Sunday, May 29, 2022

New Telescope Familiar Sights

As the proud owner of a 130-mm (5-inch) Newton reflector with tabletop Dobsonian mount from Astronomers Without Borders, I have been taking advantage of the clear nights to learn the new instrument. Collimating the mirrors was always a challenge for me. I will check them again one more time before going out tonight.

Geographically, I live in a suburb, but my skies are urban by definition: No part of the Milky Way is visible – Bortle 8/10. The last couple of nights and early mornings out, I counted about 60 to 70 stars. The brightest constellations, Leo and the Big Dipper, begin the tally, but only the top of Scorpius is available, though I have seen the stinger stars Lesath and Shaula. I have not seen Ptolemy’s Cluster (Messier 7) naked eye here lately though I often did in the city. (That sector of the sky was more available in the winter mornings because the zodiac was higher.)

National Geographic 76-mm Newtonian.
Not sure that it was worth $100.
 

I also bought a National Geographic 76-mm tabletop Newtonian. It has been a disappointment. I do have 70-mm refractors with which I have seen double stars and open clusters. This will not do that. I tried better oculars costing twice what this tube did but they were no help. And, on point, with those small refactors, I also tried the views with the cheaper default eyepieces—Huygens, Ramsden, and Kellner—and been successful, albeit not thrilled. Even so, I attached a small telescopic crosshairs sight to the Natl G 76mm Newt and it helps to find the targets. Found, they remain blurred and sparkly and no doubles were split. 

 

That being as it is, the AWB 130-mm has been an eye-opener.

 

I started in November 2014 with a 130mm Celestron reflector but after struggling repeatedly with collimation, I donated it to the Goodwill in early 2021 after buying myself a new refractor in October 2020. (On my blog here. ) I have been very happy with the Explore Scientific 102-mm achromatic refractor and it has been my “grab-n-go” these past 18 months. However, I am also a sustaining member of Astronomers Without Borders and they sell this tabletop Dobsonian*. Finally settled in our new home, I bought one. I am glad that I did.

 

First of all, it came with a collimation eyepiece and clear instructions, which I already know well enough (in theory). The default eyepieces are called SMA: Symmetric Modified Achromatic (Kellner), basically, a three lens design that reverses the order of the traditional Kellner so that the lens curves  face each other. They are fine for what they are. However, I have been using my very much better oculars from Nagler, Stellarvue, Vixen, and Meade. 

 

On the first night, 26 May 2022, I split delta Corvii, and then the Mizar-Alcor system, both easy targets.  I was pleasantly surprised to quickly find both Messier 80 and Messier 4 in Scorpius. The first, I logged several times already and noted that it appears when Messier 4 does not. (Such clusters are difficult under city lights.) However, M4 was right there were I expected it, west of Antares. Both gave sparkly hints of their central cores with dusty envelopes at the outskirts. 

The tabletop "lazy Susan" is fine for 
children 4 feet tall. With the integrated 
"Vixen" style mounting bar, I put it on an 
Explore Scientific First Light Nano and
then (now) on an ES First Light Twilight 
with slow-motion controls.


The next night, 27 May 2022, I split Castor and Algieba (gamma Leonis) with a 14mm eyepiece (46X), but found the collimation still off.

 

On the 28th, I recollimated in the afternoon. I checked the red-dot finder alignment on delta Corvii with a 7-mm (93X) eyepiece. I then performed a “star test” on Spica, running the focus far out so that the star was a very large circle showing the shadow of the secondary mirror and yielding symmetric Airy Disks at the diffraction limits. The collimation is still a little off-center but the viewing was acceptable. 

 

2215 hours: Gamma Corvii is a blue supergiant and it was very bright and very white. I did not find Messier 68 below Beta Corvii, a frequent source of disappointment with my refractor, also. 

 

2251 to 2309 hours: However, once Scorpius was up, I found Messier 80 and Messier 4 easily and spent time viewing them with a 4mm (165X) Stellarvue 82-degree eyepiece. Unfortunately, not much of Scorpius below Antares was visible.

 

2317: Lyra was not apparent as a constellation in the east though Vega was impossible to miss and from there both Zeta Lyrae and Epsilon Lyrae double star systems were accessible. Epsilon Lyrae is everyone’s favorite, a “double double” each star with a companion, and I noted them in my log book. 

