HDTenEightyP/NetNews huggingface dataset:
From: wdb3926@rigel.tamu.edu (BRUTON, WILLIAM DANIEL)
Subject: Re: Binary stars, lifezones. HELP!
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Thu, 3 Sep 1992 23:02:00 GMT

In article <1992Sep3.122324.1@ulkyvx.louisville.edu>, jsmill01@ulkyvx.louisville.edu writes...
>I have been asked the following questions and am appealing to my 
>fellow netters who may be more familiar with the field.  A caller to 
>the planetarium has asked how one might determine the separations of 
>stars in a binary (or multiple) star system if you know the masses.

     I'm not sure but...I think one cannot really get the separation 
distances in kilometers or miles acurately.
     One can only get the separation distances in terms of the
radius of the one of the stars or vice versa using photometry.
The radii of a star is not easily found either.

The relationship between the separations distances and the radius of
one of the stars is not simple and one must use a differential
corrections program (Wilson,Divinney, Ap.J. Vol 166, 1971, p.605)
to find this relationship.  This program is quite lengthy but
you get mass radio, luminosity radio, inclination angle, and 
19 other parameters for a given light curve.  

I wish there was a simple answer to your question but I am not aware
of one.  I really think one must consider inclination of orbit,
ecentricity, angle of perigee, mass ratio, luminosity ratio, radii
of stars, etc to determine the distance between the stars.....and even then
you get it in terms of a star radius (using photometry and the Wilson-
Divinney program).  I don't think you can do much better with 
spectroscopy either.

I think that it is not too difficult to write a differential
corrections program that can give you a good estimate using 
photometery and Russell's Model.  But agian the separation is
found in terms of the radius of one of the stars or vice versa.
See "Introduction to Eclipsing Variables" by Kopal for more info. 
I hope this was helpful.   

Dan
Newsgroups: sci.astro
From: metares@well.sf.ca.us (Tom Van Flandern)
Subject: Re: A super-blue branch of super-massive stars?
Organization: Whole Earth 'Lectronic Link
Date: Wed, 26 Aug 1992 03:00:28 GMT


gsh7w@fermi.clas.Virginia.EDU (Greg Hennessy) writes:

> If you can tell me how many of these supermassive stars there are, and what
> they look like, I can look for them in the UIT data. M87 doesn't have them.
> M31 doesn't have them. M82 doesn't have them. See the Aug 10 issue of Ap J
> Lett for the papers on the first two, and the one on M82 should be
> submitted within the month.

     It was not obvious at a glance which paper dealt with M87.  Can you be
more specific?

     The most likely place to find the supermassive stars in these galaxies
is the core, which apparently was not imaged.  After collapse, supernova, and
high-speed ejection, such objects will not remain *in* their parent galaxies
for long.  They will be found in the neighborhood.  By that stage, the light
will no longer have a strong UV component either, because of the collapse and
shielding effects.

     How about a UIT composite image of the core of these galaxies?  I would
expect a UV excess to be found there, although I have not yet found a way to
predict its strength as a function of galaxy type.  -|Tom|-

-- 
Tom Van Flandern / Washington, DC / metares@well.sf.ca.us
Meta Research was founded to foster research into ideas not otherwise
supported because they conflict with mainstream theories in Astronomy.
Newsgroups: sci.astro
From: wdb3926@zeus.tamu.edu (BRUTON, WILLIAM DANIEL)
Subject: Re: Cleaning a mirror
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Sat, 29 Aug 1992 06:50:00 GMT

>>
>>Has anyone ever re-silvered a mirror before?  How big of a pain was it?
>>
> 
>Do you mean re-silver or re-aluminize?
>

I beg your pardon.  I meant "re-silver" in the broader since.....
"to plate with a lustrous substance".  I should have been more clear.

>
>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.
>

Thanks for the info.  We found a large vacuum chamber (~1meter diameter)
with resistive boats for aluminum (metal) deposition in a local solid state 
physics lab that is currently being use for making High Tc superconductors.  
I think they will let use us it.  So one might check into these kinds of labs
to save some money.  

