HDTenEightyP/NetNews huggingface dataset:
From: palmer@cco.caltech.edu (David M. Palmer)
Newsgroups: sci.astro
Subject: Re: perseids
Date: 5 Nov 1992 23:46:40 GMT
Organization: California Institute of Technology, Pasadena
NNTP-Posting-Host: alumni.caltech.edu

pad@galaxy.nsc.com (Paul Denny x8349) writes:

>Also in the discussion on impact by Swift tuttle 
>a change in arrival time of several days is claimed
>to be possible due to non gravitational effects
>but I thought that the new peak in the perseids
>is only a few hours different from the old one
>implying to me that the orbit has only changed a few
>hours after 135 years - why should it change several
>days next time round?

Non-gravitational effects are what might delay the comet by 17 days
so that it reaches Earth orbit at the same time as the Earth has
its annual perseid meteor shower.  If there were no non-gravitational
effects on the comet, the comet will pass through the orbit of Earth
17 days after the Earth passed the same point.  (I may have the
sign wrong on whether a delay or an advancement is required.)

The 'few days' of moving the Perseid shower from the August 11 of
this year to the August 14 of the year 2126 is an artifact of our calendar.
Our calendar is set up so that the Vernal Equinox always occurs
near March 21.  However, because of the precession of the equinoxes,
successive vernal equinoxes do not occur exactly one orbit apart.
If we defined a year so that the Sun always passes a specific star (e.g.
Regulus) near the same date each year, then the Perseids would also stay
at a fixed date, because the orbital track of the Perseids does not
significantly precess relative to the fixed stars.
(Although the orbital track of the Perseids probably has some precession
at some level.)

There are terms such as Tropical Year etc. which indicate the period
between equinoxes and the period between the Sun passing Regulus
and the period between perihelia etc..  I don't know them.

-- 
		David Palmer		 palmer@alumni.caltech.edu
Newsgroups: sci.astro
From: clarke@acme.ucf.edu (Thomas Clarke)
Subject: Re: NEWS: Galileo Cleared of Heresy Charges by Vatican
Organization: University of Central Florida
Date: Wed, 4 Nov 1992 14:24:32 GMT

Maybe the high gain antenna will deploy now.

--
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
From: wa2ise@cbnewsb.cb.att.com (robert.f.casey)
Newsgroups: sci.astro
Subject: Re: Know an adjective for black holes?
Date: 13 Nov 92 04:23:38 GMT
Organization: AT&T

"Dark"?      :-)
Newsgroups: sci.astro
From: tomrice@netcom.com (Tom R. Rice)
Subject: Re: Real Men Astronomers [Was Re: e-mail activated telescope?]
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 
Date: Sat, 7 Nov 1992 02:06:02 GMT

hbh@athena.mit.edu (Heidi Hammel) writes:


>So do I get to keep my title of "Real Man" astronomer
>even though I mostly work in a warm room at a computer? ;-)


	No problem, so long as you actively demonstrate the
	humility, an attribute totally lacking in the persona
	of my last (female) astronomy professor :=)

	We all have to recognize that times have changed!

	trr

-- 
"Start off every day with a smile and get it over with."  --W.C.Fields
Tom R. Rice   WB6BYH                   Holler Observatory - 
tomrice@netcom.com                     Longitude:  121 d  30 m  20 s W 
CIS: 71160,1122                        Latitude:    37 d  25 m  10 s N
From: max@west.darkside.com (Erik Max Francis)
Newsgroups: sci.astro
Subject: Position function of planetary orbit?
Date: 9 Nov 92 21:07:01 GMT
Organization: The Dark Side of the Moon +1 408 245 SPAM

I'm interested in a position function for a body following a conic 
section around a large mass.

Using polar coordinates, getting r as a function of theta is no sweat, 
but finding theta as a function of t is something else entirely.  I 
attepted to use conservation of angular momentum (l = m r^2 omega = 
const.) to find an equation (omega = dtheta/dt), but no luck; the 
integral didn't want to be integrated very easily.  (And that integral 
wasn't the solution; I still had to solve for theta afterward, so I 
couldn't just use numerical integration.)

