BEGINNERS' ADVICE: Viewing the "Pleiades" (M-45)
Stephen Waldee
VIEWING TECHNIQUES FOR STUDYING M45-"THE PLEIADES"
By Stephen R. Waldee, Partner
Waldee-Wood Astronomical Software
c/o ALLEGRO MUSIC - Software Division
1478 Kimberly Drive, San Jose, CA. 95118
Voice: (408) 723-3655; Fax: (408) 723-2944
Email: toc...@ix.netcom.com
toccata-...@worldnet.att.net
Known since antiquity, the "Pleiades" cluster has
introduced many observers to the pleasures of astronomy.
The late American comet-hunter Leslie Peltier, a farmer by
profession, poetically recalled his childhood fascination
with the comforting winter apparition of M-45, then almost
universally known. In a modern age when genuine experience
with astronomical objects is limited to specialists, so great
is the mythical celebrity of this grouping that some
scientifically-illiterate flying saucer buffs have targeted
M-45 as the homebase of creatures who abduct humans to satisfy
their insatiable Pleiadean curiosity!
John Sanford's guide, "OBSERVING THE CONSTELLATIONS",
summarizes important aspects of this famous asterism:
"The Pleiades, or Seven Sisters (M45), is a nearby young
galactic cluster, the stars of which are imbedded in nebulosity
shining by light reflected from microscopic solid particles...
the [blue] color deriving from the very hot stars...Seeing the
members individually is a test for acuity in eyesight, as they
are close together and vary in magnitude from Alcyone's 2.86 to
Pleione's 5.09. William Rutter Dawes, keen-eyed double star
observer of the mid-1800s, saw 13 stars here without optical aid.
Burnham remarks that there are at least 20 stars in the vicinity
which could be glimpsed..." (quoted by permission in the Waldee-
Wood computer program EYEPIECE 2.0.)
M-45 is one of the sky objects included in our new DOS program
EYEPIECE, which performs calculations of telescope and eyepiece
optics, and includes a database of objects for use in selecting
nebular filters and in doing prime-focus astrophotographic
calculations.
The Pleiades has often been a favorite object of this observer,
as it can be seen to advantage not only by naked eye, but also
with virtually any optical aid. In fact, a typical amateur
telescope is not the most appropriate instrument for viewing the
Pleiades. Due to its enormous angular dimension, and the
incredibly bright magnitude of the main stars in this cluster,
most telescopes have too narrow a field of view, and blind the
observer with the brilliance of the major sparklers in the
cluster.
The ancient name for this group -- The Seven Sisters -- was
not a particularly accurate description, for almost twice this
number of stars may be glimpsed by keen naked-eye observers in
a dark sky. Percival Lowell (of Martian 'canal' fame) claimed
he could see 18; young Ryan Wood, son of EYEPIECE co-author Ron
Wood, counted 16 when he was a mere 14 years of age; on the same
occasion, your author (then thrice his age) saw a scant 8 stars!
The renowned nebulosity of the Pleiades, discovered
visually by comet-hunter Wilhelm Tempel in 1859, and confirmed
by the Henry Brothers in 1885 with long-exposure photography, may
be spotted on nights of exceptional atmospheric clarity by using
high-resolution optics. However, most observers who look at the
Pleiades with a telescope or binoculars are SURE they are seeing
the famed nebulosity -- as depicted in David Malin's fabulous
photographs -- because of the internal reflections and light-
scattering of their optical instruments!
The author has studied the Pleiades carefully for several
winter seasons, in order to confirm a visual sighting of the
nebulosity. Starting with a lowly Astroscan telescope, up to
a fabulous Astro-Physics Star-Fire apochromatic refractor, the
writer has not been able to sincerely state that the nebulosity
is viewed by eye as it is depicted in a photograph.
The nebulosity around the stars Merope, Alcyone, and some of
the other bright stars in the cluster glows by reflection of
the photons emitted from these bright stars that are scattered
off the dust clouds in the cluster. A light-pollution-reduction
filter that reduces only the wavelengths of manmade streetlights
is necessary to view this nebulosity: do not use a hydrogen or
oxygen-line filter, or you will cut off the pale bluish light
that is so easily recorded on photographic film.
