HDTenEightyP/NetNews huggingface dataset:
From: sla@umbra.UCSC.EDU (Steve Allen)
Newsgroups: sci.astro.fits
Subject: Re: World Coordinate System proposal
Date: 6 Nov 1992 21:31:05 GMT
Organization: UCO/Lick Observatory
NNTP-Posting-Host: umbra.ucsc.edu
Summary: are pixels sampled or binned? where is the edge/center?

In article <DWELLS.92Nov5190043@fits.cv.nrao.edu>
dwells@fits.cv.nrao.edu (Don Wells) writes:
>Bob Hanisch distributed copies of a paper which he and I prepared in
>February 1988. This paper documented the conclusions reached during a
>WCS workshop held in Charlottesville in January 1988; it should be the
>starting point for a new round of discussions of WCS issues.

In looking over this paper I am left asking a question about the
CRPIX1 and CRPIX2 values at the point of tangency on the sky.

The question boils down to another question:  Are FITS images representing
binned data or sampled data?  How do you tell?

By binned data I mean that pixels are represented by adjacent rectangular
regions and that the value of the pixel represents some kind of integral
(i.e., of the surface brightness of the sky) of a pixel response function
which is nearly uniform over the entire rectangle.

By sampled data I mean that pixels are represented by point samples within
each rectangle, or more precisely, that the pixel response function can be
thought as being very much smaller than the inter-pixel spacing.

In sampled data it is reasonable to think of the "middle" of the pixel as
having an integral coordinate.  In binned data there is some variance of
convention, but many people consider that the "middle" of a pixel has
a half-integral location (e.g., the boundaries between pixels are integral).

There are some applications where the distinction between sampled and binned
data should be made in order to assure a more rigorously correct
interpretation.  In either case, it is important to tell the next user of
this data which convention of pixel numbering is used to specify the
CRPIX values.

For the sake of this WCS proposal, which convention is being used?
_______________________________________________________________________________
Steve Allen          | That was the equation!         |   sla@lick.ucsc.edu
UCO/Lick Observatory | Existence!...Survival must     | If the UC were opining,
Santa Cruz, CA 95064 | cancel out programming! -- Ruk | it wouldn't tell me.
Newsgroups: sci.astro.fits
From: cur@rlstar.bnsc.rl.ac.uk (Malcolm J. Currie)
Subject: Re: World Coordinate System proposal
Organization: National Radio Astronomy Observatory
Date: Sun, 8 Nov 1992 00:52:43 GMT

------- Start of forwarded message -------
From: cur@rlstar.bnsc.rl.ac.uk (Malcolm J. Currie)
To: fitsbits-request@fits.CV.NRAO.EDU
Subject: Re: World Coordinate System proposal
Date: Sat, 7 Nov 1992 19:39:15 GMT

Steve Allen writes:
>From my experience I infer that the astronomical community has
>pretty much established that the first pixel in an array is the pixel with
>the integer tag 1 which has floating point boundaries 0.5 and 1.5
>(middle of pixel is integral).

In Starlink we use pixel indices that, by default, start at 1.  However,
our definition of pixel co-ordinates has the first pixel (index 1)
between floating-point boundaries of 0.0 and 1.0, since we regard pixels
as binned data.  Isn't it more logical to start at the origin rather
than 0.5? 

Our NDF data structure permits axis widths to be defined in addition to
axis centres.  So for sampled data the widths could be made much smaller
than inter-pixel spacing. 

- -----------------------------------------------------------------------
Malcolm J. Currie   |     Span: RLVAD::CUR
Starlink Project    |     Janet: CUR@UK.AC.RUTHERFORD.STARLINK
                    |     +44-235-821900 x6735
- -----------------------------------------------------------------------
------- End of forwarded message -------
Newsgroups: sci.astro.fits
From: hanisch@stsci.edu (Bob Hanisch, ST ScI)
Subject: Re: World Coordinate System proposal
Reply-To: hanisch@stsci.edu
Organization: Space Telescope Science Institute, Baltimore MD
Date: Fri, 6 Nov 1992 22:12:11 GMT