Does anyone have the function or a straightforward way to get it?

Thanks . . .

----------
Erik Max Francis   Omnia quia sunt, lumina sunt.  Coming soon:  UNIVERSE _ | _
USmail:  1070 Oakmont Dr. #1 San Jose CA 95117  ICBM:  37 20 N  121 53 W _>|<_
UUCP:  ..!apple!uuwest!max   Usenet:  max@west.darkside.com   464E4F5244   |
From: newberry@kepler.as.arizona.edu (Mike Newberry)
Newsgroups: sci.astro
Subject: Re: Know an adjective for black holes?
Date: 13 Nov 92 21:48:57 GMT
Distribution: na
Organization: University of Arizona, Tucson, AZ

In article <1992Nov13.033454.29942@cbnewse.cb.att.com> random@cbnewse.cb.att.com (David L. Pope) writes:
>From article <69374@cup.portal.com>, by Robert_N_Brauer@cup.portal.com:
>>>   To refer to the Earth, I can use  "terrestrial".
>>>   To refer to the stars, I can use  "stellar".
>>>   To refer to galaxies,  I can use  "galactic".
>>>   To refer to black holes,  what can I use?
>>>
>>>Any suggestions would be appreciated.  Thanks.
>
>From my meager knowledge, I recall that a black hole is referred to
>as a 'singularity'. To refer to a black hole in the manner of the
>examples above, one would use 'singular'*.
>
>	*Copywrite 11/12/92
>	
>			Random

How about "your holiness" or "his holiness", or the like?

Mike Newberry
Newsgroups: sci.astro
From: daigle@APOLLO.HP.COM (Joe Daigle)
Subject: Re: Experiences with telescope mail order
Date: Thu, 5 Nov 1992 20:13:25 GMT
Reply-To: daigle@apollo.hp.com
Organization: Hewlett-Packard Company, Chelmsford, MA

In article <37770004@hpopd.pwd.hp.com>, stevep@hpopd.pwd.hp.com (Steve Pearce) writes:
|> / hpopd:sci.astro / meier@Software.Mitel.COM (Rolf Meier) /  5:49 pm  Nov  3, 1992 /
|> In article <1992Nov3.102808.18336@news.unige.ch> pfennige@scsun.unige.ch (PFENNIGER Daniel) writes:
|> 
|> >I am considering purchasing a Schmidt Cassegrain telescope to one of the 
|> >companies advertising in Sky and Telescope.  Has anybody any advice or
|> >good or bad experience to share with the sci.astro group (or with me by e-mail)?
|> 
|> A couple of years back I decided to purchase a Celestron C8. I already had a
|> C80 and to save money I wanted to unload the C80 tube and purchase just the
|> C8 tube assembly. I was living in California at the time and decided to use
|> the services of Pauli's Optical of Danbury CT. They agreed to purchase my old
|> Steve Pearce, Hewlett-Packard, Pinewood, UK
|> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|> 
|> 



For what it's worth, I also have had some bad dealings with Pauli's (who I believe also owns
Wholesale optics of PA).   Last Christmas I decided to buy a telescope.  So, I started to call
around to see what was available.  One of the places that I called was Pauli's.  I asked
him what I could get a new C4.5 for.  He proceeded to talk me into a Meade Schmidt-Newtonian,
which was "used, but in like-new condition".  When he found out that I was "right up the road"
he talked me into driving down to get the scope, because it would save me shipping.  When
I got there, his attitude was completely different from when I talked to him on the phone.
He now had the attitude of "well, there it is, take it or leave it" because, I believe,
that he knew I had just driven 4 hours to get the scope, and he had me either way.

There is a lot more that went on, that I do not want to bother the net with, that would
make this message really *LONG*.

I am not saying dont buy from them, just that this guy struck me as a really shady character.
I would bet that you are a lot better off buying from Adorama or Focus.  They at least
care what their customers think about them.  This guy knew he had me, and took every
advantage of me he could.  Buyer beware.....



