Roger Ivester: Amateur Astronomer

Posted December 15, 2015 by rogerivester
Categories: Roger's Articles

     Thank you for visiting my site. I’m hopeful that you’ll find it both interesting and possibly beneficial in your future observations.  


      I became interested in astronomy in the mid-60’s at the age of twelve. One of my older brothers had purchased a 60mm EQ refractor.      

     I grew up in the foothills of North Carolina, in a very rural area.  It was a fabulous place for a budding new amateur astronomer, completely devoid of light pollution. The sky was velvety black with the Milky Way extending almost to the southern horizon.     

     It wasn’t until the mid-70’s that I acquired my very own telescope, a 4 1/4-inch Edmund Newtonian EQ reflector.  This was not my first choice, as I really wanted the 6-inch Super Space Conquerer, but it was the best my budget would allow.   

     By this time the fabulous skies of my early years were gone. I’d moved to an area packed with houses and street lights, but I made the best of the situation and continued to observe.     

     In 1985 a local astronomy club was formed and I became a member with my youngest son, Brad.  This got me back into astronomy after a five year hiatus.  It was Brad that wanted to join the astronomy club.  I’m glad he did.      

      In 1992 I became a much more serious observer, with a new 10-inch EQ Meade reflector.  And fortunately by this time, I was also living in a much darker area.  I began making pencil sketches, which really helped me to become a far better visual observer.  

     I am the co-founder of the Observer’s Challenge report, along with Fred Rayworth of Las Vegas.  The Observer’s Challenge is an international deep-sky observing report, which allows any serious amateur the opportunity to share notes, sketches and images for a preselected deep-sky object on a monthly basis.  The challenge report will celebrate its 13th year in 2021.   All of the reports to-date are included in the following link.

      In October 2018, Sue French, “Contributing Editor” for “Sky & Telescope Magazine” became the Observer’s Challenge special advisor, after many years as a participant.  Sue wrote the very popular monthly “Deep-Sky Wonders” column for twenty years.  As of November 2019, Sue has agreed to help compile and edit the challenge report.  

     I was fortunate to be able to play a role in the Mount Potosi Observing Complex in Southern Nevada, facilitating a $50,000 telescope donation by Dr. James Hermann, M.D. from North Carolina. The facility has been featured in Astronomy Magazine, the Las Vegas Review Journal and other publications.  



NGC 6572, Planetary Nebula in Ophiuchus: July 2021 Observer’s Challenge Report #150

Posted July 19, 2021 by rogerivester
Categories: Uncategorized

Roger Ivester, North Carolina


Sue French, New York

July 2021

Report #150

NGC 6572, Planetary Nebula in Ophiuchus

Sharing Observations and Bringing Amateur Astronomers Together


The purpose of the Observer’s Challenge is to encourage the pursuit of visual observing. It’s open to everyone who’s interested, and if you’re able to contribute notes and/or drawings, we’ll be happy to include them in our monthly summary. Visual astronomy depends on what’s seen through the eyepiece. Not only does it satisfy an innate curiosity, but it allows the visual observer to discover the beauty and the wonderment of the night sky. Before photography, all observations depended on what astronomers saw in the eyepiece, and how they recorded their observations. This was done through notes and drawings, and that’s the tradition we’re stressing in the Observer’s Challenge. And for folks with an interest in astrophotography, your digital images and notes are just as welcome. The hope is that you’ll read through these reports and become inspired to take more time at the eyepiece, study each object, and look for those subtle details that you might never have noticed before.

This month’s target

Our object for the 150th monthly edition of the Observer’s Challenge is the tiny, but bright, planetary nebula NGC 6572, variously nicknamed the Emerald Nebula, the Blue Racquetball, and the Turquoise Orb. These names highlight the range of hues perceived by different observers. The nebula is young, perhaps only a few thousand years old. Its diminutive size led to its inclusion in some early star catalogs. NGC 6572 has a visual magnitude of 7.3, as determined by Stephen O’Meara, while its central star dimly shines at 13th magnitude. As with many planetary nebulae, published distances vary wildly. Values in the vicinity of 5000 light-years seem most likely. This pretty little gem was discovered in1825 by Wilhelm Struve.

