Limiting Magnitude in Binoculars

(edz) wrote in message . com...

edz -

Thank you again for taking the time to actually go out and collect
some field observations on limiting magnitude for binoculars. Having
prepared one of these cluster magnitude charts myself, I know how
much time it involves. Your collection of observations is a good
start in the right direction.

This post was made without reviewing the entire current thread, but
have bottom posted to the most recent entry. My apologies in advance
if some points have already been addressed.

The overall objective of the July binocular limiting magnitude thread
concerned whether generally accepted formulae for the prediction of
limiting magnitude in telescopes could be applied directly to
binoculars in varying conditions of light pollution. It was suspected
there might be an inherent difference in the depth to which binoculars
could see as compared to monocular telescopes of the same aperature
rating, because the total surface area of the binocular is 1.414 (or
the square root of 2) of a similar sized rated monocular. It was
concluded that there was a lack of reported studies, particularized to
binoculars, in popular and professional astronomny literature
concerning the limiting magnitude of binoculars. For example,
Harrington's popular work, Star Ware (1994), reports a "binocular
limiting magnitude table", that is simply a reprint of earlier work on
the limiting magnitude of monocular telescopes from Sidgwick's Amateur
Astronomer's Handbook.

The Carlin formula was discussed as a working hypothesis. The Carlin
(Carlin 1997) formula has the form:

m = 3*Log(A) + 2*Log(X) + 0.6 + v

where
m = magnitude of faintest star (point source) visible in binocular
A = aperture in cm
X = magnification
v = magnitude of faintest star visible to the naked eye

At the end of the July thread, it was concluded that amateur astronomy
generally could benefit from the gathering of amateur field
observations designed to accept or reject the Carlin formula as a
hypothesis, or to develop an alternative model, for the limiting
magnitude of binoculars. Such information would be of use in
responding to "what can I see at night" questions from binocular
observers, considering the increasing post-industrial environmental
problem of light pollution. Older Sidgwick-type telescopic models do
not account for light-pollution as a factor; the modern Schaefer
(1989) model was developed for and tuned using amateur observations
from monocular telescopes.

Unfortunately, I do not agree with one of the conclusions of the
Cloudy Nights article "Limiting Magnitude in Binoculars".
Specificially that CN's conclusion that "the formula prediction
produces results too high (by 0.5) at mag 5.8 NELM and equally to low
at mag 4.4 NELM." Similarly: "Is Carlin's formula incorrectly applied
by assuming the calculated increase in magnitude should be added
linearly to current NELM? . . . Chart 2 clearly shows the difference
in predicted affect of NELM vs actual affect of NELM. . . . . The
limiting magnitude in binoculars (or scopes) will increase or decrease
as NELM changes, however the relationship is not linear."

See "Summary and conclusions" in "Limiting Magnitude" at
http://www.cloudynights.com/articles...culars.htm/#20

and

"What effect does NELM have?" in "Limiting Magnitude" at
http://www.cloudynights.com/articles...culars.htm/#10

Although it is important that you, unlike most other amateurs, made
the effort to collect observations, a sufficient number of
observations have not been collected to reject or accept, from a
statistical viewpoint, the Carlin formula for predicting limiting
magnitude, when applied to binoculars instead of monocular telescopes.

Boiling down the CN "Limiting Magnitude" article, 15 useful
observations were recorded, as listed in Table 1:

===============================
Table 1 - Extracted CN observations

Date NELM Bino Star Mag
09/22/2003 5.6 10x50 S7 10.1 *
09/16/2003 5.6 12x50 S12 10.0
09/22/2003 5.6 12x50 S8 10.2
09/12/2003 5.0 15x70 S10 10.1
09/21/2003 5.1 15x70 E10 10.5
08/19/2003 5.2 15x70 E3 10.3
09/16/2003 5.6 15x70 E6 10.4
09/22/2003 5.6 15x70 E12 10.8 *
09/16/2003 5.6 16x60 E6 10.4
09/22/2003 5.6 16x60 E12 10.8 *
09/12/2003 5.0 16x70 No rpt 10.3
08/19/2003 5.2 16x70 E3 10.3
09/16/2003 5.6 16x70 E12 10.8 *
09/22/2003 5.6 16x70 S20 10.8 *
09/22/2003 5.6 08x42 S5 9.5

Table 1 - Notes:

* = Rounded magnitude

NELM = Naked eye limiting magnitude with 4° of cluster

Star = Faintest "direct vision" star reported by CN on an
observing night with one scope. Excludes averted vision reports.

Mag = Magnitude of fainest star seen by CN on an observing night
with one scope.

