HDTenEightyP/NetNews huggingface dataset:
From: zellner@stsci.edu
Subject: The color violet?
Organization: Space Telescope Science Institute
Distribution: na
Date: Wed, 30 Sep 1992 00:30:34 GMT

If you look at violet light, what do you see?  By "violet", of course, I
mean light of a wavelength that is shorter than "blue".  For example,
between 3800 and 4200A, which is within the detection spectrum of the
"blue" cones in our eyes but substantially shorter than their peak
sensitivity at around 4500A. 

Obviously violet isn't the same thing as purple, which is a mixture of
red and blue.  Purple can be located on the standard color charts, but
where is violet on such a chart? 

If only the blue cones are stimulated, how can we see any color but blue?
While our red cones peak at wavelengths shorter than 6000A, we can see
some light at 7000A or longer.  But we don't have a word for a color
redder than red.  Why do we have the color "violet" that is bluer than
blue? 

So:  Have you ever seen the color violet?  The blossoms of the flowers
we call "violets" are purple, not violet.  That is, they reflect blue
and red light but not much green.  I think the same is true of almost
any natural or artificial pigment.  It is notoriously difficult to make
a filter that transmits short wavelengths only.  The standard violet
filters used in photography or astronomy have a substantial "red leak"
and are actually useful only when used with rather red-blind detectors
and/or hot stars.  The same is true even of the standard U or ultra-
violet filter of astronomy; if you look at the sun through one of them,
you see a red sun.  

How about in a rainbow?  Actually it's rather hard to see much blue in 
a rainbow, I presume because Rayleigh scattering removes a lot of it
before it reaches near-surface altitudes, and also because the sun isn't
very bright in blue light.  Did you ever see violet in a rainbow?  Don't
be misled by the red (or purple?) of the secondary bow or supernumerary 
arcs! 

Where could you actually see pure violet light?  Within a spectroscope,
obviously.  As an undergraduate I once had the job of calibrating a
grating monochromator.  As I recall I got down to perhaps 3000A, but I
wasn't sure if I was really seeing light that short, or just scattered
light within the instrument.  Anyway, it didn't look blue, it looked
rather ashy, really no color at all.  Do any other perceptions differ? 

Are any "neon signs" truly violet, that is, without admixture of other
colors?  How about the "bug zappers" that one buys in a hardware store? 
And what is the color "indigo"?

Cheers, Ben Zellner

Newsgroups: sci.astro
From: tholen@galileo.ifa.hawaii.edu (Dave Tholen)
Subject: Re: Help.Analemma question???
Organization: Institute for Astronomy, Hawaii
Date: Thu, 1 Oct 1992 07:37:37 GMT

> I am looking for the answer to a basic question regarding the analemma.
> If you look at a picture of the analemma you notice that the top part of
> the figure eight is smaller than the bottom part. This top part represents
> when the sun reaches its highest point in this part of the sky during the
> summertime. However, summertime is the longest season lasting 94 days. Why
> isn't this shown in the analemma as a larger part of the figure eight??
> Please try to keep explanation basic (I am probably overlooking something,
> anyhow) this is for high school astronomy students.

If the Earth's orbit were a perfect circle, the analemma would be a figure
eight, symmetrical about both the vertical and horizontal axes.  However,
the Earth's orbit is not a perfect circle, thus it behaves according to
Kepler's Second Law, slowing down as it approach aphelion, which is in early
July, just after the northern solstice.  That makes the time correction
between the mean Sun and the true Sun less, making the northern half of the
analemma skinnier.  The southern half occurs near perihelion where the Earth
is moving faster, thus the Earth has to rotate more to return the Sun to the
same meridian on the sky.
From: j.jahn@abbs.hanse.de (Jost Jahn)
Newsgroups: sci.astro
Subject: Sunspots at 05.10.1992.
Reply-To: j.jahn@abbs.hanse.de
Date: 05 Oct 92 21:03:00 MET
Distribution: sci
Organization: ABBS AstroMail, D-W 2121 Dahlenburg / Germany
X-Version: ZerUU V6.45c

Sunspots at 05.10.1992., 0 h UT.

No.    Pos.  Cl.  Ar.  Mag. SF  F  M  X
---------------------------------------
7293 09S 84W Hax   40   a    1     1
7294 11S 62W Hsx  200   a    2
7295 13N 40W Cso   60   b
7296 08N 39W Axx    0   a
7298 16N 05W Cso   50   b    1
7299 13N 12E Bxo   10   b
7300 13N 33E Bxo   20   b
7301 16S 12E Cso   70   b    5
7303 13S 17E Cso   30   b    3
7304 05N 08W Axx    0   a
7305 12N 42E Dsi  100   b    1
7306 08S 65E Bxo   10   b


Optical and x-ray flares in 04.10.92.