NGC 6572 displays bipolar outflows in deep images. There’s evidence of interaction between the collimated outflows and the nebula’s elliptical shell. The interaction has broken up the elliptical shell such that parts of the shell have been accelerated, while the outflow has been slowed down and/or deflected. This supports the idea that such outflows are common in planetary nebulae and may play an important role in shaping nebular shells.…520..714M/abstract 

Mike McCabe: Observer from Massachusetts

The observer’s challenge object for July 2021 was NGC 6572, a bright planetary nebula in the constellation Ophiuchus, and I feel lucky to have gotten to have gotten an observation of it at all this month. Here in the northeast U.S. we’ve been experiencing record rains for this time of year, and clear nights have felt like a precious commodity. As luck would have it, on the exact night of the new moon we got a break and had a clear enough sky to do some observing. I put a scope out before dinner and waited for darkness.

The conditions were fairly typical of an early summer evening, with a high moisture content in the air lending to just fair transparency, but those same conditions also provided a somewhat steady state of seeing. On my sketch I noted the seeing as 2/5 early on, but further assessment as the evening wore on resulted in a rating of at least 3/5. And even though the target was quite bright by the observer’s challenge standards and I probably could have easily gotten away with a medium sized refractor, I chose the 10” F/5 Newtonian regardless. 

The target was a relatively easy star hop from the 3rd magnitude star Cebalrai, including a quick drop in on IC 4665, the “Summer Beehive” cluster, just because it was there. At low power the planetary nebula is virtually stellar, with very little evidence that you’re not looking at just a plain old star. Boosting the power up though begins to reveal the fuzzy discos nature of the object, and true to the form of many planetary nebula, magnification doesn’t seem to dim it excessively. Even though the dimensions listed in various resources shows the object to be somewhat elongated, it never appeared anything other than round to me.

With a variety of nicknames, including Blue Racquetball, Emerald Nebula, Green Nebula, and Turquoise Orb, I figured one more couldn’t hurt. I hereby dub thee “Fuzzy Blue Star”, because that’s exactly what it looked like to me. It’s well known that color interpretation is a highly individual thing, and greens are my weakest area in color vision. I feel a little like I’m missing out on something in all these astronomy observations, like the green in the coma of a comet, the green flash on the Sun, and now the emerald in this planetary nebula. But I fret not. I’m happy with the colors I see, even if it gives my wife fits when I tell her something is green, quite to the contrary of popular interpretation. She calls me colorblind. I tell her I see colors just fine. What does she know, anyway?

Glenn Chaple: Observer from Massachusetts

NGC 6572 – Planetary Nebula in Ophiuchus (Mag: 8.1, Size: 16” X 13”)

The visual observer is all too aware that, with the exception of double stars like gold and yellow Albireo and ruby-red carbon stars like R Leporis, the deep sky is a pretty colorless place. Bright planetary nebulae like this month’s Observer’s Challenge, NGC 6572 in Ophiuchus, are a notable exception.

NGC 6572 was discovered by the Russian-German astronomer Friedrich Georg Wilhelm von Struve in 1825. Struve was in the midst of a survey to catalog double stars when he came upon “a star surrounded by bright green ellipse of fuzzy light.” At the time, astronomers were unaware of the true nature of such a curiosity. Today we know that NGC 6572 is a planetary nebula – an expanding luminous shell of gas ejected by an aging star. It’s relatively young as planetary nebulae go, perhaps no more than 2600 years.

The 2000.0 coordinates for NGC 5672 are: R.A. 18h 12m 06.6s , Dec. +6° 51’ 13”. I star-hopped there by starting at the 5th magnitude star 71 Ophiuchi, the unlabeled star just south of 72 Ophiuchi on Finder Chart A. Finder Chart B shows an 8th magnitude star, SAO 123133 just northwest of 71 Ophiuchi. A line from this star through 71 Ophiuchi and extended 1.3° brought me to a triangle of 8th magnitude stars, NGC 6572 was a little less than a degree SSE of the southernmost star in the triangle.

At 39X in my 10-inch f/5 reflector, NGC 6572 appeared stellar. At 208X, it was definitely non-stellar when compared to a pair of stars immediately to its east, It seemed slightly elongated in a north-south orientation and was decidedly pale blue. I was unable to detect the central star, which is said to be 13th magnitude.