Do not be misled by reflections, flaring, and light
scattering around the bright stars in average-quality or even
very good telescopes. In the author's 8" f/5.2 richest-field
reflector (with a superb primary mirror) there is sufficient
light-scatter to cause a general glow around all the bright
stars of this cluster. Moving the scope to -- say -- the nearby
belt stars of Orion will soon confirm that any star of the same
magnitude as the bright ones in the Pleiades may cast a general
glare in the field of view.
I made several crackpot experiments recently to try to
determine a new way of discerning the nebulosity in M-45. Since
the light of the cluster members is so bright, an 8" or larger
scope presents a blinding image to the eye; yet stopping down to
a smaller aperture would reduce the resolution that MIGHT yield
a glimpse of the fine sheen that Malin's photograph documents.
I first tried using a variable-polarizing filter intended
for lunar observing in order to reduce the brightness without
limiting angular resolution. But, swinging the scope over to
other bright stars, I confirmed that this filter had internal
reflections that cast a bright glow around a star like Sirius or
Alnilam.
So I tried a neutral-density moon filter that reduces the
light transmission to about 13% of normal at ALL visual
wavelengths. By then adding the broadband light-pollution-
reduction filter, I began to detect distinct traces of the
nebulosity, particularly around Merope (Tempel's famous 'comet'),
Alcyone, and Electra. Of course, it is necessary to observe
on a night with exceptionally steady seeing, which is difficult
to achieve in winter weather conditions.
Even if one is not intent on detecting the elusive
nebulosity, M-45 is a wonderful sight even in binoculars or a
small beginners' telescope. Yet the typical Christmas-present
toystore refractor will not provide the wide field of view
necessary for appreciating the entire group. Binoculars,
a richest-field scope, or even a good finderscope will give
the proper perspective to this beautiful aggregation.
M45 is so bright that it is possible to obtain a
sufficiently wide field by using an ocular that produces an exit
pupil of 10 to 12 mm, reducing the apparent scope aperture and
light gathering but permitting the full two degrees of the
cluster to be accommodated. Of course, users of reflector
scopes will have to "dodge" the dark spot in the center of
the field that appears when employing an exit pupil larger than
the pupil of the viewer's eye. If you are not sure how to
calculate the exit pupil of eyepieces used in your scope,
download the demo of our EYEPIECE program (EYEDEMO.ZIP) at:
http://www.rahul.net/resource/current/hiprograms/hiprograms.html
and test it to see what ocular best suits your needs for
viewing all of the extent of the full cluster.
A wonderful picture of the Pleiades may be found at the
Chuck Vaughn home page:
http://www.aa6g.org/astro.html
Better yet, get out and LOOK at the Pleiades, if even with
your own two eyes!
Stephen R. Waldee
Partner, WALDEE-WOOD ASTRONOMICAL SOFTWARE
Copyright (c) 1996 - Stephen R. Waldee. All Rights Reserved.
No publication of any part or whole of this article may be made
for profit without permission from the author. This article may
be posted for non-commercial use on astronomical bulletin boards
and networks, and may be copied and printed by astronomy club
newsletters.
Stephen Waldee
On Sun, 24 Nov 1996 23:15:12 GMT, toc...@ix.netcom.com (Stephen
Waldee) wrote:
>VIEWING TECHNIQUES FOR STUDYING M45-"THE PLEIADES"....
Friends...I apologise for this repost. I closed the FREE AGENT
newsreader a few moments ago, and a message came up saying "YOU HAVE 1
NEWSGROUP MESSAGE LEFT TO SEND> y/n" and of course I said
YES...and the thing disgorged this OLD post I did many, many days ago!
Why it did that I cannot say...only the spirit Gods of Windows .ini
files know the mysterious answer. I would like to take credit for the
egomania that it would lead me to send the message again, but sadly --
not even MY own hyperinflated self-esteem would have promulgated it.
Yet, all in all, it may serve as a followup to some of the recent
questions or comments about viewing M-45, how many stars one can see,
and so forth.
On second thought...maybe I SHOULD repost EVERYTHING every couple of
weeks......NOT!
Yours,
STEVE WALDEE
Jay Reynolds Freeman
Steve Waldee's long and discouraging commentary on the difficulty
of seeing Pleiades nebulosity fails to state that the Merope Nebula is
easy.
That nebula is very unsymmetrically placed with respect to Merope --
it looks like a long, broad streamer trailing out away from the star,
away from the center of the Pleiades. All of the effects which one
might confuse with a nebula are symmetric about the stars, thus the
difference is very obvious. What's more, the Merope Nebula is
sufficiently bright that I have seen it with (I think) every size of
binocular and telescope with which I observed the Pleiades; that's
from 7x50 on up. A friend has observed it in a 7x35; I will have to
try that, myself.