Observations extracted from Cloudy Nights Site:
http://www.cloudynights.com/articles...noculars.htm#9
(accessed 10-5-2003)

========================

"An observation" for the purposes of this discussion is the faintest
star seen:

1) by an observer on a one night
2) using a particular binocular class
3) that can be paired with a unique NELM observation taken within that
night.

"NELM", as explained by Harold Lang in the July threads, for the
purposes of applying Carlin's formula refers to the naked-eye limiting
magnitude in the area of approximately 4° around the area of
observation. It may be off-zenith but should be located close to the
area of observation.

ZLM refers to "zenithal limiting magnitude" or the visual limiting
magnitude at the observer's local zenith. McBeath 1991 defines visual
limiting magnitude as being "usually defined as being equal to the
brightness of the faintest star just visible to the slightly-averted,
fully dark-adapted, unaided eye." Off zenith NELM readings might be
taken for any part of the local observer's sky, i.e. - the NELM near
Ursa Major. Without reporting the date, time and location of the
observation, it is not possible to normalize NELM observations from
different observers for the effect of atomspheric extinction.

Based on the text of the "Limiting Magnitudes" article alone, not
contacting Ed directly for data clarifications and not reviewing his
recent data clarification posts in depth, observations on the dates
listed in Table 2 are discarded for the purpose of this discussion:

========================
Table 2 - CN observations discarded for this post

Date Reason discarded

08/23/2003 From published description, binoculars cannot be paried
with specific measurements.

09/10/2003 Cannot pair NELM near cluster field on two dates (v4.0 and
4.5) with measurements on differing dates

09/11/2003 Cannot pair NELM near cluster field on two dates (v4.0 and
4.5) with measurements on differing dates

09/14/2003 No NELM near field of open cluster reported. Only NELM
around Ursa Major reported.

Source: Observations extracted from Cloudy Nights Site:
http://www.cloudynights.com/articles...noculars.htm#9
(accessed 10-5-2003)

========================

Table 3 lists 4 observations of "averted" limiting magnitude that were
not applied for the purpose of this discussion on the grounds of
consistency in data collection:

========================
Table 3 - Averted vision readings - Deferred in favor of direct
reading and where the averted reading is the lowest magnitude for that
scope on that night

Date NELM Bino Star Mag Comments
9/21/2003 5.1 15x70 S16 10.8 "The faintest star was barely
glimpsed."
9/22/2003 5.6 08x42 S9 10.0 "S9-10e was suspected averted"
9/22/2003 5.6 12x50 E6 10.4 "averted suspected"
9/22/2003 5.6 16x60 E7 10.8 "E7-10e averted suspected"

Observations extracted from Cloudy Nights Site:
http://www.cloudynights.com/articles...noculars.htm#9
(accessed 10-5-2003)

========================

As can be seen in Table 4, a cross-table summary of Table 1 above,
an insufficient number of observations has been made within each
binocular class to make any statistically valid conclusion rejecting
or accepting the Carlin formula as a predictive tool for amateur
binocular observers:

========================
Table 4 Count of NELM-Mag CN
observations by binocular class
and magnitude observation

Mag range
Bino 5-5.5 5.6-6 Total
10x50 1 0 1
12x50 2 2
15x70 3 2 5
16x60 2 2
16x70 2 2 4
08x42 1 1
Total 5 10 15

Source: Table 1 above.
========================

For example, only 1 useful reading was taken in the 8x42 and 10x50
classes; 2 in the 12x50 class; 2 in the 16x60. As discussed in the
remainder of this post, the remaining observations regarding 70mm
aperature binoculars are also of insufficient number to warrant
reaching any firm conclusions at this time, although the data
collected is as good start.

Nevertheless, some initial working discussions can be had by
combining the nine useful 70mm aperature readings at 15 and 16
magnification into one theoretical 15.5 magnification cohort:

========================
Table 5 - Extracted CN observations
for 15x70 and 16x70 class N=9

Date NELM Bino Star Mag Carlin predicted
09/12/2003 5.0 15x70 S10 10.1 10.5
09/21/2003 5.1 15x70 E10 10.5 10.6
08/19/2003 5.2 15x70 E3 10.3 10.7
09/16/2003 5.6 15x70 E6 10.4 11.1
09/22/2003 5.6 15x70 E12 10.8 11.1
09/12/2003 5.0 16x70 No rpt 10.3 10.5
08/19/2003 5.2 16x70 E3 10.3 10.7
09/16/2003 5.6 16x70 E12 10.8 11.1
09/22/2003 5.6 16x70 S20 10.8 11.1
===================================

Graphically, Table 5 is shown in Figure 1, posted at my personal web
site:

http://members.csolutions.net/fisher...ude_CN_obs.gif

Lumping the 15 and 16 magnitude observations into one cohort for the
purposes of working discussions is justifable because the result of
the Carlin formula is not very sensitive to minor changes in
magnification. Recall the Carlin formula is:

m = 3*Log(A) + 2*Log(X) + 0.6 + v

where 2*Log(X) is the log of the magnification, and
v is the subjective NELM estimate of the observer.