NGC 6572 is approximately 5000 light years away. This translates to an actual diameter of ⅓ light year.  

Jaakko Saloranta: Observer from Finland

July: NGC 6572 – Planetary Nebula –Ophiuchus

NGC 6572 with 10 inch GSO @ 625x (5′)

The observation and sketch was made from a suburban observing site with a naked eye limiting magnitude of ~5.8 near zenith and SQM-L reading of 19.80 from the same region. Telescope used was a 10 inch GSO telescope with multiple magnifications. Weather was fairly average: temperature in the low 50s, rising humidity towards midnight and some cirrus clouds starting to emerge at around 11.30 pm.

I felt I couldn’t get a clear view of the object – probably due to the average seeing conditions and somewhat low altitude of the object (32 degrees above the horizon). What I did manage to see was a “barely N-S elongated planetary with some structure in the middle. From time to time ring structure seems visible with some additional detail around it. No central star.” I could not discern any color from the object although I am familiar with the several – quite colorful nicknames – for this object.

Gregory Brannon: Observer from North Carolina

I went observing on the 11th. My cousin Quinn was with me, and I showed her M92 and M13, before deciding to try to find two planetary nebulae, Minkowski’s Footprint, and the Observer’s Challenge object for this month, NGC 6572. I was unable to find Minkowski’s Footprint after a while of trying, so I gave up for the time being and went for 6572.

By now, the clouds were coming across the sky in bands, obscuring and then revealing the part of the sky I was using in about equal measure. It took some time to star hop, using the screenshot from stellarium mobile as reference both mirrored and unmirrored. It became easier when I realized actually there was a dim but visible star right next to the object. At that point it was a race against time as a band of clouds, a band of clear, and a final neverending haze was approaching. The nebula appeared as a bright blue star at mid power (80x), nearly a point source, but with the weird averted vision behavior consistent with my experience of planetary nebulae. I scrambled to put a higher power in (I had already prepared the UHC filter), but in my haste I was a little too greedy with the magnification. At 428x it was not in the field of view. I pulled the Barlow out and put just the 7mm in (171x), and by then the cloud band was coming through. I lost it by the time the cloud band departed. Back at 80x, I located it again, switched to 7mm, and confirmed that it was a nebula. Very surface-bright and very noticeably pale-blue, very elongated (easily 2:1), and very small. I tried to scramble to go to the higher power (at that surface brightness I felt I could), but then the neverending haze arrived. I settled for a sketch from memory.

2021-July-12 10:40 PM EDTNGC 6572 – Planetary Nebula in Ophiuchus10″ f/5 Dobsonian, 2.5x Barlow, 7mm 58° eyepiece, 429x, UHC filterThe planetary nebula is a brilliant pale-blue at low power, its color and peculiar behavior under averted vision being the only thing which reveals its non-stellar nature. At 171x, it is noticeably elongated and yet retains significant surface brightness at a small size. It is almost stellar at first glance. At 429x, with the UHC filter, the blue coloration is even more dramatic and the nebula mecomes a bright blue ball with a slightly dimmer elliptical fringe elongated N/S, and slightly more sharply elongated in the North.

I also observed the object with the CPC800 (8″, 250x, no filter) belonging to the Cline Observatory, during a practice session on the Thursday before our re-opening to the public. It almost seemed to show a little better contrast though less saturation, and I felt it had a bit sharper edges and pointier ends. But this is the sort of thing your brain imagines. I got a brief impression out of observatory director Tom English–something to the effect of “nice color.” (Later: but not large or obvious enough to show during public nights.) Another observatory volunteer mistook it for a star at first.

Mario Motta: Observer from Massachusetts

NGC6572 is a very tiny object (16×12 arc seconds). Got this last week, poor night with some turbulence, with an H alpha, O3 , and S2 filters. Very short exposures as it is very bright. Visually a small “blue spot”.

Image attached, about 20 minutes each filter, O3 dominated…thus very blue. No detail that I can see. Only good image on line I found is by the Hubble, but can’t match that one! However, a nice object.

