A 4-Inch (102 mm) Refractor Can Be An Excellent Deep-Sky Telescope: Finally Sirius B, Barnard’s Galaxy, and Much More….


After more than 20 years, I finally replaced the original 6 x 30 finder on my 102 mm refractor, with an 8 x 50.  A larger finder makes it much easier when attempting to find the exact location of that very faint deep-sky object. 



At current, I’m working my way through another double Star list, taking my time to sketch each double, noting the colors, checking the position angle and also drawing a few field stars.   

The value of a correct image diagonal:

I’m now using a correct image 90º diagonal.  The view through a standard 90º diagonal, whether using a refractor, Schmidt-Cassegrain or Maksutov-Cassegrain makes it impossible to correctly draw “scientifically” a deep-sky object.  

The mirror-reverse image as seen through a (90º diagonal) does not allow me to draw the objects scientifically correct.  I like to make all my sketches showing north at the top and west to the right.  

Gamma Virgo - Correct Position Angle


Double star sketches:


Documenting my deep-sky objects over the years has been very rewarding.  The following represents some of my observing notes, sketches, and articles.     


Pencil Sketching expanded: 

A while back it occurred to me that there should be a listing of the various types of deep-sky sketching.  After a bit of thought I came up with the following:  

Visual detailed sketching:  Observing an object through a telescope via an eyepiece. Drawing the object on paper “as verbatim” as possible using a pencil, chalk or other.

Impression astro-sketching:  A sketch made at the eyepiece, using a pencil, chalk or charcoal and representing what the observer mentally perceives, without a great degree of scale or detail.  Want to know more about this type of sketching?  Pull out your copy of the “Messier Album” by John Mallas and Evered Kreimer. 

Computer-enhanced sketching:  An astro-sketch generated using a computer, from “sometimes” a rough pencil sketch.  However, if you choose this system, please let it be known to your readers, that it is a computer assisted drawing.  

The following represents a few of my “visual detailed pencil sketches” seldom using anything more than a No.2 pencil and a blank 5 x 8 notecard with a three inch circle.  

I try to make my sketches as realistic as possible, never embellishing, regardless of how faint the object is.  My objective is to present the deep-sky sketch as close as possible to the eyepiece view.    

Scanned Image 161780000

Scanned Image 160920001

SN in M82 Revised -1

Pacman Nebula - NGC 281

I wanted to include a picture of my “vintage” Meade model DS-10A f/4.5 reflector telescope.  This scope has served me well since my purchase back in February 1992.  Five years later in 1997, I purchased my 102mm Orion/Vixen f/9.8 achromatic refractor.  

This might prove that a lifetime of enjoyment as an amateur astronomer can be enjoyed with “humble” telescopes, but of good quality and not necessarily the most expensive ones.  

And remember…the telescope that’s used the most is the best telescope. 


Seeing Sirius B: 

“Finally….after more than 35 years, I was able to see Sirius B, better known as the “Pup.”  Date of observation:  March 14th 2012

Telescope:  4-inch (102mm) Orion/Vixen f/9.8 achromatic refractor.  Conditions:  Excellent seeing and transparency    

How did I become interested in this famous star and its faint companion?  

I purchased my first serious telescope in 1977, which was a 4 1/4-inch f/10, Edmund Scientific reflector.  Even though this was not my first choice for a telescope, it was the best my budget would allow at the time.  My first choice would have been the 6-inch Edmund f/8 EQ (Super Space Conquerer) reflector.  

I started reading anything and everything about astronomy, and was fortunate to find “The Edmund Sky Guide” by Terence Dickinson and Sam Brown.  In this book was a paragraph concerning Sirius and its companion which caught my attention.  Double stars were something new to me at that time.  

The following books by Edmund Scientific books helped me find my way into the world of amateur astronomy.   If not for these books, it would be highly doubtful I’d be writing this entry.  They taught me how to become an amateur astronomer.  

I’m really glad that I purchased the Edmund books…


Back to Sirius B: 

Due to the extreme and overwhelming brightness of Sirius as compared to the much fainter companion, it can be extremely difficult to see the dimmer star.  

I tried for at least a couple of years (mid-70’s) in a feeble attempt to see the companion (a.k.a the “Pup” or Sirius B) with my humble 4 1/4-inch Edmund reflector, but without success.   

During the fall of 2011, double star expert, astronomy author, lecturer and double star enthusiast, James Mullaney, informed me that he had heard of an amateur being able to see the companion using a 4-inch refractor. 

I had pretty much given up on seeing Sirius B in 2012, thinking it was not possible with an amateur scope.  However, after hearing that an another amateur had been successful at seeing the companion gave me the idea that I should try again.  

It was my plan to use my 102mm f/9.8 achromatic refractor: 

This telescope has allowed me to separate many close and difficult doubles over the years, often achieving or exceeding “Dawes Limit.”   


When Sirius B was at a relatively wide separation during the 70’s, again, I was using a spherical mirror, 4 1/4-inch f/10 reflector, not exactly the preferred telescope for accomplishing such a feat.  

