HDTenEightyP/NetNews huggingface dataset:
From: zowie@daedalus.stanford.edu (Craig "Powderkeg" DeForest)
Subject: Re: condensation inside a SCT
Organization: Stanford Center for Space Science and Astrophysics
	<1992Aug31.135435.24258@athena.cs.uga.edu>
Date: 31 Aug 92 00:32:51

In another article, mcovingt@athena.cs.uga.edu (Michael A. Covington) writes:
   You can get a clear filter that screws onto the back of the telescope
   to keep out moist air.  Fill the telescope with very dry air from a
   hair dryer, then put the clear filter on.  (Lumicon sells them.)

   I've done this with good results, except that in my case the filter
   is actually on the front of my diagonal (which I seldom remove).

Forgive me if I'm wrong -- but this sounds like a good way to _encourage_
dewing!  The way a hair dryer works is by heating up the air that passes
through it, to increase the amount of water vapor it can accomodate. 
Of course, once it [the air] cools down again, any excess water will
re-condense out of it.  

It seems to me that air from your air conditioner or your fridge would be
a better gas to use.  

A poor-man's way to flood with dry nitrogen (a good thing) is to put a little
bit of LN2 inside [but not on the optics!] and let it all boil off.  You'll
get immediate dewing due to the chill, of course, but most of the H20 in the
scope will come out the vent as mist.  When you seal it up and the temperature
rises back to normal, you'll have a dry interior.
--
Craig DeForest:  zowie@banneker.stanford.edu  *or*  craig@reed.bitnet
----------------------------------------------------------------------------
"So, if you guys make a living looking at the SUN, why do you spend so much
        time at the SYNCHROTRON, working UNDERGROUND at NIGHT?"
Newsgroups: sci.astro
From: jcj@tellabs.com (JCJ)
Subject: Arp's "bridges"
Originator: jcj@sunl18
Organization: Huh?
Distribution: na
Date: Wed, 26 Aug 1992 13:59:08 GMT

Some of the side discussions on the Meta Model made me wonder about
the intergalactic "bridges" that Arp alleges between different redshift
objects.  Has anyone tried to determine the redshift from one object
to another along the bridge to see if there's a smooth transition
from one value to the other?  
Newsgroups: sci.astro
From: bankst@kauri.vuw.ac.nz (Timothy Banks)
Subject: Re: Double lined spectroscopic binary
Organization: Victoria University of Wellington, New Zealand
Distribution: sci.astro
Date: Sun, 30 Aug 1992 22:49:40 GMT

In article <BtLurq.Kor@breeze.rsre.mod.uk> jvb@uk.mod.hermes writes:
>Could someone tell me what a double lined spectroscopic binary star is. I know
>that a spectroscopic binary is a binary star that is known to be a binary by 
>looking
>at the spectrum and seeing that an emission line is double (right?)
>
>Also (this'll probably be in the reply anyway!) what is the difference between
>a single lined spectroscopic binary and a double lined spectroscopic binary.
>

A  spectroscopic  binary  is a star in which the  orbital motion of the
component stars "cause"  detectable changes in radial (line  of sight)
velocity. This is the well known Doppler effect -  where  if the  star
is  moving away from us its spectral lines will be redshifted, and  if
approaching us they will shifted towards the blue end of the spectrum.
Ofcourse, radial  velocities  are  usually given relative  to  the Sun
rather  than  the  Earth, so  that  our  orbital  motion  is  removed!

Ofcourse, if the binary's orbital plane is at 90 degrees to our line of
sight  we won't  see any radial  motions either!   Most spectroscopic 
binaries  are close  binaries, where  the components are close and the
orbital  velocity  high.  When  the components  are  nearly  the  same
brightness the  spectra from both will  be visible. This is  a  double
lined spectroscopic binary. However, if one of the stars is very  much
fainter than its  companion, then  only the brighter  star's  spectral
lines will be detectable - making it a single lined system.  Ofcourse,
with increasing  observational and  analysis capabilities  some single
lined systems are  now being reclassified as doubles  (see RT  Scl  as
an example).