Thanks again.
Dan
TAMU
			
Newsgroups: sci.astro
From: yerazunis@cthulu.enet.dec.com
Subject: Re: C8 Coma for astrophoto, radial guider bug
Organization: Turing Police
Date: Wed, 26 Aug 1992 22:35:19 GMT


In article <5vbnkx+.benoit@netcom.com>, benoit@netcom.com (BENOIT SCHILLINGS) writes...
>I've started to use my C8 for prime focus astrophoto.
>The result look sharp at the center of the field but i'm
>surprised to see how important the coma is at the edge
>of the field !
>What's the point of a Schmidt if it's to get so much coma.
>Also for guiding, coma stars are not that fun...
>  
>Are there any coma corrector that would fix that without
>changing the f ratio ?
>Also i would like some comments about the reducer/corrector
>of Celestron. How sharp is it at the edge of the field.
>How is guiding with that reducer ?
> 
>I use an Ultima 8 and the radial guider from C.
> 
>Thank you for your comments.

Hmmmm... well, to start out with, I have a C8 (same optic tube as your 
Ultima) and I have NO problems with coma, even using the radial guider.
(I have another beef about the radial guider, but that's neither here nor
there).  

My first hunch would be to check your scope's collimation.  A mis-collimated
Schmidt has a distortion pattern that looks a lot like coma, and varies
over the field of view as well; you may be seeing miscollimation.

Second: I have the reducer-corrector as well.  I find that it works
nicely; no problem with guiding with the radial guider in back of the 
reducer/corrector.

Now, back to the radial guider- you notice that little prism that reflects
light up into the guide eyepiece?  Well, it's hinged by two pieces of thin
aluminum that flex every time you turn the image shift thumbscrew!  After
a few dozen flexes, the thin aluminum breaks, and the prism is "violently 
ejected" from the guider by the spring.  My cure is to re-cement the prism
mounting ring to the tube with two dots of silicone rubber; the silicone has
enough give in it to let the spring mounting work again, and doesn't 
let go (at least mine hasn't).

	-Bill

Copyright 1992 William S. Yerazunis (aka Crah the Merciless)
All rights reserved, no responsibility taken.

     "Blessed are the heat-seekers"
From: mcovingt@athena.cs.uga.edu (Michael A. Covington)
Newsgroups: sci.astro
Subject: Re: Advice needed for Purchase (Novice)
Date: 3 Sep 92 23:39:57 GMT
Organization: University of Georgia, Athens

Whatever you do, get a good _steady_ tripod and mount!

-- 
+ 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: MEDELMA@cms.cc.wayne.edu (Michael Edelman)
Subject: Re: Telescope question
Organization: Wayne State University, C&IT
Date: Thu, 3 Sep 1992 16:07:58 GMT

In article <mcdonald.266@aries.scs.uiuc.edu>
mcdonald@aries.scs.uiuc.edu (J. D. McDonald) writes:
 
      [...]
>
>However, Meade guarantees "user satisfaction" and their add claims
>are pretty severly restrictive. They can indeed make SCTs that are 1/10
>wave. I've got one, it performs wonderfully.
 
Is the primary 1/10 wave, or the entire system? I'm told that's extremely
difficult to accomplish. How did you measure it?
 
>
>>compounded by poor baffling
>The baffeling in Meades is perfect, geometrically, and very well
>blackened indeed.
>
>>and the fact that the
>>corrector plate is only an approximation of the correct figure.
>
>I don't know what you mean by this... my scope must have a corrector
>plate that is right, because it is 1/10 wave. Do you mean that it
>has the "high zone" in a place that causes more than the minimum chromatic
>aberration? My scope seems to have titally negligible chromatic
>aberrration.
 
I am told that Celestron and Meade manage to produce large SCTs at such
a low price by using correcting plates that are not ground to a true
4th-order aspheric curve, but ar vacuum formed to a close approximation
only.
 
>>It's
>>certainly possible to build compound reflecting telescopes that outperform
>>most achromats- cf Questar, for one.
>Not really. An 8 inch Questar would be inferior to an 8 inch Meade
>or Celestron because of the dramatically worse chromatic aberration
>in the Maksutov.
>
I think you're way off on this one- Questar does make a 7" (and a 12") for
about $8,000. It is said to be of unmatched image quality for its size.
A number of authors (none of which come to mind ;-) ) I have read say the
Maksutov is superior to most any other design.
>
>>However....a properly figured newtonian of long focus (f/8+) with a small
>>secondary can rival a refractor for contrast and resolution. The major
>>mass-market manufacturers don't make such a telescope. Pity.
>
>The reason for that is that no one would buy them. Long focal length
>implies mounting problems .... and if you can mount a 6 inch f/8,
>you can equally mount an 8" f/6 or 10 inch f/5, which will,
>with good figure, annihilate the performance of the 6 inch. There is
>no substitute for aperture.
 