 

2344 to 2353: Scanning Scorpius again, I found Mu Scorpii, a naked-eye double. Lesath and Shaula (Upsilon and Lambda Scorpii) were visible but there was no outline to the “Teapot” of Sagittarius, and I could not make Zeta Scorpii naked eye. I did not try for its open cluster which I have logged in the past. 

 

* [Note: It was the late John Dobson (1915-2014) who pioneered large reflector telescopes on wooden “lazy susan” swivel mounts. He ground the mirrors from porthole plate glass retrieved from ship salvage yards. After living in a Hindu monastery, he took his astronomy to the streets. See Wikipedia here: https://en.wikipedia.org/wiki/John_Dobson_(amateur_astronomer)  and YouTube here: https://www.youtube.com/watch?v=bVbX19kabNc ]

 

PREVIOUSLY ON NECESSARY FACTS

 

Seeing in the Dark: Your Front Row Seat to the Universe 

Steven Weinberg on Gravity Waves 

Galileo and Saturn: Epistemology not Optics

Binary Star Project 

 

 

Tuesday, May 24, 2022

Limerick

Unlike theorems in geometry and proofs in algebra the forms of speech and literature are open to ad hoc change by their users. Therefore, ultimately, human communication depends on context and analogy which then allow misunderstanding unless you are "in" with the in-crowd. Thus, we have weak verbs and strong verbs, regular and irregular.  In English grammar we learn “singular” and “plural” but our plural is only a dual: bird, birds; ox, oxen. English lost the true plural form (1-2-Many) though Russian and other Indo-European languages kept it. Over time some forms stabilize

 

The sonnet can be 12 lines (Petrarchan) or 14 (Shakespearean). See the Poetry Foundation at  https://www.poetryfoundation.org/learn/glossary-terms/shakespearean-sonnet


In English, the limerick is a stable poetic form. “Typically, the first two lines rhyme with each other, the third and fourth rhyme together, and the fifth line either repeats the first line or rhymes with it.” -- Academy of American Poets here: https://poets.org/glossary/limerick

 

There once was a gal from Nantucket. 

From the Nantucket Inquirer and Mirror.
She has a website: http://www.dorothydstover.com

 Previously on Necessary Facts

 

Forbidden Planet 

Linguistics Debate: What Colors Are Your Rainbow? 

As You Think So You Speak 

Spoken American Grammar 

 

Monday, May 23, 2022

Library Telescope Project

About a dozen local astronomy clubs have arranged for their city libraries to acquire telescopes that can be lent to patrons. The story comes from Sky & Telescope for October 2014: “Check Out This Telescope!” by John Jardine Goss. He tells of the Adams Library in Chelmsford, Massachusetts. They accepted an offer from the New Hampshire Astronomical Society (NHAS) which had been supporting this program in their communities for six years.

When we moved to Kyle in December 2021, I got a library card before I updated by driver’s license. (In 1990-1992, I served on the White House Commission on Libraries and Information Services. I held a taxpayer’s Michigan State University Libraries card for many years when we lived in central Michigan and I depended heavily on them while writing for the numismatic trade periodicals.) The Kyle City Library had two board seats vacant. So, I applied and was appointed by the city council on 12 April 2022. Bringing the telescope project seemed like a good way to serve.

 

In the Sky & Telescope story, the instruments were tabletop Dobsonian (“dob”) variety Newtonian reflectors. That choice was broadly supported by other clubs who took the idea to their community libraries. For one thing, the lack of a tripod is not a barrier and removes one set of problems. For another, these tend to be in the 4-inch (100 mm) range, which is more than sufficient to explore the Moon, the planets, large clusters, and other targets easily available in the cities and suburbs. 

 

The NHAS also developed a set of modifications to make viewing easier as well as to prevent tampering. Even so, in one case one telescope came back in pieces because the patron made the effort to disassemble it. There are a few other less horrible horror stories. Overall, based on internet chat group reports, perhaps as many as 200 of these telescope are being loaned from about 60 different libraries. Problems were exceptions. Nonetheless, lessons were learned. 

