Continuing my previous posts on the Analemma, one can calculate the Sun's position during the day here in Las Vegas, NV. This position is typically given by angles -- azimuth, and altitude. The azimuth is clockwise from north, which is conventional for aviators. So the Sun rises in the East, about 90 degrees, and sets in the West about 270 degrees. At the midday zenith is South. Hence, one sees the value for having a southern exposure in terms of getting the day's light. At this time of year, we see that it is near vertical at 70 degrees.

This project is available under GNU GPL at https://github.com/str255/sun-mc
For your location edit the example parameters in equation_of_time.mc.

duration of the day over year in Las Vegas

Continuing my previous posts on the Analemma, one can calculate the rising and setting times here in Las Vegas, NV. From there, the duration is simply the difference from setting and rising. I am acutely aware of the functioning of our air conditioner because it was 115F -- hot and dry -- today. From the graph, I can see that this month -- July -- may be the most difficult month. Hopefully, August should be cooler. The day's length this month is over 14.5 hours, while August goes to 14 hours. The power did snap off for a few minutes this afternoon. I lost all power, and with it the internet and wifi. It came back soon thereafter. The LIFX lightbulb had some difficulty with the hard stop. By December, we have less than 10 hours sunlight.

Day light savings give the day rise and set lines a jagged edge in March and November. 

This project is available under GNU GPL at https://github.com/str255/sun-mc
For your location edit the example parameters in equation_of_time.mc.

Here is an analemma I generated for Las Vegas, NV of the year 2016. There is a lot of literature on this going back thousands of years. The word comes from the Greek analemma -- "prop, support". This is similar usage to the use familiar in mathematics of Lemma which as a supporting proposition. I can argue that the sundial is probably one of the first instruments devised by first man -- a simple stick in the ground whose cast shadow determines the measurement of a day. Further study by the first men, evolved into an understanding of that shadow changing with the seasons. And when the shadow is shortest separated the day from morning (AM) to afternoon (PM). Noon should be 12:00. However, it isn't. The difference is the "equation of time". And declination measures the length of the shadow. " The declination of the Sun, δ☉, is the angle between the rays of the Sun and the plane of the Earth's equator." See https://en.wikipedia.org/wiki/Position_of_the_Sun

This project is available under GNU GPL at https://github.com/str255/sun-mc
For your location edit the example parameters in equation_of_time.mc.

setting up raspberry pi with wireless keyboard and wifi. dongle

I got a wireless keyboard with wireless mouse from Adafruit as well as a wifi dongle. These all worked smoothly with very little configuration difficulties.

To get the wifi dongle to work, just edit /etc/wpa_supplicant/wpa_supplicant.conf with your ssid, psk, and key_management.

The keyboard works right out of the box -- the major difficulty is finding the USB dongle. Follow the instructions to set your keyboard for US layout.https://www.adafruit.com/product/1738

In which I admit failure, and revert to the RainBird controller

My attempts to reboot the Arduino and it's wifi shield failed. So, I wired the Rainbird controller back. Now everything is running as it was. Things are O.K.