Unfortunately, while  the doppler shifts in  a  double lined  give the
relative  velocities,  and  so  relative  masses  of  the  stars,  the
absolute  individual masses can not  be calculated  unless the orbital
plane's  angle  of  inclination  is  also  known.  Fortunately my  old
stomping ground of eclipsing binaries comes to the rescue, as analysis
of the  light curves gives  you  that  angle.  This  is where binaries
are very  handy - they are only direct way of determining  many of the
interesting stellar parameters.

-- 
  Timothy Banks, Physics Department, Victoria University of Wellington, NZ.
       bankst@kauri|rata|matai.vuw.ac.nz, banks@beagle.phys.vuw.ac.nz.
    "He's dead, Jim!" "OK, you take the tricorder, I'll take the wallet!"
Newsgroups: sci.astro
From: seymour@ast.saic.com (Ken Seymour)
Subject: Re: Cleaning a mirror
Organization: SAIC
Date: Fri, 28 Aug 1992 19:42:59 GMT

In article <27AUG199221480457@rigel.tamu.edu> wdb3926@rigel.tamu.edu (BRUTON, WILLIAM DANIEL) writes:
>In article <BtnJ6A.6yJ@zorch.SF-Bay.ORG>, mike@zorch.SF-Bay.ORG 
>(Mike Smithwick) writes...
>> 
>>What is the recommended way to clean a mirror? I have an Astroscan
>>and the mirror is getting coated with a layer of crud. Can I use
>>camera lens cleaning fluids or would those damage the surface?

I clean my mirror in a small basin of soapy water.  I use dish washing
liquid.  Then I use a clean, well-used handkerchief or cotton batting
and _CAREFULLY_ rub the surface of the mirror coating _WHILE IT HAS
SOAPY WATER ON IT_.  Then I rinse the mirror and leave it tilted in a
dish drain.  Believe me, I was real nervous the first time I did this.
But I have done it twice now to the same mirror and it still performs
great!

>> 
>>mike
>> 
>>Mike Smithwick - ames!zorch!mike
>> 

[stuff about metal polish deleted]

>	This is a last resort technique for us.  If it is not successful
>then I suppose one can remove the metal and re-silver the mirror.
>
>Has anyone ever re-silvered a mirror before?  How big of a pain was it?
>

Do you mean re-silver or re-aluminize?

I'm certain that the Astroscan has an aluminized mirror, not a silver
one.  In the old days, mirrors were coated with silver and had to be
re-coated every few months or so (I don't remember the precise
interval).  

Today's modern mirrors are aluminized and the coating can last years.
Re-aluminizing requires a vacuum container with heating elements in it.
Bits of aluminum are hung on the the heaters.  Then you seal the whole 
apparatus, pull a vacuum inside it, and turn on the heaters for a
measured amount of time.  This evapoates the aluminum and the longer it
is evaporated, the more goes on the mirror.

I read about all of this somewhere.  I haven't actually done it.  It
sounds like it requires a lot of work and special equipment.  It would
be much easier to send you mirror to one of the half dozen or so places
that do it for you.  When I still had hope of fininshing my 8" mirror, I
looked into it and my recolection is that it was about US $50 to have it
aluminized.  There is a small charge to remove an existing coating.

Many of these places are in the Los Angeles area.  There is a listing of
them in the annual Sky and Telescope resource guide.  (I am at work so
please don't ask me what month's issue it is).  The one name I can
remember is Moravak Optical in Signal Hill, CA.  I'm not sure if they're
in business still.

I seem to recall someone on the net stating that an Astroscan cannot
have its mirror removed and replaced.  Is this true?