--
Jay Reynolds Freeman -- fre...@netcom.com -- I speak only for myself.
Kenneth Drake
I think seeing the Pleiades nebulosity is no more difficult than seeing
the gegenschein which I saw for sure from the Ultimate Star Party last
month with the help of Barbara Wilson.
For those that don't know, the gegenschein can be seen as a 10-15 degree
patch of very faint light at a point on the ecliptic 180 degrees from
the
location of the sun. It is caused by light reflecting back off the small
dust particles in the zodiacal band.
Kenneth Drake
Stephen Waldee
Jay Reynolds Freeman wrote:
> Steve Waldee's long and discouraging commentary on the difficulty
> of seeing Pleiades nebulosity fails to state that the Merope Nebula is
> easy.
> That nebula is very unsymmetrically placed with respect to Merope -
> away from the center of the Pleiades. All of the effects which one
> might confuse with a nebula are symmetric about the stars, thus the
> difference is very obvious. What's more, the Merope Nebula is
> sufficiently bright that I have seen it with (I think) every size of
REPLY:
Jay has rightly put his finger on an appropriate point regarding the
precise appearance of the Merope nebula, in a comment that as usual
reflects his remarkable gifts as an observer.
The variability of detection of this nebula was one of the most
debated topics in visual astronomy in the decades after Wilhelm
Tempel discovered it in the mid-19th century. In fact, in some
ways, it was THE controversial topic for a while, stirring up the
kind a acrimony that we see today in the famous Schramek Hale-Bopp
business.
Tempel saw the nebulosity; practically nobody else did. Tempel was
the FIRST to see it, not the Herschels, or Messier, or Mechain.
There was no "history" to support him.
It took the Henry Brothers' photograph of c.1883 to confirm it, right
at the dawn of the astrophotographic era. I found their original
paper, in French, in the UC/Lick Science library archives, and
Rich Page and I translated it. The paper contained an interesting
early effort at printing a photograph: more a drawing or recreation
than an actual reproduction. The wisps of nebulosity were BARELY
visible (the Henry telescope was a 13" f/10 instrument) but they
DID confirm Tempel.
Now that we know what the cluster looks like with incredible long-
exposure pictures by Malin et. al., it is less difficult to
try to detect the nebula. But I myself, in contrast to Jay,
frequently have trouble discerning the actual nebulosity above
the internal reflections in the optics as discussed in my article.
Jay uses superb instruments that in some ways are more suited to
this particular task than my telescopes.
Thus, Jay points out that one may do an incredible amount of
highly-effective visual astronomy with small aperture but
high-quality telescopes.
Thanks, Jay, for your addendum!
STEVE WALDEE
Jay Reynolds Freeman
> Jay has rightly put his finger on an appropriate point regarding the
> precise appearance of the Merope nebula, in a comment that as usual
> reflects his remarkable gifts as an observer.
If I have any remarkable gift as an observer, it is merely tenacity.
I am sure that I -- and many others -- have higher-performance visual
physiology than, for example, heavy smokers or (touch wood) persons
with disease or deterioration of the eye. Excluding these cases,
however, it is rare for me to see anything that I cannot show to
whatever line of beginners and casual passers-by presents itself. Yet
it often takes many minutes and much coaching before the person at the
eyepiece makes the detection, and therein lies the point.
Too many amateur astronomers, even experienced ones, think that
seeing things comes free and easy, with no more effort than opening
your eyes: But as currently popular slang so evocatively articulates,
** NOT!! **.
Vision is an acquired skill. You have to learn it, you have to
practice, and you have to be prepared to keep learning new things, and
practicing them, too.
Buying a bigger telescope to see more is like buying a bigger kettle
to be a better cook, or buying a bigger computer to be a better
programmer. Not that it won't help -- it probably will -- but cooking
and programming are abilities that depend far more on knowledge and
experience than on artifacts. And so too is visual astronomy. People
with garages full of telescopes (pardon me while I try to close the
door to mine) are in great part victims of materialism, marketeering,
and hyperbole.
> Jay uses superb instruments that in some ways are more suited to
> this particular task than my telescopes.
