 |
Newsletter
of the
Big
Bend Astronomical Society, Inc.
June,
1999
Jim
Walker, Editor
|
| Minutes
of the June 9th Meeting |
|
by Jim Walker, Secretary
|
Vice President Bernie Zelazny called the meeting to order
at 7:30 PM in the absence of President Bill Baker. There were 21
people present.
Bernie reviewed the May 3 meeting of the Board, the minutes
of which were printed in the May Newsletter. There were no additions
or corrections.
| Treasurer Betty Grimm presented
the following written report:
Bank balance 03/31/99
$902.64
April Activity
Receipts (Dues)
20.00
Disbursements
($500 to savings, $50 to IDA)
550.00
May Activity
Receipts
206.82
Balance 03/31/99
902.64
Less Lighting Fund
100.00
Working balance 05/31/99
579.46
|
First National Bank in Alpine Savings Account
Opened 09/25/98
Balance 03/31/99
$714.46
April transfer from working funds
500.00
May disbursements
150.00
Balance 05/31/99
$1,064.46
|
Murray Newman Fund 01/19/99
CD 925.00
Interest
10.32
Murray Newman Fund 05/18/99 CD
2,952.79
Fund CD Balance
3,888.11
|
First Science Nights at the HET
Dr. Matthew Shetrone,
Resident Astronomer with the Hobby-Eberly Telescope at McDonald Observatory,
told us the HET is now officially at work. With the installation
of the Low-Resolution Spectograph the HET is now doing science, making
its first original observations that are adding to our knowledge of the
universe.
Matt showed
us images taken with integration (exposure) times of 15 seconds to 10 minutes
with the HET's CCD camera. Anyone who has ever taken a long, tedious,
time exposure with a small telescope and a film camera can especially appreciate
the speed of a big scope and a CCD (charge-coupled device), a very sensitive
and very fast electronic camera. The HET is designed for spectroscopy,
but it is necessary to observe an image of a portion of the sky in order
to select an object for examination with the spectrograph.
The spectrograph,
like a prism, separates the light from an object into its component wavelengths,
each wavelength corresponding to a color. Emission lines are the
bright regions of a spectrum, and absorption lines are regions where a
spectrum is darkened by passing through a gaseous cloud that selectively
absorbs particular wavelengths. These lines in the spectra of distant
objects are shifted toward the red end of the spectrum, that is, their
wavelengths are lengthened. This red shift indicates that distant
objects are moving away from us - hence the big-bang theory of the origin
of the universe.
The Z value
of a spectral line from a moving object is the shift of its observed wavelength
compared with the same spectral line from an object at rest with respect
to the observer. Matt showed us a portion of the spectrum from a
20th magnitude quasar having a Z of 2.95. It is possible to estimate
the velocity of an object from the observed red shift, and then to estimate
its age using the rate of expansion of the universe, the Hubble constant.
This quasar was estimated to be about 10 billion years old.
The 91 individual
mirrors in the HET must be aligned each time the scope is moved to look
at another object. Moving and aligning takes about 10 minutes, and
an observation also takes about that long, so the scope is now working
at about 50% efficiency - using half the available time for actual observations.
The addition of new sensors on the backs of all the mirrors, at a cost
of $500,000, will maintain the alignment of their edges all night.
This will increase the efficiency of the scope at once to 75%, and perhaps
eventually to 90%.
The HET recently
confirmed a Type II supernova, but the Keck Telescope people in Hawaii
had reported the discovery a little earlier. No doubt there will
be other occasions when the HET will be first. Go team!
-
On the Lighting Front
-
by Jim Walker
Texas Lighting Bill HB916
The governor
signed our bill into law on June 19. We now have another reason to
celebrate Juneteenth Day!
Unfortunately,
the bill applies only to state funded facilities. At the request
of TxDOT, Pete Gallego, the sponsor, amended the bill, changing the "full
cutoff" provision to "cutoff." The new provision will allow 2 1/2%
uplight. This is disappointing, but the bill at least represents
a beginning. And there will be other legislative sessions in other
years.
A copy of
the enacted version of the bill is attached.
A lot of work by a lot of people went into this piece of legislation.
Local Lighting
Our new light
meter has already proven useful in several measurements I have made around
town. The foot-candle is the unit of measurement, which is the light
falling on a point 1 foot from a 1 candela source. The candela is
the modern unit essentially equal to the light emitted by a standard candle.
Some examples:
A well-lit classroom (204 ACR, at front table)
50 fc
3 offices
38 to 57 fc
2 parking lots (maximum, directly under lights) 10 to
22 fc
8 service stations (maximum under canopy)
11 to 130 fc
Town &
Country was the brightest of our service stations. Does anyone need
2 or 3 times the brightness of a well lit office or classroom to gas up
a car? And think about what happens when you leave such an overlit
area and drive onto a normally lit street or highway: How well can
you see while your eyes are dark-adapting to a normal level of lighting?
Alpine Planning
and Zoning Board. City Manager Lively made a place for me on the
agenda at the June 7 meeting of the P & Z Board. Before the meeting,
I gave Doug a copy of a lighting ordinance for Alpine that I put together
based on several other ordinances from other parts of the country (he kindly
made copies for the Board members and for the City Council).
I gave an
updated version of my testimony at the hearing on HB916 in Austin, and
my presentations to the County Commissioners and the City Council.
In addition, I did a show-and-tell with a model full cutoff fixture that
I could also use in an unshielded mode. Our new light meter was useful
in making measurements under various conditions. Several BBAS members
were at the meeting.
I believe
my presentation was well received, but time will tell. If the P &
Z Board approves the ordinance, it will then go before the Alpine City
Council. This will not happen overnight, but we do have the attention
of the city government, partly thanks to the appearance of the New Town
& Country service station.
Please read
carefully the attached ordinance for
Alpine, and please let me know if you have questions or criticisms.
I will ask for your formal support of this ordinance at our July meeting.
¡COMING EVENTS!
REGULAR MEETING: Wednesday,
July 14, at 7:30 PM.
Arrangements still in progress. We'll contact everyone by phone or
email - stay tuned!
NEXT Star Party:
Saturday, July 10 at 9:00 PM
at John & Brenda Bell's in
LIMPIA CROSSING (near Ft. Davis)
(Sun sets at 9:06 PM).
Click
for printable map to the Bell's.
Note: This is a very large image file that prints
out 8.5" x 11"
and takes about 90 seconds to download with a
28.8. modem
ALTERNATE STAR PARTY DATE:
Sunday, July 11, same place & time.
Please note: There will be no potluck suppers until we go off
daylight saving time in the Fall.
Please call or e-mail Jim
Walker at 364-2467, or Bernie
Zelazny at 837-1717 if you need further information.
Go to Schedule
Page for more info
|
¡1999 Dues Now Payable!
It's that time of year again.
Dues for 1999 are now payable.
If you have not yet paid your dues
for this year please send a check to
Betty
Grimm, BBAS Treasurer.
Our dues are still $20.00 per year
payable on a calendar-year basis,
the same as for 1996, our first
full year of the society.
|
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