Two Deep Sky Targets

 On 28 November, I viewed the Double Cluster in Perseus for the first time. The following night, I was able to find the globular cluster Messier 15 in Pegasus.

I live on the southside of a city of 1.8 millions. So the northern sky is usually washed out with light. For example, as easy as it is to find Polaris, the other stars in Ursa Minor are not visible. I have readily found the double star eta Cassiopeiai with several small telescopes, and I have viewed the Andromeda Galaxay often. So, I measured out some distances and spent about 45 minutes seeking the double cluster catalogued as Caldwell 14. (It is not a Messier object.) Interestingly, it was noted as a permanent patch of light by Hipparchus circa 130 BCE. Guidebooks call it a naked eye target, but I have never seen it from here. 

The telescope was an Explore Scientific achromatic 102-mm refractor. The oculars were Celestron 32-mm Ploessl alone and with 2X Barlow and a Celestron 17-mm Ploessl for comparison, and then a 14-mm Meade 5000 with an 82-degree field-of-view. Both clusters fit within the 17-mm FOV of 1.34 degrees. 

The next night, I made a concerted effort to locate M-15. It took about 45 minutes and much referencing of star charts, but when it came into view, it was immediately perceivable. 

I had tried to mark it by its altitude compared to Altair but looking about halfway between Jupiter and Deneb in Cygnus worked better.

The best view was with the Meade 5000. I used a 7-mm Nagler Type 1 82-degree though at a modest 94X magnification the view was too close to appreciate and the wider view presented both better context and better contrast.

Also, the skies those two nights were exceptionally clear following some rain and I was able to see the double star gamma Capricorni also called Deneb Algiedi, Tail of the Goat, and I verified it in the telescope.

PREVIOUSLY ON NECESSARY FACTS

Eyewitness Testimony: Popper, Wittgenstein and the Innocence Project

Gregory M. Browne's Necessary Factual Truths

Bringing Philosophy to Athens: Aspasia of Miletos

Understanding Objectivism

Learning Lyra

My spatial reasoning scores are always lower than my verbal acuity grades. Consequently, the standard star charts for Lyra, a simple quadrilateral constellation marked by one of the brightest stars in the sky, has been oddly difficult to navigate. Therefore, I returned to basic methods. I have not yet found everything that I mapped out for discovery, but I am confident about the first half of the picture.

What it is supposed to look like

What I mapped in the sky

Although Lyra is supposed to be above Cygnus, clearly, to me, it is not. Of necessity, finding the double stars epsilon Lyrae and zeta Lyrae was a challenge. I have viewed and recorded the famous "double double" epsilon Lyrae several times. It is a target that I know. It is easily above and to the right of Vega.  ("Viewing Epsilon Lyrae" and "Binary Star Project" on this blog.) 

Three of Lyra's stars near Vega are interesting doubles. Barely above Vega is 4th-magnitude Epsilon Lyrae, the Double-Double. Epsilon forms one corner of a roughly equilateral triangle with Vega and Zeta Lyrae. The triangle is less than 2° on a side, hardly the width of your thumb at arm's length.

Binoculars easily resolve Epsilon. And a 4-inch telescope at 100× or more should, during good seeing, resolve each of Epsilon's wide components into a tight pair.

Zeta is also a double star for binoculars. It's much closer and tougher, but is plainly resolved in a small telescope.

And Delta Lyrae, upper left of Zeta by a similar distance, is a much wider and easier binocular pair. Its stars are reddish orange and blue.

https://skyandtelescope.org/astronomy-news/this-weeks-sky-at-a-glance-november-12-20/

At first, I tried following the guides in support of my direct views in the telescope. But I came to understand that the rich star field offered other objects that could match the verbal descriptions.

So, I lay down on a chaise longue with my binoculars and drew out the sky as it appeared to me. And while doing that, I also was able to identify the binary stars, zeta and (of course) epsilon.

  

The cellphone Compass app is handy and the app for Measure includes a Level which is accurate enough for my purposes.

I also made estimates of the separations based on the field-of-view (FOV) calculations for the 12x42 Buhnell binocular, as well as the telescope I was using, my Explore Scientific 102-mm f/6.47 achromatic refractor. 

That left me confident of those views though still open on the problem of locating delta Lyrae. 