I pulled my index cards, and find that I have logged 31 observations
of the Merope Nebula, with 16 different instruments, from 7x50
binocular to 17.5-inch Newtonian. The range includes six binoculars,
five Newtonians, two SCTs, two refractors, and a Maksutov. I rarely
waste time with a truly lousy telescope, and some of these instruments
were indeed world-class, but by no means all of them. I observed with
exit pupils from 2 to 7 mm, and the 2 mm pupil was in a relatively
small instrument -- a four-inch refractor (albeit a good one, a Vixen
conventional doublet). I suspect that most types of commercial
astronomical telescopes will show this object, even the Tasco 60 mm
refractors, if one can only get the exit pupil up to a reasonable
size.
I should hastily add that the purpose of this post is not to
criticize Steve Waldee, whose articulate commentaries have added
scarce facts and useful suggestions to many threads on this newsgroup.
Yet I must speak out, for I would be chagrined and embarrassed if
readers used non-existent special talents of mine as rationalization
for not stretching their own visual abilities to the limits of the
possible; those limits are worth attaining, and few do.
Clear skys.
And more importantly, clear eyes.
David E. Johnson
In article <freemanE...@netcom.com>,
Jay Reynolds Freeman <fre...@netcom.com> wrote:
>In article <3299CD...@ix.netcom.com> Stephen Waldee <toc...@ix.netcom.com> writes:
>
>> Jay has rightly put his finger on an appropriate point regarding the
>> precise appearance of the Merope nebula, in a comment that as usual
>> reflects his remarkable gifts as an observer.
>
> If I have any remarkable gift as an observer, it is merely tenacity.
>I am sure that I -- and many others -- have higher-performance visual
>physiology than, for example, heavy smokers or (touch wood) persons
>with disease or deterioration of the eye. Excluding these cases,
>however, it is rare for me to see anything that I cannot show to
>whatever line of beginners and casual passers-by presents itself. Yet
>it often takes many minutes and much coaching before the person at the
>eyepiece makes the detection, and therein lies the point.
> Too many amateur astronomers, even experienced ones, think that
>seeing things comes free and easy, with no more effort than opening
>your eyes: But as currently popular slang so evocatively articulates,
>
> ** NOT!! **.
>
>Vision is an acquired skill. You have to learn it, you have to
>practice, and you have to be prepared to keep learning new things, and
>practicing them, too.
Agreed here...when I first looked at Jupiter with my scope (a 60mm Meade
refractor), all I saw was a blank disk and the satellites. However,
concentrating on the image on subsequent viewing sessions, I slowly began
to be able to see the equatorial belts. This serves as a perfect example
of learning how to see when using the scope. On my recent viewing of M42
with the scope (which I've viewed several times before with), this was the
first time that I was able to see ANY detail in the nebula, considering
the small scope size and my location with all it's light pollution. I was
distinctly able to make out the dark "spike" that protrudes into the heart
of the nebula by the trapezium area. This was done by concentrating on
the image as well. The air was more transparent than it had been for some
time, so that had and effect as well, I'm sure.
To me, I know that I'm seeing all the detail that I CAN currently see,
when I feel the almost "straining" effort of the concentration. However,
with Jupiter, and now I would think with M42, I'll be able to see what's
there more easily on initial glancing of the image, rather than having to
spend a number of minutes examining it. But, in continuing to concentrate
on the images, I'm sure I'll learn to discern more detail than I have so
far.
(Now I just wish I could say that my visual physiology is well
...unfortunately I am somewhat heavily nearsighted.)
--
David E. Johnson
d...@wwa.com http://www.nyx.net/~dajohnso/home.html
Chicago, Il.
"Like a madman laughing at the rain. A little out of touch, little
insane. It's just easier than dealing with the pain..."
Matt or Belinda Tarlach
Jay Reynolds Freeman wrote:
>
> Steve Waldee's long and discouraging commentary on the difficulty
> of seeing Pleiades nebulosity fails to state that the Merope Nebula is
> easy.
>
> it looks like a long, broad streamer trailing out away from the star,
> away from the center of the Pleiades. All of the effects which one
> might confuse with a nebula are symmetric about the stars, thus the
> difference is very obvious. What's more, the Merope Nebula is
> sufficiently bright that I have seen it with (I think) every size of
> from 7x50 on up. A friend has observed it in a 7x35; I will have to
> try that, myself.
