The Official Publication of the Bucks-Mont Astronomical Association, Inc
© 2000 BMAA, Inc
GO FOR IT!
- by Alan Pasicznyk
It was back in 1989 while attending a star party that I first heard BMAA member Ed Radomski remark that he only had a few more Messier objects to observe and record in order to complete the entire list. I had just purchased a Celestron C 4.5 and was busy blitzing through the night sky and his comment hit me rather oddly. "That's like going to the zoo and visiting all the animals alphabetically", I mused," starting with aardvark and ending with zebra". There is just too much to see, too much fun to be had without embarking on such an arduous task. But fortunately for me, I had begun keeping a notebook with the purchase of my new telescope.
In not too long a time I began to accumulate about 40 of those so called "Messier objects" as observations in my notebook, and realized that I was more than halfway to obtaining the Regular Messier Certificate for observing 70 of the objects. I really wasn't sure how far I could go with a 4 1/2 inch Newtonian, but finally to my own amazement I was able to observe all "110" (More on that number later).
It is in that spirit, that I later came up with the idea of the BMAA issuing a certificate of its own, in order to promote deep-sky observing among our own members.
It is a simple idea that goes like this: Observe and record any 35 Messier objects according to the rules set up by the Astronomical League for Messier objects, and receive a BMAA "Halfway" certificate, acknowledging that you are half way to observing the 70 needed to get an A.L. Regular Messier Certificate. An example copy of the BMAA certificate is shown below:
The rules of the A.L. are also quite simple... Each Messier object to be counted must be independently located, observed, and recorded with the following data:
- Date of observation
- Night sky observing conditions
- Aperture of instrument used
- Power used
- A short note describing what the object looked like
The Astronomical League rules also state:
"Since the purpose of the Messier Club is to familiarize the observer with the nature and location of objects in the sky, the use of an automated telescope which finds the objects without effort on the part of the observer is not acceptable. Also "marathon" sessions where all the objects are found in one occasion is to be discouraged by beginners depending on other experienced observers to find the objects".
Personally I think that star-hopping is the most rewarding way to find the objects, and that is how I found, as well as sketched all 110, although setting circles are allowed according to the A.L. rules. Digital setting circles which use encoders, however, are not allowed.
The observation notes are then to be reviewed by a BMAA club officer for accuracy and completeness. Thus following all A.L. rules enables those 35 objects to be counted toward the 70 required for receiving a Regular Messier Certificate and later possibly even an Honorary Messier Certificate for completion of observing all of the objects.
I should mention here that these objects do not have to be observed only with a telescope, binoculars are also acceptable, although you will eventually have to resort to a telescope to "catch 'em all". (Unless you have 4" aperture binoculars!).
And now a word about those "110" objects...
The year was 1758 and Newtonian Mechanics made it possible to calculate the positions of planets and comets. Halley had predicted his comet would return, and a French astronomer by the name of Charles Messier hoped to be the first to reacquire the comet observationally. Unfortunately, it was first seen by a farmer named Palitzsch in Saxony. With that, Messier began to search for any new comet, and began making a list of "deep sky fuzzies" that were not comets so that he would not at a later time mistake them for real comets. Messier did discover a good deal of new comets (about 21 by most accounts), and was referred to as the "ferret of comets" by Louis XV. It is therefore with great irony that he is presently remembered from his list of "things which are not to be looked at as being comets".
Being human, Charles Messier did not keep perfect astronomical notes. Positions of several objects were mislabeled, a double star was originally seen as nebulous (M 40), and several objects were discovered by his contemporary Pierre Mechain. In addition, modern day astronomers have nicknamed NGC 205 near the Andromeda Galaxy as "M 110". M 102 is an accidental repetition of M 101, and NGC 5866 has been substituted as being M 102. M 91 is unexplained, but there is evidence that Messier was looking at NGC 4548.
So if M 110, M 102, M 91, and M 40 are thrown out, a purist would say that there are only 106 Messier objects. But what about those discovered by Pierre Mechain? When I went for my Honorary certificate, I did "all 110", just to be sure. But for the BMAA certificate you only need 35 anyway so don't sweat it!
ANYWAY, all you have to do is make 10 copies of the form enclosed in this newsletter. Fasten them together with a staple, and you're all set. Then label the "M" numbers from 1 to 110 and fill in the blanks as you observe. I have included two of my own observations as an example of what kind of information you might record. Good luck, Happy hunting, and Clear skies!
M45 Date: March 13 1990 Time: 9:00P EST
Power: 36X Seeing: Fair Type Instrument: 4.5 Inch F8 Newtonian
Notes: The naked eye dipper shape is lost at 36X, six stars near Alcyone resemble a small suspension bridge.
M108 Date: March 16 1991 Time: 10:30P EST
Power: 28X Seeing: Very Good Type Instrument: 4.5 Inch F8 Newtonian
Notes: A barely detectable, highly elongated patch of light. Seen with averted vision only.