PREVIOUSLY ON NECESSARY FACTS

Copernicus on the Revolution of Heavenly Bodies

De Magnete by William Gilbert

In Support of the Entry-Level Telescope

Big Bang Theory: More Friends than Seinfeld

Discovering gamma Arietis

Having packed away the three 70-mm entry-level refractors I was enjoying (last week), I returned to my Explore Scientific First Light 102-mm doublet refractor but now using the better oculars, 82-degree sealed from Meade (14mm; Series 5000) and Nagler (7mm; Type 1), and a Vixen 25-mm SLV Plössl for wider views. The mount was an Explore Twilight I gear-driven Altitude-Azimuth.

10 November 2200 hours. Nominally “clear” but with not much sky, still clearing from rain with high overcast. In Aries only alpha (Hamal) and beta (Sheratan) were easily visible. So, I swept the area. Below Sheratan was another faint star and I found the double gamma Arietis (Mesarthim). Both were about equally bright. The next day, I checked An Anthology of Visual Double Stars by Argyle, Swan, and James (Cambridge, 2019). 

Gamma Arietis was found by Hooke (1664) and verified by Herschel (1779) as being “almost equal” in magnitude. 

Land-based estimates of magnitude for them is Gamma-1 = 4.58 and Gamma-2 = 4.52 while more recent estimates from Hipparcos are 4.75 and 4.64 respectively. Combined they appear as 3.86 from the ground. Their common orbital period is about 5000 years.

 

Two thousand years ago, the vernal equinox was in Aries. (It is now in Pisces and moving to Aquarius, which brings in very many cultural references to new ages.) The coordinates for Mesarthim are given as 

Right Ascension 01 hours 53 minutes 31.76 seconds; 

Declination +19 degrees 17 minutes 37 seconds. 

 

PREVIOUSLY ON NECESSARY FACTS

Newton versus the Counterfeiter

A Successful Imitation of Alan Turing

Coins and Stamps

Burnham's Celestial Handbook

Book Review: The Science and Art of Using Telescopes

The essence of the book is given in the opening. Get past the beginner stage by finding new interests; specialize in subbranches of observational astronomy (page 2; page 4). After that, the writing devolves into a rambling monologue directed at knowledgeable amateurs. The information provided serves more as reminders of what we know, rather than providing new learning or directing us to important resources. Early on and throughout, the author tells us to find out about the current markets for instruments and accessories by referring to “monthly magazines” none of which he names. In point of fact, Popular Astronomy from the SPA appears bi-monthly, and the independent Amateur Astronomy comes out quarterly. The book offers no suggestions for websites, discussion boards, chatrooms such as Facebook and Reddit, or other online social media.

Author Philip Pugh does name his favorite brand of equipment, Sky-Watcher. He cites them 16 times (as “Skywatcher”), which is as often as he cites Meade (7), Celestron (6), Takahashi (2), Astro-Physics (1) , and Tele Vue (1) combined. Other labels are similarly passed over with brief mentions. 

The Science and Art of Using Telescopes
by Philip Pugh, Springer, 2009. 

The references to Astro-Physics and Tele Vue underscore the fact that this book is poorly edited. The brand names are misspelled as Astro Physics (page 250) and indexed as Astro physics; and Televue. Takahashi is misspelled as Takashi (page 28) and Takahasi (page 250). Plossl (never, as proper, Plössl or Ploessl) appears in the index as two lists: Plossl and Plossl eyepiece. 

 

Those small errors reveal the lack of professional proofreading. That speaks to the painfully obvious fact that this book reads like a first draft. The author loves (even in parenthetical comments!) exclamation points! Pugh just wrote this off the top of his head and Springer accepted it uncritically.

 

As an indication that the author did not have his manuscript fact-checked by an independent reader or even check his own work, the definition of ED (extra-low dispersion glass) is wrong, and wrongly stated. He calls ED “extra dispersion” throughout the book, and in the Glossary: “An extra dispersion lens is an improvement in the achromatic objective lens theme where it uses extra dispersion flint glass to improve performance.” (page 368). 

ED Extra-low dispersion

"Nikon's original ED (Extra-low Dispersion) glass lenses effectively compensate for color fringing especially at high magnification." -- https://imaging.nikon.com/lineup/sportoptics/how_to/guide/fieldscopes/choosing/choosing_03.htm

"ED stands for "extra-low dispersion," which refers to the composition and optical properties of the glass used for the lenses.  ED glass is specially formulated and contains rare-earth compounds that greatly reduce a visual defect called chromatic aberration." -- https://www.celestron.com/pages/ed-glass

ED glass enhances apochromatic lens design by producing extra-low dispersion of the wavelengths of light passing through it thereby giving an even better apochromatic performance.  -- https://explorescientificusa.com/collections/apo-triplet

In this chart, standard glass is shown on the far left. To the right of it are two commonly used extra low dispersion (ED) glasses. -- https://www.stellarvue.com/optical-glass-types/