Date     Beg. Max. End   Posit. Xray Opt
----------------------------------------
04.10.92 2211 2227 2238 05S 90W M2.4 SN


 
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From: era_pul@arkimedes.ki.ericsson.se (Peter Ulfheden consultant)
Newsgroups: sci.astro
Subject: Comet orbital elements
Date: 6 Oct 92 11:48:55 GMT
Distribution: sci.astro
Organization: Ericsson Radio Sytems AB, Sweden

Hi,
Can any one please mail me the orbital elements for the latest comets,
of course Swift-Tuttle in particular.

Thanks

Peter
--

=======================================================
 Peter Ulfheden              |  era_pul@ki.ericsson.se
 Amorinav. 3                 |  Phone: +46 8 751 02 15
 S-191 44 Sollentuna, SWEDEN |  Fax:   +46 8 35 04 29
=======================================================
From: adams@chuck.dallas.sgi.com (Charles Adams)
Newsgroups: sci.astro
Subject: Re: The color violet?
Date: 3 Oct 92 14:15:39 GMT
Organization: Silicon Graphics, Inc.

In article <BvIKrH.GKH@Novell.COM>, Mark_Dakins@Novell.COM (Mark Dakins) writes:
|> In article <1992Oct2.045657.9863@news.Hawaii.Edu> joe@montebello.soest.hawaii.edu writes:
|> 
|>     (stuff deleted)
|> 
|> >                                    I don't know about you, but when
|> >I look at a rainbow I see lots of violet at one end and have difficulty
|> >finding the hint of blue wedged between the much wider bands of green
|> >and violet!
|> >
|> 
|> As a interesting aside to this, try an experiment I have done a couple
|> of times.  Rig up a way to project a high dispersion solar spectrum
|> on a piece of paper and take it to work (school).  Have your friends
|> draw lines dividing what they "see" as "the colors" of the spectrum.
|> Don't let them see each others work beforehand. 
(stuff deleted)
|> 					Mark Dakins

Great Idea Mark!!

Side comments.

    1.  Calibrate points at .40microns to .75 microns in steps of .05 on
        page.  (What kind of paper?  Tint always the same across the country?)

    2.  Find pure color paint samples, say at Home Depot, and have subject
        match on spectrum.  These should be uniform across the country.

    3.  Since experiment involves human subjects, spend 5 years going through
        paper work for OSHA, DEA, AMA, NSA, EPA, and other govt. agencies. ;-)

The reason for 1 is to get a quantitative range of variance between the test
group.  If you go back through the literature, you'll find that the 1931
CIE Chromaticity Diagram was created from a population sample size of less
than 10 (ten)!!!  Of course, better medicine, etc. and other environmental
changes may have changed the human response curves to light.  

My personal interest in this subject is related to color gradations of the
sky at sunset and sunrise as a function of atmospheric parameters.

ciao,
-- 

   Chuck Adams, K5FO @ 70+ wpm cw 
   adams@sgi.com
Newsgroups: sci.astro
Subject: Addition to: Need a list of suitable CCD Flatfield sites...
From: belgarath@vax1.mankato.msus.edu
Date: 29 Sep 92 22:37:38 -0600
Organization: Mankato State University

In article <1992Sep29.145702.1@vax1.mankato.msus.edu>, belgarath@vax1.mankato.msus.edu writes:
>         Does anyone know where we can find a list of suitable flatfields for
> CCD imaging?  Either the list itself, or the location of the list would be
> greatly appreciated. Please send responses to the e-mail address below.
>                                                        Thanks!
>                                                        Jeremy Hallum
> 
>                                                        Mankato State U
>                                                       
>         belgarath@vax1.mankato.msus.ed
> 


        Due to the influx of mail asking what the hell I actually wanted,
here's an addendum to the message. We here, are looking for deepsky flatfields
(places where there are relatively few visible stars, or no stars at all) for a
CCD imaging class.  The professor remembers seeing a list in a journal, but he
doesn't remember where.  If someone knows where the list is located, or has it
on a text file, could they please send the list (or location) to
belgarath@vax1.mankato.msus.edu  
                                                         Thanks!
                                                         Jeremy Hallum

                                                         Mankato State U.
From: Frederick.A.Ringwald@dartmouth.edu (Frederick A. Ringwald)
Newsgroups: sci.astro
Subject: Re: The color violet?
Date: 1 Oct 92 01:28:51 GMT
Organization: Dartmouth College, Hanover, NH
X-Posted-From: InterNews1.0a5@newshost.dartmouth.edu

In article <1992Sep29.193034.1@stsci.edu>
zellner@stsci.edu writes:

> Where could you actually see pure violet light?