* * * * * * *
- BMAA member Alan Pasicznyk chairs 'Transient Phenomena' and contributes articles often. [ -ed]
2001 MEMBERSHIP DUES ARE DUE NOW!
Astronomy 101 is an informal Q & A session before each General Meeting at 7:30p,
December 6: A partial solar eclipse for Christmas (Linda van der Spek)
The next BMAA General Meeting is scheduled for Wednesday, December 6 at 8:00p
BMAA MESSAGELINE - 215/579-9973
BMAA WEB SITE: bmaa.freeyellow.com/
Bucks-Mont Astronomical Association
2000 Calendar Of Events
The CONSTELLATION is the official publication of the Bucks-Mont Astronomical Association, Inc, a 501(c)3 non-profit organization incorporated in the Commonwealth of Pennsylvania and exists for the exchange of ideas, news, information and publicity among the BMAA membership, as well as the amateur astronomy community at large. The views expressed are not necessarily those of BMAA, but of the contributors and are edited to fit within the format and confines of the publication. Unsolicited articles relevant to astronomy are welcomed and may be submitted to the Editor.
Reprints of articles, or complete issues of the CONSTELLATION, are available by contacting the Editor at the address listed below, and portions may be reproduced without permission, provided explicit acknowledgement is made and a copy of that publication is sent to the Editor. The contents of this publication, and its format (published hard copy or electronic) are copyright © 2000 BMAA, Inc.
In an effort to transmit the CONSTELLATION electronically to the membership of BMAA, please provide a current e-dress to the Editor. Abbreviated issues are available on the web site, but complete editions will be e-mailed to members in good standing.
Submission deadline for articles is the 15th of the month prior to publication.
photographed at SDV-XIV
11" Celestron at f-6,
60 min. exp on Fuji Press 800 film.
- photo by Bruce Collier
At the November meeting, the club had a membership quorum and elected the officers for the year 2001 as follows:
President - Ed Murray, 215/493-2843 firstname.lastname@example.org
Vice President - Antoine Pharamond, 215/412-9291 email@example.com
Treasurer - Ed Radomski, 215/822-8312 firstname.lastname@example.org
Secretary - Ken Wieland, 215/362-7228 email@example.com
Continuing the Messier Objects - Starting Again
- by Bernie Kosher
Last month we talked about starting at the beginning, with the old stand-bys, the Messier objects. Abbreviated 'M___', these number up to 110. Yeah, I know I said I only accept the first 103, but wiser heads prevailed and convinced me to include notes on all 110 currently accepted objects.
Some background info on this extraordinary individual seems appropriate.
Charles Messier was a Frenchman, employed as a clerk-assistant to Nicholas DeLisle, the titular 'Astronomer of the Navy.' His observing was limited, at first, to scanning the stars as a semi official duty. Born June 26th, 1730, the 10th of 12 children in Badonviller in Lorraine. He left his home to seek a career in Paris at the age of 21.
Messier's neat handwriting and drafting abilities led DeLisle to offer employment to the young country boy. His original tasks at DeLisle's observatory in the Hotel de Cluny involved copying maps and transcribing documents. He later was assigned to keeping the observatory's records, more in keeping with his interest in the heavens. After being moved up to a full clerking position, he was given observing time, and became 'fanatical' about comets.
Of prime interest at the time was the predicted return of Halley's comet. Edmund Halley had been the first to announce that comets traveled in closed orbits, and predicted the return of this comet as he suspected that it was the same one seen at intervals over the years. His prediction of a 76 year orbit, so easily calculated today, was revolutionary at the time. The world had just gotten around to accepting a sun-centered solar system after all.
Anyhow, credit for the comet recovery on Christmas night, 1758 is given to Palitzch. He visually spotted a fuzzy glow at the limit of naked eye vision while returning from a neighborhood party. News of the discovery and confirmation did not reach Paris for months.
Meanwhile, dear old Messier had been searching an area of the sky assigned by DeLisle from his own calculations. He found a faint glow on Jan. 21st, 1759 which later proved to be the comet. In Messier's own words, 'I would have discovered the comet two months earlier, when the comet was further from the sun, if the area assigned me had not been so limited'. Apparently, DeLisle was a bit of weenie, his arrogance in believing in his own calculations and limiting the search to only those specific areas of the sky loosing him the acclaim which comet discoveries invoked at the time.
Messier also did daylight observations of sunspots, along with meteorological work. He was finally elected to the Paris Royal Academy of Science after many ballots. It seems they were reluctant to give this distinction to a mere observer.
Messier was called the "Ferret of comets". At the time, he was in competition, albeit friendly, with a fellow Frenchman named Pierre Mechain. Between them they owned cometary discovery at the time. Many of Messier's objects were actually discovered by Mechain, and the information was freely exchanged between them.
I have heard and read that Messier composed his list of objects as they were a mere annoyance to a comet hunter. His list supposedly helped him avoid mistaking the objects for comets. I think this is horse hockey. In light of his lifelong commitment to observing and the diligence he paid to his duties, I think they were just as attractive to him as they are to us. His drawings of the locations of these objects are true works of art. Being hand drawn in the most intricate detail, they immediately impress the viewer with his pride and ability.