>
When viewing the Pleiades with the naked eye under really good
conditions, I have thought several times that I could make out a
fuzziness or nebulosity in the central and eastern portions of the
cluster where the nebulosity shows best in photos. Could I be seeing
the actual reflection nebula, or is it light from stars in the cluster
too dim to resolve with the naked eye?
-Matt Tarlach
Stephen Waldee
On Mon, 25 Nov 1996 19:47:59 GMT, fre...@netcom.com (Jay Reynolds
Freeman) wrote as a series of comments by newsgroup respondents
regarding the visibility of the Pleiades nebulosity, and specifically
the Merope nebula:
>In article <3299CD...@ix.netcom.com> Jay Freeman counters:
>People with garages full of telescopes (pardon me while I try to close the
>door to mine) are in great part victims of materialism, marketeering,
>and hyperbole... I have logged 31 observations of the Merope
>Nebula, with 16 different instruments, from 7x50
>binocular to 17.5-inch Newtonian. The range includes six binoculars,
>five Newtonians, two SCTs, two refractors, and a Maksutov. I rarely
>waste time with a truly lousy telescope, and some of these instruments
>were indeed world-class, but by no means all of them.
Jay has thus recorded a clear view of the Merope nebula with
instruments that are not all of exceptional quality, unlike Steve
Waldee, who has often had difficulty seeing it. Yet I doubt that
Jay and I observe more than 15 miles apart!
It's interesting to discover, using one of the world's most familiar
objects, the differences of perception of two observers. That very
well categorizes the quandary of pre-photographic professional
astronomers during the 19th century. The "personal equation" was
first and foremost an element in evaluating practically anyone's
published observation of a celestial object.
I did a series of talk on the photographic history of the Orion
nebula, and for it I researched the remarkable 300+ page dissertation
on the nebula by the first director of Lick Observatory, Prof. E. S.
Holden. He studied observations of the nebula back to the days of
Christian Huygens; dozens of engravings recorded careful reproductions
of the originals dating back to the 1600s. Such wonderful observers
as Cassini, Mechain, Messier, the Herschels, and Trouvelot were
presented; only Trouvelot's effort resembled a modern photograph. Of
the old drawings, Messier's at least had some SEMBLANCE of reality,
though the stars were severely out of place.
Holden himself -- though he was NOT regarded by his later colleagues
as a careful observer -- made a visual study and photometric series on
the Triangulum region with the 26-inch Naval Observatory refractor,
and determined to his complete satisfaction that the nebula was widely
and wildly variable! He closed with the confident assertion that the
'new science' of photography would confirm him. Perhaps in some ways
it has...but not in the manner that HE would have expected!
In Holden's time there was a general question about the Triangulum
region: most professional observers asserted that the asterism was in
a 'hollow' in the nebula containing no background nebulosity; today,
with our high-transmission eyepieces and light pollution filters, we
can easily detect the milky background behind the points, though it is
indeed not as bright as the boundaries of the 'fish mouth' region.
I reproduced these drawings from Holden's study in slides that I
showed at about 6 different northern California astronomy clubs, and
the audience was quite surprised at the variance in observation and
descriptions of the nebula...some resembled grotesque bellowing
elephants; others were angular, sharp, and almost "art-deco" in their
stylization. Practically none of these drawings...made by the
absolutely leading observers of their periods...was accurate in any
way, neither resembling what most people now see through modern
telescopes and oculars, or what almost ANY kind of photograph records.
A chastening lesson for those of us -- certainly not a sophisticate
like Jay but some who might tend to take a hard line about the
'subjective' aspects of visual astronomy -- to learn well.
Yours,
Steve Waldee
Partner, WALDEE-WOOD ASTRONOMICAL SOFTWARE
Jay Reynolds Freeman
> When viewing the Pleiades with the naked eye under really good
> conditions, I have thought several times that I could make out a
> fuzziness or nebulosity in the central and eastern portions of the
> cluster where the nebulosity shows best in photos. Could I be seeing
> the actual reflection nebula, or is it light from stars in the cluster
> too dim to resolve with the naked eye?
I have occasionally thought I have detected Pleiades nebulosity with
the naked eye, but I know of no convincing way to rule out dim stars,
scattering within the eye or within the atmosphere, and so on.
Todd Gross
>> Too many amateur astronomers, even experienced ones, think that
>>seeing things comes free and easy, with no more effort than opening
>>your eyes: But as currently popular slang so evocatively articulates,
>>
>> ** NOT!! **.