At the Flandrau Planetarium, across the street from NOAO headquarters
in Tucson, that's where. There's a splendid exhibit of the solar
spectrum. If the Sun is out (fancy that, in Arizona of all places...),
the light gets dispersed into a spectrum about 10 or 12 feet wide. I
saw all my favorite lines, H alpha, Na D, He I 5876, H beta (in the
blue-green), all the way up to Calcium H and K. But wait, you might
say, those are in the UV, and I'd say you're right, your eye can't see
that far into the UV. They have a piece of fluorescent material on that
end of the screen, which glows a greenish tint and makes those lines
visible.

The colors of the continuum are fairly saturated: green looks green,
not white. What's billed as violet looked like violet to me: H gamma is
there. So empirically, I *can* see violet light, although I'm not sure
*how* I see it, physiologically. 

(Come to think of it, what do you mean "pure" violet light? Spectral,
as in 100% saturated? There's plenty of scattered white light in that
room, but unless you're fussy, we might neglect this. If you are fussy,
are there lasers available that work in this region? Shine one onto a
white screen in an otherwise totally dark room, and what color do you
see reflect from the screen?)

fred.ringwald@dartmouth.edu
From: meier@Software.Mitel.COM (Rolf Meier)
Newsgroups: sci.astro
Subject: Re: Help.Analemma question???
Date: 30 Sep 92 16:23:33 GMT
Organization: Mitel. Kanata (Ontario). Canada.

In article <1992Sep29.191403.21374@organpipe.uug.arizona.edu> newberry@astro.as.arizona.edu (Mike Newberry) writes:

>5) The time of perihelion IS NOT synchronized with the time of the winter
>   solstice (January 17(?) vs. December 21, respectively).
              ^^^^^^^^^^

Perihelion is January 3 or 4, aphelion is around July 3 or 4.

_______________________________________________________________________________
Rolf Meier						Mitel Corporation
Newsgroups: sci.astro,sci.physics
From: F1.DAO@isumvs.iastate.edu (David Oesper)
Subject: FITS to GIF Image Conversion?
Organization: Iowa State University, Ames IA
Date: Tue, 29 Sep 1992 04:39:51 GMT

Is there a FITS to GIF conversion program available for the IBM or
Macintosh?
Newsgroups: sci.astro
From: siamack@iastate.edu (Siamack Bondari)
Subject: Re: TIME HAS INERTIA
Keywords: TIME, INERTIA, proof?
Organization: Iowa State University, Ames IA
Date: Wed, 30 Sep 1992 20:19:09 GMT

In <29SEP199214232446@csa1.lbl.gov> sichase@csa1.lbl.gov (SCOTT I CHASE) writes:

>In article <1992Sep25.104840@karma.astro.Virginia.EDU>, pcp2g@karma.astro.Virginia.EDU (Gilligan) writes...
>> 
>>Where exactly does this come from? According to the conservation of energy,
>>the TOTAL energy of the universe is constant; possibly, in the Big Bang
>>theory, the KINETIC energy of the universe is decreasing (being
>>converted to gravitational potential energy).

>Not true.  The total energy of our Universe is decreasing with time. 
>Photons in the CBR are red-shifting into oblivion as the Universe expands.
>The energy in these photons is simply disappearing.  Bummer, huh?
>It is in fact impossible to construct any bilinear quantity which you
>might want to call "energy" in GR because it is not time symmetric (i.e., 
>does not admit a static solution, at least without a cosmological constant.) 
>In other words, for those of you who like Noether's theorem, there is no
>constant of the motion associated with time invariance of the Lagrangian.

>Please see the sci.physics FAQ for details.