Admittedly, his own words tell us he started the list to identify the objects as permanent fixtures and not comets. But he continued to add to his original 45 objects for the rest of his life. He lived to the ripe old age of 87, although he had gone into a sort of retirement two years earlier.
Among his achievements in cometary discoveries, either independently or shared, are 16 unequivocal finds. Some lists claim up to 27, and some 36, though these are clouded by who actually was the first and deserved the credit.
The M objects are of the following types.... not known at the time of Messier who described his objects as cometary or some such similar title.... Gaseous or diffuse nebula 7 Galactic clusters 27 Globular clusters 29 Planetary nebula 4 Galaxies 33 Supernova remnant 1 Asterisms 2
I know this doesn't add up to 110. I'm not sure why.
William Herschel, perhaps the most famous observer of all time, listed the thousands of objects he located with his 24 and 48 inch telescopes. Out of respect for Messier, he did not give his own listings to M objects. The NGC of Dreyer does give their designation for M objects.
This is getting to be a long article. More in the future.
* * * * * * *
- BMAA member Bernie Kosher provides the monthly 'Tips' column. He can be reached at firstname.lastname@example.org. [ -ed]
Knife Edge Testing at the Focus: Looking Past the Turbulence
- by John C Deitz
Figure one diagrammatically reminds us how the knife edge principle works. Here the knife is outside the best focus (least confusion) and casts a shadow where rays are blocked (from the LEFT part of the primary). This is the situation when the knife is introduced from the right and is located outside the focus. Study the drawing and imagine what will happen if the knife edge is closer to focus and introduced from the right. If the knife edge is at the best focus it is easy to see that the field of view will darken quickly and evenly.
If the wavefront is advanced or retarded for part of the diameter of the primary a situation like Figure two will result. Here the knife cuts all of the rays from one part of the objective while others are only partly dimmed. In the last issue of CONSTELLATION we considered what happens when different temperature air masses disturbed the wavefront. However, if the knife-edge is carefully placed at the best focus (by trial and error) the careful observer may be able to detect those aberrations of the wavefront that are the result of defects of the optical system. On most nights these will be hard to see, but are easily detected when the atmosphere settles.
We started this exploration of knife-edge testing with a look at disturbances introduced by the atmosphere. This was the right place to start in that tube problems can often be controlled, while the defects of the optical system are harder to do something about. Also, the disturbances from the atmosphere are often much greater than those of the optical system! Nevertheless, such testing will open the observer to greater understanding of optical performance. Return to the use of the knife-edge on a frequent basis as you will find some changes over time. Some of the observations as to the knife-edge will vary with tilt of the telescope, temperature, tension from objective support, etc.
This examination of the optical system is not quantitative. However, it is very sensitive to changes in the wavefront, and can demonstrate very small defects in the system.
Figure three shows the appearance of a Maksutov-Cassegrain that yields excellent images, yet I have seen this shadow pattern under the knife-edge test at focus on a semi-regular basis. I suspect it comes from distortion of the corrector as a result of the weight of the secondary. Figure four shows a knife edge pattern observed in a 17.5in Coulter "light bucket". This mirror is grossly undercorrected. For comparison Figure five represents what is seen in an overcorrected system.
Such testing is useful for figuring optical components, and is one of the best methods for Cassegrain and other compound systems. Used to this end the test is a null test for spherical aberration. Testing your telescope under the stars will lead to valuable insights into optical performance. Almost as much fun can be had with Cor Berrevots freeware ABERRATOR at: http://home.wxs.nl/~erkma000/aberrator.htm.
In an upcoming issue we will explore the Ronchi test for really quick evaluation of optical performance. This is no more difficult to build than the knife edge tester. You will need another plastic 35 mm film can, the hole punch, and a piece of Ronchi grating- available form Williman-Bell for less than four dollars. Eight or more test eyepieces can be made from a single 2 in x 2in 133 line grating. Handle the grating like any optical surface- with care, and keep in mind it is much more susceptible to scratching than glass.
Illustration 1With the knife edge intorduced into the beam from the right and located OUTSIDE the best focus the shadow of the knife will appear to come from the LEFT. The rule: "outside opposite".
Illustration 2If light from different parts of the mirror focus at dif-ferent distances the shadow pattern becomes complex, with different areas of light and dark. In the case of air currents (with different temp-eratures). The difference is dramatic. However, the technique will show minor differences in the optical path length with calm seeing and a little practice on the part of the observer.
Illustration 3A steep local disturbance can be dramatic as seen on this Meade 7 inch Maksutov-Cassegrain. Despite the dramatic appearance this telescope performs exceptionally well.
Illustration 4A 17.5 inch Coulter was found to be greatly UNDERCORRECTED.
Illustration 5The OVERCORRECTED condition is "flipped" relative to the undercorrected.
* * * * * * *