The difference between 15 and 16 magnification on a 70mm aperature
(2*LOG(16)-2*LOG(15)) contributes only 0.05 magnitude to Carlin's
predicative result. So grouping the Cloudy Nights 15 and 16
magnification measurements into one hypothetical "15.5" magnification
group is warranted for discussion purposes.

Conversely, the predictive result of the Carlin formula is much more
sensitive to variations in the subjective estimate of NELM around the
area of observation. Taking the bottom 9/22/2003 reading in Table 5,
above, as an example, the NELM is 5.6, the faintest star seen is
v10.8 and the Carlin prediction is v11.1. Now if the variation in the
observer's subjective estimate of NELM is only +-0.3 magnitudes, then
the 9/22/2003 observation may actually lie at v10.5 or on Carlin's
predictive line at v11.1.

I generally recall that amateur observers using general star charts
can estimate ZLM accurately to within +-0.5 magnitudes. (Citation
omitted.) The +-0.5 variance in ZLM collection can be improved to
between +-0.1 to 0.3 using special purpose magnitude finder charts.
(While I have no doubt as an experienced observer that you can
estimate NELM accurately to 0.2-0.3 mags, your NELM sources were not
standardized and are not reproducible.) Two standard online sources
providing such charts a

McBeath, A. Visual limiting magnitude determination charts. J.British
Astr. Assoc. 101(4), 213-218 (1991)
available online through NASA ADS at:
http://adsabs.harvard.edu/cgi-bin/np...e1256dbbb04629

International Meteor Observer Association. 2003. Visual Meteor
Observations. (Web page).
http://www.imo.net/visual/ (accessed October 5, 2003) with
links to:

IMO Limiting magnitude areas
http://www.imo.net/visual/major01.html#table2

IMO Limiting magnitude tables for LM areas
http://www.imo.net/visual/lm.html

I prefer the IMO charts, as the IMO provides a total of thirty
estimating areas and their star counts are sufficient to estimate
magnitude in 10ths of "v".

(The IMO web server response is erratic. You may have to try
accessing it on more than one day to get a connection. I believe the
IMO homepage is physically located in Europe. A useful local astronomy
club project might to be mirror the IMO limiting magnitude tables on a
U.S. based server for better North American access. The American
Meteor Assoc. does not mirror the IMO limiting magnitude tables.
Personally, I grabbed an offline personal reference copy of the IMO LM
tables using MS-Internet Explorer's "save as web page - complete"
option.)

For the purpose of testing Carlin's formula on binoculars by
collecting NELM data in a 4 degree circle around the observation
cluster, variation in NELM can be minimized by choosing an
observation cluster (such as your selection of Brocchi's Cluster) that
is within or immediately adjacent to one of the areas defined in NELM
estimating charts provided by these two sources.

Figure 1 graphically represents a +-0.5 variation in the gathering of
NELM with high and low bars on each plotted observation point.

members.csolutions.net/fisherka/astronote/optics/Binocular limiting
magnitude CN obs.gif (created October 6, 2003)

The only way to resolve the statistical variation in subjective
estimatation of NELM is to collect a larger sample using standard
reference sources like McBeath or the IMO, i.e. - collecting between
16 and 30 observations spread throughout all sky brightnesses shown in
Figure 1 for one class of binoculars. Then you will have enough data
to make statistical inferences either accepting or rejecting the
Carlin formula as a working hypothesis.

My Figure 1 does not differ from the CN conclusion that "the actual
BLM very closely matches the [Carlin] formula prediction in the range
to just both sides of mag 5.2 NELM." Where my Figure 1 and this post
differs from the CN article's conclusion is about making any
extrapolations outside the area of useful observations collected
between v5.2 and v5.6, e.g. - CN's conclusion that "But the formula
prediction produces results too high (by 0.5) at mag 5.8 NELM and
equally to low at mag 4.4 NELM."

An insufficient number of useful observations have been reported to
date to make any interpretations outside the v5.2-v5.6 box of useful
Cloudy Nights observations.

My suggestions for improving amateur observation collection, in
particular by taking steps to minimize the variation inherent in
estimating visual limiting magnitudes, a

1) Collect a total of thirty observations in any one binocular class
before doing analysis and interpretation. Concentrate on a particular
binocular class until a recommended level of 30 total observations are
collected across all sky brightnesses.

