Hemisphere Solar Tracker Usage Instructions
How to use the Hemisphere Solar Tracker
Discover the intricate dance of the Sun with the Hemisphere Solar Tracker (HST). A device that combines a hemispherical globe, a magnetic compass, and a spirit bubble level, all mounted on a tripod for stability and accuracy. By making hourly shadow markings, this tracker not only captures the Sun's journey across the sky but also transforms solar observation into a tangible, educational experience, enhancing your understanding of the celestial movements that light our world.
Before starting, be sure to see the NASA guidelines on Sun observation.
To use this guide, your HST should already be mounted on to the tripod. When mounting the HST to the tripod, be sure to use non-ferrous mounting bolts such as brass or plastic, so as to not interfere with the Compass.
To use this particular device, always keep the Sun behind you. Stand in such a way that the reflection of the Sun on the dome of the HST does not reflect into your eyes. You may want to also use a piece of masking tape or a paper shield to place between your eye and the reflection of the Sun.
You can review the video instructions if you would like.
I. Gear preparation
Set an alarm to ring once an hour. This is a reminder to take a reading every hour.
Prepare the sticky dots. You may want to write numbers on them. You can number them according to the number of readings you expect to take. Or you can write the hour of your readings onto the dots.
Put your dots, tweezers and logbook by the door. Wait for the alarm.
II. Location preparation
A. Find a location.
While waiting for your alarm, leave your Laboratory. You need to choose a spot outside that will be in the Sun all day. Make sure this Data Collection location is NOT in a place where it will be disturbed by other people or animals.
Use this site to predict where the Sun is likely to move across the sky. Choose your location accordingly.
If you are in the Northern Hemisphere, make sure that there are no obstructions, like buildings or trees South of the tripod's location. You do not want any shadows during the movement of the Sun that will be cast upon the HST.
III. Install the Unit
A. Tripod preparation
Set one of the legs of the tripod to be shorter than the others. Place this on the ground on the side of the tripod pointing South. Use the compass to determine which way is South.
Loosen the yaw, roll, and pitch set screws on the tripod. Use the yaw to to align the compass to North. Use the pitch and roll to adjust the bubble level to be in the exact center. Then tighten the set screws.
Level the unit by using the two axis Level which is built into the tripod. Adjust the tripod legs, if necessary.
The Bubble Level on the HST should be as centered as possible.
B. Align the compass with magnetic North.
How to find your Correct Compass Bearing
Go to this website to calculate your offset from True North.
Calculate your Latitude and Longitude:
- Enter your location in the "Location" box.
- Hit the "Get & Add Lat/Lon" button.
Correct your Compass Bearing:
- Enter "0" into the "Compass Bearing:" box.
- Hit the "Calculate" button.
- Make a note of the True Bearing.
- Rotate your HST to the True Bearing, when you're in the field.
IV. Data Collection and Processing
A. Heed the Alarm
This is the fun part - Data Logging!
When the alarm goes off, grab your gear and go outside to your HST.
B. Take the readings
When using this device, stand with the Sun behind or at a right angle away from you to avoid Sun glare reflecting on the dome.
If the Sun's reflection has a chance of being in your eyes, cover it with masking tape or a paper shield.
Using tweezers or a small hand, apply a dot to the dome, place it where the shadow cast from the dot is centered and covers the central Sun icon on the HST.
Repeat this once per hour.
Hold the dot in front of the dome. Make sure that the dot casts a shadow inside the dome. Look for the point where the shadow of the dot fully covers the Sun shape in the middle of the dome.
You can also use a grease marker.
Place the tip of the marker where it casts a shadow on the Sun shape in the middle of the dome.
Draw an 'X' where shadow of the the center of the x is at the center of the Sun shape.
Things to note in your Logbook:
- Date
- Time the experiment starts
- Longitude
- Latitude
- True Bearing
- Time of Sunrise
- Time of Solar Noon
- Time of Sunset
- Make a note of the time whenever you add a dot.
IMPORTANT Do not move the device after the first reading is taken.
C. Disassemble the experiment
Before moving the tripod, be sure to leave some markers on the ground for the next time you want to run the experiment. Show the location of the tripod legs with some rocks or other type of marker.
Bring the HST into lab and remove it from the tripod.
D. Data processing
To convert the readings on the globe into usable data, bring the HST indoors and use the swing-arm to convert the positions of the dots into azimuth and elevation/altitude.
Place the HST flat on a table. Set the the swing arm on to the protractor of the HST.
Move the swing arm to the center of each dot. Take the readings from the center of the dot. Use the vertical scale for the elevation which is measured in degrees above the horizon.
Read the numbers on the Swing Arm to get the elevation/altitude and the azimuth of the Sun.
Use the horizontal circular scale for azimuth which is the direction measured in degrees clockwise from North. Read the numbers on the base of the Swing Arm to get the azimuth of the Sun.
Record these numbers in a notebook. Match each dot to the time the dot was placed onto the dome in the field.
Make a note of each dot's number and it's corresponding elevation/altitude and azimuth. Write those numbers down in the logbook.
Congratulations! Your data logging is complete for the day!
Now, it's not necessary to monitor the Sun's path daily. Decide on the frequency of your data collection. Starting with monthly tracking is a good practice. Additionally, tracking the equinoxes and solstices is absolutely vital for gaining a comprehensive understanding of the Sun's movement in the sky."