Rony De Laet: Observer from Belgium

NGC 6572 is a small but very bright planetary nebula. At 100x it looks like a swollen turquoise star. With each higher magnification, the object’s true nature becomes clear. The best views are at 400x and at 600x. No filter is needed. I see a bright elliptical nebula oriented north-south. It features a central disk of an even higher brightness. The eastern and western edges of the central disk are brighter. These edges seem to continue along the border of the elliptical nebula, forming an S-shape  The central star is not visible, but the central spot of the disk seems a little brighter. All these details are very subtle. It takes time and moments of good seeing to see them. Moving my attention from the centre of this planetary to its borders, I can’t neglect the outer nebulosity. Many observers consider this extended glow as the unavoidable glare of the bright planetary. I am not convinced. When I repeatedly move the planetary through the field of view, the extended halo becomes a well-defined physical part of the planetary nebula.

Site : Bekkevoort, Belgium (51° N)
Date : July 17, 2021
Time : around 23:50 UT
Telescope : Taurus 16”
EP: Morpheus 9mm 76°, 200x / 6.5mm 76°, 280x / 4.5mm 76°, 400x / Omegon 3mm 55°, 600x
Filter : none
Seeing : 4/5
Sky brightness : 20.2 magnitudes per square arc second near zenith (SQM reading).
Sketch Orientation: N up, W right.
Digital sketch made with Corel Paint Shop Pro X2, based on a raw pencil sketch.

Roger Ivester: Observer from North Carolina

NGC 6572 – Planetary Nebula in Ophiuchus 

Date:  May 2021 

Telescope:  6-inch f/6 Newtonian Reflector 

Eyepiece:  20mm + 2.8x BarlowSketch Magnification:  128x

NELM:  ~4.9 Magnitude

I knew that fine detail of this planetary would not be possible from my back yard, using a 10-inch reflector.  So, I chose to use a 6-inch f/6 reflector, mostly for convenience, but not really expecting much difference from the 10-inch.

With the 6-inch, this planetary is very small, mostly round and featureless, but with a pale bluish color.  

This is definitely a large telescope object for the visual observer.  

Lunar X by Guest Host: Barre Spencer and Gary Addington From North Carolina

Posted July 17, 2021 by rogerivester
Categories: Uncategorized

While attending a meeting (July 16, 2021) of the Catawba Valley Astronomy Club:

We were looking at the Moon through the club’s 10-inch Dobsonian, and I saw something that I have read about, but never seen until tonight.

This phenomenon is visible for a few hours each month, about six hours before the Moon enters its First Quarter phase. The bright silvery X appears right along the lunar terminator. This is the line that separates the light and dark sides of the Moon.

I’ve been observing the moon and taken hundreds of lunar photos, but obviously never at the right time.

So, it has taken me at least 30 years to finally see the LUNAR X. If you’ve never seen the X, give it a try, you will not be disappointed…

NGC 5746, Galaxy in Virgo: June 2021 Observer’s Galaxy Report #149

Posted June 14, 2021 by rogerivester
Categories: Work File Only - Observer's Challenge Reports

Monthly Observer’s Challenge

Compiled by:

Roger Ivester, North Carolina


Sue French, New York

June 2021

NGC 5746, Galaxy in Virgo

Sharing Observations and Bringing Amateur Astronomer’s Together



This month’s target

William Herschel discovered NGC 5746 on 24 February 1786 with his 18.7-inch reflector. His handwritten journal reads:” Extremely bright, much extended in the parallel, 8 or 9 arcminutes long, bright nucleus.”

A recent study by John Kormendy and Ralf Bender in the Astrophysical Journal presents NGC 5746 as a structural analog of our own galaxy. Both are “are giant, SBb–SBbc galaxies with two pseudobulges, i.e., a compact, disky, star-forming pseudobulge embedded in a vertically thick, ‘red and dead,’ boxy pseudobulge that really is a bar seen almost end-on.” According to the authors, the lives of these galaxies have been dominated by minor mergers and bar-driven evolution for most of the history of the universe. They place NGC 5746 at a distance of 26.7 Mpc (87 million light-years).…872..106K/abstract

NGC 5746’s V(V_T) visual magnitude is 10.32 ± 0.13, and its surface brightness is 12.6. The galaxy’s visible extent through medium-size amateur telescopes under dark skies is in the vicinity of 7.4′ × 1.3′.