2) Observations should be collected by a number of different observers
to prevent the effect of observer bias (and/or skill) in estimating
NELM from overwhelming other effects.

3) NELM should be estimated using charting areas in one of the two
reference sources listed above. This provides a commonly available
methodology for use by differing observers at different locations.
Alternatively, amateur prepared NELM charts should be published online
and first "vetted" by the amateur observing community.

4) A limited number of observations should be taken within 1 hour
after the first 1/2 hour reaching full dark-eye adaption to minimize
variations in the subjective appearance of sky brightness that can
occur after several hours of viewing with a dark adapted eye. This is
intended to minimize variations in NELM between different skill levels
of amateur observers.

5) The cluster selected of estimating binocular limiting magnitude
should be within or immediately adjacent to either a McBeath or IMO
visual limiting magnitude charting area.

6) The date, time, lat and lng of observations should be reported so
the observations of differing observers can be pooled and normalized
for atmospheric extinction effects. Reporting the local horizon
altitude of the observed cluster would be helpful.

7) Cluster magnitudes should be derived from a common online
available reference source, such as the easily accessed Webda open
cluster data site. http://obswww.unige.ch/webda/ (accessed
10/2003). This provides a common methodology for use by differing
observers at different locations. (I'll address using the Webda
online open cluster database to quickly generate telescopic limiting
magnitude charts in a separate post. Edz's reference to the chart for
Brocchi's Cluster from Covington qualifies.)

Item #5 is a tall order considering that the selected cluster, like
Brocchi's Cluster, needs to be adjacent to a McBeath or IMO charting,
has to have stars that are sufficiently spatially dispersed in
arcseconds to allow binocular viewing, and also must contain enough
stars dispersed across a magnitude range applicable to binocular
observation (e.g. v8.0-13.0).

Brocchi's Cluster is sufficiently close to the IMO visual limiting
magnitude chart area for Aquila to estimate NELM. While enjoying the
open cluster festival between Cepheus and Perseus this year, I made
some back of the napkin notes on potential clusters suitable of
binocular limiting magnitude tests. My rough notes list the following
candidates:

a) M52, the Salt and Pepper open cluster between Cep and Cas; IMO
Charting Area 7 in Cep is the closest charting area for estimating
NELM. I believe there is an online published chart of magnitudes for
M52, but have not tracked down the cite for the purposes of this post.

b) Caldwell 28 (NGC 752), a nearby open cluster of primarily OB
stars, that is near McBeath's beta Andromeda Chart No. 2 and IMO
Charting Area 18, for estimating visual limiting magnitude.

c) Stock 2, the Muscle Man Cluster, next to the Perseus
Double-Cluster; no nearby McBeath or IMO charts.

d) M34 (NGC1039), open cluster in Perseus; M34 is bracketed between
NELM charting areas IMO Chart 2 for eastern Perseus and IMO Chart 18
and McBeath Chart 2, both for And.

e) NGC1664, open cluster in Auriga that is within McBeath Chart 3
for alpha Auriga (Cappella) and is near IMO Charting Area 17, also for
alpha Auriga.

f) NGC1647, a large nearby OB open cluster in Taurus between alpha
Tau and beta Cap. It is near IMO Charting Area 8 for eastern Taurus.

g) NGC1746, a non-existent recovered object consisting of OB open
clusters NGC1750 and 1758, also between alpha Tau and beta Cap, and is
near IMO Charting Area 8.

But other than make a list of candidates, I have not evaluated or
charted any of these candidates in detail. I have not progressed as
far as your excellent effort.

Ed, you've done a lot of great work, for which you should be
commended. It's amazing how much it takes to collect 15 good data
poinsts. By discussing your article at some length and evaluting the
strenght of analysis, I do not intend to deter you from your great
efforts or the continuing development of the July and October threads
on binocular limiting magnitude in either light polluted or high
quality Bortle skies.

Regards - Kurt

References:

Carlin, N.O. 1997. Another interpretation of the data from Blackwell,
H.R. (1946): Contrast Thresholds of the Human Eye. (Web page).
http://w1.411.telia.com/~u41105032/visual/limiting.htm
(accessed July 2003)

Clark, Roger N. 1991. Appendix B entitled "Finding your limiting
magnitude". In Visual Astronomy of the Deep Sky. Cambridge
Univ. Press. (Compendium of magnitude charts of open clusters
suitable for telescopic, but not bincoular, limiting magnitude
testing.)