In article 1deo6pINNlj9@darkstar.UCSC.EDU, sla@umbra.UCSC.EDU (Steve Allen) writes:
>In article <DWELLS.92Nov5190043@fits.cv.nrao.edu>
>dwells@fits.cv.nrao.edu (Don Wells) writes:
>>Bob Hanisch distributed copies of a paper which he and I prepared in
>>February 1988. This paper documented the conclusions reached during a
>>WCS workshop held in Charlottesville in January 1988; it should be the
>>starting point for a new round of discussions of WCS issues.
>
>In looking over this paper I am left asking a question about the
>CRPIX1 and CRPIX2 values at the point of tangency on the sky.
>
>The question boils down to another question:  Are FITS images representing
>binned data or sampled data?  How do you tell?
>
> etc....

This issue was discussed during the meeting in Boston, and it was agreed
that the proposal has to be revised to indicate the conventions being
used.  The consensus was that for FITS, pixel (1,1) is the pixel in the lower
left-hand corner of an image and that for the purpose of the WCS, this
pixel represents data from 0.5 to 1.5 in pixel coordinates.  This clarification
will be added to the proposal.

---
Robert J. Hanisch                       Tel. (410)338-4910   Fax. (410)338-5090
Space Telescope Science Institute       NSI: hanisch@stsci.edu [130.167.1.2]
3700 San Martin Drive                   DECNet: STSCIC::HANISCH [6549::] 
Baltimore, MD  21218  USA               Bitnet: hanisch@stsci

Newsgroups: sci.astro.fits
From: cur@rlstar.bnsc.rl.ac.uk (Malcolm J. Currie)
Subject: Re: Proposal for World Co-ordinate System
Reply-To: cur@star.rl.ac.uk
Organization: National Radio Astronomy Observatory
Date: Sat, 7 Nov 1992 19:45:04 GMT

Steve Allen writes:
>From my experience I infer that the astronomical community has
>pretty much established that the first pixel in an array is the pixel with
>the integer tag 1 which has floating point boundaries 0.5 and 1.5
>(middle of pixel is integral).

In Starlink we use pixel indices that, by default, start at 1.  However,
our definition of pixel co-ordinates has the first pixel (index 1)
between floating-point boundaries of 0.0 and 1.0, since we regard pixels
as binned data.  Isn't it more logical to start at the origin rather
than 0.5? 

Our NDF data structure permits axis widths to be defined in addition to
axis centres.  So for sampled data the widths could be made much smaller
than inter-pixel spacing. 

-----------------------------------------------------------------------
Malcolm J. Currie   |     Span: RLVAD::CUR
Starlink Project    |     Janet: CUR@UK.AC.RUTHERFORD.STARLINK
                    |     +44-235-821900 x6735
-----------------------------------------------------------------------
Newsgroups: sci.astro.fits
From: johno@sdd.hp.com (John Ongtooguk)
Newsgroups: sci.astro
Subject: Re: Experiences with telescope mail order
Date: 5 Nov 1992 21:38:23 GMT
Organization: Hewlett-Packard, San Diego Division
Distribution: world
NNTP-Posting-Host: hpsdlg10.sdd.hp.com

In article <1992Nov5.203738.3699@engage.pko.dec.com>, yerazunis@cthulu.enet.dec.com writes:
|> 
|> .........Try someplace reputable, like
|> FC Meichner's in Boston, or Orion in CA.

   I've ordered smaller items from University Optics, Orion, and 
   Wholesale Optics in Penn and have had good service from all. 
   Orion has a nice return policy which I've used once on an
   eyepiece which didn't like my fast scope, and the quickest
   receipt after ordering was from Wholesale Optics.  

   John Ongtooguk (johno@sdd.hp.com)
From: bunner@vms.macc.wisc.edu (Dana A. Bunner)
Newsgroups: sci.astro
Subject: Re: Black's Inexpensive Telescope (Opinions?)
Date: 9 Nov 92 22:47:26 GMT
Article-I.D.: macc.1992Nov9.235102.7919
Organization: University of Wisconsin Academic Computing Center

In article <16894B810.MEDELMA@cms.cc.wayne.edu>, MEDELMA@cms.cc.wayne.edu (Michael Edelman) writes...