-- 


Joseph W. Daigle
                          

Open Systems Software Division   Hewlett Packard Company
MS CHR-03-DC                     508/436-4227
300 Apollo Drive                 EMail: daigle@apollo.hp.com
Chelmsford, MA 01824             HP TN: 436-4227

Newsgroups: sci.astro
From: Mike.Word@launchpad.unc.edu (Mike Word)
Subject: How to Visit Arecibo
Summary:  Who do I contact to see the radio facility at Arecibo Puerto Rico?
Organization: University of North Carolina Extended Bulletin Board Service
Distribution: usa
Date: Fri, 13 Nov 1992 22:31:47 GMT

I will be visiting Puerto Rico late in December and would like to know
who to contact to get a tour of the Arecibo radio facility. Any names, e-mail
addresses or phone numbers would be helpful. Thanks.
Mike Word
jmw9681@usav01.glaxo.com

--
   The opinions expressed are not necessarily those of the University of
     North Carolina at Chapel Hill, the Campus Office for Information
        Technology, or the Experimental Bulletin Board Service.
           internet:  laUNChpad.unc.edu or 152.2.22.80
Newsgroups: sci.astro
From: awootten@polaris.cv.nrao.edu (Al Wootten)
Subject: Re: Elements for Swift-tuttle
Organization: National Radio Astronomy Observatory
Date: Fri, 13 Nov 1992 15:28:05 GMT

In article <BxMCvz.9Gt@rahul.net> mike@rahul.net (Mike Smithwick) writes:

   What are the current elements for Swift-tuttle? I've two sets here and
   they are both missing one or two values so I can't use them.

I just posted these but forgot to mention that the elements were precessed
to 1950.0 from the J2000 which appears in the MPC.  Sorry!
--
+--------------------------------------------__---------+
| Alwyn  Wootten  (awootten@nrao.edu) 	     \/	GBT	|
| National Radio Astronomy Observatory        ^         |
| 520 Edgemont Road, Charlottesville, VA 22903-2475, USA|
| (804)-296-0329 voice  Let's build The Millimeter Array|
| (804)-296-0278 FAX           {>    {>    {>    {>     |
+------------------------------^-----^-----^-----^------+
From: jmcd@cea.berkeley.edu (John McDonald)
Newsgroups: sci.astro
Subject: C-5 old/new compatibility
Date: 9 Nov 92 20:59:48 GMT
Organization: Center for EUV Astrophysics


Hi Network!

I have a C-5 that dates way back, i'm not sure how old it
is.  I really like it, but it is mounted in a less than 
secure manner on an old German equatorial mount without a 
clock drive.  With the new release of the C-5 from 
Celestron, what are the odds that their nice one-arm fork
mount is compatible with my nice old scope, without me having
to drill holes in the tube of the old scope?  Anyone have any
info on this?  Maybe someone could tell me the mounting
dimensions (how far apart and how many holes there are) if 
anyone out there already has one of the new scopes? 

Thanks!

johnny

begin 664 signature.uu
M:F]H;E\M7U\M7U\M7U\M7U\M7U\M7U\M7U\M7U\M7U\M7VUC9&]N86QD"@E!
M<G1I<W1S(%!R;W9O:V4@06QI96YS"E]?+5]?+5]?+5]?+5]?+5]?+5]?+5]?
M+5]?+5]?+5]?+5]?+5]?+5]?+0IC96YT97(@(" @("!F;W(@(" @("!E=78@
2(" @("!A<W1R;W!H>7-I8W,*
Newsgroups: sci.astro
From: phfrom@nyx.uni-konstanz.de (Hartmut Frommert)
Subject: Re: Orbit Determination
Organization: Dept. of Physics, University of Constance
Date: Wed, 11 Nov 1992 11:35:12 GMT

kfarmer@wsuaix.csc.wsu.edu (keith farmer;S10000) writes:
[..]
>   P=coordinates of an object in 3-space at t=0
>  mP=mass of object P
>  vP=velocity in 3-space of P at t=0

>  mQ=mass of P's primary

>And assuming that the primary Q is relatively stationary and centered on
>(x,y,z)=(0,0,0)

i.e. you assume relative coords

>Determine:

>r(t)=the orbital path of P through time

I assume that you want to determine that in the Newtonian theory of gravity.

