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Call for Participants in Binocular Study of M45

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#1 EdZ

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Posted 05 December 2003 - 02:23 PM

CALL FOR PARTICIPATION IN STUDY
Testing for Limiting Magnitude in Binoculars
------------------------------------------------
Update 3-21-04
The newest M45 primary observing chart has been added to my gallery. All numbers are the same as previous. More have been added. I link to it here
M45 LM Observing Chart updated 2-24-04
PRINTING ADVICE - click on save photo, save to your My pictures directory. Open your pictures directory, click on file to open file, click print to run photo printing wizard.


Update 2-26-04
Although not posted here, I have significantly added to the observation charts. I've been out a dozen times with 20x80s and with Oberwerk BT100 at various magnifications from 24x to 50x. There are still sufficient targets to handle that magnification, but the variety in the range of mag11.2 to mag11.8 was a little lite. I've added maybe 30 targets in the mag10.5 to mag12 range.

I still have not exceeded mag12 with any binocular or scope up to 5"SCT at 96x and TV85 at 120x, but with the BT100 I have seen mag11.2 to 11.5 at 24x to 31x and at 36x to 50x I've seen mag11.7-11.9.

Contact me if you need a deeper chart for very big binocs. There is plenty here for all kinds of smaller binocs. You can see what to expect from smaller binocs by looking at this summary here.

M45 Star Counts / Limiting Mag various binos


Updated 1-2-04
I have revised the Observation Chart. It now includes targets to mag 12.0. This should accomodate even the largest binoculars in use up to mag 6 skies.

There are now three different versions of the observing chart. The complete chart has all stars labeled. The data table listing the magnitudes has a value for every star labeled on this chart. There are two other charts. One has only stars from mag 10.0 up to mag 12.0.

The third chart, useful only for the BIG binoculars, has labels only for the stars from mag 10.9 to 12.0. The Fujinon 16x70s, my best performers, in mag 5.6 skies can see only 2 or 3 stars from this group. Like I said it's really for BIG binocs.

I have posted the Table of Magnitudes. It lists the magnitude for every star labeled on the charts. Again I will say, it is not necessary to know the magnitudes prior to observing. However, I'm sure you would like to know what your results are.

The Naked Eye Limiting Magnitude charts have been slightly modified to include a few more stars identified. You can now verify NELM from about mag 3 up to mag 6.35. If you have skies better than mag 6.0 and need additional info, contact me, I will expand the charts.

Thanks edz 1-2-04
---------------------------------------------------------


WHY?
In order to gather additional study data for a Binocular Limiting Magnitude article, I am requesting participation and input from members of the binocular astronomy community.

Recently I prepared a comprehensive study used to determine the Limiting Magnitude of various binoculars. This new study is to see if the original results can be duplicated. The results of the original effort can be found on CN Articles and Reviews as a Lab report at
Limiting Magnitude in Binoculars - Technical Lab report

One of the greatest requirements of a study such as this is the need for a tremendous amount of data points. The study noted above includes the results of close to 800-1000 observations. In order to complete a similar study, it will be necessary to compile data sets for many different binoculars on different nights of seeing conditions. Data is particularly needed for 80mm, 100mm and 120mm binoculars and for all sizes of binoculars at sites with skies ranging from mag 3 to mag 7.

HOW MUCH INFO IS NEEDED?
Consider the effort required to determine the limiting magnitude for one binocular on one night with one set of observations might require recording at least 50-100 stars. From those 50-100 points, only a handful, maybe the faintest 5 or 10, will fall into the upper tier of observations recorded and you can see how quickly the effort grows to get the data needed. Of course, you could attempt to skip right to the significant points and just make 10 observations, but unless you have an intimate knowledge of the targets and can immediately find your way to the most difficult targets, that is not likely to succeed. Several hundred resultant data points in the upper 10% will be needed.

HOW IS IT CONTROLLED?
Consistency of data points is a prerequisite. That is the purpose of developing a chart such as the charts you see attached here. These are charts of the area surrounding M45, The Pleiades. It is broken down into 6 distinct sections. Each section contains a variety of star magnitudes. One copy of the chart shows symbols indicating general magnitude groups. The other copy shows all the same stars numbered. Areas within the sections of the charts have light figure lines drawn in to help orient within the section. Sections are labeled clockwise A, B, C, D, E and F.