>>
>>Vision is an acquired skill. You have to learn it, you have to
>>practice, and you have to be prepared to keep learning new things, and
>>practicing them, too.
>Agreed here...when I first looked at Jupiter with my scope (a 60mm Meade
>refractor), all I saw was a blank disk and the satellites. However,
>concentrating on the image on subsequent viewing sessions, I slowly began
>to be able to see the equatorial belts.
This is especially true with extended dim galaxy observation. What once would
have alluded me totally.. I mean TOTALLY, I can now observe and find detail
in.
Over the early Fall, I observed, and drew NGC 891 in suburban skies. (C14) It
was so ghostly and dim that previously I would have not picked it up (limiting
magnitude 5 at my place - that's why) However the drawing I made included a
central bulge, and a dark lane running throughout. At the time, I had no
knowledge that this is a fairly celebrated photographic object for those same
features.
Patience and good use of averted vision pulled those features in, w/o
foreknowledge of their existence
Thanks! - Todd
_________________________________
BOSTON TV METEOROLOGIST TODD GROSS
Weather/Astronomy Home Page: http://www.weatherman.com
Administrator, Meade Advanced Product User Group: ma...@shore.net
Administrator, New England Weather Observer Mail List: wxob...@shore.net
IRC Channel Operator: #Weather (Undernet)
Originator of the NE.WEATHER newsgroup
_________________________________
Email: to...@weatherman.com Work Phone# (617)725-0777
Dave Nash
Stephen Waldee <toc...@ix.netcom.com> writes:
>Jay Reynolds Freeman wrote:
>> Steve Waldee's long and discouraging commentary on the difficulty
>> of seeing Pleiades nebulosity fails to state that the Merope Nebula is
>> easy.
>> That nebula is very unsymmetrically placed with respect to Merope -
>> it looks like a long, broad streamer trailing out away from the star,
>> away from the center of the Pleiades. All of the effects which one
>> might confuse with a nebula are symmetric about the stars, thus the
>> difference is very obvious. What's more, the Merope Nebula is
>> sufficiently bright that I have seen it with (I think) every size of
>> binocular and telescope with which I observed the Pleiades...
>REPLY:
>Jay has rightly put his finger on an appropriate point regarding the
>precise appearance of the Merope nebula, in a comment that as usual
>reflects his remarkable gifts as an observer.
This is, in fact, how I first saw the nebulosity, with an Astroscan
at low (16x) power.
>Now that we know what the cluster looks like with incredible long-
>exposure pictures by Malin et. al., it is less difficult to
>try to detect the nebula. But I myself, in contrast to Jay,
>frequently have trouble discerning the actual nebulosity above
>the internal reflections in the optics as discussed in my article.
>Jay uses superb instruments that in some ways are more suited to
>this particular task than my telescopes.
I'm not so sure that superb optical quality is really a requirement.
I've done most of my work with the aforementioned Astroscan and an
inexpensive commercial 10" Dobsonian, neither of which is well
optimized for high contrast (or, more accurately, low scattering of
light -- there are no baffles or other anti-scatter devices, and the
interior of my Dobsonian could be improved as well). The nebulosity
is no more difficult (assuming equal sky conditions) in these scopes
than it is in my 10x70 binoculars, which are multi-coated on all
optical surfaces and have proved to be an excellent tool for seeing
low-contrast objects like dim nebulas. OTOH for me sky conditions
make all the difference, as they do with other difficult deep-sky
objects.
>STEVE WALDEE
--
Dave Nash, School of Chemical Sciences, University of Illinois
E-mail: na...@aries.scs.uiuc.edu; WWW: http://www.scs.uiuc.edu/~nash/
--"It's 106 miles to the centerline, we've got a 10" scope, half a box
of eyepieces, it's getting dark, and we're wearing mylar glasses...HIT IT!"
Stephen Waldee
Path: ix.netcom.com!ix.netcom.com!news
From: toc...@ix.netcom.com (Stephen Waldee)
Newsgroups: sci.astro.amateur
Subject: Re: Visual skills (was: BEGINNERS' ADVICE: Viewing the
"Pleiades" (M-45))
Date: Wed, 27 Nov 1996 19:13:47 GMT
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Friends:
In the discussioni of viewing the Pleiades, Jay Reynolds Freeman has
commented in a typically apt observation:
>>> Too many amateur astronomers, even experienced ones, think that
>>>seeing things comes free and easy, with no more effort than opening
>>>your eyes: But as currently popular slang so evocatively articulates,
>>>
>>> ** NOT!! **.