It should be not too difficult :-)
Just for fun, I give a brief outline:

Just use energy and angular momentum conservation, i.e.

E = (1/2)*(mP*vP^2 + mQ*vQ^2) - G*mP*mQ/P = const

L_ = mP * (rP_ x vP_) + mQ * (rQ_ x vQ_)  = const
 ^             ^
 |       cross product
 +- indicating vector

with rP, rQ: Position vector of P and Q, respectively,
which reduces to

E = ES + (1/2) m*v^2 - G*(mP+mQ)*m/P
  = ES + m * [(1/2) v^2 - G*(mP+mQ)/P]

L_ = LS_ + m * (P_ x  v_)

with the constant equilib point kinetic energy ES and angular momentum LS_, 
the effective mass
    m = mP*mQ/(mP+mQ)
and relative velocity 
    v_ = vP_ - vQ_ (= d P_/d t ) .
In relative coord, ES == 0 and LS_ == 0, so that E and L_ may be calculated
from the initial values by insertionin the E and L_ equation. The L_ eq 
gives the orbital plane (perpendicular to L_, generated by P_ and v_), i.e. 
inclination and ascending node, while the energy E and the absolute value
L of L_ determine the shape of the orbit:

E < 0: elliptic
E = 0: parabolic
E > 0: hyperbolic

while the excentricity e and the perihelion distance p are given by

    e = sqrt[1 + (2E/m)*(L/m*(mP+mQ))^2]

 (  0 <= e < 1 : elliptic
       e = 1   : parabolic
       e > 1   : hyperbolic )

and p = (L/m)^2 / [(mP+mQ)*(1+e)]

(so if e<1 you can calculate the semi major axis to a=p/(1-e), ...)

With the angle phi of the planet from the perihelion, you have an eq for the
distance P:
  P = p*(1+e) / (1+e*cos(phi))
where phi is positive/negative when v_ points outward/inward.

A somewhat more sophisticated integration of the energy eq provides, at last,
an implicit analytic (i.e. exact) relation between time t and the angle phi:
for elliptic orbits, this reads (M := mP + mQ):

  t = tP + M^(-1/2)*[p/(1-e)]^(3/2) * 
      * [2 arctan {sqrt((1-e)/(1+e)) * tan(phi/2)} -
         sqrt(1-e^2)*e*sin(phi) / (1 + e*cos(phi)) ]

To get this in the form r(t), phi(t) instead of r(phi), t(phi) requires
some numerics.

BTW the last eq yields the revolution period, i.e. Kepler's 3rd law when you 
insert phi = 2 pi:

  T = 2 pi * M^(-1/2) * [p/(1-e)]^(3/2) = 2 pi * M^(-1/2) * a^(3/2).

Hope this helps and didn't waste too much bandwidth.
 Hartmut Frommert                 <phfrom@nyx.uni-konstanz.de>
 Dept of Physics, Univ of Constance, P.O.Box 55 60, D-W-7750 Konstanz, Germany
                                           -- Eat whale killers, not whales --
From: reynolds@yin.ucsd.edu (Andy Reynolds)
Newsgroups: sci.astro
Subject: Medieval Astronomy
Date: 9 Nov 1992 04:58:40 GMT
Organization: UC San Diego
Distribution: world
NNTP-Posting-Host: song.ucsd.edu
Originator: reynolds@song

Greetings all,
	I am interested in both astronomy and the middle ages and was wondering
if anyone might know of a good source of information on the way astronomy
was practiced in the middle ages in Europe?  Any help would be appreciated.

		Thanks,
		Andy Reynolds
		reynolds@yin.ucsd.edu
From: cbenson@cs.strath.ac.uk (Calum F Benson CS90)
Newsgroups: sci.astro
Subject: FTP sites for stars -  thanks, but ..
Date: 12 Nov 92 12:28:21 GMT
Organization: Comp. Sci. Dept., Strathclyde Univ., Glasgow, Scotland.



Firstly, a big thanks to everyone who replied to my posting looking for 
FTP star sites. There were far too many of you to reply to individually!

But one problem was the fact that most of you gave the sites by their
usual mnemonic internet address (e.g. `ftp.funet.fi') and forgot to
mention their IP (numerical) address, which is the only form of address
many systems, including this University's, can recognise.

