Pleiades,help me.
mar...@aol.com
I am conducting an experiment on light pollution and I need your help.
Please observe Pleiades on your next clear night and let me know how many
of the ten main stars you can see. Also give me your location- urban,
suburban or rural Thank you.
Samson
In <19961123020...@ladder01.news.aol.com> mar...@aol.com
writes:
Ten with the naked eye? Impossible anywhere on Earth! 6 is all
you'll SEE unaided... sorry
Rob Robinson
Samson (nuc...@ix.netcom.com) wrote:
: In <19961123020...@ladder01.news.aol.com> mar...@aol.com
Here is a case of jumping the gun again and taking pot shots....
The original poster didnt say ten naked eye stars, he said "ten main
stars". Read before you type!
--
==============================================================================
Rob Robinson Bonner Spgs KS USA http://www.sky.net/~robinson/iotandx.htm
WebSpinner for the International Occultation Timing Association
Vice-President of the Astronomical Society of Kansas City
(have a program you would like to present to the ASKC? - email me!)
94.8932 West 39.0579 North 249.7 Meters
==============================================================================
Jay Reynolds Freeman
> > Please observe Pleiades on your next clear night and let me know how
> > many of the ten main stars you can see. Also give me your location-
> > urban, suburban or rural Thank you.
> Ten with the naked eye? Impossible anywhere on Earth! 6 is all
> you'll SEE unaided... sorry
I can't contribute to the original survey personally, but certainly
there are people who have seen many more than six Pleiades with the naked
eye.
--
Jay Reynolds Freeman -- fre...@netcom.com -- I speak only for myself.
Dave Nash
fre...@netcom.com (Jay Reynolds Freeman) writes:
>> > Please observe Pleiades on your next clear night and let me know how
>> > many of the ten main stars you can see. Also give me your location-
>> > urban, suburban or rural Thank you.
>> Ten with the naked eye? Impossible anywhere on Earth! 6 is all
>> you'll SEE unaided... sorry
> I can't contribute to the original survey personally, but certainly
>there are people who have seen many more than six Pleiades with the naked
>eye.
I can usually see nine from the semi-dark skies in rural Illinois on
good nights. People with fairly sharp averted vision ought to do
even better.
>--
> Jay Reynolds Freeman -- fre...@netcom.com -- I speak only for myself.
--
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!"
Mel Bartels
In dark clear skies, I have seen 21 Pleiades naked-eye. This has been a
lifelong project of mine, and I use it to estimate sky conditions. If I
don't see at least 13 Pleiades, the skies are not good enough to bother
doing serious observing in. 20 years ago people used to say that the
North American Nebula was impossible to see, and that the HorseHead was
an impossible object. Now, these objects are often the showcase views
at dark sky star parties! It's amazing what you can see naked-eye if
you take the time to observe over the years. For instance, the Moon
presents incredible detail naked eye. M33, even the California Nebula
if you use a H-Beta filter over your eyes, can be seen. I haven't yet
seen Barnard's loop naked-eye, though I did finally see it in my 6" RFT
as a broad winding river brightest near M78. I was just at a meeting of
the RCA (Portland Oregon club) and I was surprised how low the naked-eye
count for the Pleiades was for many seasoned pros. I think this is one
object that people have 'just assumed' you can't see very much, when in
reality, there are a number of observers (someone mentioned Burnhams)
that have seen 13-20+ stars.
--
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
Jay Reynolds Freeman
For Pleiades counts, how do you define the "edge" of the Pleiades?
How far out does a star have to be before you can't count it?
Stephen Waldee
On 23 Nov 1996 02:05:57 GMT, mar...@aol.com wrote:
>I am conducting an experiment on light pollution and I need your help.
>Please observe Pleiades on your next clear night and let me know how many
>of the ten main stars you can see. Also give me your location- urban,
>suburban or rural Thank you.
Mary:
Interesting project.
When I was doing research on the Horsehead nebula some years ago, one
of the things 4 of us tested was the visibility of members of the
Pleiades. The results were (in a sky with about 6.0 naked eye stellar
limiting magnitude at the zenith): 1 viewer aged 14 could see 16
members (!); 2 viewers in their early 40s who did not wear eyeglasses
could see from 9-10; 1 remaining viewer, aged 42, could see 8 amd even
sometimes 9 (poor, uncoated eyeglasses.).
My friend Shiloh Unruh, a former staff member at Lick Observatory, was
observing with my wife and myself in late September of 1989. He
claimed to be able to see 12, and -- to prove it -- he clearly saw the
Pleiades as it rose in the eastern horizon LONG before I could detect
the cluster with my naked eye.
Recently, on (I believe) 11.06.96, I looked at the Pleiades in a sky
with a naked-eye limit of better than 6.5. By now, my eyeglass
prescription is WAY off, and my right eye is fuzzy at infinity. I was
able to see at least 7. Probably if I had been testing this just for
the purpose of your data-collecting, I might have concentrated harder
and would have been able to see the 8 members that I saw some 6 or 7
years ago.
Remember that Percival Lowell claimed that at one occasion he could
see 18!