 

The library staff gets training on the instruments so that they understand their functions, pieces, and parts. And the staff is the first to borrow the new acquisitions. A check-out/check in form with a checklist helps to guide and audit the process. One discussion of projects similar to this one is in the Outreach forum of the Cloudy Nights board here: https://www.cloudynights.com/topic/568359-library-telescope-program/. The library programs are also suported by the Astronomical League here: https://www.astroleague.org/content/library-telescope-program

 

Among the very many impacts of Covid were the contraction of in-person patronage at the libraries and the collapse of the supply chain for astronomers. Our city library is back on track. However, I found that the makes and models popular in 2008-2019 are no longer on the market as product lines were consolidated. So, I went shopping.


https://shop.astronomerswithoutborders.org/collections/frontpage/products/awb-
onesky-reflector-telescope

Easiest for myself, I bought a 130-mm (5-inch) reflector from Astronomers Without Borders. I am a sustaining member of AWB and was their Person of the Month some time back. The AWB dob was created in partnership with Celestron which writes off a portion of their costs in order to allow maximum profits to the not-for-profit to carry out its international outreach. Nice as that all is, the open-truss configuration is problematic as a library loaner. It is too accessible to the overly curious patron. 

https://explorescientificusa.com/collections/national-
geographic-telescopes/products/national-geographic-
76mm-table-top-reflector-telescope


I also acquired a National Geographic 76-mm (3-inch) from Explore Scientific for $89. It was $20 cheaper from Adorama from Amazon but I chose to pay more because Explore supports the hobby in direct ways by sponsoring star parties and publishing a free online magazine and providing customer service. Their CEO Scott Roberts also serves on the board of Astronomers Without Borders. This model is more amenable to reconfiguration. For myself, I like finding the lower limits of power and have logged binary stars, nebulae, and other targets with 70-mm refractors. “What can you see with that?” is an honest question and I can give a strong answer. 

 

For both of these, I already have other tripods that can be put to use. The AWB comes with a Vixen-style bar which is nearly universal in the hobby. Each of these can sit on a round wooden plate bolted to a different Celestron camera tripod that I have.

 

These will help to inform the library board and the library director about the kinds of choices and their capabilities. The library loaner will need a “zoom” eyepiece. These oculars change their focus points and therefore their effective magnification. They are about twice as expensive (at least) as a good mid-range eyepiece but this is will make viewing easier for the patron and obviate the losses to the library. In any case, neither of these tabletop dobs comes with quality oculars. Today, the 4-lens Plössl eyepiece (also appearing as Ploessl or Plossl) is the baseline but these arrive with simpler Huygens, Ramsden, and Kellner configurations. 

 

For myself, I have seen nebulae and separated binary stars with the “value-priced” attachments, but the fact remains that better glass delivers more subtle details. Also, among the modern oculars are several series with much wider fields of view (FOV) than their 17th, 18th, and 19th-century ancestors. Right now, my preferred eyepieces are a 14-mm 82-degree FOV Meade Series 5000 and a 7-mm 82-degree FOV Nagler Type 1. They will do well in the new Dobsonians.

 

[Note: It was the late John Dobson (1915-2014) who pioneered large reflector telescopes on wooden “lazy susan” swivel mounts. He ground the mirrors from porthole plate glass retrieved from ship salvage yards. After living in a Hindu monastery, he took his astronomy to the streets. See Wikipedia here: https://en.wikipedia.org/wiki/John_Dobson_(amateur_astronomer)  and YouTube here: https://www.youtube.com/watch?v=bVbX19kabNc ]

 

PREVIOUSLY ON NECESSARY FACTS

Focus on Simon Ploessl 

Libraries of the Founders 

Copy Rights and Wrongs 

Another Example of Unlimited Constitutional Government 

 

 

Sunday, May 22, 2022

Product Review: Bresser EQ3 and 70mm f/10 Refractor

Keep the telescope. Throw away the mount.

 

This instrument is an embarrassment to the tradition of German engineering. Like very many other sellers of consumer optics – telescopes, binoculars, microscopes -- Bresser GmbH, GutenbergstraĂźe 2, 46414 Rhede, buys much of its production from China. This telescope, and especially its mount, betrays its Chinese origin with cheap engineering and poor production. The optics are fine. This telescope works as well as the other 70mm refractors that that I have from Meade and Celestron and the National Geographic label (all of them also made in China). Within the range of consumer goods, the optics are a given. It is the mechanics that fails. 

 

The first clue is the grease. Chinese routinely apply thick grease that hobbyists remove and replace with machine oil. 