So a word of advice for the future - will you all please give both forms
of address wherever possible! 

Thanks again anyway, though.

Calum


+---------------------------------------------+---------------------------+
|                                             |       CALUM BENSON        |
|   "Studying for the wrong chapter is like   | 4TH YEAR COMPUTER SCIENCE |
|    cutting your fingernails too short"      | University of Strathclyde |
|                                             |     Glasgow, Scotland     |
+---------------------------------------------+---------------------------+
|        cbenson@uk.ac.strath.cs AND cadx609@uk.ac.strath.ccsun           |
+-------------------------------------------------------------------------+


     	
Newsgroups: sci.astro
From: kgrossha@radford.vak12ed.edu (Kurt Grosshans)
Subject: Re: Intro
Organization: Virginia's Public Education Network (Radford)
Date: Tue, 10 Nov 92 02:29:49 GMT

ae472@yfn.ysu.edu  writes:
> 
> Hi, everybody. My name is Manuel Lozada. I joust bought the 
> October issue of "Astronomy". I found it very interesting
> and now I want to learn from the begining this wonderful field.
> I'm a Computer Science student at the University of Puerto Rico.
> I had visited several times the Arecibo Telescope, wich is the 
> world's largest, and made observations. For now, my interests
> are in knowing the differences between Refractor telescopes,
> Reflector telescopes, Schmidt-Cassegrains telescopes, etc.
> I would appreciate very much what I can learn from you and I'll
> be reading this net often. Thanks in advance.
> 
> 
> ----------------------
> Manuel E. Lozada
> University of Puerto Rico
> 
> stud106@cutb.upr.clu.edu
> ae472@yfn.ysu.edu
> -- 
>        
You can gain a tremendous amount of information by going to
your local library and borrowing:

How To Use An Astronomical Telescope by James Muirden.
Published by Simon & Schuster, NY, NY

Very well written for the beginner.
-- 
=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=
Kurt Grosshans
kgrossha@radford.vak12ed.edu

Xref: sparky sci.astro:11725 sci.space:15417
From: max@west.darkside.com (Erik Max Francis)
Newsgroups: sci.astro,sci.space
Subject: Re: ANSWER: Recognizing a Dyson sphere if you saw one
Date: 6 Nov 92 17:32:23 GMT
Organization: The Dark Side of the Moon +1 408 245 SPAM

Frederick.A.Ringwald@dartmouth.edu (Frederick A. Ringwald) writes:

> No - the main point to the article is that the filling factor does not
> necessarily have to be high, so plenty of light from the central star
> would get through. What we'd see is a Sun-like star, with a small IR
> excess indicating a 300 K shell with size on the order of 1 AU: in
> other words, something not necessarily easily distinguishable from a
> natural object. Unless there's something obvious, such as narrow-band
> radio signals...

Oh.  So you're assuming that the Dyson sphere would be semitransparent?  
Sounds then like it would look like an F-K shell star . . .

----------
Erik Max Francis   Omnia quia sunt, lumina sunt.  Coming soon:  UNIVERSE _ | _
USmail:  1070 Oakmont Dr. #1 San Jose CA 95117  ICBM:  37 20 N  121 53 W _>|<_
UUCP:  ..!apple!uuwest!max   Usenet:  max@west.darkside.com   464E4F5244   |
Xref: sparky sci.astro:11761 sci.space:15471
From: claudio@nmsb.larc.nasa.gov (Claudio Egalon)
Newsgroups: sci.astro,sci.space
Subject: Re: Hubble's mirror
Date: 7 Nov 1992 20:03:21 GMT
Organization: NASA Langley Research Center, Hampton, VA  USA
Distribution: world
Reply-To: claudio@nmsb.larc.nasa.gov (Claudio Egalon)
NNTP-Posting-Host: b1230bmac8.larc.nasa.gov

Henry Spencer is right. Although it was sometime ago that I read an 
article in Physics Today- which explained very nicely the real messed 
up-, I still recall that there was three diferent instruments that were 
used to measure the curvature of the primary mirror. Two of them 
used refraction principle and one of them used the reflection 
principle (don't remember the details so I may commit some  
mistakes. If so, I apologize). The results of the other two instruments 
that used the refraction principle to measure the mirror curvature 
matched up but... the measurements produced by the one that used 
reflection, reflective null corrector, was different and, since it was 
thought to be superior to the other two,  no one bottered about 
finding out why the discrepancy between the measurements... of 
course untill they found out that there was something wrong with  
Hubble. 