Yours,
STEVE WALDEE
Partner, WALDEE-WOOD ASTRONOMICAL SOFTWARE
Chris Marriott
In article <freemanE...@netcom.com>, Jay Reynolds Freeman
<fre...@netcom.com> writes
>> Ten with the naked eye? Impossible anywhere on Earth! 6 is all
>> you'll SEE unaided... sorry
>
> I can't contribute to the original survey personally, but certainly
>there are people who have seen many more than six Pleiades with the naked
>eye.
>
From my back garden I can't see ANY individual stars looking directly at
the Pleiades; all I see is a patch of "mist". I don't know if that's due
to my relatively poor eyesight, or to light polution (typical limiting
mag is around 4).
Chris
----------------------------------------------------------------
Chris Marriott, SkyMap Software, U.K. e-mail: ch...@skymap.com
Creators of fine astronomy software for Windows.
For full details, visit our web site at http://www.skymap.com
Bernhard Rems
Hi there,
ch...@chrism.demon.co.uk wrote:
> From my back garden I can't see ANY individual stars looking directly at
> the Pleiades; all I see is a patch of "mist". I don't know if that's due
> to my relatively poor eyesight, or to light polution (typical limiting
> mag is around 4).
I would blame your eyesight. I have worse light pollution and still see
stars in the Plejades. See a doctor - live improves with better eyesight
:-)
Regards,
Bernhard
Bernhard Rems
bgr...@daheim.ping.at
William Demmery
Samson (nuc...@ix.netcom.com) writes:
> In <19961123020...@ladder01.news.aol.com> mar...@aol.com
> writes:
>>
>>I am conducting an experiment on light pollution and I need your help.
>>Please observe Pleiades on your next clear night and let me know how
> many
>>of the ten main stars you can see. Also give me your location- urban,
>>suburban or rural Thank you.
>
> Ten with the naked eye? Impossible anywhere on Earth! 6 is all
> you'll SEE unaided... sorry
I beg to differ. Fifteen years ago, my brother and I regularly picked out
eight or nine of them from decent skies on Vancouver Island, without waiting
to dark-adapt and without trying hard. I imagine someone with really acute
vision could snare ten from an outstanding site. In any case, six is a
piece of cake with cooperative skies...
-WCD-
Mel Bartels
Thoughts on Counting Pleiades
As with any challenging observing project, be prepared to spend many
hours over weeks, months and years. Each time you come back, you will
be a bit more familiar and see a tiny bit more. For instance, it was
years before I succeeded in seeing the Cone Nebula in a 24". Most of
the time, when observing at, or just beyond, the limits of what’s
observable, you will fail. But every so often, you succeed. Perhaps
Skinner’s chickens, pecking furiously at random reinforcement, at last
have their revenge!
You must absolutely get to the darkest most transparent skies at highest
altitude you possibly can. Wait until the Pleiades transits. Get a
lawn chair and blanket and commit an hour or two each observing session.
Learn the positions of the Pleiades by studying star atlases. Just like
you find the Andromeda Galaxy by finding the great square, then two
over, then two up, know where to look in the Pleiades. Most star
atlases that I have seen draw a fairly tight circle, about 1.5 degrees,
around the Pleiades. Any star inside is countable.
Burnhams, in Volume III, page 1874, is correct when he states that,
"There are at least 20 star in the group which might be glimpsed under
the finest conditions, having a brightness just below usual naked-eye
range;" This is true, but the next clause is not true, where he goes on
to say,
"the crowded massing of the stars, however, makes this impossible."
Actually, the star separations are far greater than the naked-eye
resolution of 1-2 arc minutes. You can test your own naked-eye
resolution by looking at Epsilon Lyra. You should see two adjoining
specks of light. If you see clear black inbetween, your resolution
limit is closer to 1 arc minute, if you see the specs as an elongated
star, you resolution limit is closer to 3 arc minutes. The average
resolution is supposed to be 2 arc minutes, but I have found when asking
people at star parties to tell me what they see, most of them do not see
clear black inbetween, indeed many do not see an elongation.
Break apart the Pleiades into regions. Start with the brightest four
stars of the square: Alcyone, Merope, Maia, and Electra. Next find
Taygeta, Celaeno, and Atlas. Right on top of Atlas is BU Tauri, a
variable star that ranges from 4.8 to 5.5 magnitude.
Probably the biggest problem in going for faint stars in the Pleiades is
the nebulosity. In good dark skies, you should see the Pleiades
enveloped in a fairly bright solid glow. This is similar to the problem
of the central star in the Ring Nebula, where it too is embedded in a
faint glow of the ring’s interior. The central star in the ring is
supposedly at 15.5 to 16 magnitude, but it is more difficult than a
stand alone 15.5 star to see. You can see faint stars in nebulosity,
but it takes more effort and time.
Now, you are at 8 stars and ready for the next level. Just above Maia
are two stars close together, 21 and 22 Tauri, at 5.8 and 6.4
magnitude. A little to the east is an unnamed 6.7 magnitude star,
easier to see because it is by itself. The most extreme north star is
18 Tauri, a 5.6 magnitude star just on the edge of our circle.
Between Maia and Alcyone is a star of 7.1 magnitude. Just to the north
of Alcyone is a line extending to the east of three stars, magnitudes
7.4, 7.3, and 6.2. South of Alcyone are two stars, magnitude 7.0 and
7.3. Much further to the south, right at the edge of our circle, is a
5.5 magnitude star. Between this star and 27 Tauri to the northeast are
3 stars of 6.1, 6.7, and 7.2 magnitude.