>>>
>>>Vision is an acquired skill.
The issue has been the relative visibility of the nebulosity in the
Pleiades, as provoked by my (surprisingly controversial!) article.
Jay adds that success is not so much to be attained the use of
great instruments, but in acquiring the personal skills to perceive
and understand what falls on the eye...the 'brain' part of the
eye-brain system may not be fully aware of the actual physiological
signals from the retina, until we learn to interpret the signals.
When I was researching early nebular photography at the
UC/Lick science collection and archives in Santa Cruz, and
even at the plate vault on Mt. Hamilton (in conjunction to my wife's
and my volunteer work with the Visitor's Program at Lick
Observatory) I came upon the Pleiades nebular confirmation
by the Henrys, as recounted earlier. I found the long-forgotten
paper, still untranslated, in, I believe, 1986 or 87.
In following the trail back to Wilhelm Tempel, the original visual
observer of the nebulosity, I was struck by the vituperative nature
of the rebuttals of those who argued that if what was seen by ONE
could not be immediately seen and corroborated easily by ALL,
the error of the original observation was proved.
Five or six generations later, we chuckle at the shortsightedness
and contentiousness of many of the skeptics on that issue.
The nebulosity was there; because it was not generally
seen in the conventional small-aperture, long-focal-length,
high-magnification observatory instruments without low-loss modern
optical coatings, its existence was controversial, placing it very
much in the "NOT PROVED" or even "NOT TRUE" category.
This is not to denounce skeptics! But in the era before modern
technology to record and transmit incontrovertible data,
professional astronomers (working with such ludicrous instruments as
limelight photometric reference light-sources) often posted
observations that had little more enduring scientific merit than the
comments of any amateur today -- crank or serious observer -- on this
newsgroup!
We've all heard the term "NIMBY": not in MY back yard!
Well, there was during the 19th century in professional astronomical
circles, a syndrome noted by Dr. Donald Osterbrock in his discussions
of the debates regarding nebular lines measured at Lick Observatory in
the exquisite seeing of Mt. Hamilton, and the denunciations issued by
the Potsdam Astrophysical Observatory in Germany, using its small-
aperture visual spectroscope under turbulent skies.
Endless tirades were offered by German astronomers, decrying the
observations of James Keeler and other Lick astronomers. I might
characterize them with the new term: "NIMT" - not in MY telescope!
Related articles appearing in professional astronomical journals, as
reprinted in late-19th-century issues of the ASP publications, read
like some of the exchanges on subjective issues in this
newsgroup, and were NEARLY as unruly!
The work of Charles Perrine and Keeler in establishing the
36" 'fast' Crossley photographic telescope at Mt. Hamilton to
augment the largely visual-use Clark refractor & spectroscope,
plus the later developments by Vesto Melvin Slipher at Lowell
Observatory -- which largely recovered the tarnished reputation
of that organization, suffering from the adverse publicity generated
by P. Lowell's canal claims -- put to rest much of this NIMT
angst.
We return to these good old days of yesteryear, in comparing
personal visual experiences of faint nebular objects. It's lots of
fun, and dedicated observers including all the respondents on
this particular thread, are enjoying it mightily, and of course all
agree about the 'personal equation' element.
I think the thrust of my main argument...now long lost in the dust of
this series of exchanges...is that some telescopes have lots of
internal light-scattering. One who has not done many dozens --
perhaps even hundreds -- of visual observation of the utterly
brilliant star cluster M-45, may have some difficulty in discerning
where the internal reflections leave off, and where the nebulosity
begins.
As Jay so well illustrates in his responses, someone who has made
and confirmed an observation may QUICKLY show another person
what to look for in the eyepiece view...often the other individual
does a veritable "V-8 Vegetable Juice"-like smighting of the
forehead, crying, "Of course! I see it now!"
As I sit in my office staring at the CRT, in the middle of a bright
November day during the period of the full moon, I ask myself
how I might -- in a way that complements a hands-on starparty
demonstration -- offer some help to others who may have
the difficulty in discerning the nebulosity that I have had.
Yet, my written narrative is but a poor, pale substitute for
the sharing of ideas and experiences with a telescope
under the stars in a moonless sky.