Phillips S. Harrington, Star Ware (2d ed. 1994) (John Wiley & Sons,
Inc.) republished at
http://www.stargazing.net/david/cons...manystars.html
accessed July 2003

International Meteor Observer Association. 2003. Visual Meteor
Observations. (Web page).
http://www.imo.net/visual/ (accessed October 5, 2003)

McBeath, A. Visual limiting magnitude determination charts. J.British
Astr. Assoc. 101(4), 213-218 (1991)
available online through NASA ADS at:
http://adsabs.harvard.edu/cgi-bin/np...e1256dbbb04629

Sidgwick, J.B. Amateur Astronomer's Handbook. (3rd ed. 1980 Dover)

Univ. of Lorraine. 2003. Webda Online Open Cluster Database.
http://obswww.unige.ch/webda/ (accessed 10/2003)

Zarenski, E. (Cloudy Nights, amatuer observer). 2003. Limiting
Magnitude in Binoculars.
http://www.cloudynights.com/articles/LM-binoculars.htm
(accessed October 2003)

(PrisNo6) wrote in message

Ed, you've done a lot of great work, for which you should be
commended. It's amazing how much it takes to collect 15 good data
poinsts.
Regards - Kurt


Your statement that only 15 good data points can be found from all the
set is completely invalid as it is based on grossly improper
assumptions.

Your monumental analysis that you painstakingly developed, based on
incorrect assumptions, without having asked any questions is not what
I would expect from anyone in the astronomy community.

You clearly go down a path to reduce the number of valid points
without ever asking any questions from the original author. You could
not possible have believed that's all there was. In fact, the data
reported in my article is only the maximum point for every
observation. The complete data set includes logged records from
somewhere between 600 and 800 stars from over 50 binocular/nights of
observations.

The whole basis for my observations was to report maximums and work
with my own data set to get there. In fact every observation for
which I reported a maximum has at least 30 to 50 data points leading
up to the maximum with as few as 2 or 3 but possibly as many as 7 or 8
data points clustered in a very tight range of 0.1 or 0.2 magnitudes
around the maximum for each binocular on each night. So in essence, I
could have reported possible 5 or 6 times on average as many points
for over 50 binocular/nights. But I elected to not publish my entire
data set. I elected to work with the results of my own data, since I
knew the essence of my own data.

You on the other hand elected not to ask, and in so doing you
developed a critical analysis without all the information and you
reached unfounded conclusions based on improper assumptions.

You probably could have fostered a good working relationship by asking
any number of very important questions that would have been critical
to your beginning assumptions you should have started out with.
Instead, you proceeded down a a very narrow path, without all the
information, without any benefit of first hand information, without
checking, and apparently without consideration.

I'm sorry, I don't appreciate one bit what you did here.

edz

(edz) wrote in message . com...

Tony, I must say you seem to be taking on the qualities of Quincy.
Any particular reason why.

Absolutely! I have three reasons.

First, this is a subject that interests me intensely. Actually, I don't
care all that much about binocular LM, but I hypothesize that telescopic
LM should track binocular LM quite closely, assuming identical exit pupils.

Second, your results w.r.t. correlation between NELM and instrumental LM
are wildly discordant with my own, and I am trying to figure out why.

Third, I hate to place theory above empirical data, but I find your
conclusion w.r.t. NELM vs. binocular LM absolutely impossible; it is
as much at odds with my notions of reason as (say) creationism.
Therefore, I am trying to poke holes in your observations in hopes
of rescuing my basic faith in science.

Why impossible? Well, I claim the following. Assuming:

1. Insignificant transmission losses, and
2. Insignificant optical aberrations, and
3. Identical fields of view, and
4. Identical modes, i.e. monocular vs. binocular
5. Identical effective pupils, i.e. the intersection of the
instrument's pupil and the eye's pupil
6. Identical sky conditions

then every 2.56 increase in aperture *must* yield a 1-mag increase in LM.
Why? Well, imagine a cluster of stars ranging from mag 4 - mag 9
placed at a certain distance, and you are observing it naked-eye.
You will get a certain LM. Now move that cluster 2.56 times as far and
observe it through an ideal 2.56x binocular with a very large aperture,
so that the effective exit pupil is determined entirely by your eye's
pupil and not at all by the aperture of the instrument. I claim that
the photons reaching your retina are *exactly* the same as in the
first case; the sky brightness will be identical, the actual star
magnitudes will be reduced by 2 mag, but the apparent star mags as
seen through the 2.56x binoculars will be exactly as in the first
case. Therefore, you will see precisely the same stars, yielding
a BLM 2 mag higher than the NELM.