 

I bought the telescope and mount from Explore Scientific on 31 March 2022 and it arrived on 7 April. It was easy to assemble but I also could see that it had basic design problems. First and foremost, there was no way to orient the setting circles for Right Ascension and Declination. 


With the telescope aligned correctly to North,
the Right Ascension is wrong by 48 minutes.
The circle would not move, glued into place
with heavy grease.

When set to my latitude (30 degrees North) and aligned on Polaris the setting circles read 23 hours Right Ascension and 70 degrees North Declination. Polaris is at 2 h 31 m RA and 89° 15’  


With the telescope set correctly,
the declination is wrong by 20 degrees.
The circle could be hard-set at the factory
to 90 degrees. (89.25 degrees is more exact.)
But the circle should still be adjustable.


Regardless of any other movements or settings, the setting circles were fixed in place as if they are glued there. Indeed, they were: with grease. 


After several sessions over two months of taking this down and setting up and trying this and that, I finally pried the setting circles loose and washed them off with rubbing alcohol. (I have GooGone, but I did not want to risk damaging the circles.) Also, the axes would move some distance and then stop. If I slewed the telescope manually, I could get more motion and move easily some short distance in the opposite direction.

 

After the first failures on the first afternoon, I remounted the telescope on an Explore First Light Nano altitude-azimuth mount and tested its optics. I alternately used both the 25 mm and 9.7 mm Plössl oculars. After aligning the finder with Sirius, I quickly found the Messier 41 open cluster and then Messier 42 the Great Orion Nebula and its Trapezium asterism. I also split the binary Mintaka (delta Orionis). I located another asterism that I know, sigma Orionis. I was pleased with the result. The easier of the two binaries was distinct. The smaller pair gave only some hint and only because I knew what I was looking for an looking at. They are much clearer in my larger Explore Scientific 102mm achromatic doublet refractor. Viewing the waxing crescent Moon I also was happy to find that the focus did work well with two filters screwed into the oculars. I ended the test with Mizar-Alcor (zeta Ursae Majoris), easily and clearly revealing Mizar’s visual companion. The optics of this telescope are good. 

 

Problems with the Mount

 

The right ascension (RA: hours-minutes of arc from the peripoint of Aries) axis would move a little in one direction and then move back more in the other. If I rotated the telescope manually, the slow motion cable would move the RA axis more in one direction and then less in the other.

 

Five days later (12 April 2022) I set the telescope up again in my office so that I could work indoors during the day. The gears locked. With all clutches open, the counterweight shaft with the Dec scale 0-9-0 would not move. Using the motion control knob, the RA moved a little and then quit. This happened often when I first set up the telescope. At other times the declination axis (Dec) would behave the same way, not moving the axis while turning the knobs, though in those cases, the RA would move. Before it locked up the RA would alternately respond with large movements in one direction but only small motions in the opposite travel.  

  • I disassembled the Dec axis. 
  • I removed the three hex pins holding the collar. 
  • I removed the counterweight and its shaft. 
  • I removed the cover with the worm gear. 
  • I was able to turn the axis freely through several rotations. 
  • Using a locking pipe wrench, I was able to move the Dec axis.
I put it back together, noting that the shaft must be somewhat loose, looser than hand-tightened, in order for the circle to move relative to its pointer.
  

15 April 2022 18:30 I watched half a dozen YouTube videos and read four articles online. Most of them were useless, very basic, not at all mentioning any of my problems. One stood out. How to use setting circles on a small telescope (and why they don't work!) Astronomy and Nature TV here: https://www.youtube.com/watch?v=geQszAVWMok

 

At the 2:35 mark, he gives a “Bluffer's Tip” for setting the polar alignment. It was the missing piece of the puzzle. In reality, I have to do the same thing I have done for a computerized “go-to” mount: star alignment. After setting up the telescope mount in Latitude and Direction (with a compass or your cellphone, for example), use a reference to identify a known bright star and its Right Ascension and Declination. In this video, he uses Dubhealpha Ursae Majoris

 

That solved one basic problem. So, I hauled out the telescope again (in daylight this afternoon). I found that with all of the movement back and forth, assembly and disassembly, the setting circles are now loose enough to move by hand. 

