FWAS Observing Site
The FWAS observing site is in southwestern Wise county. It's
about 45 miles from downtown Ft. Worth, has a large parking area,
campground, clubhouse, and a restroom. There are 20 concrete pads
with electricity, four larger round concrete pads for big Dobsonians.
The club owns four 10 inch Dobsonians and two 12 inch Dobsonians
for member's use.
The site is open to all FWAS members at all times. Members are
asked to please keep site and clubhouse clean, and latch the
gate upon leaving. It's also a good idea to take a look at
the forecast
and check the Clear Sky Clock, provided below, before you plan any trips.
Clear Sky Clock
Below is the Canadian Meteorological Centre's (CMC) Clear
Sky Clock for the Observing Site in Wise County. To learn how to read
the Clock Click Here. The graphic shows the Cloud
Coverage, Sky Transparency and Sky Darkness for a 10 mile radius around the
observing site.
How to read the Clear Sky Clock
Summary: Find a blue block in the first row.
There probably wont be any clouds in the sky then.
Details: Read the image from left to right.
Each column represents a different hour. The first two colored blocks
in the columns are the colors from CMC's forecast maps for Fort Worth
Astronomical Society Observing Site, for that hour. The two numbers
at the bottom of a column is the local time, in 24hr format, of that
hour. (Local time for Fort Worth Astronomical Society Observing Site
is -6.0 hours from GMT.)
The image above shows one hour resolution.
But currently CMCs forecasts only every 3 hours. CMC is planning true
hourly resolution for summer 2002. In the meantime, the Clock image
above will typically show the same color for each triple of 3 hours.
The line, labeled cloud
is visible-light cloud forecast. It forecasts percentage cloud
cover. Dark blue is clear. Lighter shades of blue are increasing
cloudyness and white is overcast. This forecast may miss low cloud
and afternoon thunderstorms. CMC's text page explaining this
forecast is here.
The line, labeled tran,
is the transparency forecast. Here 'transparency' means just
what astronomers mean by the word: the total transparency of
the atmosphere from ground to space. It's calculated from the
total amount of water vapor in the air. Dark blue means excellent
transparency befitting Arizona. Light blue is better than average
and pale blue is worse than average. White means that there is at
least some broken cloud. Look at the cloud forecast for the same
time to see how much cloud there will be.The transparency forecast
seems to be somewhat pessimistic. CMC's text page explaining the
this forecast is here.
The line
labeled darkness is not a weather forecast. It shows
when the sky will be dark, assuming no lightpollution and a
clear sky. Black is a dark sky. Deep blue shows interference
from moonlight. Light blue is full moon. Turquoise is twilight.
Yellow is dusk and white is daylight. For those who prefer numbers,
the scale is also calibrated. The colors represent the limiting
visual magnitude at the zenith. The legend row at the bottom shows
the magnitude that each color represents, from mag 6, for a dark
sky, to mag -4 for daylight. It is based on Ben Sugarman's
Limiting Magnitude calculations
page. It takes into account the
sun an moon position, moonphase, solar cycle and contains a
scattering model of the atmosphere. It doesn't consider light
pollution, dust, clouds, snow cover or the observer's visual
acuity. So your actual limiting magnitude will often be
different.
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