ISS.