Higany

Thank you for the excellent project! This was my first try with the Raspberry Pi.It captured a fireball on the first night when I tested it with my ASI120MM.I purchased a used ASI120MC on Ebay for cheap and a ruggedized outdoor CCTV dome for it on Ali. The RPi is in a box in my Astro-shed. The dome has a dew-heater, made of 4pcs. 5W 1,2ohm resistors in series and it is powered from 5V, the total heating power is ~5W. The heater is controlled by an ESP8266 microcontroller, it has a DS18B20 temperature sensor in the dome and an SHT30 temperature and humidity sensor outside, and an N-channel MOSFET for switching the resistors. The heating turns on if the dome temp is only 4°C above the outside dew temperature and turns off at 4,5°C difference. First it was set to 3°C, but that was not enough…

Thank you for the excellent project! This was my first try with the Raspberry Pi.It captured a fireball on the first night when I tested it with my ASI120MM.I purchased a used ASI120MC on Ebay for cheap and a ruggedized outdoor CCTV dome for it on Ali. The RPi is in a box in my Astro-shed. The dome has a dew-heater, made of 4pcs. 5W 1,2ohm resistors in series and it is powered from 5V, the total heating power is ~5W. The heater is controlled by an ESP8266 microcontroller, it has a DS18B20 temperature sensor in the dome and an SHT30 temperature and humidity sensor outside, and an N-channel MOSFET for switching the resistors. The heating turns on if the dome temp is only 4°C above the outside dew temperature and turns off at 4,5°C difference. First it was set to 3°C, but that was not enough to prevent dew. This could be done with the Pi as well probably, but I am more experienced with the ESP. Why ESP and not Arduino? It has OTA, and it uploads the data to Thingspeak too and a web server and a remote snow-melting function will be added in the future.The resitors and the temp sensor are on a 4mm plywood shield. Everything on the shield was painted matte black with acrylic paint (including the metal parts of the lens too) to prevent reflections inside the dome. Without it you can even read the text on the lens in the reflection. I had to mask out the street lamps with black electrical tape, because they ruined the long exposure images.I purchased a 1.39mm F1.8mm 5MP M12 mount lens on AliExpress for $13, and a M12 to CS-Mount adapter for $1.55. (The CS-mount T2 adapter comes with the factory lens of the ASI camera) This 1.39mm lens gives a full circular 180° FOV with the 1/3" sensor of the ASI120MC and it has quite good quality even with better cameras. I had to remove the "built-in" IR filter of the ASI to get focus, but it is very easy to remove that filter, just twist off the front of the ASI and the filter sits on a rubber O-Ring. I removed the IR filter from the lens too, but it is not necessary. The system works 24/7, it uploads an image every 15/20 seconds (day/night) to the Hungarian weather observer community site: https://www.idokep.hu/webkamera/Zolkabolka2The only bug I found, that sometimes the image is shifted, 1 normally exposed top half and 2 underexposed quater on the bottom. This can happen day and night, and with the ASI120MM and ASI120MC too.One development idea: Support for Linux UVC cameras? There are USB-camera modules available from China with Sony IMX chips, for example with the IMX291 for about $55. The same excellent chip as in the ASI290MC, but for less than 1/6 of the price. Unfortunately the ASI driver doesn't support these modules, only the Linux UVC driver. I think I will build another for my fellow astronomer friends... Thank you!