>***********************************************************************
>Dan
>Texas A&M Observatory 
>***********************************************************************


-- 
Ken Seymour
seymour@ast.saic.com
Newsgroups: sci.astro
From: dal3@cbnewsg.cb.att.com (dale.e.parson)
Subject: condensation inside a SCT
Keywords: condensation SCT C8
Organization: AT&T
Date: Mon, 31 Aug 1992 13:37:11 GMT

I've had my Celestron C8 since November, 1991, and only in my last 2
observing sessions have I had moisture condensation problems on the
inside of the corrector plate. The first time, inverting the scope
with the visual back off got rid of it pretty quickly. The second
time, Saturady night, inverting simply deposited the moisture on the
primary mirror. Only 2 things have changed recently.

1. We had a very humid week, and my assumption is that moist air is
trapped inside the scope, in which case the question becomes how to
get rid of & KEEP moisture out (dessicants recommended?). After the
2nd trouble session I stood the scope behind a window in the morning
sunlight pointed down with the back off in the hopes that a little
light baking in the sun would get most of the moist air out; humidity
was low that day, so hopefully I got most of it out, but haven't had
a chance to try it. Also I'm moving it to a drier room on a higher floor.

2. I started using a 'dew zapper' heating element at the front of the scope
about 5 sessions ago. I can't see any way this would aggrevate inside-scope
dewing, but I never had the problem before. Previously dewing was always
on the outside, which yielded readily to a hair dryer.

Thanks in advance for any recommendations.


Dale Parson, Bell Labs, dale@mhcnet.att.com

 ---------------------------------------------------------------------- 
|    "These words are too solid, they don't move fast enough           |
|     to catch the blur in the brain that flies by, and is gone..."    |
 ----------------------------------------------------------------------
|     Suzanne Vega                                                     |
 ----------------------------------------------------------------------
From: hla@ecs.soton.ac.uk (Helen Ashman)
Newsgroups: sci.astro
Subject: Where the FAQ ? (Aurorae hunting)
Keywords: FAQ aurora
Date: 28 Aug 92 14:03:52 GMT

Where can I find the FAQ for this group? I want to look for
the aurorae. The postings in this group usually refer to U.S.
localities; I will be looking from the UK (going to the Orkneys
and Shetland Islands, about 55-60 degrees north).

Thanks from (very) amateur astronomer,

Helen Ashman.
hla@ecs.soton.ac.uk
From: jcj@tellabs.com (JCJ)
Newsgroups: sci.astro
Subject: Particle/Cosmology/Relativity Texts?
Date: 27 Aug 92 13:30:09 GMT
Distribution: na
Organization: Huh?
Originator: jcj@sunl18

Reading the MM-Big Bang debate and looking through my old textbooks
(14 years!), I've come to the conclusion that I've forgotten more 
than I learned -) ...  So I'd appreciate it if I could get some
recommendations for contemporary texts in:

1) standard model of particle physics

2) general relativity

3) cosmology

I have my bachelor's in astro and I took the obligatory calculus 
through diff. eq's and a semester of mathematical physics in grad 
school (although I confess that course was a real bitch - I still 
wonder if I was a total idiot or the prof was from another planet).
I don't think I'm masochistic enough to tackle MTW yet but I find
the "Sci. Am." style overviews less than satisfying.  Thanks.
Xref: sparky sci.astro:9252 sci.space:12257
From: mcovingt@athena.cs.uga.edu (Michael A. Covington)
Newsgroups: sci.astro
Subject: Re: Cleaning a mirror
Summary: Silver obsolete ?
Date: 31 Aug 92 04:07:01 GMT
Article-I.D.: athena.1992Aug31.040701.13407
Organization: University of Georgia, Athens

In article <1992Aug28.142738.15691@nsisrv.gsfc.nasa.gov> dsc@gemini.tmc.edu (Doug S. Caprette Bldg. 28 W191 x3892) writes:

>Silvered mirrors have been obsolete for about 60 years or so, with the
>exception of a few specialized application.

That's funny... my Meade 2080 (vintage 1986) has one, overcoated with something
to keep it from tarnishing.

