Lightning Strikes Observatory

About a month ago lightning struck an amateur observatory belonging to
a member of my astronomy club http://www.howardastro.org. The
observatory dome was made of fiberglass. I have not talked to the
owner, but I received this information from Company Seven, which has
first hand knowledge of the incident.

I have not seen the observatory, before or after the strike -- but I
have seen one of the damaged 'scopes, a Takahashi refractor of about 4"
aperture. The tube has two burn marks, one near the dew shield and one
on the tube near the focuser. The latter is roundish with a diameter of
2-3". The paint is gone and the underlying aluminum shows some signs of
slight surface melting, though the tube was not perforated. There is
also some blackening in the area. The damage appears to be typical of
that caused by electrical arcing. I did not have the opportunity to
look at the damaged area from inside the tube. The objective, which was
pristine, is spotted with an unknown material on its front surface. The
material gives the /appearance/ of being vaporized metal that condensed
in extremely thin spots. It is not considered economical to repair this
'scope.

It gets worse. A 6" Astrophysics refractor and its Astrophysics 1200
mount (neither of which I have seen) were destroyed. The Astrophysics
tube is said to have been destroyed from melting and fusing. The optics
were also destroyed, with pitting and loss of coatings. The mount has
its gears welded together, and is also a total loss.

The owner of the observatory reports that he has talked to a couple of
others whose fiberglass-domed observatories have been struck by
lightning.

Davoud

--
usenet *at* davidillig dawt com

Davoud wrote:
[snip]

The owner of the observatory reports that he has talked to a couple of
others whose fiberglass-domed observatories have been struck by
lightning.

The veiled inference here is that fiberglass domes are more of a risk
that your Aluminum one ? lol

Not hardly.


Bill



--

William R. Mattil : http://www.celestial-images.com

"William R. Mattil" wrote in message
. ..
Davoud wrote:
[snip]

The owner of the observatory reports that he has talked to a couple of
others whose fiberglass-domed observatories have been struck by
lightning.

The veiled inference here is that fiberglass domes are more of a risk that
your Aluminum one ? lol

Not hardly.

I took it more to mean that you should have a lightning rod and grounding.

Davoud:
The owner of the observatory reports that he has talked to a couple of
others whose fiberglass-domed observatories have been struck by
lightning.

William R. Mattil:
The veiled inference here is that fiberglass domes are more of a risk that
your Aluminum one ? lol

Not hardly.

John Nichols:
I took it more to mean that you should have a lightning rod and grounding.

What a jerk Mattil is! No wonder I don't see his posts directly :--)
What I wrote meant nothing at all; I quoted what I was told and made no
veiled references to anything whatsoever. Re-reading my post, I can
find no reference to my own observatory.

A lightning rod would be a great idea on such a structure; although the
dome in question was not the highest structure around, (nearby house
and trees) it is possible that the AP refractor on its pier was the
highest sizable bit of metal around and thus vulnerable.

This doesn't mean anything either: when I was in the communications
racket I noted that small fiberglass radomes on the roofs of buildings
were at least as vulnerable as nearby aluminum flagpoles and high metal
HF antenna masts.

Davoud

"Davoud" wrote in message
...
About a month ago lightning struck an amateur observatory belonging to
a member of my astronomy club http://www.howardastro.org. The
observatory dome was made of fiberglass. I have not talked to the
owner, but I received this information from Company Seven, which has
first hand knowledge of the incident.



Didn't the idiot insure scopes like that?

Davoud:
About a month ago lightning struck an amateur observatory belonging to
a member of my astronomy club http://www.howardastro.org. The
observatory dome was made of fiberglass. I have not talked to the
owner, but I received this information from Company Seven, which has
first hand knowledge of the incident.

MT, reading something I did not write, replied:
Didn't the idiot insure scopes like that?

The man is much closer to a genius than he is to an idiot. But
alongside you a common garden slug looks like a genius. Of course he
has insurance.

Davoud

--
usenet *at* davidillig dawt com

Davoud wrote:

Davoud:

The owner of the observatory reports that he has talked to a couple of
others whose fiberglass-domed observatories have been struck by
lightning.


William R. Mattil:

The veiled inference here is that fiberglass domes are more of a risk that
your Aluminum one ? lol

Not hardly.


John Nichols:

I took it more to mean that you should have a lightning rod and grounding.


What a jerk Mattil is! No wonder I don't see his posts directly :--)
What I wrote meant nothing at all; I quoted what I was told and made no
veiled references to anything whatsoever. Re-reading my post, I can
find no reference to my own observatory.

A lightning rod would be a great idea on such a structure; although the
dome in question was not the highest structure around, (nearby house
and trees) it is possible that the AP refractor on its pier was the
highest sizable bit of metal around and thus vulnerable.


Lightning protection provided by surrounding structures and trees is
limited to about 1 1/2 times their height. Anything outside that
distance is fair game to mother nature. Anything inside that distance is
fair game to mother nature also. Don't expect anything to protect you
if mother wants you.

Dave N

This doesn't mean anything either: when I was in the communications
racket I noted that small fiberglass radomes on the roofs of buildings
were at least as vulnerable as nearby aluminum flagpoles and high metal
HF antenna masts.

Davoud

On Sat, 12 Aug 2006 19:13:02 -0400, Davoud wrote:

The owner of the observatory reports that he has talked to a couple of
others whose fiberglass-domed observatories have been struck by
lightning.

Interesting story. As someone whose own observatory was hit, I can
sympathize. I only lost all the electronics to the EMP; the optics were
fine. Amazing to hear of the mechanical damage. I can imagine that a
non-conductive dome would provide limited protection. It's a hard
problem to handle. A lightning rod would prevent the mechanical damage,
but probably wouldn't prevent the electronics from being seriously
damaged. At some point you just have to accept that you can be unlucky,
and make sure you have insurance. Not everything can be prevented.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On Sun, 13 Aug 2006 02:35:28 GMT, Chris L Peterson
wrote:

Interesting story. As someone whose own observatory was hit, I can
sympathize. I only lost all the electronics to the EMP; the optics were
fine. Amazing to hear of the mechanical damage. I can imagine that a
non-conductive dome would provide limited protection.

I would think that the voltages present in lightning would exceed the
breakdown voltage of the dome, making the dome no protection at all
except to keep the rain out. Lightning could blow a hole in a light
weight metal dome.

--
The night is just the shadow of the Earth.

On Sat, 12 Aug 2006 22:25:47 -0500, William Hamblen
wrote:

I would think that the voltages present in lightning would exceed the
breakdown voltage of the dome, making the dome no protection at all
except to keep the rain out. Lightning could blow a hole in a light
weight metal dome.

Lightning does blow holes in thin metal- it is fairly common with
airplanes, for instance. But it isn't likely to pass through the dome
and arc into the interior of the observatory. The current travels on the
surface of conductors. That's why you are generally safe inside a car
(or an airplane) when it is hit by lightning. Even the fiberglass dome
affords some protection, since the lightning might find the path of
least resistance via the surface. People are not usually hit by
lightning inside their houses, even if they have thin, non-conductive
roofs.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com