Roger Ivester: Observer from North Carolina

NGC 5746 – Galaxy in Virgo 

Date:  May 30, 2021

Telescope:  6-inch f/6 Newtonian 

Sketch Eyepieces:  16mm + 1.9x Barlow 

Magnification:  109x

Field of View:  0.60º

Very easy to locate and see using 46x, mostly in-part being only 20 arc minutes West of bright star,  3.7 magnitude 109 Virginis.  

My best view came at 109x, and presenting the galaxy as highly elongated, oriented almost perfectly N-S.  The core is fairly bright and elongated with faint extensions, coming to a point at both the N and S tips.  

For my sketch, I moved 109 Virginis out of the field of view, to reduce the extreme glare.  

Globular Cluster, M3, NGC 5272 in Canes Venatici: May 2021 Observer’s Challenge Report #148

Posted May 19, 2021 by rogerivester
Categories: Work File Only - Observer's Challenge Reports


Compiled by:

Roger Ivester, North Carolina


Sue French, New York

May 2021

Report #148

Messier 3 (NGC 5272), Globular Cluster in Canes Venatici

Sharing Observations and Bringing Amateur Astronomers Together


This month’s target

Charles Messier discovered M3 on 3 May 1764 with a 3.5-inch refractor. The French text of Messier’s catalog in the Connaissance des Temps translates into English as: “Nebula discovered between the Herdsman and one of the Hunting Dogs of Hevelius; it does not contain a star, the center is brilliant & its light imperceptibly fades, it is round; when the sky is good, one can see it with a refractor of one foot [at the time, telescopes were generally described by their length]; it is reported on the Chart of the Comet observed in 1779. Mémoires de l’Académie of the same year. Reexamined 29 March 1781, still very beautiful.”

According to William H. Harris’ Catalog Of Parameters For Milky Way Globular Clusters, , M3 resides 10.2 kiloparsecs (~33,000 light-years) away from us and 12.0 kiloparsecs (~39,000 light-years) from the galactic center. It shines with an integrated V-magnitude of 6.19, and the spectral type of the integrated cluster light is F6. Does its color look slightly yellow to you?

May 2021 Observer’s Challenge Complete Report: may-2021-observers-challenge-_m3-2

Roger Ivester: Observer from North Carolina

M3 (NGC 5272) globular cluster in Canes Venatici 

Date: March 2021 

Telescope:  10-inch f/4.5 reflector

Eyepiece:  20mm + 2.8x Barlow 

Sketch magnification 160x

Field of View:  0.38º 

80mm refractor:  Little or no resolution, appearing mostly round with an intense core, and a fainter enveloping halo.  

10-inch reflector at 160x:  Excellent resolve of stars, mostly round, and with a large number of outlier stars beyond the halo.  A very interesting dark lane was noted in the SE-NE of the cluster.  

NGC 3226 and NGC 3227, Galaxies in Leo: April 2021 Observer’s Challenge Report #147

Posted April 16, 2021 by rogerivester
Categories: Work File Only - Observer's Challenge Reports


Compiled by:

Roger Ivester, North Carolina


Sue French, New York

April 2021

Report #147

NGC 3226 & NGC 3227, Galaxies in Leo

Sharing Observations and Bringing Amateur Astronomers Together

This month’s target

William Herschel discovered this interacting galaxy pair on 15 February 1784 with his 18.7-inch speculum-metal reflector. His hand-written journal of the discovery reads: “Two nebulae almost close together. Perhaps 1½ or 2′ asunder, they are pretty considerable in size, and of a roundish form; but not cometic; they are very faint.” He also notes that on this night he first used: “A new, large object Speculum. It is very bright but not quite as distinct as my first, I shall however use it all the night.”

Together known as Arp 94, NGC 3226 and NGC 3227 are wedded in a gravitational dance 47.2 ± 0.2 million light-years away from us. Their complex dance has spawned a remarkable array of tidal tails as well as one tidal dwarf galaxy — a gravitationally bound condensation of gas and stars formed during the repeated encounters of the two parent galaxies.

The most recent journal paper on this captivating system can be perused here:

Observer’s Challenge Complete Report:


NGC 3226-3227: Interacting galaxy pair in Leo 

Date: March 2021

Telescope: 10-inch f/4.5 reflector 

Sketch Magnification: 114x

Field of View: 0.52º 

NGC 3227: Fairly bright, and easy to locate and see even at low magnification.  At 114x, elongated, oriented NW-SE, brighter central region, but subtle.  I first observed this galaxy pair and made my first sketch on April 14th 1993.   