>-Scott
>--------------------
>Scott I. Chase			"The question seems to be of such a character
>SICHASE@CSA2.LBL.GOV		that if I should come to life after my death
>				and some mathematician were to tell me that it
>				had been definitely settled, I think I would
>				immediately drop dead again."      - Vandiver

Mr. Chase:
    Can you please elaborate further the statements in your above reply.
    Also, could it be that the " disappearing photon energy"  is spent on
overcoming the INERTIA OF TIME in the process of forward movement of Time?
From: inr@eccles.caltech.edu (I. Neill Reid)
Newsgroups: sci.astro
Subject: re: Columbus nationality
Date: 26 Sep 1992 22:01 PST
Organization: California Institute of Technology
Distribution: world
NNTP-Posting-Host: eccles.caltech.edu
News-Software: VAX/VMS VNEWS 1.41    

 Actually, it's a little known fact that Christopher Columbus was
descended from a renegade monk from the island of Iona who learned 
of Vinland from a beached Viking, driven ashore after the Battle
of Largs. And his (Columbus') descendant was admiral of the fleet
during the cod war.....

 (take that, Sigurdsson )
Newsgroups: sci.astro
From: hporopudas@tnclus.tele.nokia.fi
Subject: Re: "I Apologize"--Fine. Now GET LOST.
Organization: Nokia Telecommunications.
Date: Sun, 4 Oct 1992 10:42:48 GMT


In article <stone.718033618@cwis>, stone@cwis.unomaha.edu (Travis Stone) writes:
>
> Hannu, the Bearer of Brotherhood and Good Will to All Men
> says:
>
>> By these suffering of ordinary people I ment that when
>> man is unhappy he suffers mentally.
>
> Apparently not as much as YOU are, chum....
>
> In case you haven't noticed, this is sci.astro, an informal
> forum for the discussion of things astronomical---NOT "Lifestyles
> of the Mentally Disturbed", as YOU seem to think it is.  If you
> want to get down and talk astronomy and astrophysics, then by
> all means---welcome aboard, have a seat, let's talk; but if
> your sole purpose is to come here and clog the newsgroup with
> pseudoreligious psychobabble, and then start flame wars with
> other folks, then weigh anchor and make sail, buddy---there are
> lots of other news groups out there that are tailor-made for
> just such shenanigans.
>
> T.R. Stone
> University of Nebraska-Omaha
> irrelevant

  I don't like at all this kind of stupid 'net-psychologist'.
  Try to concentrate to matters proposed instead to persons.

  Please take this kind of robbish to alt.psycho ... or somehing like that.

  Anyway, what degree 'high-school' student you are. ?

   ---Hannu.
From: palmer@sfu.ca (Leigh Palmer)
Subject: Re: The color violet?
Organization: Simon Fraser University
Date: Thu, 1 Oct 1992 00:56:12 GMT

In article <1ad3c1INN2b4@smaug.West.Sun.COM> Richard.Mathews@West.Sun.COM
(Richard M. Mathews) writes:

>The red cones have a small, secondary peak of sensitivity in the violet
>range.  Violet thus triggers blue response plus a little red response.

Those of us who do photometry have begun to evolve red-leak cones with
phase inverting synapses for alias inhibition. We never confuse purlet
with viople! :<)

Seriously, filters used in Johnson UBV photometry have an analogous 
"defect" in color discrimination. The Johnson R filter leaks a little 
U light (or vice-versa; I can't recall which, and I don't have a 
reference handy). It is fixed with a workaround which employs a fourth 
filter which is all leak, the signal from which is subtracted from the 
R signal.

Leigh
Newsgroups: sci.astro
From: palmer@sfu.ca (Leigh Palmer)
Subject: Atmospheric light scattering outcome
Organization: Simon Fraser University
Date: Tue, 6 Oct 1992 17:48:39 GMT

The scattering I observed before sunset turned out to be a local phenomenon.
The night was brightly moonlit, but it was possible to see down to mag 6 only 
30 degrees from the moon with 7x35 binoculars. My students and I managed to 
pick out Uranus in Sagittarius, less than 30 degrees from the 10 day old moon 
and only 15 degrees up, using a finder chart and the binoculars. I own half a 
dozen pairs, but I had eighteen students, some of whom brought their own, and 
only a few succeeded in the quest for Uranus. Neptune, nearby and expected to 
be mag 8, was not seen in the sky glow.

We looked at the standard objects for this time of year with the Celestron 8, 
the Ring, epsilon Lyrae, M13, Albireo, etc. M13 was unimpressive in the
skyglow. I looked for R CrB but could not see it. Is it out again? (I was 
*really* looking for T CrB, but I didn't let on to the students.) I see I 
missed a minimum of Algol, an opportunity lost. Saturn and the moon were both 
good, though I didn't see the Saturnian surface features which have been 
mentioned recently in sci.astro. Titan and the Cassini division were both 
evident, though I couldn't make out any more Saturnian moons with our own only 
4 degrees away.