Last night (March 14th 2012) using the refractor:

I made preparations to observe Sirius.  After letting the telescope cool down for at least an hour and making a few visual test…I determined the seeing was excellent!  

My excitement was building as it had been a long time since first reading about Sirius and Sirius B so many years ago.   

I had casually observed Sirius on many occasions over the years with a variety of telescopes, but never seriously looking for or expecting to see the companion.

Afteadjusted my astro-chair and removing the diagonal, I started with a magnification of 83x, but to no avail.  I increased the magnification to 232x, all the while keeping my eye perfectly still.  No turbulence, and Sirius was almost pin-point, not the large bloated star that I was so used to seeing over the years. 

I looked very carefully for at least 30 or more minutes, and suddenly, there it was!

After almost 40 years, I had finally seen the companion to Sirius, but It was not possible to hold Sirius B constantly.  I would call it extremely difficult. 

I had glimpsed Sirius B the previous month (February 2012) but conditions were not all that good, and just had to have another observation to confirm my sighting.  

Fall of 2016 using a 4-inch Takahashi FC-100H, f/8 fluorite doublet: 

Another sighting of the companion of Sirius using a 4-inch Takahashi FC-100H, f/8 doublet fluorite refractor in the fall of 2016.  The companion was actually very easy with this scope.  A group of at six or more amateurs took a look.  

Using the face of a clock, and all without telling their position of the companion until everyone had viewed Sirius, correctly identified the position of Sirius B.  Some were very skilled observers, but a couple or more were not, however, all could “fairly easily” locate and see the companion.  I was actually not surprised, as it was so precise and pinpoint in this telescope. 

Completing a list of deep-sky objects: 

Finest Deep-Sky Objects

One of my first reference books was “The Finest Deep-Sky Objects” by James Mullaney and Wallace McCall.  I had observed all 105 objects many times, accumulating over 600 or more, 3 x 5 note cards, complete with notes and sketches.  

However, one of the objects of this list was missing…the companion to Sirius.  After my visual sighting of Sirius B, I now have notes and sketches of all objects listed in that great list of deep-sky objects.  

I couldn’t have selected a better reference book to start with: 

The 105 objects featured in the FDSO’s is comprised of many famous and popular double/multiple stars, but also galaxies, star clusters, red stars and nebulae.  

This book was the perfect primer for a new and budding amateur like myself, as It gave me an introduction to all types of deep-sky objects.  

Such as:  to encourage the study of double and multiple stars and to learn how to enjoy the “jewels of the night sky.”  This name was coined for the beautiful color contrast of so many doubles.   

Colors include:  vivid blue primary, and a tiny red secondary.  The number of contrasting colors have been called rust, blue, red and orange and yes…even green!   Sound interesting?  

And unlike faint and very faint galaxies and nebula, they are often very easy to locate and observe on nights of poor transparency.  Nights that most other deep-sky objects, such as a faint galaxy might not be visible.  Many doubles can be observed effectively in severe light pollution.  Something many amateurs deal with on a regular basis.  

Then there is the beauty of single red stars:   

Most often each person will see star colors differently in both doubles and red stars.   What colors will you see with contrasting color doubles, as compared to those of others?   And will you conclude there is such a thing as a true red star??  What about a green star?? 

Amateur astronomy is suppose to be fun, so colorful doubles and red stars might just add to that fun.   And then compare your notes with the some of the great double star observers of times past.    

Double and Red Stars: 

We need to keep this facet of amateur astronomy from going away, and keep it alive for the future.  Double and multiple star observing seems to be less and less popular with each new generation of amateurs.  

Back to Sirius B: 

After seeing Sirius B, I went to bed smiling, as another observing goal had been accomplished.  It was a great feeling!

Have you seen Sirius B, better known as the Pup?  Why not give it a try?  

Sirius. “A dazzling blue-white sapphire with famed white-dwarf companion!  Orbital period 51 years.  Now widening but still not an easy split most nights.  Mags -1.5/8.5  Sep.  7”  “The Cambridge Double Star Atlas”  by James Mullaney and Wil Tirion

Why not consider a small refractor for some visual observing of other deep-sky objects?    

I have always been interested in the possibilities of using a small telescope, especially a good quality refractor.  A refractor can present pin-point star images and a velvety black background which can improve the contrast of most deep-sky objects.  The superior contrast of a refractor can often times allow views of deep-sky objects to rival or even exceed larger telescopes of more complex designs.  

NGC 6822 (Barnard’s galaxy) in Sagittarius:

It should also be noted that a very low surface brightness object, can often times be better observed at low magnification with a small refractor.  A good example of this would be NGC 6822 (Barnard’s Galaxy) in Sagittarius. 

“A weak glow but definite glow in 6 cm, where it appears elongated N-S and shows a very slight central concentration.  In 25 cm motion of the field helps in showing the low surface brightness galaxy, but it is difficult and ill-defined at best.” Observing Handbook and Catalog Of Deep-Sky Objects by Christian B. Luginbuhl and Brian A. Skiff.  

Finally…after almost 25 years (many years I attempted with my 10-inch reflector) but had never been successful.  In September 2014, I was able to sketch and make notes of this elusive galaxy, NGC 6822, using the 102mm refractor.  