In answer to the original poster's question, though, the way to clean the
mirror in an Astroscan is to rinse it gently with a dilute detergent
solution, then rinse with alcohol to get it to dry fast and smoothly.
Crucially, rinse, don't scrub.  Really severe crud might require very
light swabbing with a soft brush or with a piece of cotton.
-- 
+ Michael Covington - Artificial Intelligence Programs - U of Georgia - USA 
+ Unless otherwise noted, these are private opinions, not official statements.
+ VOTE NO GEORGIA LOTTERY - we need not imitate mistakes of other states.
Newsgroups: sci.astro
From: st1ls@rosie.uh.edu (Doug Knesek)
Subject: Magnetic fields and relative position of planets
Organization: University of Houston
Date: Thu, 3 Sep 1992 21:31:00 GMT

I am searching for data pertaining to the magnetic fields produced by all of 
our solar system's planets and the relative position (in degrees or radians
with respect to their orbits around the sun).

I also need the magnetic field intensity of the sun itself.

Also, are the magnetic field contributions from other planets and the sun
extracted form the data for any given planet, or is the data "raw"?

Can anyone please point me to any FTP sites that archive relevant information?

Thank you,
Doug Knesek
From: mcdonald@aries.scs.uiuc.edu (J. D. McDonald)
Newsgroups: sci.astro
Subject: Re: C8 astrophotgraphy, optical specs
Date: 1 Sep 92 23:25:40 GMT
Organization: UIUC SCS

In article <1992Sep1.111122.25@nsrvan.vanc.wa.us> sysevm@nsrvan.vanc.wa.us writes:


>       Does anyone have the optical spec for each of the elements of a SCT?
Sure. The manufacturers. And they aren't telling. They seem to think that
"keeping it secret" will be to some commercial advantage. 


>       How about the specs for the elements of the paracorr and the celestron
>       MPCC?


Ditto.


I've "obtained" the specs for my Meade 2080 by "reverse engineering". 
First, I'm assuming that primary and secondary are spherical. Otherwise
their admitted manufacturing method of "mix and match" would be silly,
and in any case,  using aspheric mirrors when you can correct it
with the corrector is even sillier. 

Then I carefully measured the distances from the vertices of the two mirrors
and the focus. Given all this, plus the focal length, the powers of the 
mirrors, and the asphericity of of the corrector, turn out to be completely
determined. The refractive index of the corrector is immaterial ...
you just vary the curve depth to get zero spherical aberration. It sure
look to me like they are using ordinary plate glass, as it is quite 
green!

You can vary the quadratic term of the corrector plate freely ...
I've chosen to make it produce zero third order chromatic, which is
close to what you get with Schmidt's vacuum method of manufacture.
The follow file is for the Beam3 commercial ray-trace program:

 7  surfaces                CASS.OPT                                           
  Index     Zvx     Curv      A2     A4        A6           Mi           
---.--:----.-----:--.------:.-----:-.---------:.----------:--------------
      :      .1  :   4.01  :      :           :           : Iris         
  1.0 :      .35 :   0     :.0002 :-0.00001061:-.000000003: Lens         
 1.517:      .5  :   0     :      :           :           : Lens         
  1.0 :  12.50000:-0.031284:      :           :           : Mirror       
      :    .65   :-0.097970:      :           :           : Mirror       
      :     12.9 :   .7    :      :           :           : Iris         
      :  21.0000 :         :      :           :           : Film         
                        
Note the closeness of the secondary to a 10 inch radius of curvature ...
it probably really is 10 inches!

The results of this look pretty much what one actually sees. Still, it
is only a guess.

Doug McDonald
From: mcovingt@athena.cs.uga.edu (Michael A. Covington)
Newsgroups: sci.astro
Subject: Re: When is the annular eclipse over Kansas?
Date: 4 Sep 92 18:37:51 GMT
Distribution: usa
Organization: University of Georgia, Athens

In article <24585@oasys.dt.navy.mil> wolfe@oasys.dt.navy.mil (Ernest Wolfe) writes:
>My in-laws in Kansas say that there will be an annular solar eclipse
>there sometime next spring or the following spring and want to have
>an eclipse party.