Though they'd be half the length of similar refractors...which people
do buy. I doubt the 8" f/5 would have better contrast than a 6" f/10.
Maybe some experts can help us resolve some of these differences?
>
>Doug McDonald
 
  -mike edelman
Newsgroups: sci.astro,sci.geo.geology
From: cain@geomag.gly.fsu.edu (Joe Cain)
Subject: Re: Cratering rate estimates.
Organization: Florida State University Geology Dept.
Date: Fri, 4 Sep 92 02:43:48 GMT

In article <1992Sep3.203338.17648@sarah.albany.edu> ss6349@tyr.albany.edu (Steven H. Schimmrich) writes:
>
>   I'm looking for estimates of cratering rates throughout geologic time for
>the earth, moon, and inner planets.
>   I would like primary references

	I just received the excellent update by Hartmann of his "Moons
and Planets" and note that he has about two pages of references for
his chapter 10 on Planetary surfaces: petrology, primative surfaces
and cratering.  

	Names that are included in this list include:
Burns, B. 1982 thesis on venus analysis using Arecibo
Chapman, C. R. and Jones, ...Mars
Hartman, on martian cratering
Neukum, G...moon
Soderbloom...lunar
Strom, R. B, Voyager 2..

there is a book on Inpact and Explosion cratering that may have some
leads  Roddy, Peppin and Merrill eds.

Woronow, AQ. 1978 Lunar cratering

should be a good start



Joseph Cain		cain@geomag.gly.fsu.edu
cain@fsu.bitnet		scri::cain
Newsgroups: sci.astro
From: jcj@tellabs.com (JCJ)
Subject: Arp's bridges? [repost]
Originator: jcj@sunl18
Organization: Huh?
Date: Wed, 2 Sep 1992 13:59:56 GMT

Sorry if this has already been posted, but my posting machine has been
acting up lately...

Has anybody measured the redshift along one of Arp's alleged "bridges" 
between objects of different redshifts?  If so, I'm curious if there is 
a smooth transition in the value of z.  Thanks.

	
Xref: sparky sci.astro:9373 sci.space:12357 sci.geo.geology:1866 sci.misc:1547
From: mcovingt@athena.cs.uga.edu (Michael A. Covington)
Newsgroups: sci.astro
Subject: Re: Telescope question
Date: 3 Sep 92 23:37:29 GMT
Organization: University of Georgia, Athens

In article <mcdonald.266@aries.scs.uiuc.edu> mcdonald@aries.scs.uiuc.edu (J. D. McDonald) writes:

>>mcovingt@athena.cs.uga.edu (Michael A. Covington) writes:
>>> equating a 3-inch refractor to a 6-inch reflector in this day
>>>and age is a bit excessive.  I'd think the comparison is more like 5-inch
>>>versus 6-inch.
>
>The physics of it ... backed up by serious experimentation on my part...
>says that a perfect obstructed system (refractor or reflector, it of
>course does not matter) will be unequivocally better than an unobstructed
>system whose diameter equals (outer diameter of obstructed system - 
>diameter of obstruction). An obstructed system will appear, looking at
>planets, roughly equal to an unobstructed system with diameter 
>(diameter of obstructed system - diameter of obstruction/2).

Nice to see theory and practice agree so well!

>However, Meade guarantees "user satisfaction" and their add claims 
>are pretty severly restrictive. They can indeed make SCTs that are 1/10
>wave. I've got one, it performs wonderfully.

Although I've never done any rigorous testing, I've always had the 
impression that my 2080-LX3 MCSO is excellent, better than some other
SCTs that I've looked through.

(And that my Celestron 5, vintage 1980, is a little weak on optical
quality.  Does anyone know what Celestron's policy is -- whether they
will check it out at this late date?  At the time I got it, I didn't
have any other telescope to compare it to and didn't really know what
to expect from an SCT.)


-- 
+ 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: gregg@gordian.com (Gregg Bone)
Subject: Televue 16mm Nagler eyepiece for sale
Organization: Gordian
Distribution: usa
Date: Tue, 1 Sep 1992 19:36:15 GMT

Great eyepiece.

Better than new, I have not even received it from the store yet.  I ordered
a new Televue Genesis refractor and it comes with the 16mm Nagler.  Since I
own a 16mm Nagler and have no use for two, I would like to sell the new one.
Lumicon sells for $289.  I would like $200.  Make offer through email.

I am not sure this is the right group to post this kind of message to, so
please flame with suggestions of the right group.