Perhaps the hallmark of his style is that he avoids unequivocal statements. Pugh cannot discuss telescopes (pages 6-8) without digressing to his preferred choices among binoculars, even though “Choosing Binoculars” is the next section after “Choosing a Telescope.” Paradoxically, that section is not at all about choosing a single telescope but argues very well that you need more than one. The author’s apparent fear of absolute statements results in meaningless advice. “While it is true that the Usual Suspects (see the appendix) can sometimes look better under clear conditions, some gems such as M81 in its full glory have to be enjoyed while the chance is there.” (page 41). That sounds like good advice: whatever your skies right now, take the opportunity to view what you can. But if you read the words carefully, Pugh is saying that M81 can be seen in its full glory even though not under clear conditions, which contradicts the opening clause. 

 

That example is from the section “Too Cloudy to Go Out?” (page 40-41) which is about why is it not really too cloudy to go out because telescopes can often cut through poor seeing conditions. Faint clusters, dim companion stars, and more can all be viewed under bad conditions. I get the point, but an editor would have retitled the heading. 

 

Aversion to unequivocal assertions delivers many instances of “however.”  

“Unguided exposures at long focal lengths can be troublesome on some mounts because of tracking errors. However, you will find that auto-guiding can compensate for this very well. Celestron offers a version of this mount. Moving up in quality and performance, companies such as Astro Physics, Takahasi [sic], and Software Bisque manufacture excellent mounts. However, considering the typical cost, they are not mounts for a beginner!” (page 250). 

Why are such mounts not suitable for a beginner who can afford them? He never says. 

It is disappointing in a book that recommends finding new interests that the author provided no pointers to the organizations that support the many sub-branches of observational astronomy and citizen science. On page 114, the author discusses occultations but only someone who knows the hobby well would know about the International Occultation Timing Association (IOTA) or the fact the the Society for Popular Astronomy has an Occultation section and that the chair of that committee will generate a spreadsheet for you of occultations predicted for your location. Similarly, for lunar, solar, and planetary viewing (Chapters 2, 3, 4), the Association of Lunar and Planetary Observers (ALPO) was founded in 1947 for amateurs, and the American Astronomical Society (open to amateurs) also has its Division for Planetary Sciences. For deep sky viewing, AAVSO (the American Association of Variable Star Observers) maintains a peer-reviewed archive of data, much of it provided by amateurs.

PREVIOUSLY ON NECESSARY FACTS

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

Turn Left at Orion

Michael Shermer's Moral Arc

The Science of Liberty

70-mm Shootout

Start with the mount. Just as the scabbard called “Avalon” was more powerful than “Excalibur” (the blade it sheathed), the positioning mechanism (“mount”) is more important than the telescope. In every case here, you could keep the telescope, but throw out the mount. But any telescope is better than no telescope. Given the limitations, if $159 is your price point, then these will show the stars you cannot see.  

Meade 70-mm StarPro Refractor

Celestron 70-mm AstroMaster Refractor

National Geographic 70-mm Refractor

Celestron AstroMaster 70 AZ Refractor Focal length=900mm; ratio f/13. $189.95 from Mile High Astro. Comes with two Kellner oculars, 20mm and 10mm.

 

Meade StarPro AZ 70mm Refractor Focal length=700mm; ratio f/10. $159.99 from Mile High Astro. Comes with three Kellner eyepieces, 26mm, 9mm, and 6.3mm oculars; and a 2X Barlow lens.

National Geographic Refractor Focal length=700; ratio f/10. $109.99 from Explore Scientific. Comes with two Ploessl oculars, 26mm and 9.7mm, and a 2X Barlow lens.

 

The Meade mount is not easy to use. Altitude and Azimuth clutches must be very, very tight and even then, the azimuth does not work well when it works at all. At best I can turn the handle and at the same time nudge the telescope from the strut. 

CELESTRON
PAN-TILT MOUNT

The Celestron pan-tilt mount is even worse. It is too tight even after disassembly, degreasing, and relubrication with WD-40 Silicon. In these tests, the Celestron was usually on an Explore Scientific First Light mount. In fact, after fighting with the mounts, the first night, I set them into an Explore Scientific Twilight I mount for its ease and stability. 

The mount and tripod of the National Geographic is a bad design. The altitude (or declination) is a twist knob screw drive and that works well. However, the thumbwheel for the right-left (azimuth or right ascension) was immovable with my left thumb, and jerky with my right.