May 1994.  Cambridge University Press will have a book out, with detailed
maps and other information, authored by me, possibly with a co-author.
-- 
+ Michael Covington - Artificial Intelligence Programs - U of Georgia - USA 
+ Unless otherwise noted, these are private opinions, not official statements.
+ VOTE NO GEORGIA LOTTERY - we need not imitate mistakes of other states.
Xref: sparky sci.astro:9176 sci.space:12142
From: vanavery@acsu.buffalo.edu (Keith Vanavery)
Newsgroups: sci.astro,sci.space
Subject: WANTED: Quicksat.zip satellite tracking program
Date: 23 Aug 92 23:05:14 GMT
Organization: UB

Would some kind soul out there in Usenetland e-mail me quicksat.zip?

I checked archie; it isn't available via ftp.  I don't have a modem to download
it from TS Kelso's Celestial BBS.

Thanks in advance.


Keith
-------------------------------------------------------------------------------
>ERROR: no .sig file found
From: MEDELMA@cms.cc.wayne.edu (Michael Edelman)
Newsgroups: sci.astro
Subject: Re: Aero-Ektars Available
Date: 27 Aug 92 16:51:04 GMT
Organization: Wayne State University, C&IT

With John and Thomas' help I managed to order one of these lenses. There
were two left as of 10:50 this morning after mine was accounted for.
        --mike
From: bj368@cleveland.Freenet.Edu (Mike E. Romano)
Newsgroups: sci.astro
Subject: Space Poop Message Deleted?
Date: 3 Sep 1992 21:52:45 GMT
Organization: Case Western Reserve University, Cleveland, Ohio (USA)
NNTP-Posting-Host: slc5.ins.cwru.edu


On Wednesday Sept 2 1992 I posted a message entitled: Space Poop
about debris orbiting earth.
That was about 7 pm California time...about an hour later a 
Mr. Steuven replied to my posting with a "what's your point"
sort of response, etc.
AMAZING....
Now the next day I find my original positing was entirely
missing from the newsgroup as well as Mr. Steuven's.
Who does this: and isn't this supposed to be an un moderated
newsgroup?
Anyway here we go again:

Since 1957 more than 3,300 launches have produced 7,000 
trackable objects currently in orbit, equalling approx 3000
tons of man made material.  Of these 7000 catalogued objects
only 400 are operational satellites.  
and fragments including lens covers, separations bolts and
clamp bands.
Further, there are from 30,000 to 70,000 smaller objects
but larger than 1 cm which have not been catalogued. Any
pieces in this size range can damage spacecraft.

Through the effect of air drag these objects continue to
lose altitude and eventually rain down to earth.
Objects above the altitude of 1000 km are in the geo
stationery orbit and will remain there for 1000 years
orbitting the planet some 5 million times and posing
a constant hazard of collision with other objects.
Most of these objects have a velocity of at least 3 km/sec
Interactive collisions in earth orbits will eventually
generate sufficient debris to create a dense Debris Belt
and prevent further launchings.
see for example  July 1992  Acta Astronautica, etc.
-- 
            Mike Romano     Univ. Calif. Berkeley
From: wayne@csri.toronto.edu (Wayne Hayes)
Newsgroups: sci.astro
Subject: Re: Standard model of QSOsex
Date: 23 Aug 92 19:55:42 GMT
Distribution: sci

I wrote:
>> Hmmm, it's not clear to me that two stars of different (but "high") masses
>> are going to even orbit elliptically.  I have no idea how Tom claims the
>> gravitational masses change with "amount of matter" (== inertial mass, I
>> hope!), but I just tried a simple formula: gravitational mass = inertial
>> mass ^ 0.9, and modified my old  NBody simulator, and the orbits of two
>> masses was NOT elliptical, not by a long shot.

metares@well.sf.ca.us (Tom Van Flandern) responds:
>     Hmmm, something isn't communicating here.  The dynamics of a star's
>motion are independent of its own mass, gravitational or inertial.