I know nothing about the "Black's" scopes ... 

>The only 4.5" Newtonians I've heard anything good about are the Orion,
>for around $400 and the Vixens: Alt-azimuth for $250 or equatorial
>for $350. The Vixens have a pretty decent aluminum tripod, too.

The Vixens have recently dropped their price.  My local store now offers
the 4.5" Newtonian on equatorial mount for $298.  The mount looked pretty
good, better than the Meade 4420 sitting next to it for $349 (now 
discontinued).  A disadvantage of the Vixen is that it employs .965"
eyepieces, but two are included for the $298 price (I believe 8mm & 18mm).

Dana
From: max@west.darkside.com (Erik Max Francis)
Newsgroups: sci.astro
Subject: Re: Planet X
Keywords: asteroid, planet
Date: 4 Nov 92 18:01:47 GMT
Organization: The Dark Side of the Moon +1 408 245 SPAM

kmarvel@charon.NMSU.Edu (Kevin Marvel) writes:

> Clyde Tombaugh, the discoverer of Pluto, and an emeritus faculty member here
> at NMSU always makes a point of stating in his talks to 110 students, that
> he feels there is no planet X and if there was he would have found it.  He 
> observed the WHOLE ecliptic plane (+/- some 10's of degrees) at times when an
> object in the solar system would have been most visible (conjunction) 
> and he says it ain't there.  Anyone who has actually blinked 3*500 some odd
> plates and seen over 4 million stellar images, discovered asteroids, comets,
> variables etc. AND Pluto, and says that there is no planet X  I believe.
> This assumes of course that the planet reflects some light and is of some
> finite size, not sure of details here but chances of a significant body
> out there are low.

Many of the scenarios about a tenth planet say that the orbit might be 
inclined _well_ above the ecliptic, as angular momentum is less important 
out there.  (After all, the Oort cloud is spherical, no?)

A large, frozen gas giant out there would be very, very dim.  Imagine 
something at ~70 au.  Very, very little light would be reflected back.

It's been posited that there might be thousands of Pluto-sized objects 
out there between Pluto's orbit and the Oort cloud; it's been suggested 
that we might have a chance of seeing one or two if we start doing 
infrared maps of the entire sky.  This would help find another big planet 
out there, too.

----------
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:11769 sci.space:15482
From: rick@posms.cactus.org (Rick Kirchhof)
Newsgroups: sci.astro,sci.space
Subject: Re: Hubble's mirror
Date: 8 Nov 92 00:18:01 GMT
Organization: Department of Redundancy Dept., Austin

In article <PXiye-Go3@lopez.marquette.MI.US> stick@lopez.marquette.MI.US (Stick,CommoSigop) writes:
>In <yssPTB4w165w@bluemoon.rn.com> gerry@bluemoon.rn.com (Gerard M. Foley) writes:
>
>>dhl@mrdog.msl.com (Donald H. Locker) writes:
>
>>> Now that I know a little about mirror-making, I'd like to hear again
>>> how the Hubble mirror contractor messed up the figure of the main
>>> mirror.  I understand it has spherical aberration, but wonder how
>>> [Rockwell?] managed to do that.
>>> 
>>It wasn't Rockwell (I forget axactly who it was, but it was an
>>otherwise reputable New England outfit) and put briefly, they
>>fouled up the test, performing it incorrectly, and never
>>checked by any independent method.
>
>   According to Dr. Steve Maran, who works on the HST project at the
>Goddard Flight Center, and who was recently a guest lecturer at my college,
>none of the above is true.  The company that ground the mirror did it
>exactly to the specs they were given.
>
>   The specs were wrong.
>
>
That is not the case.  The primary mirror was produced by Perkin-Elmer.
This has been the subject of MUCH investigation by NASA.  The end result
is that Perkin-Elmer manufactured a large primary mirror to exceedingly
accurate standards obtained from a incorrectly manufactured optical test
cell they also made.  The "smoking gun" is in their mirror lab, as NASA
requested all relevant project materials mothballed upon project 
completion.

