Archive for June 2018

Cline Observatory Double Star List – Compiled By Tom English – June 2018

June 22, 2018

Tom English has put together an excellent list of twenty five doubles and four multiple stars, which at first glance would seem to be compiled for only those new to this facet of amateur astronomy.  However, for those of us who have enjoyed double star observing for decades, we know there is no such thing as a beginners list.

Double star lists can be comprised of the most difficult pairs due to their close separations and sometimes with unequal magnitudes, or those with wide separations and beautiful contrasting colors.  It was the latter which coined the name: “The jewels of the night sky.”

This list contains some beautiful and interesting doubles, all of which can be observed with a very small telescope.  The famous double star, Epsilon Bootis is probably the most difficult double on the list, which has always required a 4-inch aperture for me.  Many observers have reported seeing the companion to Epsilon with a 3-inch, and from Webb….a 2-inch, or even smaller.   

Are you stressed, too tired to take out that big telescope, but would like to enjoy an hour or so of relaxation under the night sky?  So….why not a 60 mm refractor or a 3-inch reflector?  Oh yes….don’t worry about the bright moon or ambient lights as both have little effect on most double stars.     

At one time I thought anything less than a three or four hour observing session was not worth the effort to take a telescope outside.  I became so consumed with observing….there was no way I could miss one clear night.  My observing became more of a job, and I was always grateful for a cloudy night.  The obsession to observe did not allow me to make the decision to not observe, only something like a cloudy night, rain or snow, which was beyond my control.  I’m happy to say….I am now cured of this malady.  🙂 

Want to become a better double star observer?  I’ve listed a few things as following which have helped me over the years:  

I’ve never been able to observe through a telescope eyepiece and stand at the same time, much less attempt a pencil sketch.  

Careful and skilled observing requires patience and comfort.  

And for those extremely close and difficult doubles, an eyepatch is necessary for the non-observing eye.  It’s important to relax the facial muscles and  it’s “absolutely” essential to hold the observing eye very still and on-axis….hence the need to be seated.   

Roger Ivester  

“If I waited for perfection, I would never write a word”   Margaret Atwood

The Cline Observatory Double and Multiple Star List

Cline Observatory Double Star List

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Epsilon Bootis – Double Star – W. Struve’s “The Most Beautiful One”

June 19, 2018

Observer’s Challenge object for June 2019:  

Epsilon Bootis:  Called “Pulcherrima” or “the most beautiful one” by Struve.

At one time, observing double stars was the most popular facet of amateur astronomy, however, I think we can all agree, this is not the case as of current.  Sad indeed!   I say….fortunate indeed is the amateur who discovers the joy of observing double stars.

Nothing is more beautiful than a close pair with vivid and contrasting colors, such as Epsilon Bootis.

Want to have some fun tonight?  You don’t have to be concerned with the brightening moon, or ambient lighting, but take a look and try the very challenging double star Epsilon Bootis.

Good seeing is definitely required to see the companion of Epsilon.  On many nights with less than good seeing, I’ve failed to see the companion, even with a 102 mm refractor, or a 10-inch reflector with an effective aperture of 4-inches, using an off-axis stop-down mask.  

It is an unequal double with the primary being magnitude 2.37 and the secondary at 5.12, with a separation of 2.9″ which makes this double difficult for many observers.

I see the colors as a beautiful yellow and a vivid blue, with a clean separation at 175x using a 102 mm refractor.

This is an opportunity to observe one of the 2019 objects….a full one year early, but after viewing, you will want to observe this famous double many more times, now and in the future.

Quoting from Celestial Harvest by James Mullaney:

! Izar, Magnificently-tinted but tight pair. “Most beautiful yellow, superb blue.” Rather difficult in apertures under 4-inches.  A 3-inch at 150x shows two beautifully-colored diffraction disk nearly in contact!  ….called “Pulcherrima” or “the most beautiful one” by Struve.  JM

Many have seen the companion with a 3-inch, and from Webb, even a 2-inch, however, for me, it’s always been at least 4-inches of aperture.  What will be the smallest telescope which will allow you to see the companion?