As is pointed out in a later post, Tom assumes the "passive"
gravitational mass is equal to the inertial mass which is greater than
the "active" gravitational mass.  In this case, Tom is right.  My
quick-and-dirty simulator assumed the active and passive gravitational
masses were equal and less than the inertial; in this case the forces
on the two stars are not equal and opposite so of course the orbits go
awry.

However I don't understand *why* this is so.  First, I assume that in
the Meta Model, object B feels the gravitational force of object A when
it "catches" some of the C-gravitons of object A.  Tom claimed that the
reason a black hole won't form is because the C-gravitons "have
trouble" "getting out" of the interior of a massive object and thus
it's active gravitational mass is less than it's "amount of matter" (==
inertial mass).  But if gravitons are having trouble "getting out" of
object A (so that object B sees a lesser force coming from A), this
means that the force of gravity in the *interior* of object A must be
STRONGER, since it is "catching" it's own gravitons rather than letting
them go -- ie the particles inside of A are more strongly attracted to
each other because they are catching more of each other's C-gravitons
than the standard model would predict.  I other words, I'm assuming a
"conservation of C-gravitons", and since the force is less "outside" of
object A, then this must be counter-balanced by the force "inside"
being greater.  This would seem to imply to me that a super-dense
object is even more UNstable in the meta model than in the standard
model -- the more dense it is, the less it's "external" active
gravitational force and the STRONGER it's "internal" gravitational
force becomes, so any object which is predicted to collapse to a black
hole in the standard model should collapse even *faster* in the Meta
Model.

Tom?

-- 
The primary goal of science is to describe whatever scientists see as being
in need of description.

Wayne Hayes     INTERNET: wayne@csri.utoronto.ca        CompuServe: 72401,3525
Newsgroups: sci.astro
From: benoit@netcom.com (BENOIT SCHILLINGS)
Subject: Re: > C8 stories + radial guider bug
Date: Thu, 27 Aug 92 22:58:56 GMT
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 

That was a fast reply.
So if i read that diagram as it should be, a 1.2 cm (1/2 inch) from
the center of the field, a star image will be about 120 microns
long.
Compare to the required 20 microns this is pretty big.
Now i can see why guiding is not that great.

What program did you use to do this ray tracing ?
How much improvement will i have by moving the corrector ?
How much degradation will i have on the axis with that ?

I guess we should compile a list of improvement to be
done on the SCT family.
It seems to me that the design didn't change in 10 years.
Just when i think about the way the focusing is done, it
seems that many things could have been improved.


Thank you again          

Newsgroups: sci.astro
From: jarleb@athena.uio.no (Jarle Brinchmann)
Subject: Re: Space Poop
Reply-To: jarleb@athena.uio.no (Jarle Brinchmann)
Organization: University of Oslo, Norway
Date: Thu, 3 Sep 1992 11:22:54 GMT

In article <183veaINNccf@usenet.INS.CWRU.Edu>,
bj368@cleveland.Freenet.Edu (Mike E. Romano) writes:
> 
> Mr. Steuven:  you ask, "what is my point"?
> 
> Let me answer then by:  read your journals, .......
>                       esp. Acta Astronautica vol 26 July 1992.
> -- 
>             Mike Romano     Univ. Calif. Berkeley


Is this a private battle, or may anyone join the guessing game ?

Personally I do understand your concern about debris in space, but
if you want to start a discussion then you should try to avoid such
(admittedly funny) mistakes in your posting...


If I may ask a question..
Is there any plans whatsoever to remove or collect some of the debris
up there ?

 I haven't really calculated anything, but I guess that any
big space-station would have to face the problem that quite a lot of
debris are flying around up there.


				Jarle.