To be fair, the quality of the mirror was extremely good as tested by
their rig.  If the test cell had been correct, the mirror would have been
correct.  Perkin-Elmer just did not produce what NASA asked for.

It is ironic that several other types optical tests could have shown a
gross error such as this.  They were never used.  In addition, Eastman
Kodak, who also made a primary mirror to the design specs, requested 
that the better of the two mirrors be used.  This was never done.

For independent verification of all of this, see several issues of SKY &
TELESCOPE.  The subject has been reported several times there.

-- 
Rick Kirchhof   Austin, Texas                   | Experience is what you
Domain: rick@posms.cactus.org                   | get when you don't
Bang path: ...!cs.utexas.edu!peyote!posms!rick  | get what you want.            
===========================================================================
Xref: sparky sci.astro:11770 sci.edu:1142 junk:62308 sci.space:15485 sci.space.shuttle:2669
Newsgroups: sci.astro,sci.edu,junk,sci.space,sci.space.shuttle
Subject: Space_nz. Information Service.
From: space_nz@kiwi.gen.nz (Spacelink)
Date: 7 Nov 92 20:46:44 GMT
Reply-To: space_nz@kiwi.gen.nz (Spacelink)
Organization: Household UNIX, Auckland, New Zealand

Space_nz is a Space Information Bureau based in New Zealand.  Our aim is
to supply answers to people's questions whether they be simple or complex
on the history of human accomplishments in space.

You can contact us through our Email address of space_nz@kiwi.gen.nz,
or by writing to Spacelink at PO Box 331402, Takapuna, Auckland 9, New Zealand,
(Please enclose an SASE), or by Fax on 64-9-8494282.

This is a free service for the curious, supplied by a team of voluntary
Spaceflight enthusiasts.

This Article is to put our Previous Posted Article right with regards to our 
email address.
-- 
DOMAIN:  space_nz@kiwi.gen.nz
SNAIL:   PO Box 331402, Takapuna, Auckland 9, New Zealand
FAX:     64-9-849-4282
Newsgroups: sci.astro
From: pkj@halcyon.com (Paul Johnson)
Subject: Which telescope should I buy?
Organization: The 23:00 News and Mail Service
Distribution: usa
Date: Sat, 7 Nov 1992 23:19:43 GMT

I am currently looking to buy a telescope
for general night sky viewing. I am a new
user for a telescope and would like one 
that is easy to use and has good quality.
I would also like to spend less than 500
dollars. If anyone has a suggestion on
which telescope I should buy, please
contact me at pkj@halcyon.com
Thank you for your time.
Paul.
From: mmm@cup.portal.com (Mark Robert Thorson)
Newsgroups: sci.astro
Subject: Questions About Nickel-Iron Meteorites
Date: Thu, 12 Nov 92 22:04:34 PST
Organization: The Portal System (TM)

I have some questions about the Wilmarstatten (sp?) patterns in
meteorites.  These are the lines which appear if you cut a nickel-iron
meteorite, polish the surface, then treat it with acids or something.
You can see lots of good examples at the Smithsonian.

I remember hearing somewhere that metal meteorites cool very slowly
-- over many years or even centuries -- and that these patterns are
caused by the large grain structure which develops.

This has always bothered me.  I don't see how they could cool so slowly.
Although surrounded by vacuum, which is an excellent thermal insulator,
meteorites are also surround by the cold blackness of space.  I would
guess that a quantity of molten metal placed in space would freeze solid
and become cold to the touch within a few days at most.

It seems plausible to me that Wilmarstatten patterns are actually an
instance of Lueders' lines, and have nothing to do with crystallization.
Lueders' lines form on a highly stressed piece of metal when slippage
planes form.  When they occur on a pressure vessel or a ship hull or something,
they are considered a very bad sign, i.e. an indication that failure is imminent.
Lueders' lines often form in a cross-like pattern, where half the lines
run in one direction and the other half run in the perpendicular direction.
Wilmarstatten paterns also have this sort of cross-like arrangement.