You are now over 20 stars in the count! My personal standard is to
record three observations before I count it as real. An observation may
only consist of a several second ‘popping into view’ in the most extreme
cases.
Also, as time goes by, one gains a certain ability to guess how an
observation might go. One can look at a field, and almost instantly
tell if the observation is a possibility. There are many objects that
Barbara Wilson, Stephen O’Meara, and the other gifted deep sky observers
have seen, that I am still trying my darndest to see!
David Doff
In <19961123020...@ladder01.news.aol.com> mar...@aol.com
writes:
>
>I am conducting an experiment on light pollution and I need your help.
>Please observe Pleiades on your next clear night and let me know how
>many
>of the ten main stars you can see. Also give me your location- urban,
>suburban or rural Thank you.
I am afraid this project is flawed. There are two variables - light
pollution and individual eyesight. Unless you can eliminate the latter,
you will not get information about light pollution.
Even under good conditions, I can usually see only four stars. People
with good eyesight will see eight (strange that they are called the
Seven Sisters, becuase if you can see 7 you can certainly see 8).
-------------------------------------------------------------------------
David Doff, Geology Department, Trinity College, Dublin 2, Ireland.
dd...@tcd.ie http://www.tcd.ie/Geology
-------------------------------------------------------------------------
Kenneth Drake
Thank you, Jay! The same problem comes up when we see discussions on
this subject for Tapezium, GreatSquare, Bowl of the Big Dipper, etc.
Allthough some are easier to define "edge" than others.
Kenneth Drake
Kenneth Drake
David Doff wrote:
>
> I am afraid this project is flawed. There are two variables - light
> pollution and individual eyesight. Unless you can eliminate the latter,
> you will not get information about light pollution.
>
> Even under good conditions, I can usually see only four stars. People
> with good eyesight will see eight (strange that they are called the
> Seven Sisters, becuase if you can see 7 you can certainly see 8).
>
> -------------------------------------------------------------------------
> David Doff, Geology Department, Trinity College, Dublin 2, Ireland.
> dd...@tcd.ie http://www.tcd.ie/Geology
> -------------------------------------------------------------------------
Laid back in a comfortable lawn chair early one October morning I was
able to
see all 7 stars with my Ray Bans on. No nebulosity seen.
"DRAKO"
Jay Reynolds Freeman
Several comments:
> > For Pleiades counts, how do you define the "edge" of the Pleiades?
> > How far out does a star have to be before you can't count it?
I hope people noticed that Mel Bartles's recent posting provided the
obvious answer, which is to work with a specific sequence of stars, so
that one can say "I could see x and y, but not z".
Another point: To observe casually with the naked eye is to expose
the eye to light pollution from the entire visual field. Sites differ
dramatically on how bad that is -- in the mountains or desert it may
be quite dark in all directions, but many pretty good sites have
lots of skyglow near the horizon, or cities and towns visible in
the distance. And just skyglow and starlight are often noticeable.
To eliminate much of this source of error, it might help to observe
through a simple "1x binocular", made by taping together two paper
tubes -- perhaps toilet-paper tubes -- with a spacer in between, and
coloring the insides black. I expect that at most sites, observers
would see more Pleiades with such a device than without one -- at
least, observers who did not wear glasses. A fancier gadget --
something like a welder's hood with a wide tube attached where the
dark glass goes -- might do for glasses-wearers.
Last comment: I myself have never been much into naked-eye magnitude
limits, because I do wear glasses for distant vision, and my
prescription is rarely as "on" as I would like it to be.
Kenneth Drake
Jay Reynolds Freeman wrote:
> Another point: To observe casually with the naked eye is to expose
> the eye to light pollution from the entire visual field. Sites differ
> dramatically on how bad that is -- in the mountains or desert it may
> be quite dark in all directions, but many pretty good sites have
> lots of skyglow near the horizon, or cities and towns visible in
> the distance. And just skyglow and starlight are often noticeable.
>
> To eliminate much of this source of error, it might help to observe
> through a simple "1x binocular", made by taping together two paper
> tubes -- perhaps toilet-paper tubes -- with a spacer in between, and
> coloring the insides black. I expect that at most sites, observers
> would see more Pleiades with such a device than without one -- at
> least, observers who did not wear glasses.
> Jay Reynolds Freeman -- fre...@netcom.com -- I speak only for myself.
Jay,
I have a pair of "0-Mags", A gag gift given to my x-wife years ago.
Susan Spore,
myself, and others used them at the TSP this year. They fit the
description of
yours pretty well. I recall that we were trying to better the NSP
naked-eye limit
of David Nash. The consensus was that no gain was had by the use of the
blackened
tubes. BTW, we were able to reach 8.3 but keep in mind that we were
using the PPM
as our mag reference so we really don't know if that was the true limit
or not.
Kenneth Drake
Mel Bartels
I just posted a webpage about counting pleiades at
http://zebu.uoregon.edu/~mbartels/visual/pleiades.html
Incidently, Patrick Moore, according to Mallas' Messier Album once asked
the british public to count pleiades. The replies ranged most often
from 6 to 8.
