A product of NOAA's Air Resources Laboratory, in Boulder, Colo, the sunrise/sunset calculator went on line two years ago, according to John Augustine, a NOAA meteorologist in Boulder, Colo. The updated version became available this week.

"We wanted the ability to calculate solar noon in the field," said Chris Cornwall, a NOAA/CIRES electrical engineer. "That's important when you have instruments that have to be aligned north and south."

What started out as a purely scientific device has found favor with people from all walks of life, Augustine and Cornwall said.

"We have photographers who use it to take advantage of the available daylight," Cornwall said. "There was also a request from an architect who was working on solar lighting for a building in Hawaii and needed to know when and where the sun would be."

In addition to questions from students, Augustine added that they've received many requests from religious people who need to know the exact time of sunrise and sunset for the beginning and end of religious holidays.

The original program was developed by Cornwall and Aaron Horiuchi from work started by Chris Lehman.

Since the calculator has been updated, Augustine and Cornwall estimate that it's accurate "from 1,000 BC to 3,000 AD."

Relevant Web Sites * NOAA's solar calculator
http://www.srrb.noaa.gov/highlights/sunrise/gen.html
* NOAA Research
http://www.oar.noaa.gov/
* NOAA's Air Resources Laboratory
http://www.arl.noaa.gov/
* NOAA's Surface Radiation Research Branch
http://www.srrb.noaa.gov/