I'd like to know whether all nickel-iron meteorites exhibit Wilmarstatten
patterns, or whether only some of them do.  I know the stones at the
Smithsonian showed a lot of variation in how pronounced the pattern is
and how long the lines are.  I suppose if they had some stones that were
totally blank, they might have considered them uninteresting and put them
in storage.

If some stones are blank, I think that might support my theory because
it would indicate that some stones had been subjected to a process which
formed the patterns while others had not.  The process I have in mind
would be a close approach to a black hole.

I'd like to know if nickel-iron meteorites exhibiting Wilmarstatten patterns
are monocrystalline, oligocrystalline, or polycrystalline.  If my theory
is correct, a meteorite could be as polycrystalline as an ax head, and it
still could exhibit Wilmarstatten patterns.
Newsgroups: sci.astro
From: skoester@magnus.acs.ohio-state.edu (Scott A Koester)
Subject: Jumpstart.....
Organization: The Ohio State University
Date: Tue, 10 Nov 1992 23:40:07 GMT


    I was wondering if anyone out there could suggest some books that I could 
read in order to get a jumpstart on things i might learn in school. I'm 
majoring in Astronautical Engineering (or stressing it as much as possible) and
would like to start reading information and digesting some things that apply to
this. I'm a sophomore at Ohio State right now and getting ready to start my 
Engineering courses (after getting the core stuff out of the way). I would like
to get ahead and start getting down some concepts that are going to become 
important and stressed, plus i am a curious person and intensly infatuated with
space and how we can explore it. Reponses via email please, thanks.


Scott Koester
Newsgroups: sci.astro
From: mike@rahul.net (Mike Smithwick)
Subject: Magellan image reader for mac
Organization: a2i network
Date: Fri, 13 Nov 1992 00:57:23 GMT

[]

Is there a PD image reader/converter for the Mac that will handle the
Magellan CD-ROM images?? And if so, is it available anywhere for ftp?


Mike

-- 
"Friends don't let friends vote Democratic"

Mike Smithwick - mike@rahul.net
From: sysevm@nsrvan.vanc.wa.us
Newsgroups: sci.astro
Subject: Re: Real Men Astronomers [Was Re: e-mail activated telescope?]
Date: 6 Nov 92 19:37:46 GMT
Article-I.D.: nsrvan.1992Nov6.113747.44
Organization: National Systems & Research, Vancouver WA

In article <1992Nov5.183901.28034@athena.mit.edu>, hbh@athena.mit.edu (Heidi Hammel) writes:
> higgins@fnalo.fnal.gov (Bill Higgins-- Beam Jockey) writes:
>> kent@patience.Stanford.EDU (Mark Kent) writes:
...
>>2. Anita Cochran, Heidi Hammel, and other lady astronomers *are* Real Men.
> 
> :-}  Well, okay - but just don't tell my SO ;-).  Seriously, though, it is
> tough to find a professional astronomer who does *not* work in a warm room.
> Most large telescopes are run that way.  Even Real Men like me do it :-). 
...
> astronomers, I'll add that even in a warm room, Mauna Kea's 14,000-ft
> altitude can be a real challenge.  There are headaches, hypoxia-induced
> stupidity, extreme dryness (RH < 5%), etc.  And then there was the run in
> 1991 .... My observing sequence went: std star 5 min, Neptune 15 min, throw
> up 10 min, std star 5 min, Neptune 15 min, throw up 10 min, std star 5 min,
> Neptune 15 min, ad nauseum .....  It is so difficult to get telescope time
> that you just grit your teeth and keep going, flu or not.  I got some
> useful data out of that run, but it was not the easiest or most pleasant
> of experiences, even for warm-room key-board-pecking observing...  
> 
> So do I get to keep my title of "Real Man" astronomer
> even though I mostly work in a warm room at a computer? ;-)
> 
> heidi
> --

	"Real Man" of course means 'tough human' and you qualify. But thats not
why I've followuped. I just thought I'd say that the air at 14k is rich, warm
and dense if you spend some time there and don't go there to fast. Having spent
2 months (on more than 1 time) above 17k I can say that the air at 21,000' is
warm, rich, moist and dense when you come down from 23,000. Climbing is fun.