 

The remaining problem is that after traveling in one direction, the setting circles RA and Dec stop moving. The slow motion cables do turn but the axes stop traveling. One or the other will turn and then not, but then travel in the opposite direction when the cable turn is so turned. The cables turn; the telescope does not travel.

 

7 May 2022 Before going out I made a table of prominent stars in my early night sky and continued testing the mount. 

 

The axes would not hold their settings.

I aligned on magnetic north with a compass, then re-aligned on True North with my cellphone.

1.     I located Polaris. The readings were 19h 30m and 0 instead of 02h 31m and 89 degrees. I set the Right Ascension wheel to 2h30m.

2.     Next, I turned to Arcturus. The readings were 9h 50.5m and 50 degrees. I reset the circles to 14h 15m and 19 degrees. 

3.     Finding Spica the readings were 15h and 10, close to the actuals of 13h25m and -11d  (11 South). The declination setting circles do not differentiate the two halves of the circumference.

4.     Locating Regulus the setting circles showed 6h 30m and 0d 20m, far from the actual values of 10h (10h 08m) and 12 degrees (11d 58m).  

I gave up for the night and viewed with an Explore Scientific 102-mm f/6.47 achromatic doublet on an Altitude-Azimuth mount.

PREVIOUSLY ON NECESSARY FACTS

Baader-Planetarium Micro-Guide Reticle 

$2500 Viewed Through a Telescope 

70-Millimeter Shootout 

Product Review: Celestron AVX (“Advanced AX”) Mount and Tripod 

Celestron AVX Mount: Twelve Nights of Viewing and Learning 


Sunday, April 17, 2022

Sunny Easter 2022

Sunny is our cat. Laurel found the faux Egyptian bookends at an estate sale and I cleaned them up and set them out to dry. 



Previously on Necessary Facts

Only a Cat 

In Like a Lion 

New Cat: Sunny 

Désirée (Miss Kitty)


Sunday, April 10, 2022

Daysmith Coffee

It is nice to see vendors in the store again in the wake of the continuing Covid concerns. Derek and Daniel, founders of Daysmith Coffee, were set up at the Wheatsville Co-op. 

https://drinkdaysmith.com

From their website:
COFFEE + BENEFITS

Our mission at Daysmith is simple: to transform wellness with everyday goodness. That’s why we make delicious coffees that combine the benefits of vitamins and plant-based nutrients to support your health and power your day

GOODNESS

It all starts with our ultra smooth coffees and creamy oat milks. We know taste is number one, so we've taken our time to perfect our recipes with ultra smooth coffee and creamy oat milk to maximize deliciousness.


WELLNESS

All our coffees are infused with vitamins and plant-based nutrients to provide targeted benefits and support your health.

LESS IS MORE

We pride ourselves on what’s IN our cans, just as much what we’ve left OUT of them. While other coffees are loaded with calories and sugars, we’ve cut them down. All our coffees have only 15-70 calories and 0-5g of sugar per can.

PREVIOUSLY ON NECESSARY FACTS

Awesome Austin Foods at the Wheatsville Co-op 

Two Hot Mamas Salsa 

Crisp Greens at the Wheatsville Co-op

Sunday at the Co-op 

Salsa Showdown: Jaime's versus Royitos 


Tuesday, April 5, 2022

Astronomy: Two Minor Books for the Backyard

There’s a lot of books out there for backyard stargazers. Amateur astronomers with some experience tend to recommend a few favorites with longevity. 

  • Turn Left at Orion: Hundreds of Night Sky Objects to See in a Home Telescope by Guy Consolmagno and Dan M. Davis (Cambridge University Press; five editions 1989 to 2019); 
  • Nightwatch: A Practical Guide to Viewing the Universe by Terence Dickson (Firefly Books; four editions 1989 to 2019); 
  • and The Backyard Astronomer’s Guide by Terence Dickinson and Alan Dyer (Firefly Books; four editions 1991 to 2021). 
These two books are not at that level but there’s nothing wrong with them. You would have to search well to find them for more than $10 online and your local used bookstore probably has them for that much or less (and no shipping). And as always, check the city library.

Starwatch by Ben Mayer (New York: Perigee Books, 1984).

 In a layout favored by book designers in the 1970s Starwatch by Ben Mayer offers two unique teaching aids for learning the night sky. The author shows how to construct “starframes” from clear kitchen wrap stretched on coat hangers bent into rectangles. Scaled with the illustrations in the book you can hold the frame up to the sky to find constellations and the deep sky objects within them. 