-- 
Gregg Bone (gregg@gordian.com)     US Mail: Gordian
Phone:     (714)850-0205                    20361 Irvine Ave
Fax:       (714)850-0533                    Santa Ana Heights,CA 92707-5637
Newsgroups: sci.astro
From: mcdonald@aries.scs.uiuc.edu (J. D. McDonald)
Subject: Re: Telescope question
Organization: UIUC SCS
Date: Thu, 3 Sep 1992 14:06:09 GMT

In article <168576E18.MEDELMA@cms.cc.wayne.edu> MEDELMA@cms.cc.wayne.edu (Michael Edelman) writes:

>In article <1992Sep3.034229.13646@athena.cs.uga.edu>
>mcovingt@athena.cs.uga.edu (Michael A. Covington) writes:
>      [...]
>>There is an old piece of folklore that says a 3-inch refractor is equal to
>>a 6-inch reflector.  It's late 19th century folklore, from the days of
>>silvered mirrors with low reflectivity.
>>
 equating a 3-inch refractor to a 6-inch reflector in this day
>>and age is a bit excessive.  I'd think the comparison is more like 5-inch
>>versus 6-inch.

The physics of it ... backed up by serious experimentation on my part...
says that a perfect obstructed system (refractor or reflector, it of
course does not matter) will be unequivocally better than an unobstructed
system whose diameter equals (outer diameter of obstructed system - 
diameter of obstruction). An obstructed system will appear, looking at
planets, roughly equal to an unobstructed system with diameter 
(diameter of obstructed system - diameter of obstruction/2).

>>
>>
>From what I've read and seen in the past year, I'd add a few comments to
>that. One, the *average* commercial newtonian has a pretty poorly figured
>mirror, adding to the problem. And the typical commercial schmidt-cassegrain
>has a much worse image, 

However, Meade guarantees "user satisfaction" and their add claims 
are pretty severly restrictive. They can indeed make SCTs that are 1/10
wave. I've got one, it performs wonderfully.

>compounded by poor baffling 
The baffeling in Meades is perfect, geometrically, and very well 
blackened indeed.

>and the fact that the
>corrector plate is only an approximation of the correct figure. 

I don't know what you mean by this... my scope must have a corrector
plate that is right, because it is 1/10 wave. Do you mean that it
has the "high zone" in a place that causes more than the minimum chromatic
aberration? My scope seems to have titally negligible chromatic
aberrration.

>It's
>certainly possible to build compound reflecting telescopes that outperform
>most achromats- cf Questar, for one. 
Not really. An 8 inch Questar would be inferior to an 8 inch Meade
or Celestron because of the dramatically worse chromatic aberration
in the Maksutov.


>However....a properly figured newtonian of long focus (f/8+) with a small
>secondary can rival a refractor for contrast and resolution. The major
>mass-market manufacturers don't make such a telescope. Pity.

The reason for that is that no one would buy them. Long focal length 
implies mounting problems .... and if you can mount a 6 inch f/8,
you can equally mount an 8" f/6 or 10 inch f/5, which will,
with good figure, annihilate the performance of the 6 inch. There is
no substitute for aperture.

Doug McDonald
Newsgroups: sci.astro
From: joe@andosl.anu.edu.au (Joe Elso)
Subject: Re: C8 astrophotgraphy, optical specs
Organization: Comp. Sci. Lab., Autralian National Uni.
Date: Wed, 2 Sep 92 05:47:41 GMT

In article <mcdonald.262@aries.scs.uiuc.edu> you write:

|> 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!

Ditto for the C11's corrector - it definitely doesn't look like
pyrex.  What's more, the edge is so jagged - like somebody hacked it
out of a pane of window glass in their backyard toolshed. Ugh!

-- 
Cheers,
Joe Elso, CSLab, ANU
joe@andosl.anu.edu.au
Xref: sparky sci.astro:9225 rec.radio.amateur.misc:14435
From: marchant@cea.berkeley.edu (Will Marchant)
Newsgroups: sci.astro,rec.radio.amateur.misc
Subject: Amateur radio coordination of laser guide star observing
Followup-To: sci.astro
Date: 25 Aug 1992 17:54:28 GMT
Organization: Center for EUV Astrophysics
Distribution: ca
NNTP-Posting-Host: sag4.ssl.berkeley.edu
Keywords: LLNL, LGS

Greetings Folks!

You may have been reading in sci.astro about the Lawrence Livermore National
Labs (LLNL) laser guide star experiment. This is a bright laser beam shown
into the San Francisco East Bay area skys. The LLNL folks need amateur
observations of this to study the beam's characteristics.