NGC 3226: Much smaller and a fainter than NGC 3227, mostly round, but with a very slight elongation, NNE-WSW.  At 190x, and with averted vision, a stellar nucleus is visible.  Roger Ivester

Sue French: Observer from New York

Through my 130-mm refractor at 23×, I see a moderately faint glow at the position of the interacting pair NGC 3226 and NGC 3227. At 63× it becomes evident that two galaxies dwell here. Although their halos blend together, each harbors a small, distinct, brighter center. NGC 3227 is the brighter and larger galaxy of the pair, its oval façade leans east-southeast. Precariously perched on NGC 3227’s north-northeastern tip, NGC 3226 is wrapped in a halo that tips northeast.

NGC 3222 makes an appearance in the field of view 117×, 13′ west of the interacting duo. This little galaxy appears very dim and holds a weakly glowing, starlike nucleus. A 14th-magnitude star winks in and out of view near the galaxy’s SW×W edge. At this magnification, NGC 3226 grows brighter toward the center, while NGC 3227 displays an oval core with a prominent stellar nucleus. I estimate combined length of the pair to be about 41⁄2′.S

The Southern Cross by Commercial Airlines Pilot: James Yeager

Posted March 29, 2021 by rogerivester
Categories: Uncategorized

Jim Yeager has always allowed me to use any of his aerial photos, which over the years have included, a beautiful photo of the Barringer Crater in New Mexico, covered with snow, and the Mount Potosi Observing Complex in SW Nevada. Both of which I’ve used in previous blog articles and other.

I really like the following image, as I’ve never seen the Southern Cross.

Jim’s notes and photo:

Here is somewhat of clear picture taken with an iPhone using a 3 second exposure on a descent out of 41,000 feet about 100 miles north of Lima, Peru.

You can see Alpha and Beta Centauri pointing to the Southern Cross.

The residual cockpit lights, moonlight behind us, and the haze of high altitude cirrus kept us from seeing the Magellanic Clouds.

Other aerial photos by Jim Yeager:

Incredible and Remote Private Observatory in Landrum, South Carolina

Posted March 23, 2021 by rogerivester
Categories: Roger's Articles

I have seen many private observatories over the past 40 years (plus) as an amateur astronomer, but nothing to the level of this one. It has bedrooms, a darkroom (for the days of film) kitchen, living room, bathrooms, without stairs, but with a “handicap” ramp to the observing room on the second floor. Even some stained glass windows.

It is so hidden on top of a mountain that “seemingly” few living near the facility were aware of its existence. Debbie and I found this amazing.

It’s only about an hours drive from our house.

Deb and I were invited to come for this visit by the owner. When leaving, we were told to come back at any time, but for some reason, we’ve not been able to find our way back. Maybe this year?

When we drove around the last curve going up the mountain and saw the observatory, we both thought it looked like a small castle which might be found in Scotland or England. You decide…

The following photos were made on April 25, 1993. Roger Ivester

In the following picture:

Note the photo propped against the wall behind Debbie, which was a very renowned and famous photo of one section of the Veil Nebula which (at that time, and in the days of film astrophotography) was considered extraordinary. The Veil Nebula is a supernova remnant.

September 2020 OBSERVERS CHALLENGE _Veil Nebula

A highly viewed and studied deep-sky object by both amateur and professional astronomers alike.

The supernova photo was taken using a 6.3-inch Takahashi reflector. The primary telescope in the dome is a 7-inch Astro-Physics refractor, as pictured below.

iOptron CEM70 – Center Balanced Equatorial Mount: By Guest Host: Mario Motta

Posted March 19, 2021 by rogerivester
Categories: Uncategorized

I was considering making a take-apart mount but finally realized I could not build one light enough with all the features I desire, so, I purchased an iOptron CEM70G mount. (guilt for an amateur telescope maker!)” Mario Motta

My story:

Up to this point I have always built my own equipment, such as my 32-inch f/6 reflector telescope in Gloucester, Massachusett, which is my main telescope for imaging, and in a dome attached to my house.