Mayer also shows how to build a projection system that he calls a “problicom” for revealing new objects that have appeared on successive nights. His system requires two slide projectors. Mayer also insists that you can take pictures of the night sky with a standard 35mm camera and a 50mm lens. That being as it may, it is true that with a different machine on the same principle, Clyde Tombaugh discovered Pluto. Modern technology offers other solutions but the method is sound. 


Those two projects open and close the book. Most of the book is a tour of 25 constellations in the northern night sky. The rest of the book is about celestial coordinates, comets, meteors, adapting to the dark, and other standard topics. For the constellations, every layout includes a classical artistic drawing, a guide to estimate the location, the geometric arrangement of the stars, and a list of interesting targets for your telescope.



 






The Stars : The Definitive Visual Guide to the Cosmos by Robert Dinwiddie, et al., delivers a solution to an esoteric problem with all books: we project a spherical sky onto a flat page. This criticism came up on the Cloudy Nights discussion board as a reason not to give a planisphere to a child. I reject the criticism but I understand the point. The illustrations in this book are spherical projections. Those prints are also pieces of a puzzle that could be reproduced, cut and pasted onto a sphere. Also included are call-outs to favored targets: the Messier objects (of course), binary stars, and so on. 

 

The Stars: The Definitive Visual Guide to the Cosmos
by Robert Dinwiddie; David W Hughes;
Geraint H Jones; Ian Ridpath; Carole Stott;
Giles Sparrow (New York, New York : DK Publishing
and  London : Dorling Kindersley Limited, 2016)




 




PREVIOUSLY ON NECESSARY FACTS

Copernicus on the Revolution of Heavenly Bodies 

De Magnete by William Gilbert 

Galileo’s Two Sciences 

Vectures: Monetizing Urban Transportation 

 


Monday, March 28, 2022

Recent Astronomical Observing

We bought this home in part for its larger backyard and better views of the sky. Nominally, we are still under Bortle 7-8 conditions with the Milky Way not apparent naked eye. However, the high wall around the yard does block a lot of neighborhood lighting. 

 

Messier 47 First View (18 March)

I participate in the Cloudy Nights discussion board. Thanks to Voyageur responding to the topic "Underwhelmed" in the Beginner's forum, I found Messier 47 in Puppis, 18 March 2022 at 2047 CDT. I viewed it until 2120 using different oculars with my ES 102-mm f/6.47 refractor - 32mm and 14mm with and without a 2X Barlow. The 14mm (82 degrees) alone was best. I counted 40, then 50 stars. 



Initially, I was not sure if the target was M47 or M46. They are physically close. However, after I came in, I read Wikipedia and the two are distinctly different in view. I did sweep the area several times but did not find Messier 46 that night. I did find it later.

 

Messier 80 First View (20 March)

 

I found M80 where I expected it, below beta Scorpii (Graffias, a complex system that I see as a binary), and Antares, about halfway and somewhat inward to the body of the Scorpion. It stood out as a classic globular cluster, a "puffball" with a somewhat brighter center but not to be resolved into individual stars with the small aperture and low magnification (D=102mm; 32mm and 14 mm; 20.625 and 47.14 X). Nonetheless, it was a find and I attribute my success to beginner's luck. Also on the same morning, I first found the small open cluster NGC 6231 near zeta Scorpii. A week later, the mornings were warmer and I sketched the view.


 

The allegedly easier Messier 4 does not appear easily in my sweeps near Antares. Reviewing my logs I located it on 14 July 2015, 11 and 13 June 2020, and 31 July 2021. I found it again on 26 March.

 

I revisit familiar objects such as the open clusters Messier 44 (“Beehive”), Messier 7 (“Ptolemy”) and Messier 22, in addition to double stars such as Castor (actually six; only two are available for small telescopes), and mu Scorpii, among many others. I am happy to find again targets that I previously logged such as M6 (“Butterfly”) and Messier 28. 

 

Dubhe alpha Ursa Majoris (23 March) 

With 32 mm and 14 mm (20.6 X and 47.1 X) oculars I checked Dubhe one of the Pointers in the Big Dipper for a companion star because of the ambiguity in my references. Wikipedia says that it is a spectroscopic binary. Sue French (Celestial Sampler) says that it is "easily split" with the companion 380 arc-seconds away. 