Chris Marriott
In article <6LSVB...@daheim.ping.at>, Bernhard Rems
<bgr...@daheim.ping.at> writes
>Hi there,
>
>ch...@chrism.demon.co.uk wrote:
>
>> From my back garden I can't see ANY individual stars looking directly at
>> the Pleiades; all I see is a patch of "mist". I don't know if that's due
>> to my relatively poor eyesight, or to light polution (typical limiting
>> mag is around 4).
>
>I would blame your eyesight. I have worse light pollution and still see
>stars in the Plejades. See a doctor - live improves with better eyesight
>:-)
I can see stars with averted vision; just not looking directly at the
cluster.
jose...@aol.com
Only 6? Wrong, Samson. I've seen 9 myself.
Joe Bergeron
C++ Freak
> >
>
> From my back garden I can't see ANY individual stars looking directly at
> the Pleiades; all I see is a patch of "mist". I don't know if that's due
> to my relatively poor eyesight, or to light polution (typical limiting
> mag is around 4).
>
>
Go and see the optometrist.
Klaas
Chris Marriott
In article <329895...@ix.netcom.com>, Kenneth Drake
<dr...@ix.netcom.com> writes
>Laid back in a comfortable lawn chair early one October morning I was
>able to
>see all 7 stars with my Ray Bans on. No nebulosity seen.
What do you mean by "all 7" stars. There are at least 9 bright members
of the Pleiades - Atlas, Pleone, and their 7 daughters!
Martin Tom Brown
In article <QipN0nA$mBmy...@chrism.demon.co.uk>
ch...@chrism.demon.co.uk "Chris Marriott" writes:
> In article <freemanE...@netcom.com>, Jay Reynolds Freeman
> <fre...@netcom.com> writes
> >> Ten with the naked eye? Impossible anywhere on Earth! 6 is all
> >> you'll SEE unaided... sorry
> >
> > I can't contribute to the original survey personally, but certainly
> >there are people who have seen many more than six Pleiades with the naked
> >eye.
Last year there was a BAA survey in the UK which used the Pleiades
and a region in Ursa Minor as references to check on light pollution.
From my rural back garden I see between 10 & 12 on a good night, and
if I practiced I might pick up a few more. (lim mag 5.5)
Even though I see e-Lyra as a double with dark space in between,
the problem I find for using the Pleiades is that it is too much
of an eye resolution test as well as detecting the faint stars.
> From my back garden I can't see ANY individual stars looking directly at
> the Pleiades; all I see is a patch of "mist". I don't know if that's due
> to my relatively poor eyesight, or to light polution (typical limiting
> mag is around 4).
From Manchester on the best nights I can only see 6 stars (lim mag 4)
it should be slightly better outside the city centre.
Regards,
--
Martin Brown <mar...@nezumi.demon.co.uk> __ CIS: 71651,470
Scientific Software Consultancy /^,,)__/
Rolf Meier
> Ten with the naked eye? Impossible anywhere on Earth! 6 is all
>you'll SEE unaided... sorry
Nonsense. 8 is relatively easy, 12 on a good night. Some people can
see 15-18. 6 can be seen from downtown in the largest cities.
______________________________________________________________________
Rolf Meier usual disclaimer applies
Randy Muller
Stephen Waldee wrote:
> Remember that Percival Lowell claimed that at one occasion he could
> see 18!
Didn't Percival Lowell also claim he could see canals on Mars?
Mel Bartels
Does that mean because he claimed to see men and women and dogs and cats
that they are illusionary too?
Mel Bartels
I know I was joking, but the point I was trying to make is that just
because Lowell ardently 'believed and saw' cannali doesn't mean that his
other observations ought to be tossed. Remember too that when Lowell
was announcing his cannali, others were saying quite loudly that they
did not exist.
In pre-'net days, we observed with our local and regional buddies. If
someone was serious and had good eyes and announced seeing things that
others couldn't, there was usually a couple others who could also see
the faint stuff, otherwise the person was pretty quickly shunned at star
parties. The problem now in 'net-times, is that we don't observe
together, so how can we trust each others' observations, particularly
when someone announces an observation that is pretty unusual? Certain
people like Barbara Wilson and Stephen O'Meara have acquired reputations
such that their observations are not questioned. But there are piles of
people known regionally, but not internationally, who are reliable
skilled observers of difficult and 'near-impossible' objects. For every
person that we have heard of through the grapevine, there must be ten
more that we haven't heard of.
Observing in small groups of experienced observers like the recent
new-moon record observations so that confirmation can be had is one
answer. Similarly, at large regional star parties, one can observe with
the best of them. Another thing that might help is to be clearer about
negative observations. We all are happy to report our
tiniest-aperture-view-of-the-Horsehead-ever-in-our-lifetimes, but we
rarely say how many hours went into it and how exceptional the skies
were for that one night only. For those who don't practice
'ultimate-observing', whether because of skies or time or eyes, being
clearer about the negative observing might help. I myself can report
that most of the time, I don't succeed in picking up my
'ultimate-object'.
Another thing too is to keep emphasizing how important the sky is. I
use a sky-rating system that has a two categories above the normal
seeing scale. These categories are: one-night-a-year seeing, and
one-night-a-lifetime-seeing. I just can't say how important it is to
get out under high altitude skies with surperb transparency. I mean, if
you can't see naked-eye stars to at least 6.7 magnitude, you are going
to have trouble matching others' 'ultimate-observations'. Finally, it
really does help to observe with others. I used to observe by myself
for concentration and to not be bothered, but in a star party setting
with other serious observers, they offer objects and push you into
trying harder. The ultimate motivation, frankly, is to hear someone
say, "Yes! I saw it!", because you want to see what they saw. Another
helpful tactic is to observe through a gargantuan scope of 36-41", then
go back to your smaller scope. The amount that now can be seen always
surprises me. It's as if the brain has been trained to see stuff that
it just refused to see beforehand.