Much of my problem was/has been due to light glow from a pesky unshielded street light in close proximity to my backyard.  A dark sky is critical for locating and observing this faint low surface galaxy.  And so, another difficult object is checked off my list. 

The following sketch was made using the refractor with nothing more than a No. 2 pencil, a blank 5 x 8 notecard, with the colors inverted using a scanner.

Rogers NGC-6822

The following image by Dr. James Dire of Hawaii using a 190 mm Maksutov-Cassegrain telescope.


The complete Observer’s Challenge Report for NGC 6822:


“The Observing Handbook and Catalog of Deep-Sky Objects” By Christian B. Luginbuhl and Brian A. Skiff

This is the reference book that took me to a higher level as an amateur astronomer, and it remains the book that I use most often with all my observing sessions.   

I like the descriptions by the authors describing the views with various telescopes, especially with a 60mm refractor.  This causes me to want to follow their observations and see what’s possible for me using a 60mm refractor, however, I don’t have one.  

No problem:  I have a home-made 60mm stop-down mask for use with my 102mm refractor.  This allows me the opportunity to observe the object with a 60 mm refractor, without having to add another telescope.  I can then make visual observing notes and sketches for two scopes.

Using a stop-down mask for an effective aperture of 60mm’s and a focal ratio of  f/16.7 

Seeing the companion to Polaris using an effective aperture of 60mm’s:   

Polaris has a magnitude of 2.1 and the secondary or companion at a much fainter 9.0 magnitude with a wide separation of 19 arc seconds.  The extreme difference in magnitudes can make this double more difficult to separate than you might think, especially if seeing is less than good. 

April 19th 2018:  102mm f/9.8 achromatic refractor with an effective aperture of 60 mm’s.  

Seeing excellent: 12.5mm eyepiece plus a 2.8x Barlow for a magnification of 80x.  The companion was clearly visible as a tiny bluish dot.  



What is the smallest aperture that will allow me to see the companion to Polaris?  The following photo shows an effective aperture of 45 mm’s.  However, as of current, I’ve been unable to see the companion with this aperture….  


Seeing the companion of Polaris using an 80 mm f/5 refractor:

My son surprised me with an 80 mm f/5 refractor for a birthday

April 19th 2018:  80 mm model f/5 achromatic refractor.  Seeing was excellent. 12.5 mm eyepiece plus a 2.8x University Optics Klee Barlow for a magnification of 90x.  The companion to polaris was visible as a tiny bluish dot.  Very similar to the view using the 102 mm reduced to 60 mm’s.  Beautiful in both telescopes.   



When observing with my 80mm or 102mm refractor, I always use a 1.25-inch correct image diagonal.  For me it’s essential when sketching a deep-sky object, to have the correct “scientific” orientation in the eyepiece field-of-view.  

April 20th 2018:  80mm f/5 achromatic refractor.  Similar conditions to my observation on the 19th. Using the same eyepiece combinations (90x) and was easily able to see the companion as a tiny bluish dot.  A great little scope which is very easy to take outside, including the mount…all in one trip.  If time is limited to an hour or less, this is the telescope I use. 

Beginning amateur astronomy in 1967 with a 60 mm refractor: 

My older brother purchased a 60mm f/15 EQ Jason Refractor in the mid-60’s, when I was only thirteen years old.  This was the telescope that got me interested in astronomy.  I would set it up in a weedy field beside of my house in a very rural area of the foothills of North Carolina.  I had difficulty finding anything other than the moon, Venus, Saturn and Jupiter, but eventually my observing skills did improve.  I’m really glad that I persevered and stuck with it. 

Maintenance of a refractor: 

I have always kept the lens capped on the 102mm refactor, when not in use and the OTA is always stored in a padded case.  In the eighteen years that I have owned this telescope, the objective lens has never required cleaning.   The objective lens is also permanently collimated, without any adjusters, and was in perfect collimation when I received it.  There has been no change after purchasing the scope in 1997, and with plenty of use.   

For most part, a refractor is much more durable and able to suffer less from mishandling and rough treatment than reflector’s and catadioptric telescope’s.   

A very high quality 4-inch refractor during the 50’s through the 70’s, had to be a Unitron, with the standard f/15 focal ratio.  The long focal length was necessary for an achromatic refractor telescope…to reduce false color.  

This telescope could be obtained with either of two mounts.  One being a field tripod with wooden legs, and the other…a massive bell-shaped pier with a mechanical weight-driven clock drive.  The latter was designed for a permanent location.  A 4-inch f/15 refractor with any type of equatorial mount for most part should not be considered a portable instrument.        

John Mallas who co-authorded “The Messier Album” with Evered Kreimer, used a 4-inch f/15 Unitron to examine all Messier objects between 1958 and 1962, from Covina, California.  This is a fabulous book and I still use it as a reference quite often, even to this day.    

The modern era of refractor telescope’s arrive:

However, with the advent of exotic glass, better anti-reflection coatings and short focal lengths… like the slide-rule, the day of the 4-inch and larger f/15 refractor was over.     Roger Ivester

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