 

At 20.6X using a 50-degree Tele Vue Ploessl eyepiece the active field of view is 2.42 degrees or 145 arc-minutes and I did see another star in the FOV. That was also true with the 82-degree Meade 14-mm  eyepiece (yielding 1.74 degrees = 104.5 arc-min). I thought that this was far too wide to be a gravitationally bound binary, but was only another star in the field. 

However, I had it all along. I just did not have an intuitive grasp of the measurements. I know that 380 arc-sec is 6'20" but I did not relate that to Mizar-Alcor which is an easy standard. Mizar and Alcor (“Horse and Rider”) are the center stars of the Handle of the Big Dipper. In a small telescope, they resolve easily to a three-star system with a binary companion close to Mizar. After using the 14-mm Meade (82-degree) and the 7-mm Nagler Series 1 (50 degree) and drawing those views, I put in a 40mm (SvBony Ploessl) which was a mere 16.5X and the companion was there. I checked Burnham’s Celestial Handbook and he provides an orbit and a separation of 12000 light years. 

 

Messier 46 First View (25 March)

I finally found Messier 46 at 2212 hours. After a half hour of sweeping the area where I expected to find it near Messier 47, I came inside and re-read the instructions in Sue French's Celestial Sampler. I had been making the same error as Messier: I was searching ENE instead of ESE. (The cluster was temporarily lost to the archives because Messier transposed two coordinates.) With the 32-mm TeleVue Ploessl ocular for 20.625X, I counted perhaps 20 stars in the center using averted vision to see some and another 20 all around the periphery. Overall, the open cluster is not as sparkly, bright, and attractive as Messier 47. But there it is.


Messier 22 in the east top of Sagittarius is a familiar target.

 

Messier 81 “Bode’s Galaxy” First View (27 March) 

 The sky was exceptionally clear for my location. The small, open cluster at the head of Orion, near lambda Orionis (Meissa) stood out. Knowing where it runs, I could almost see the Milky Way. Following instructions on Cloudy Nights posted by Migwan—diagonally across the Bowl of the Dipper, continue the same distance—it took about ten minutes to locate M81. It appeared as a bright-ish round patch with a bright-ish center. I viewed it until 2117. I did not find the nearby companion galaxy M82. When the sky clears later in the week, I will go out again and search. 

 

Observational astronomy has an epistemological foundation: understanding what you are looking at better enables you to see it. One comparison for myself is junior high school woodworking: cut with a saw; take it closer with a file; finish it with sandpaper.

 

Recent Astronomical Research

As an editor for the History of Astronomy Division of the American Astronomical Society, I usually dragoon other people into writing for the monthly webpage. Recently, I assigned myself several articles. "Planets Have Rings" (here) appeared earlier this month. I am now writing about Agnes Mary Clerke. In July my topic will be the discovery of stellar x-ray sources. 

 

I am awed by what we can achieve now versus what was being done 100 years ago. In Problems in Astrophysics (1903), Agnes Mary Clerke reported on the suggestion of "dark matter." So, even before quantum mechanics informed astrophysics, they were piecing together a coherent view of the cosmos. And they were doing so with instruments far inferior to today's commercial off-the-shelf technology. This photograph was captured by an amateur colleague. Expand the view and you can see a jet of light extending from the lower edge of the galaxy.



"The elliptical galaxy M87 is the home of several trillion stars, a supermassive black hole and a family of roughly 15,000 globular star clusters. For comparison, our Milky Way galaxy contains only a few hundred billion stars and about 150 globular clusters. … The jet is a black-hole-powered stream of material that is being ejected from M87’s core. As gaseous material from the center of the galaxy accretes onto the black hole, the energy released produces a stream of subatomic particles that are accelerated to velocities near the speed of light." -- https://www.nasa.gov/feature/goddard/2017/messier-87

 

PREVIOUSLY ON NECESSARY FACTS

 

Binary Star Project 

Red Shift: Six Years with Astronomy 

Astronomy 

Seeing in the Dark: Your Front Row Seat to the Universe 

Measuring Your Universe: Alan Hirshfeld’s Astronomy Activity Manual 


See also:

The Problem of Induction: Karl Popper and His Enemies 
Harriman’s Logical Leap Almost Makes It