Therefore, insofar as 1 mag increase in NELM does not yield 1 mag
increase in BLM, it must be due to a failure in one of the 6 conditions
that I listed above. But it is hard to imagine all of them together
adding up to such a whopping discrepancy as 1.5 mag vs. 0.5 mag.
Light loss and optical aberration in high-quality binoculars are
both very low. The reduced FOV of binoculars as compared to the
unlimited FOV of the naked eye may have an effect, but it is surely
small. This can, of course, be tested with the classic pair of
toilet-paper rolls. Binocular vs. monocular viewing may be an
issue with telescopic LM, but cannot be an issue with binocular LM.
That leaves only pupil. But can the difference between your 7mm
pupil and the binocular's 5mm pupil really cause such a vast
discrepancy? Hard to believe. I suppose that, too, could be
tested with 7x50 or 10x70 binoculars.

Note that if, as you describe for Schaefer, you increase the aperture
while holding the magnification constant, or increase the magnification
while holding the aperture constant, then you are changing the exit
pupil, and hence the background sky brightness, and then all bets
are off.

- Tony Flanders

(PrisNo6) wrote in message


Although it is important that you, unlike most other amateurs, made
the effort to collect observations, a sufficient number of
observations have not been collected to reject or accept, from a
statistical viewpoint,

HAVING TAKEN A BRIEF LOOK AT MY LOG I ESTIMATE THAT I HAVE RECORDED
OVER 1000 OBSERVATIONS. FROM MY REPORT, YOU COULD HAVE READ THAT I
RECORDED OVER 500 VALID OBSERVATIONS.


Boiling down the CN "Limiting Magnitude" article, 15 useful
observations were recorded, as listed in Table 1:


YOU CLEARLY DID NOT READ MY ENTIRE ARTICLE AND MISREPRESNT SOME VERY
IMPORTANT INFORMATION THAT I DID INCLUDE.

Table 3 lists 4 observations of "averted" limiting magnitude that were
not applied for the purpose of this discussion on the grounds of
consistency in data collection:

MY LOG INCLUDES WELL OVER 100 AVERTED OBSERVATIONS.

========================
Table 3 - Averted vision readings - Deferred in favor of direct
reading and where the averted reading is the lowest magnitude for that
scope on that night


As can be seen in Table 4, a cross-table summary of Table 1 above,
an insufficient number of observations has been made within each
binocular class to make any statistically valid conclusion rejecting
or accepting the Carlin formula as a predictive tool for amateur
binocular observers:

========================
Table 4 Count of NELM-Mag CN
observations by binocular class
and magnitude observation

Mag range
Bino 5-5.5 5.6-6 Total
10x50 1 0 1
12x50 2 2
15x70 3 2 5
16x60 2 2
16x70 2 2 4
08x42 1 1
Total 5 10 15
For example, only 1 useful reading was taken in the 8x42 and 10x50
classes; 2 in the 12x50 class; 2 in the 16x60. As discussed in the
remainder of this post, the remaining observations regarding 70mm
aperature binoculars are also of insufficient number to warrant
reaching any firm conclusions at this time, although the data
collected is as good start.

YOU ATTEMPTED TO WRITE YOUR OWN TECHNICAL ANALYSIS FROM MY WRITTEN
DESCRIPTIONS OF ONLY A SELECTION OF MY OBSERVING NIGHTS. IN REALITY I
HAVE ANYWHERE FROM 50 TO 100 OBSERVATIONS RECORDED FOR EVERY ONE OF
THESE 1'S AND 2'S YOU SHOW ABOVE.

YOU SHOULD HAVE KNOWN BETTER THAT I COULD NOT HAVE WRITTEN A COMPLETE
ANALYSIS SUCH AS I DID BASED ON A PALTRY FEW DATA POINTS.

What you did was take someone else's summary report data and
misrepresent it and manipulate it to try to make a defensive stand.

In my opinion you owe the astronomy community an apology.

edz

(PrisNo6) wrote in message


I generally recall that amateur observers using general star charts
can estimate ZLM accurately to within +-0.5 magnitudes. (Citation
omitted.) The +-0.5 variance in ZLM collection can be improved to
between +-0.1 to 0.3 using special purpose magnitude finder charts.
(While I have no doubt as an experienced observer that you can
estimate NELM accurately to 0.2-0.3 mags, your NELM sources were not
standardized and are not reproducible.) Two standard online sources
providing such charts a

I took great pains to develop NELM charts with all points in small
localized areas so estimates were more consistent. Charts that have
the eyes roving over very large wide areas performing star counts
leave the user open to far too much error. All my NELM charts are not
only reproducable, but are readily avaiulable, if you want to take the
time and effort to discover.

An insufficient number of useful observations have been reported to
date to make any interpretations outside the v5.2-v5.6 box of useful
Cloudy Nights observations.

You have absolutely no idea how many useful observations were made as
this is not your data and I suspect you know this is a false
statement.