HOW CAN EVERYONE DO IT THE SAME WAY?
When observing, I use the numbered chart to circle the stars I see.

The targets were chosen after several preliminary observations in mag 5.2 & 5.4 skies using various 50mm-70mm binoculars to record the maximum that could be seen in each area. The preliminary observations show 90-100 stars observed with 10x50s and 12x50s, while 135-145 stars were observed with 16x60s, 15x70s and 16x70s.

ARE THERE TARGETS TO SUIT EVERYONE?
I used low power (30x-40x) 78mm, 85mm and 125mm scope observations in the same mag 5.2 & 5.4 skies to supplement the binocular observations. This provides for targets just beyond the binocular limits I reached in mag 5.4 skies, targets that might be seen under excellent dark skies, and will provide targets for larger binoculars. A 125mm scope at 40x shows 260 stars within the outlined boundaries. These charts include a selection of the brightest mag 10.5+stars that were observed with the scopes but not yet seen in preliminary observations with binoculars.

HOW DO YOU KNOW THIS CHART SHOWS ENOUGH?
A 5 inch(125mm) SCT scope with a 30mm Ultima at 45x could just barely make out mag 11.2-11.3 stars, none higher. The 125mm scope did not see mag 11.9 or 12.0 stars until magnification was increased to about 100x. With the 5 inch, a 12.0 mag star was not seen with a 26mm Meade SP at 50x. It was momentarily glimpsed using 18mm UO ortho at 75x and was seen steady using 12.5 mm UO ortho at 110x. The increase in magnification needed to see a mag 12.0 star gives a very good indication of what it would take to see a mag 12.0 star in binoculars. This would lead me to expect that no one will be able to observe mag12 stars even with large 100mm-120mm binoculars unless possibly viewing under pristine skies.

A TV85 did not see mag 11.3 at 40x but it could be seen at 100x. The TV85 did not see mag 11.9 or 12.0 even at 100x.

Mag 11.0 stars were first seen in a 78mm scope at 40x. A mag 11.4 star was not seen in 78mm at 40x but was barely seen at 65x.

Assuming a 20% gain for two-eyed vs. one-eyed viewing, a 78mm aperture is approximately equivalent to a 70mm binocular and the 85mm scope is approximate to a 77mm binocular. The 125mm SCT has the equivalent light gathering (due to c.o.) of 115mm aperture, approximately equal to a 105mm binocular.

WHAT NEEDS TO BE DONE?
The labeled chart has about 180 numbered targets. There is probably sufficient variety in each section to observe just one section if the whole chart effort seems too overwhelming. After several attempts, observations of the entire chart can be accomplished and recorded in about 20-30 minutes, depending on the observer. It is not necessary to know the exact magnitude of the targets observed. This information will soon be developed and a magnitude table with all the star number designations will be published. This will help eliminate any potential picking of the next highest data point.

EVERYBODY"S SKIES ARE DIFFERENT.
The Pleiades is a good object to use for recording the NELM. Furthermore, the best reading for NELM to use in a study such as this is one taken exactly in the target area. Another close-by area for recording NELM is the V of Taurus. Both of these NELM targets provide for a variety of stars ranging from bright to 6th magnitude. Expect to spend several minutes of effort to record a NELM of 6th mag. many sources including Burnham's Celestial handbooks have decent magnitude data for determining NELM in these two areas. Without an accurate reading of the NELM, the binocular observations cannot be used in the study. NELM charts provided upon request.

HOW CAN DATA FROM ALL OVER BE COMPARED?
If you choose to participate in this effort, the requirements are simple.
Record the date and time of the observations and the instrument used.
Record seeing conditions and Naked Eye Limiting Magnitude to 1/10th mag.
Record the target starss seen at the time of the observations, not afterwards.
Observed stars can be written down by numerical designation, i.e. A1, A23 or can be marked with an x on a clean chart. Print as many charts as needed.
Observations can be glimpsed but must be definite, not suspected.
It is helpful to use at least two binoculars on a given night.
Verify NELM again at the end of the observing session.
Completed written data observations can be emailed. Marked charts can be scanned and emailed. Hard copies of marked-up charts can be snail mailed. Include name or initials.
Contact me by PM for address.