*However* as  I recall (and I may be wrong) the error in the RNC 
came along because the WRONG surface in the instrument was 
providing the reflection and not that because the instrument was 
built improperly. Aparently there was an scratch in a surface that was 
suposed to be black, for absorbing incoming radiation, and it was this 
scratch that worked as the WRONG reflecting surface. So,  that how 
the wrong prescription came about. Another reference for the 
investigation on the problem of the mirror was the report put out by 
Lew Allen's review board (I guess I have a copy of it at home and I 
am confindent that you people can get one from NASA but I do not 
know whether they  will charge you or not). Maybe, not oddly 
enough, there were other complaints about the handling of the  
project  like people did not like to be bothered with criticism (read 
peer review)... So aparently, the problem was both technical and 
arrogance.

Claudio O. Egalon


Xref: sparky sci.astro:11697 sci.space:15388 sci.space.shuttle:2647 news.answers:3856
From: palmer@sfu.ca (Leigh Palmer)
Subject: Re: Position of Celestial Object Using Triangulation
Organization: Simon Fraser University
Date: Fri, 13 Nov 1992 20:38:47 GMT

In article <BxLAL4.3Hq@news.iastate.edu> F1.DAO@isumvs.iastate.edu (David
Oesper) writes:
>I have just purchased a Celestron Micro Guide Eyepiece which has,
>among other things, a finely graduated linear scale for the
>measurement of angular distances on the sky.
>
>Can anyone suggest a reference describing the mathematics,
>algorithm, or computer program to solve the following general
>problem?
>
>Given three stars of known position in the field (equinox 2000.0
>coordinates, for example) with coordinates (alpha1,delta1) and
>(alpha2,delta2) and (alpha3,delta3), and the angular distance from
>each star to a fourth object with unknown coordinates
>(alpha0,delta0) where these distances are given as d1, d2, and d3,
>respectively, how would you go about calculating the position of the
>fourth object and the probable error of that position?  Given the
>relative crudeness of our measurements, would we be able to ignore
>the effects of precession, nutation, proper motion, and stellar
>aberration to get a reasonably accurate position for the object?  It
>is a given that all four objects will be in the same field of this
>12.5 mm-focal-length eyepiece, and thus very close to each other.
>
>Isn't this just a simple exercise in triangulation?

Yes, it is, and given the field of view, you can make it an exercise in plane
trigonometry. After converting your alphas to degrees, multiply them by the
cosine of the declination. These converted alphas (gammas, say) can now be used
together with the decs as a simple cartesian coordinate system, and
intersections of circles will determine the unknown position for you. By the
way, having three objects to compare to overdetermines the position. Two
objects should suffice for the measurement - provided you know whether the
image is right-side up or left-right reversed - or not - or not!

Since you are doing a differential measurement (relative astrometry) the
sources of "error" in the resulting object's "measured" RA and dec will entail
those errors inherent in the RA and dec of the reference objects. The only
additional errors are those inherent in your measurements.

Leigh
From: cfifer@rvgs.vak12ed.edu (Craig Fifer)
Newsgroups: sci.astro
Subject: Re: looking for raytracing...followup
Date: 11 Nov 92 02:10:12 GMT
Organization: Virginia's Public Education Network (Roanoke)

Would you consider posting the results of your queries (product
names, how to contact authors, etc.)  I would be very
interested in hearing from you.

-Craig Fifer
cfifer@rvgs.vak12ed.edu
-- 
_____________________________________________________________________________
|   Never play leapfrog with              |   Craig Fifer                   |
|   a unicorn!   -Murphy                  |   3736 Heritage Road, S.W.      |
|                                         |   Roanoke, Virginia  24015-4518 |
Newsgroups: sci.astro