After all….every amateur should attempt to see a double star called “the most beautiful one.”

Roger Ivester

 

NGC 4236, Extremely Faint Galaxy In Draco – May 2018 – Observer’s Challenge Report #110

June 7, 2018

To read the complete LVAS Observer’s Challenge report, click on the link:

MAY 2018 OBSERVERS CHALLENGE – NGC-4236

Rogers NGC-4236 Inverted b

10-inch reflector, and spending four hours in my attempt to see galaxy NGC 4236, of which the first three were unsuccessful.  However, during the forth hour, at well past 1:00 AM EDT, could glimpse an extremely faint, elongated NNW-SSE oriented blur of light as shown in my sketch.  The galaxy appeared featureless due to the extreme low surface brightness, and visible only intermittently with averted vision. 

Sky conditions were poor with a NELM of 4.9, which is about normal for springtime in the foothills of North Carolina.  There is a distinctive tilted half-circle of five stars, NNE of the galaxy which works well to assist in determining the exact location of this very faint galaxy, or better said, extremely faint galaxy. 

On the previous night, under the same conditions, using a 6-inch reflector, the galaxy was invisible, despite spending two hours in my search. 

Roger Ivester

 

Image by Dr. James Dire from Hawaii

NGC4236

NGC 4236 By Dr. James R. Dire

NGC 4236 is a faint, nearly edge-on barred spiral galaxy in the constellation Draco.  The constellation is often overlooked due to its low surface brightness.  The galaxy is relatively large in our sky, spanning 24 x 6.8 arcminutes. Its integrated magnitude is 9.63. NGC4236 is located 11.7 million light years away and is part of the M81 galaxy group.  It rivals M81 in size. However, M81 is 3 magnitudes brighter!

NGC 4236 is located “above” the open cup of the Big Dipper Asterism. Its distance above the cup is approximately the same as the distance between the two starts forming the top of the cup – Dubhe and Megrez.  NGC4236 lies just over a degree west of a linear trio of stars: 4, 5 and 6 Draconis.  Both 4 and 6 are 5th magnitude and are orange and yellow, respectively, while 5 is 4th magnitude and blue in color.

Despite its brightness and location near naked-eye stars, NGC 4236 can be very difficult to find, even with a GOTO mount.  The Image was taken with a 70mm f/6 apochromatic refractor using a 0.8x focal reducer/field flattener.  The exposure was a whopping 3 hours.  In the image, north is up and east is to the left.

In the image, the bright blue star on the left edge is 5 Draconis.  The orange star is 4 Draconic. Those two stars are separated by 40 arcminutes.  The smudge just above the center is NGC4236.  The exposure captured about half the actual length of the galaxy, essentially the galaxy’s central bar and the inner, brighter spiral arms.

To help identify the galaxy in the eyepiece, note the arc of three stars on the northeast side of the galaxy.  The top star is magnitude 8.3, while the lower two are magnitude 10.5.  There is also a magnitude 9.8 star on the south end of the galaxy’s major axis.  Seeing these four stars in the eyepiece allows one to center the galaxy in the eyepiece and then using averted vision to see the galaxy.

I viewed NGC 4236 this month in three telescopes.  The first was a 190mm f/5.3 Maksutov-Newtonian reflector using a 14mm eyepiece (71.4x).  I centered the galaxy using the four stars around it as described above.  Direct vision did not produce the galaxy. However, with averted vision I was barely able to make out the elongated shape of the very diffuse galaxy.

I next viewed the galaxy using an Orion 12-inch, f/4.9 Dob using a 20mm Televue Nagler eyepiece (75x).  The galaxy was just as difficult to see in this scope as the Mak-Newt.  This was probably because the Dob’s optics are nowhere as good as the Mak-Newt.  Plus, I later discover that the primary mirror on this astronomy club telescope was extremely dirty (I have since professionally cleaned it and recollimated it).

Finally, I viewed NGC4236 with a friends Orion 14-inch, f/4.6 Dob with clean optics and a good collimation. Through this telescope, the galaxy could be seen directly.  I could see about the same visual detail as in my image!   JD