I had predicted the apparition of two artificial satellites and the NOSS 2-1 
constellation, a three staellite formation flight, which was to be my evening 
grand finale. *None* of my predictions turned out, though we saw about a dozen 
other satellites during the hour and a half we were out. On returning to my 
home by the lake I estimated that 300 m of altitude had bought me between one 
and two magnitudes in transparency.

The students were enthusiastic and interested the whole time. I kept the
session short (an hour and a half) and the questions never stopped. I had one
quite sophisticated student who helped me keep the unelectrified Celestron
pointed at the object of the moment, which was a big help. Eighteen is too many
students for one person to handle.

I conclude that it is valuable to hold sky sessions even when observing 
conditions are not very good. If they are kept short there are plenty of 
things to see. This time I prepared for only about an hour at the computer 
before hand. Next time I will spend more time at the computer before the 
session, restrict the attendance to about ten students per experienced 
observer, and provide an AC supply or a battery driven drive corrector. I will 
also find out more about Swift-Tuttle, though it probably was invisible last 
night given my limitations. It took me three or four minutes to find M13!

Leigh
Newsgroups: sci.astro
From: clarke@acme.ucf.edu (Thomas Clarke)
Subject: Russian Maksutov
Organization: University of Central Florida
Date: Fri, 2 Oct 1992 12:17:54 GMT

Has anyone bought the 6 inch aperture Russian Maksutov
telescope?  If so, how is it?  Optically?  Mechanically?

Wistfully looking at ads in S&T, thinking about buying
a portable telescope, and wondering if the Russian Maksutov
could be a poor man's large aperture Questar.  That is
almost as big as a Schmidt Cassegrain, but with the quality
and freedom from adjustment of the small Maksutov.

--
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: jdnicoll@watyew.uwaterloo.ca (James Davis Nicoll)
Newsgroups: sci.astro
Subject: Open Clusters
Date: 29 Sep 92 02:25:08 GMT
Organization: University of Waterloo


	Pardon a no-doubt stupid question, but is there a 
textbook on the structure of open clusters? The astronomy
texts I have mention ocs in passing, mentioning that they
are Pop I stars and have populations in the hundreds or 
thousands: just how high a count can that thousands be?
For trivial reasons, it would be nice if I could find a
open cluster with a 'membership' of tens of thousands of
members: how are the estimates of the number of cluster
members made?

					James Nicoll
From: serge.singh@f416.n711.z3.fido.zeta.org.au (Serge Singh)
Newsgroups: sci.astro
Subject: COULTER TELESCOPES
Date: 30 Sep 92 22:58:17 GMT
Organization: Fidonet. Gate admin is fido@socs.uts.edu.au

Original to: Snyder@ronin.lerc.nasa.gov
I RECENTLY PURCHASED A COULTER 17.5 INCH. IT ARRIVED IT ARRIVED IN FOUR
MONTHS AND WORTH EVERY CENT. YOU DONT HAVE TO REMOVE THE MIRROR TO TRAVEL. I
HAVE MODIFIED MINE SO THAT IT CAN BE CARRIED IN MY MAGNA.


--- TMail v1.30.5
 * Origin: K.K.K BBS - Killer Kenders of Krynn (3:711/416)
From: tonya@hpldsla.sid.hp.com (Tony Arnerich)
Newsgroups: sci.astro
Subject: I (don't) Got the Blues
Date: 29 Sep 92 19:10:51 GMT
Organization: HP Scientific Instruments Division - Palo Alto, CA

One (mathematical) variable, two unknowns...

I did some astrophoto work last Saturday from Fremont Peak, CA, in
which I did two things for the first time:

	- I used Konica SRG-3200 film
	- Photographed through Mt.Pinatubo haze

I photographed M42, and the red emission nebula came through wonderfully.
However, the blue reflection nebulae around the other parts of Orion's
Sword recorded very poorly. I compared my prints and negatives to published
photos, and concluded that the blue objects should have been far more
prominent in my shots. Details: 13cm f/8 EDT refractor, film not hypered,
16 minute exposure time, Orion nearly at the meridian, no filters, prime
focus.

My question: In netland experience, is the poor recording of the blue
nebulae caused more by the film's spectral response, or is it perhaps
due to the filtering/scattering effects of the Pinatubo cloud? (The sky
was very murky visually, BTW. Looking at Saturn earlier in the evening,
there was a prominent hazy halo about the planet which I determined was
atmospheric in origin - the optics were nearly spotless).

Thanks for any info you give.

tonya@hpldsla.sid.hp.com
Newsgroups: sci.astro