An amateur radio repeater in Livermore CA will be used to coordinate the
observations. Those of you with a "police" type scanner might care to listen
to 147.120 MHz (narrow band FM) about the beam status during the posted
test times. (Amateur radio operators: The AD6X repeater is on 147.120+ with
PL100.0 and is an "open" repeater free for general use.)

There are some planned amateur television (ATV) transmissions probably using
the W6CX ATV repeater on Mt Diablo. If you have a cable ready television, point
an antenna at Mt Diablo and set your TV for cable channel 58. Amateurs with
ATV uplink capability are especially desired to help with image intensified
cameras hooked to small telescopes.

More information can be had from rushford@novax.llnl.gov or
gavel@dagwood.llnl.gov

Will Marchant                   Center for Extreme Ultraviolet Astrophysics
marchant@cea.berkeley.edu       University of California
KC6ROL@WA6HAM.#NOCAL.CA.USA.NA  2150 Kittredge St., Berkeley, CA 94720 USA
From: w.teschner@abbs.hanse.de (Wolfgang Teschner)
Newsgroups: sci.astro
Subject: looking for connection to ATMJ editors
Date: 29 Aug 92 21:00:28 GMT
Reply-To: w.teschner@abbs.hanse.de
Distribution: sci
Organization: ABBS AstroMail, D-W 2121 Dahlenburg / Germany
X-Version: ZerUU V6.45c

Hi!
Does anybody have a connection to the makers of the new ATM Journal?
The editor is William Cook, Bothell, Wash, and covering Europe are
the famous Rutten/Venrooij, Netherlands.
Thanks,
Wolfgang Teschner,
Germany

--
------------------------------------------------------------------------------
ABBS AstroMail, the first and most popular German astronomical bulletin board
------------------------- for amateur astronomers ----------------------------
    + 49 5851 7896 / V.21, V.22, V.22bis, V.32, V.42, V.42bis and MNP5
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Newsgroups: sci.astro
From: metares@well.sf.ca.us (Tom Van Flandern)
Subject: Re: Supermassive stars and HD limit (was Big Bang...)
Organization: Whole Earth 'Lectronic Link
Date: Mon, 31 Aug 1992 00:56:10 GMT


dwells@fits.cv.nrao.edu (Don Wells) writes:

> If your Meta-Theory has trouble explaining contiguous, collimated, *bright*
> structures with sizes of kiloparsecs that occur in galaxies, then maybe its
> "engine" needs to be rebuilt!  :-)

     I have said in previous posts that I am untroubled by several-
kiloparsec-length jets.  Supermassive stars should be able to produce jets
several orders of magnitude bigger than the Crab pulsar jets.  And the Crab
is still so young, doubling in size in a millenium at the present rate.
Perhaps *its* pulsar jets will be a couple orders of magnitude bigger in
100,000 years.

     You have been repeating your objection that the Meta Model must explain
jets a few kpc in length, "bigger than some whole galaxies".  But the
standard model must explain jets of high-redshift quasars which are
megaparsecs in length, "the largest contiguous structures in the universe".
Which model has the greater difficulty in explaining the scale of the jets
without ad hoc postulates?

     The final word for now will be yours, as I must prepare for two weeks of
travel.  -|Tom|-

-- 
Tom Van Flandern / Washington, DC / metares@well.sf.ca.us
Meta Research was founded to foster research into ideas not otherwise
supported because they conflict with mainstream theories in Astronomy.
From: clarke@acme.ucf.edu (Thomas Clarke)
Newsgroups: sci.astro
Subject: Re: Quasar "proper motions" (was: Standard model of QSOsex)
Date: 27 Aug 92 17:57:55 GMT
Organization: University of Central Florida

In article <BtnDo0.CDE@well.sf.ca.us> metares@well.sf.ca.us (Tom Van Flandern)  
writes:
>      If data is being collected now, we should know within 10 years or so
> which model is correct.  Please join me in rejecting any claim that quasars
> are "relativistically beamed" or other such nonsense if it turns out that
> quasars do have significant proper motions.  -|Tom|-
> 
May as well register my "standard-model-saving" explanation of
any quasar proper motions now.

From Nature News and Views, April 1, 2001:
  Recently confirmed quasar proper motions are caused by the changing  
relationship of the observer-quasar path to intervening cosmic strings.  
When the path is near a caustic, motions are magnified to an observable 
amount.  This cosmological scintillation is supported by a correlation
between proper motion and slow changes in apparent luminosity.
  A new project to map quasar proper motions across the sky
shows that the distribution of cosmic strings is consistent with 
large scale structures such as the great attractor :-)
--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
(407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu
Newsgroups: sci.astro