During my
first total solar eclipse in Aruba (February 26, 1998), I was intrigued
by the effect of the eclipse on environmental conditions like temperature
and relative humidity, and by the rapidly changing light levels surrounding
totality. However, I did not want to take time away from observing
the eclipse to manually make measurements. What I needed was a capability
to have measurements taken automatically while I enjoyed and observed totality.
Onset
Computer Corporation had the perfect solution, their series of HOBO®
and StowAway® data loggers. Onset manufactures and sells compact
programmable data loggers that can take environmental measurements at user-specified
intervals and durations. Using their BoxCar
Pro® software, the data loggers are programmed and launched via
a simple serial port cable from any PC (desktop or laptop). After
taking the data, you simply reconnect the cable and download the data.
Onset Computer Corporation graciously
lent me the loggers and software for the eclipse, and in return I shared
my results. A photo of the various loggers they loaned to me is shown
in the photo below.
I hung the HOBO®
H8 Pro RH/Temperature Logger from tree branch about five feet above
the ground (see photo below) right next to the ATMoB site. The location
was well shaded and provided a good stable location to make the measurements.
This logger measured temperature and relative humidity at one second intervals.
A HOBO®
Light Intensity Logger was secured on the clock-driven equatorial
mount of Michael Koop, one of our group members, at the main group location
on the grass behind the hotel. We oriented the logger atop his Celestron
90 mm catadioptric telescope so that the sensor was pointed directly at
the sun during the entire eclipse. A second HOBO®
Light Intensity Logger, along with a StowAway®
Light Intensity Logger, were placed flat on the floor of the of the
hotel balcony where I was located, out of the way of foot traffic.
Thus, they were pointing at the zenith during the entire eclipse.
The HOBO®
Light Intensity Loggers, with enough memory for 2048 measurements,
took data every eight seconds while the memory-rich Stowaway took data
every 0.5 seconds. I got the probes into position about ten minutes
before first contact. In an ideal world, I would have liked to have
environmental data taken all day but our itinerary did not allow for this
option.
Location of Hobo Temperature/Relative Humidity Logger