The data gathering and analysis will be conducted over a period of several months. Results will be published similar to the format of the article referenced above. If you have any questions about how the data will be compiled, analyzed and presented, please refer to the original article noted above. Volunteer participants will be acknowledged.

Original M45 chart published in Astrophotography for the Amateur, 1999, Cambridge University Press, Covington. Permission was obtained from the author to use this chart.

Thank you
Ed Zarenski
edz












#2 EdZ

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Posted 10 December 2003 - 10:56 AM

This is the same chart as shown above, but without all the numbers or symbols. It's nice and unclutered and helps to see the figures. The numbered chart should be used for recording observations. edz

Attached Thumbnails

  • 27278-M45 Covington lines clean.jpg


#3 EdZ

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Posted 02 January 2004 - 10:02 AM

This chart should have sufficient stars labeled for you to determine the Naked Eye Limiting Magnitude. This value is important. Without it, the observation data cannot be entered into a database for plotting results. If your NELM is between 3-4.5, the leg of Perseus is very close and has a few stars from 3 to 6.
Also, the main stars of the Pleiades have stars in that range.
edz

The chart has been updated recently to make it more clear to read. This chart is a composite cut and pasted together from various pages of Wil Tirion's Sky Atlas 2000.0 Deluxe. Magnitude data added from various sources. edz

update 3-21-04 the chart has been added to my gallery here
M45 NELM Hyades Chart with magnitudes labeled.
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#4 EdZ

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Posted 02 January 2004 - 10:08 AM

Updated 4-9-04
About 20-30 stars have been verified by observation and the entire list has been checked to the Tycho II database.


Update 3-21-04
the list of magnituges now reflects all the new fainter stars added to the chart. In addition several stars with integrated magnitudes have been identified and corrected. This table is updated to the 2-24-04 chart. Click on the word 'attachment' above.

thanks edz

The following Table of Magnitudes lists the magnitude for every star labeled on the chart. This is still in draft form. There are many discrepiencies found in published data. I have referenced at least 4 sources and in some cases have found 4 different magnitudes published for a given star. Where variances occur, I have attempted to verify by direct observation.

It is important that participants use the observing charts and mark up charts or list observed stars by their chart number. If you were to provide me with results in a memo that states you were able to see stars of mag 10.5 without showing me which stars you observed, and then I revise magnitudes of stars listed in the table, it would invalidate your observations. If you use the numbered charts provided, I just load the observation data into a datbase and it will look up the correct revised magnitudes.

edz

Attached Files



#5 EdZ

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Posted 02 January 2004 - 10:23 AM

This chart is for those of you with really BIG binoculars. Same chart as before, same data table, same magnitude list, but I have eliminated all the numbers except for those stars mag 10.9 to mag 12.0. As a reference point, so far under my best skies (mag5.6), my Fujinon 16x70s can only see 2-3 stars labeled on this chart. That would be insufficient information to be useful observations for the 16x70. I suspect this chart should meet the needs of maybe 20x80 owners and definitely 22x100 and 25x??? owners.

edz

Attached Thumbnails

  • 35025-M45 Covington numbered mag109+.jpg


#6 EdZ

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Posted 26 February 2004 - 10:53 AM

Anyone that has taken the time to participate in this study.

Please, if you have completed any observation forms that you wish to submit for the study, contact me by PM and I will send you my mailing address. If you would like a copy of your sheet but do not have the means to make copies let me know and I will return your sheet after I make a copy of it.

Remember forms need only show the observed stars circled but must also have a record of the Naked Eye Limiting Magnitude at the time of the observations and the instrument. Other useful information would be date, time, name or initials and experience level. I'm looking for as broad a range of conditions and intruments as I can possibly get.

To date I have recorded
over 40 observation sheets totaling over 4000 stars
with 10 different instruments
at 20 different combinations of aperture/magnification
in 7 different NELM sky conditions.

I'd like to double those numbers, but I need your help.

To that I can add 20 observations (about a 1000 targets) from my previous study.

Keep in mind, this sounds like way to much data, but only the top maybe 5 to 10 points of every session is what gets used. In addition to plotting the maximum, I am planning to develop a scatter diagram of the top 5 to 10 points from each of recorded sightings. This will help eliminate variances due to several factors; star color variances, inconsistencies in concentration on different sections of the map, tired eyes, successful employment of averted vision, to name a few.

Thanks for your participation.
Let's get those sheets in!

edz




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