	I'd love to spend a few weeks on Mauna Kea helping anyone out!

Regards, Ethan
Xref: sparky sci.astro:11811 sci.space:15587
From: bunner@vms.macc.wisc.edu (Dana A. Bunner)
Newsgroups: sci.astro
Subject: Re: Orion (was Celestron) Binoculars
Date: 6 Nov 92 23:18:56 GMT
Article-I.D.: macc.1992Nov7.002554.17257
Organization: University of Wisconsin Academic Computing Center

In article <1992Oct28.165958.8762@hplabsz.hpl.hp.com>, dsmith@hplabsz.hpl.hp.com (David R. Smith) writes...

>I looked over an Orion 8x56, and was a little disappointed.

Thanks for the up close and personal review.  Being based nearly 2000 miles
from the store, it is difficult for me to give them a trial run.

>The eye relief is not sufficient for eyeglass wearers to see the full field.

I'm surprised by this.  They are advertised as having an eye relief of 18mm,
which should be sufficient for eyeglass wearers.  

>... Focus
>travel is not sufficient for me to reach infinity focus without my glasses.
>(My corrections are -8 and -5 diopters.)

I also have trouble with this.  I once tried every 10X50 binocular in a 
sporting goods store (including Bushnell, Minolta, Nikon, and Steiner)
with finding a single one which I could focus in my right eye (-6.5 d).
I can focus with the Celestron Ultima 10x50 but not in the 8x56.  I 
also found a pair of Swift Audubons which were sufficient.

>In fairness, I should note that many binoculars share these problems,
>and nearly all that I have tried share the last one.  

Amen.

Dana
Organization: Johannes Kepler University Linz - Computing Center
Date: Friday, 6 Nov 1992 09:43:44 CET
From: <K3032E0@ALIJKU11.BITNET>
Newsgroups: sci.astro
Subject: Re: Any known Perseid meteorite recoveries??
Distribution: sci.astro

As far as I know, there is not a single meteorite in our collections known
to come from a meteor shower. Those cometary particels seem to break up very
easily, and have hardly any chance of reaching the ground.

If there is any meteorite-class that comes from comets, it's the CI-class of
carbonous chondrites. They seem to have formed in a warm, wet enviroment,
but, of course, the possible parent body is not known.

Keep looking up| - Herbert
Newsgroups: sci.astro
From: Richard.Mathews@West.Sun.COM (Richard M. Mathews)
Newsgroups: sci.astro
Subject: Re: NEWS: Galileo Cleared of Heresy Charges by Vatican
Date: 6 Nov 92 21:08:49 GMT
Organization: Sunsoft Inc., Los Angeles, CA.
NNTP-Posting-Host: astro
Originator: richard@astro.West.Sun.COM

mpound@astro.umd.edu (Marc Pound) writes:

>He had clear, compelling proof! He observed the phases of Venus, 
>and thus showed it went around the Sun not the Earth.

And remember that the phase changes are accompanied by size changes.  If
the size changes are interpreted as distance changes, the correlation of
phase with size/distance is really killer evidence.

I think also that much of the debate was over Galileo's alleged belittling
of the Pope rather than the scientific theory.  But if the Pope is not
infallible, then pointing out his faults should not be a crime.  Whether
they were censoring the astronomical theory or the characterization of
the Pope, it is still censorship.  Even looking at it from the point
of view of what was known 350 years ago, it is wrong to censor ideas
no matter how wrong you might think they are.

They did the right thing by overturning the conviction.  By arguing over
it for 13 years, they showed that they still have faults including pride
and a willingness to at least consider condoning suppression of ideas.
If my original post sounded more negative than that, it was not what I
really intended.

     Richard M. Mathews			Lietuva laisva = Free Lithuania
					Brivu Latviju  = Free Latvia
Richard.Mathews@West.Sun.COM		Eesti vabaks   = Free Estonia
					        WE  DID  IT!!!
Newsgroups: sci.astro,sci.space