Finally, I have had good luck in viewing an area, and coming back to it
time and time again, often over the years. It has taken several years
to see some of the difficult-stuff, and I feel that it takes many hours
to 'teach' the brain to finally see. Let's take the North American
Nebula. At first you don't see anything. Finally, you barely see the
Gulf of Mexico. As time goes on, you see more of the nebula. One night
you glimpse a glow to the side - the Pelican. As you study the Pelican
and learn to see it, eventually you get to the point where you see
streaks and other detail. Now, you can see the NAN naked-eye even in
less than great skies. It's like bike riding, once you learn an object,
you kindof pickup where you last were, you don't forget much.
Tom Polakis
Mary,
I think your experiment may reveal much more about visual acuity and
experience than light pollution. Even with the best of prescriptions,
my +5-diopter eyes don't show record numbers of Pleiades from true dark
sites.
A better test might involve looking for low-contrast details in the
Milky Way, or better yet, extent of Zodiacal Light or Gegenschein.
These would be equally well seen with less than perfect vision. This,
too, would have its limitations, as observer experience would influence
the results.
Tom Polakis
Brian L. Rachford
>>> > many of the ten main stars you can see. Also give me your location-
>>> > urban, suburban or rural Thank you.
>
>>> you'll SEE unaided... sorry
>
>>there are people who have seen many more than six Pleiades with the naked
>>eye.
>
>good nights. People with fairly sharp averted vision ought to do
>even better.
>
>>--
>
>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!"
At the risk of a "me too" post - me too. I've seen 9 before in dark
skies in the mountains of SE Wyoming without making a huge effort
(limiting magnitude around +7). I've seen 7 or 8 in rural SE Iowa
under "pretty-dark" skies. After the Moon gets out of the way, maybe
I'll try again in a few days.
Brian
____________________________________________________________________
Brian L. Rachford, grad student | rach...@sparky.uwyo.edu
Dept. of Physics and Astronomy | rach...@uwyo.edu
University of Wyoming, Laramie | http://plains.uwyo.edu/~rachford/
Prof. Balderdash P. Blatherskite
On Mon, 25 Nov 1996 17:17:09 -0800, Mel Bartels <mbar...@efn.org>
wrote:
>I know I was joking, but the point I was trying to make is that just
>because Lowell ardently 'believed and saw' cannali doesn't mean that his
>other observations ought to be tossed.
Mel, you are too modest. I have seen
202 Pleiads,
using a 0.1 mm aperture CRASSTAR Fluoroscope.
Yours,
P. Blatherskite, PhD
University of North Dakota, Hoople
Randy Muller
Mel Bartels wrote:
> Does that mean because he claimed to see men and women and dogs
> and cats that they are illusionary too?
Of course not. And yes, I realize you're joking, or at least
exaggerating!
My point was that I felt that Percival Lowell was perhaps not the most
careful observer, and perhaps his observing reports should not be cited
as a good example of exceptional observational skills.
> just because Lowell ardently 'believed and saw' cannali doesn't mean
> that his other observations ought to be tossed.
I agree. But I think the fact that his observations of Mars tell us a
lot about him, rather than Mars, and that these observations of him help
us judge and decide about his observations of, for example, the
Pleiades. He was an observer who tended to 'see what he believed',
rather than 'believing what he saw'.
This is not a clearcut issue though, as you pointed out:
> Another helpful tactic is to observe through a gargantuan scope of
> 36-41", then go back to your smaller scope. The amount that now can
> be seen always surprises me. It's as if the brain has been trained
> to see stuff that it just refused to see beforehand.
With a trained brain we can see much more than we can without one. But
the training has to be accurate. We can train our brains by using
larger scopes or by spending a lot of time in a particular area.
Without such training, we are more limited. With bad training or
incorrect belief, we are handicapped.
Finally, I appreciate your careful and detailed exposition of observing
-- the depth of experience really shows.
I also appreciate Steve Waldee's accidental, but lyrical post on
observing the Pleiades which fueled this thread.
Clayton E. Cramer
Mel Bartels wrote:
>
> Randy Muller wrote:
> > Didn't Percival Lowell also claim he could see canals on Mars?
>
> that they are illusionary too?
>
> Clear skies, Mel Bartels Programmer/Analyst, and amateur astronomer
I saw canals on Mars at the 1971 opposition, under very high
power. I knew that they weren't there, but that doesn't prevent
the eye from playing tricks with disconnected spots and turbulence.
--
Clayton E. Cramer Technical Marketing Manager, Diamond Lane
Communications
email: cra...@dlcc.com web page: http://www.cs.sonoma.edu/~cramerc
Opinions are strictly my own; DLCC doesn't pay me for non-technical
opinions.
Kenneth Drake
The brightest stars other than the 8 that form the "Seven Sisters"
that are really inside and contained by the asterism are SAO 76173
at mag 7.1 and SAO 76152 at mag 7.6. How is it that folks are seeing
9, 11 14, or 18 stars unless they count stars outside the asterism?