3) NELM should be estimated using charting areas in one of the two
reference sources listed above. This provides a commonly available
methodology for use by differing observers at different locations.
Alternatively, amateur prepared NELM charts should be published online
and first "vetted" by the amateur observing community.

Not only did I inform the reading community what I used but the
constellations and asterisms and charts I used are commonly available
to the entire astronomical community.


5) The cluster selected of estimating binocular limiting magnitude
should be within or immediately adjacent to either a McBeath or IMO
visual limiting magnitude charting area.

Not only did I ALWAYS attempt a reading exactly within my observation
area, or exactly adjacent to it, but I also made valiant attempts to
verify in duplicity all my observations.

Edz's reference to the chart for
Brocchi's Cluster from Covington qualifies.)

As it turns out. if you read my article you would have known the
Covington Cr399 chart was inadequate to perform the task and I went
much further beyond that.

some back of the napkin notes on potential clusters suitable of
binocular limiting magnitude tests. My rough notes list the following
candidates:

None of these are useful until someone takes the extra effort to
verify and label the magnitudes of all the stars in the cluster and
publish the information for others. I have no doubt you will run into
all the same discrepencies I did, that publish magnitudes from
different sources vary by so much as to be in some cases usless.

Ed, you've done a lot of great work, for which you should be
commended. It's amazing how much it takes to collect 15 good data
poinsts.

By discussing your article at some length and evaluting the
strenght of analysis,

I can assure you I will not be discussing my article witrh YOU!

The more I read the way you *******ized my data, the more I am
infuriated. I do not want your personal commendation.

I believe you have manipulated my data for your own purposes and in
doing so have done a great dis-service to the community.

I believe you should retract what you have written.

edz

========================
Table 5 - Extracted CN observations
for 15x70 and 16x70 class N=9

Date NELM Bino Star Mag Carlin predicted
09/12/2003 5.0 15x70 S10 10.1 10.5
09/21/2003 5.1 15x70 E10 10.5 10.6
08/19/2003 5.2 15x70 E3 10.3 10.7
09/16/2003 5.6 15x70 E6 10.4 11.1
09/22/2003 5.6 15x70 E12 10.8 11.1
09/12/2003 5.0 16x70 No rpt 10.3 10.5
08/19/2003 5.2 16x70 E3 10.3 10.7
09/16/2003 5.6 16x70 E12 10.8 11.1
09/22/2003 5.6 16x70 S20 10.8 11.1
===================================

Graphically, Table 5 is shown in Figure 1, posted at my personal web
site:

http://members.csolutions.net/fisher...ude_CN_obs.gif


I DEMAND THAT YOU TAKE ANY REFERNCE USE OF MY DATA OFF OF YOUR
PERSONAL WEBSITE IMMEDIATELY.

ED ZARENSKI

(edz) wrote in message . com...
(PrisNo6) wrote in message
Your statement that only 15 good data points can be found from all the
set is completely invalid as it is based on grossly improper
assumptions. big snip
You probably could have fostered a good working relationship by asking
any number of very important questions that would have been critical
to your beginning assumptions you should have started out with.
edz

Ed,

I genuinely apologize for offending you. That was not the intent.
Your call on me for not asking first is legitimate for which again I
apologize.

Nonetheless, although you do mention taking 500 observations toward
the end of the article, in your data reporting section, nowhere do you
say that each report is an aggregation of some 20-30 individual
readings, where an individual reading of NELM, a binocular, and an
observation of a limiting magnitude star are paired. You may wish to
revise your article to clarify that point for general readers.

After reviewing your supplemental October 6 post providing further
data on September 25 observations and more detail on NELM was
collected and recorded, my own take is that your NELM data may be
overwhelmed by recording variations.

Since the Carlin formula is most sensitive to the NELM variable (as
explained in my prior post), your interpretation of your results may
be overwhelmed by that variation and may not provide a basis of
accepting or rejecting the Carlin formula as a working hypothesis.

You have elected to not publish the full underlying data set of 500
observations, or the charts you used to identify NELM in a 4 degree
field around the target cluster. That's fine, but until then I do not
have confidence in your conclusions, which remain a commendable and
herculean effort.

It sounds like you reside in the same community as Tony Flanders and
perhaps other expert level amateur astronomers that participate in
this newsgroup. Perhaps you could give them a confidential peak at
the underlying data to resolve the concerns raised by me and others in
this thread?

With respect and clear skies to you - Kurt

Ed,

I can assure you I will not be discussing my article witrh YOU!

You are over-reacting to some well-intended criticism. I enjoyed reading your clarification of the steps you took to limit variation
in the collection of NELM measurements, which was the thrust of your response post. Nonetheless, I bear you no ill will. Per your
request I will add to you my blocked senders list and will cease to communicate with you. I will however continue to participate in
binocular limiting magnitude threads.