Finally, I discussed the nebulosity of the Pleiades with the
gentlemen who assisted me in translating the original French
paper of the Henry brothers. He is a kind of quiet 'living
legend' in Santa Clara county amateur visual observing, and
has a superb 14" Newtonian, a 7" APO, and many other
instruments. He recalled that only ONCE in about 3 decades
of looking at M-45 did he obtain a night of such superb
atmospheric transparency that he could trace out by eye
the faint, wispy striations of reflected light near the
members of the cluster that may be recorded on film,
seeing them clearly, in his words, "just like a photograph!"
The intention of my article was to try to suggest techniques
where one could overcome the excessive glare of the
stars, and the internal reflections of conventional telescopes,
in order to see some of that detail.
The side issue about the Merope nebula -- only part of what
I wanted to present as the larger subject of the milky
reflection throughout the Pleiades -- has now been very
well discussed. Could anyone comment on the
general nature of increasing visual contrast to view
all of the other nebular details that may be perceived?
Sincerely,
STEVE WALDEE
Partner, WALDEE-WOOD ASTRONOMICAL SOFTWARE
Stephen Waldee
Friends:
In the discussions of viewing the Pleiades, Jay Reynolds Freeman has
commented in a typically apt observation:
>>> Too many amateur astronomers, even experienced ones, think that
>>>seeing things comes free and easy, with no more effort than opening
>>>your eyes: But as currently popular slang so evocatively articulates,
>>>
>>> ** NOT!! **.
>>>
>>>Vision is an acquired skill.
The issue has been the relative visibility of the nebulosity in the
Pleiades, as provoked by my (surprisingly controversial!) article.
Jay adds that success is not so much to be attained by the use of
Mel Bartels
All I can say is that I have seen the Pleiades naked-eye embedded in a
definite glow, a glow very much different than glare from the brighter
stars. I have never seen a hint of detail in the nebulosity naked-eye.
The weird thing is that in looking through binocs and small RTS, I can't
say that the glow is any brighter, only just that it is bigger and shows
detail. In a 20", a pleasing amount of streakiness and brightness
changes can be seen. The ParrCorr and 35mm PanOptic just perform
wonders on scopes of this size pointed at M45.
--
Clear skies, Mel Bartels Programmer/Analyst, and amateur astronomer
atm, atm-digest list-owner mailto: mbar...@efn.org
homepage: http://www.efn.org/~mbartels
How To Motorize A Dob:
http://zebu.uoregon.edu/~mbartels/altaz/altaz.html
Matt or Belinda Tarlach
Thanks for the reply-glad I'm not alone with this observation. Next
time I'm under a dark sky I'm going to compare views of the Pleiades
with other naked-eye clusters like the Beehive and the Coma cluster.
These should also have many unresolved stars, but no nebulosity.
-Matt
Dr. Louis S. Binder,O.D.
Todd is right,
Vision is taken for granted but using it correctly can extend the capabilities of your scope.
Drawing objects, even just star patterns is a great way to start enhancing your observing skills.
Attention to details is brought out after practicing drawing. You can even do this on cloudy
nights by drawing objects seen in the astronomy journals.
If you have further questions on vision and observing please fell free to ask me.
I lectured on this topic to the Clubs and Societies in Houston. I have also been consulted for a
upcoming article on star charts.
P.S. lets not get into a debate on billberry or green vs red lights at night.
--
P.S.S. Hey Todd still no Telvue Bino for sale anywhere??
Did you get a chance to try the kit bino for about $200 found on the net somewhere??
Dr. Louis S. Binder,Optometrist
Member Fort Bend Astronomy Club
& Houston Astronomical Society
Clear Skies
2nd Star to the right and straight on till morning
Janet Vialls
In article <toddg.975...@weatherman.com>
to...@weatherman.com "Todd Gross" wrote
> Over the early Fall, I observed, and drew NGC 891 in suburban skies. (C14) it
> was so ghostly and dim that previously I would have not picked it up.
You touch here on a favourite hobby horse of mine. I think one of the best
ways to train youself to see is to attempt to draw at the telescope.
Even if you never produce a good sketch, you do learn to see. After a long
gap, I have now spent about a year observing and sketching with an 8"
reflector. Now the sky has turned back to where I started, so to speak,
I really can see how my skills have improved.
--
Janet Vialls ) 'Twinkle, twinkle, little star....'
Ja...@mhorann.demon.co.uk ) Drat!! Lousy seeing again!
)
) I am not a number. I am a convergent series.