Who decides what size circle is used?
Drake
Jennifer B. Jakiel
Kenneth Drake (dr...@ix.netcom.com) wrote:
: Chris Marriott wrote:
: >
: > In article <329895...@ix.netcom.com>, Kenneth Drake
: > <dr...@ix.netcom.com> writes
: > >Laid back in a comfortable lawn chair early one October morning I was
: > >able to
: > >see all 7 stars with my Ray Bans on. No nebulosity seen.
: The brightest stars other than the 8 that form the "Seven Sisters"
: that are really inside and contained by the asterism are SAO 76173
: at mag 7.1 and SAO 76152 at mag 7.6. How is it that folks are seeing
: 9, 11 14, or 18 stars unless they count stars outside the asterism?
: Who decides what size circle is used?
: Drake
Hrm ...I've read better than 25 posts now and unless there is a
serious "oversight" on my part - I see *NO* proof of observation.
Anyone can claim they've seen 12 to 15 Pleiades - but thats a hollow
claim, equivalent to chest thumping.
Go out some night, do not review any photo or map of the Pleiades and
DRAW the cluster. Sketch the position of the stars you see. This works
best with people who have no prior knowledge of the cluster, else
bias can work its way in.
Afterwards, check the accuracy of the drawing with a chart, esp. one
with photometric data. Try to be objective.
This is an example of what I have observed in general in amateur
astronomy. I see alot of claims that are "on the edge", that is
pushing the limits of what can be observed. I've seen some fairly
outrageous claims, and unless I know the observer - I'm inclined to
doubt their validity. I can cite examples, but I perfer to withhold
judgement for the moment.
My advice is to publish those observations in a public forum (newsletter,
homepages,magazines, Webb Society -etc) so that they can be peer reviewed.
Include such info as optics used, sky conditions, visual and telescopic
limitng magnitudes, filters - etc. General claims like "15 Pleiades"
naked eye, or seeing 19 mag stars with a 20-inch don't mean squat to
me unless I know more about the observer or conditions.
Removal of bias is very important to good observations - what steps
do you take? How repeatable are your observations?
- Rich Jakiel
Mel Bartels
>>>
Go out some night, do not review any photo or map of the Pleiades and
DRAW the cluster. Sketch the position of the stars you see. This works
best with people who have no prior knowledge of the cluster, else
bias can work its way in.
<<<
Best way to remove bias is to carefully study the object/region ahead of
time and in the case of the Pleiades, develop a sequence of stars from
bright to dim magnitude. That way, you can determine your naked-eye
magnitude cutoff. Knowing exactly where to look is worth maybe 1 1/2
magnitudes, and is absolutely vital in going for the limits of
visibility.
I have a Count the Pleaides page at
http://zebu.uoregon.edu/~mbartels/visual/pleiades.html where star
magnitudes and positions are shown/discussed.
--
Clear skies, Mel Bartels Programmer/Analyst, and amateur astronomer
Steve Jolly
Mel,
Your home page--and the astronomy-related goodies you've put on it and
linked to it--is a little jewel. I just discovered it, after following
up the link on your recent postings. Great work!--thanks for putting it
together.
Highly recommended it for anyone who's browsing...
Samson
In <57pjr7$6...@crl2.crl.com> jak...@crl.com (Jennifer B. Jakiel)
writes:
>Kenneth Drake (dr...@ix.netcom.com) wrote:
>: Chris Marriott wrote:
>: >
>: > In article <329895...@ix.netcom.com>, Kenneth Drake
>: > <dr...@ix.netcom.com> writes
>: > >Laid back in a comfortable lawn chair early one October morning I
was
>: > >able to
>: > >see all 7 stars with my Ray Bans on. No nebulosity seen.
>: >
>
>: The brightest stars other than the 8 that form the "Seven Sisters"
>: that are really inside and contained by the asterism are SAO 76173
>: at mag 7.1 and SAO 76152 at mag 7.6. How is it that folks are seeing
>: 9, 11 14, or 18 stars unless they count stars outside the asterism?
>: Who decides what size circle is used?
>
>: Drake
>
>Hrm ...I've read better than 25 posts now and unless there is a
>serious "oversight" on my part - I see *NO* proof of observation.
>Anyone can claim they've seen 12 to 15 Pleiades - but thats a hollow
>claim, equivalent to chest thumping.
Thankyou + + + + + + .
Chris Marriott
In article <32A0A8...@efn.org>, Mel Bartels <mbar...@efn.org>
writes
>Knowing exactly where to look is worth maybe 1 1/2
>magnitudes, and is absolutely vital in going for the limits of
>visibility.
Isn't a "blind test" more reliable? ie NOT knowing what you "expect" to
see in advance. If something is on the edge of visibility, but you KNOW
it's there, I'd have thought that must inevitably introduce a bias into
the results!
Jennifer B. Jakiel
Mel Bartels (mbar...@efn.org) wrote:
: >>>
: Go out some night, do not review any photo or map of the Pleiades and
: DRAW the cluster. Sketch the position of the stars you see. This works
: best with people who have no prior knowledge of the cluster, else
: bias can work its way in.