To other lurkers, I apologize that these last few messages have broken down into an inappropriate flame. This is an interesting
area of amateur astronomy and I hope you will all continue to be interested in it and work on it. I will ramp back to lurker
status, not in response to Ed's intimidating style, but so that flame conflict in this thread can take a proper back seat to
discussion of the facts.

Ed's study is one of hopefully several amateur efforts. At the end of my last post to Ed, the list of candidate cluster targets,
NELM charting areas and a suggested approach may be of use as a starting point for anyone else interested in performing a study
similar to that conducted by Ed. Further amateur studies will continue to provide confirmation and insight into this area.

I believe you have manipulated my data for your own purposes and in
doing so have done a great dis-service to the community.
I believe you should retract what you have written.

Ed, I read your article several times before responding. I think I gave the "Assessing and recording NELM" section a fair read. To
my knowledge, I have no hidden agenda that you describe. To some extent, you claim of data misuse has to be laid back to ambiguity
in way you wrote the "Assessing and recording NELM" section. But that's the advantage of internet distribution. Hopefully, such
things can be weeded out early and corrected, whether the miscommunication is on the sending or receiving side. I do not believe
that my well-intended efforts are a disservice to the amateur astronomy community. Amateur science by flame intimidation is.

As far an apology for any perceived personal offense to you, you have it. As far an apology to the community as a whole, what I did
is not so far out of bounds that it deserves your over-reacting flame style. Therefore, I decline to retract my prior post as an
offense to the usenet community or as a supposed abuse of data in your article.

The thrust and underlying comment in my reply remains sound: Reducing variation when collecting NELM is key to deciding whether
Carlin's formula can be rejected as a working hypothesis. Excessive variation in NELM can break down any perceived relationship or
lack of relationship between Carlin's formula and the collected observations.

In response to my concern that your NELM readings might have a level of variation in them that would prevent accepting or rejecting
the Carlin formale as a working hypothesis, I appreciate reading your continuing clarifications of your article.

All my NELM charts are not only reproducable, but are readily available,
if you want to take the time and effort to discover.

I did take the time to look at your site prior to posting for the wide-area NELM charts you described and did not locate them. If
you can post a page link, I would like to have a look at them. I'm sure many people in this usenet group would appreciate adding it
to their observing kits.

Again, Ed, per your request, I will add you to my blocked senders list and cease to communicate with you.

Peace. Regards. Clear skies. - Kurt

"edz" wrote in message om...
(PrisNo6) wrote in message
snip

Ed, Per your request the file that is causing you so much disconcernation has been removed from my personal web site.

Be well - Kurt

"edz" wrote in message . com...
snip

http://members.csolutions.net/fisher...ude_CN_obs.gif


I DEMAND THAT YOU TAKE ANY REFERNCE USE OF MY DATA OFF OF YOUR
PERSONAL WEBSITE IMMEDIATELY.

ED ZARENSKI

Kurt (PrisNo6) grossly misrepresented my work, I've made that clear
above. This is how I feel about it.
His Method
Reworking my technical approach into a 400 line technical work of his
own. Discrediting my work with a grossly misrepresentative analysis
without ever asking a single question or requesting a single
clarification.
His Approach
He blindly analyzed my written work without full acknowledgement of
detail available. He selectively misrepresented data while obviously
overlooking pertinent facts provided in the original work.
His Argument
Not enough clarification in my source work to prevent him from making
all the wrong assumptions and improper misrepresentations he made, so
it's not his fault, it's my fault he misrepresented my work.
His Response
A defense behind supposed ambiguity. After the fact request for
clarifications. Continued claim of his valid approach while
continuing claims of supposed ambiguity in my data. Accusing me of
causing a flame war after so grossly misrepresenting my work.
Apologizing to the community for my outrage towards him.

How do you like that, I get totally misrepresented by someone with an
apparent motive to defend his own work, and by exposing his gross
misrepresentation of my work, I get accused of flaming. Of course, we
are to believe that what he did was just fine! Sounds almost like my
two teenagers defending their lack of wisdom in making inappropriately
wrong decisions in life, but not being able to admit they did anything
wrong. Do you want someone like this posting apparently informed
technical responses to your work? I don't.

I can take criticism. I can't take deceit or misrepresentation,
whether knowingly intended or not.

PrisNo6, if you thought you would be allowed to perpetrate such a
grossly wrong action and have it appear clearly thought out,
surrounded by professional reference, technically presented and
without question accurately critical, you are wrong. I am without
respect for your actions. In the corporate world, people lose their
jobs for what you did.

edz