At the end of this year I will be retiring, and per my wife’s wishes will be spending winter months in Naples Florida at our second home. However, in my Florida location I can’t build a dome for a number of reasons. This is due to (hurricanes, building restrictions, etc.)

I was considering making a take apart mount but finally realized I could not build one light enough with all the features I desire, so, I purchased an iOptron CEM70G mount. (guilt for an amateur telescope maker!)

The head weighs only 30 pounds , tripod another 30 pounds, for a manageable weight, yet, tracks very well (3 arc sec error periodic error), is very sturdy, can carry a 70 pound weight load, so it can handle up to a 14-inch scope easily. It has a built-in polar scope alignment guide scope. It even has WiFi, and 4 USB ports. 

Why the center mount instead of a german equatorial or a fork? At 43º North latitude (my 32-inch sits in a handmade fork) or german equatorial which works fine.

Look at the following images as following, “German equatorial”and see that at 43º, the center point of gravity pushes through the main mount, and weight of scope and dec axles pushes down the polar axle, a fork also works the same way.

However…at 26º N latitude, the weight of the scope and counter weight is very far forward, putting all the stress on the forward polar bearing.

Not very stable: A fork overhangs badly.

Now let’s see what a center mount does:

At 43º North latitude, it works well, but all the thrust is on the rear bearing and a german equatorial may be best. Now see what it looks like at 26º N latitude. (see image center mount) Here the weight of the scope is directly over the center of the polar axis, the weight is evenly distributed on both bearings, thus can handle a heavier load with less stress, overall an ingenious design. In reality this is nothing new, what this is… is a miniature English “cross axle mount”.

I built one for a 16-inch scope in the 1980’s and it worked very well.  See the following photo following the M42 image:

In summary, if far north, fork or german equatorials are best, but if closer to the equator, a center mount or cross axle is best.

NGC 2685 – Galaxy In Ursa Major – March 2021- Observer’s Challenge Report # 146

Posted March 18, 2021 by rogerivester
Categories: Work File Only - Observer's Challenge Reports


Compiled by:

Roger Ivester, North Carolina


Sue French, New York

March 2021

Report #146

NGC 2685, Galaxy In Ursa Major

Sharing Observations and Bringing Amateur Astronomers Together



This month’s target

German astronomer Wilhelm Tempel discovered NGC 2685 in 1882 with an 11-inch refractor. Loosely translated, his discovery description reads: Good II-III; round; with a small star in the middle; stands 4′ south of a 10th-magnitude star. 

In the Hubble Atlas of the Galaxies, Allan Sandage states, “NGC 2685 is perhaps the most unusual galaxy in the Shapley-Ames catalogue.” While most astronomers would agree with this, there remain various opinions as to why. NGC 2685 is generally regarded as a polar ring galaxy wrapped in exterior hoops of gas and dust aligned nearly perpendicular to the plane of the galaxy’s lenticular disk. The rings may have been birthed by a merger and/or accretion event. A less touted viewpoint is that this galaxy is strongly warped, and the semblance of rings is merely the result of projection effects.

This perplexing galaxy lies roughly 50 million light-years away from us. As seen photographically, the unusual array of gas, dust, and resultant stars entwining the Helix gives rise to its name. The galaxy may also house a supermassive black hole. Sue French

Date: February 3, 2021

Telescope: 10-inch reflector

Sketch Magnification: 114x

Field of View: 1/2º

Description: Small, fairly bright, elongated NE-SW, brighter bulged center with a stellar nucleus. I last observed this galaxy on March 11, 1996, from the same location and telescope with almost identical results.

From my 5.0 NELM suburban location, it is very easy to locate and see with the 10-inch, but with very little fine detail. The stellar nucleus required a magnification of 183x, and averted vision. It was my plan to observe this galaxy with my 6-inch reflector for a comparison. Hopefully, I can make this comparison next year. Roger Ivester

How to Choose Your Telescope Magnification – Sky and Telescope Magazine: By Al Nagler

Posted March 9, 2021 by rogerivester
Categories: Uncategorized

One of the best articles I’ve ever read concerning the calculation of everything involving telescope eyepieces.

I was fortunate to meet Al Nagler a few years ago. Such a nice guy….