: <<<
: Best way to remove bias is to carefully study the object/region ahead of
: time and in the case of the Pleiades, develop a sequence of stars from
: bright to dim magnitude. That way, you can determine your naked-eye
: magnitude cutoff. Knowing exactly where to look is worth maybe 1 1/2
: magnitudes, and is absolutely vital in going for the limits of
: visibility.
I beg to differ. Knowing full well what/where everything is makes the
problems of bias that much greater.This can be a form of "self fulfilling
prophesy". Knowing what is there and expecting it. No wonder you can
get an extra magnitude or two,,
This can be real problem when doing accurate, non-biased drawings of Mars.
I *know* what albedo features to expect, but its hard to draw what you
really see.
- Rich Jakiel
Mel Bartels
I hold that the most reliable observations are done by those who know
what to look for and where to look. You build a sequence of stars or
parts of the nebulosity from brightest to dimmest and ascertain where
your cutoff point is. All experienced observers pushing the limits do
this (if this is not true, please name someone).
As I said in an earlier post, one does not 'lie' about what one sees or
doesn't see, not only because you will quickly be discredited (that is,
caught saying you can see something that turns out to be nonexistent),
but because the whole point is to push your limits, not to brag to
others.
There is no doubt when observing whether one sees it or not. It may
only flash into visibility occasionally, but there is still no doubt.
Emotions play no part in it, except to keep you trying, because no
matter how hard you imagine you can see it, it still pops into view or
it doesn't.
Since you are intimately involved in the observation and there is no way
to dispassionately step back, your best bet to eliminate bias is to
carefully study the object and develop a series of tests, or portions of
the nebulosity, or a sequence of stars, to give you a range to observe
against.
Mel Bartels
>>> This can be real problem when doing accurate, non-biased drawings of Mars. I *know* what albedo features to expect, but its hard to draw what you really see. <<<
My quick reply is: only draw what you see then - this is not hard to do!
Knowing that Mars has albedo features and that Jupiter may have festoons
out this evening, that Saturn may have a white spot erupting doesn't
prejudice the observation if you are careful to draw only what you see.
It becomes hard to draw when 'you think you should be seeing it' and you
don't.
Mel Bartels
One more point I would like to make: I just don't see how being ignorant
about an object removes bias. If someone is going to sketch in
imaginary things, then he is just as likely to do it whether he knows
the shape of the object or not.
Mel Bartels
Yet another argument in favor of knowing your object before observing
it:
the case of the Andromeda Galaxy naked-eye - can you see it?
I would maintain that because I know exactly where to look in the sky
(square of Pegasus, 2 stars over, 2 stars up) and that fact that I have
seen it naked-eye for 30 years, means that I have a better chance of
actually seeing it in a given sky than someone who has never seen it
before and does not know where to look in the sky. In fact, because I
know what it should look like, what shape and orientation it will be,
and exactly where it is, my bias in observing M31 naked-eye ought to be
less than the neophyte's first effort.
R. Klappal
jak...@crl.com (Jennifer B. Jakiel) wrote:
>Go out some night, do not review any photo or map of the Pleiades and
>DRAW the cluster. Sketch the position of the stars you see. This works
>best with people who have no prior knowledge of the cluster, else
>bias can work its way in.
.... snip ...
>- Rich Jakiel
In the year of our Lord 1432, there arose a grievous quarrel among the
brethren over the number of teeth in the mouth of a horse. For thirteen
days the disputation raged without ceasing. All of the ancient books and
chronicles were fetched out, and wonderful and ponderous erudition, such
as was never heard before in this region, was made manifest. At the
beginning of the fourteenth day, a youthful friar of goodly bearing
asked his learned superiors for permission to add a word.
Straightaway, to the wonder of the disputants whose deep wisdom he sore
vexed, he beseeched them to unbend in a manner coarse and unheard of,
and to look in the mouth of a horse to find an answer to their
questionings. At this, their dignity being greatly hurt, they waxed
exceedingly wroth; and joining in a mighty uproar, they fell upon him,
hip and thigh, and cast him out forthwith. For, said they, surely Satan
hath tempted this bold neophyte to declare unholy and unheard of ways of
finding truth contrary to all the teachings of their fathers.
- Francis Bacon
(1561 - 1626)
Rich
kla...@xnet.com
41N48' 88W15'
================
Nothing in the nature of things is or has been more closely
concealed. The only thing in which it does not satisfy everybody
is that its usefulness is not clear to the unreflecting.
J.Kepler of Wurttemberg
Mysterium Cosmographicum
================
Bob Officer
On Sat, 23 Nov 1996 13:18:21 -0800, Mel Bartels <mbar...@efn.org>
wrote:
>In dark clear skies, I have seen 21 Pleiades naked-eye. This has been a
>lifelong project of mine, and I use it to estimate sky conditions. If I
>don't see at least 13 Pleiades, the skies are not good enough to bother
>doing serious observing in. 20 years ago people used to say that the
>North American Nebula was impossible to see, and that the HorseHead was
>an impossible object. Now, these objects are often the showcase views
>at dark sky star parties! It's amazing what you can see naked-eye if
>you take the time to observe over the years. For instance, the Moon
>presents incredible detail naked eye. M33, even the California Nebula
>if you use a H-Beta filter over your eyes, can be seen. I haven't yet
>seen Barnard's loop naked-eye, though I did finally see it in my 6" RFT
>as a broad winding river brightest near M78. I was just at a meeting of
>the RCA (Portland Oregon club) and I was surprised how low the naked-eye
>count for the Pleiades was for many seasoned pros. I think this is one
>object that people have 'just assumed' you can't see very much, when in
>reality, there are a number of observers (someone mentioned Burnhams)
>that have seen 13-20+ stars.
and in me too spirit I have also seen and counted 21 on a clear
night. It isn't easy but then the near impossible isn't. It just
takes time.
1. find a place really dark.
2. go there way before your "observation time" Like camp out under the
stars.
3. this works best went your observations are after 2:00am
go to bed early in a dark room...
4. wake up and use no light.. not even the red filtered ones...
5. go out side and lay down or recline relaxed so you don't move.
6. at a deep cleaning breath. let it out and then a regular breath. no
open your eyes and scan the area using averted vision...
7. close you eyes and relax and breath in and out and go to step 6.
also try to tape record your observations.
my goal is to confirm the 22 star... I have thought I have seen it a
few times, but can't get enough confirmed sightings... it is real
elusive...
I have had a few times when the count has gone over 22 but those are
rare and not repeated enough to be confirmed no counts ever twice in
a row the same....
also after a major winter storm when the skies a the most calm.
Bob Officer | bo...@vornet.com
Tracy, California |
|
Bob Officer
On Sun, 24 Nov 1996 20:42:44 GMT, fre...@netcom.com (Jay Reynolds
Freeman) wrote:
>Several comments:
> I hope people noticed that Mel Bartles's recent posting provided the
>obvious answer, which is to work with a specific sequence of stars, so
>that one can say "I could see x and y, but not z".
I count from top to bottom right to left. and area I count is a area
defind by my thumb and forfinger held about 4inches or so from my face
unclosed,
> To eliminate much of this source of error, it might help to observe
>through a simple "1x binocular", made by taping together two paper
>tubes -- perhaps toilet-paper tubes -- with a spacer in between, and
>coloring the insides black. I expect that at most sites, observers
>would see more Pleiades with such a device than without one -- at
>least, observers who did not wear glasses. A fancier gadget --
>something like a welder's hood with a wide tube attached where the
>dark glass goes -- might do for glasses-wearers.
I have used blacked out t.p. and paper towel tubes. I don't need
glasses when naked eye observer, but need them to see my fingers on
the end of my hand <far sighted>.
and thanks of the welders hood suggestion... get idea.
> Last comment: I myself have never been much into naked-eye magnitude
>limits, because I do wear glasses for distant vision, and my
>prescription is rarely as "on" as I would like it to be.
Brian L. Rachford
In article <n+UAjMAy...@chrism.demon.co.uk>, Chris Marriott
<ch...@chrism.demon.co.uk> writes:
>In article <32A0A8...@efn.org>, Mel Bartels <mbar...@efn.org>
>writes
>>magnitudes, and is absolutely vital in going for the limits of
>>visibility.
>
>see in advance. If something is on the edge of visibility, but you KNOW
>it's there, I'd have thought that must inevitably introduce a bias into
>the results!
>
>Chris
>
>----------------------------------------------------------------
>Chris Marriott, SkyMap Software, U.K. e-mail: ch...@skymap.com
>Creators of fine astronomy software for Windows.
>For full details, visit our web site at http://www.skymap.com
That remark could be considered a little insulting to a careful
observer. The placebo effect (i.e. seeing what you want to
see) is not *that* powerful for a good observer. In fact,
insusceptibility to suggestion is a prerequisite to being
a good observer. Personally, when I'm doing, say, a naked-eye
limiting magnitude check, I use known stars. But for a detection,
I make sure I have a 'lock' on a star for at least a couple
seconds at a time, which is much much longer than any transient
signals my eye/brain system may make up. I suspect other
observers do similar things with whatever objects they are
observing and maybe even shorter times are appropriate if
a person can keep seeing the object occasionally.
Mel Bartels
Some people think that because you know where to look, that you are
utterly helpless to report what you imagine, rather than what you see!
I don't understand this rather naive view. It would help if people
commenting on this would be sure that they have put in hundreds of hours
of viewing objects at the limit of visibility, then they would have a
good understanding how an experienced observer goes about the business
of reporting an object's visibility or non-visibility.
Knowing where to look for a faint star only tells you exactly where to
look: it does not predispose you to 'see' the faint star. An
experienced observer goes through a lot before satisfying himself that
he saw the star. My personal standard is that the star must be visible
at least three times, each time for a couple of seconds, in an
observation, which can last for a number of minutes of staring.
It is important to note for those starting out, that objects at the
limit of visibility come in and out of view, because seeing can vary
greatly from moment to moment. It is important to stare at the proper
field of view for long periods of time, and to keep coming back to the
field time and time again. You may still never see it, but this will at
least give you the best attempt at penetration into the sky.
Kent Madin/ Linda Svendsen
We still have some space on our group going to view the solar eclipse
and Hale Bopp, March 4-12, 1997. The comet will be just three weeks
away from its closest approach to earth at the time of eclipse totality.
INformation at:
http://www.mcn.net/~boojum/
--
Boojum Expeditions
Uncommon Adventure Travel Since 1985
Horseback Treks in Mongolia, Tibet, China, Montana and Beyond
http://www.boojumx.com tel. 406-587-0125 fax. 406-585-3474