Overall, the Meade is the best of three. I was disappointed in the Celestron because I had hoped to make good use of its longer 900 mm focal length. However, it did not stand up to simple backyard stargazing. The National Geographic was worst of the three. The objective lens was flawed, displaying ghost images from internal reflection. I already own a National Geographic that I was happy with and I bought this to test against it. The new one is not as good as the old one. The old one does not have ghosts.

From Star Ware by Philip S. Harrington

The Meade and Celestron come with Kellner eyepieces, a basic three-element design from the 19th century. Today, the baseline is the Ploessl design, also from the 19th century, but a more sophisticated four lens system that became popular in the 1980s. Kellners are considered to be cheap downgrades for these entry-level instrument packages. The National Geographic Ploessl eyepieces are Bresser branded. 

Overall, these do their best work with stars, not planets. With all three, among the first views were the Orion Nebula (Messier 42), resolving the interior Trapezium group, and then turning to the nearby open cluster Messier 41 (below Sirius). The last sessions were simple tours of the rich star field near Delta Cygni, the center of the Swan or Northern Cross. It was enjoyable because the area offers so many stars including red giants and binary stars. 

Jupiter, Saturn, and Venus were all challenging and disappointing in all three telescopes. I could identify the planets. The rings of Saturn were easy to define. However, all were plagued by cloudy, foggy glare from the bright disks. 

However, the Meade had a saving grace. It comes with an aperture reducer, a clever old hack from experienced observers, a mask--in this case a hole in the dust cover--which allows a limited cone of light increasing the focal ratio by reducing the aperture in order to bring out more details in planets, but at a cost of brightness.

After trying out all three in their "native mode" with the eyepieces provided in the package, I followed the advice offered by a customer service representative from Mile High Astro and tried them with my best oculars. 

06 November 2021 Testing with the best oculars: 

TeleVue Nagler-1 82-degree 7mm

Meade 82-degree 14mm

Vixen SLV 25mm. 

 

(discount priced)
Meade logo but no name
Series 5000 14 mm
82-degree field of view

1915 hours

Meade 70-mm StarPro with 7-mm. Nagler 

Saturn. 1 band north. 1 ring. Some hint of texture to the ring on the east side.

Titan? and Tethys? (It seemed so at the time, but the Sky & Telescope “Saturn” page (here) says no: these were just stars in the field.)

 

Jupiter. Hard to focus. Some chromatic aberration but north and south bands visible and some texture to equatorial region.

 

1938 hours

Celestron 70-mm AstroMaster with 7-mm Nagler.

Saturn. Hazy. Foggy. Titan (or star) discernable. Ring visible. 1 band north. Near limit of resolution. Image spotty and grainy.

1947 hours

Nagler 7mm Type 1

82-degree Field of View

12mm Eye Relief

7 element system

Jupiter. Hazy. Foggy. Near limit of resolution? (Inspected objective lens and diagonal prism for dew or condensation, but both were clear.)

 

1955 hours

Celestron 70-mm AstroMaster with 14-mm Meade.

Jupiter smaller (of course). Not as foggy. Still hints of diffraction rings. Two bands discernable. 

(Checked magnification: 900 / 14 = 64+. It should be a clear view.)

 

2005 hours

Meade 70-mm StarPro with Meade 82-degree 14mm.  (50X)

Jupiter. Nice view. 2 bands. Some chromatic aberration.  Not bad.

Used aperture reducer. Sharper image. More detail on planet. Not as bright. But more detail in the equatorial between the bands North and South.

 

2016

Meade 70-mm StarPro with Meade 82-degree 14mm.  (50X)

Saturn with aperture reducer.

Vixen SLV
Lanthanum coated
Twist-up eye cup
All metal body

Sharp image. No bands visible. Titan (?) discernable though faint, of course and one more moon (?) behind the planet. 

2032

Meade 70-mm StarPro with Vixen SLV 25-mm

Delta Cygni region. 

Lots of stars. Focus OK, not perfect, but close. Scanning area, settled on a red star at center and a discernable binary to the north or east. Lots of stars to look at in my Bortle 7-8 with no Milky Way. The telescope comes with a Modified Achromatic (Kellner) 26-mm, which is OK.

07 November 2036

Celestron 70-mm AstroMaster with Vixen SLV 25-mm Delta Cygni region. (see above: The area is rich with targets to observe, record, and enjoy. This telescope comes with two eyepieces, 10mm and 20mm, which magnify too much (45X and 90X) for broad and wide fields such as this, the Pleiades, and the Moon.  

Because the project began with the challenge to split the double-double of epsilon Lyrae with a 70-mm refractor, here are those notes.

 

01 November 2021

Celestron AstroMaster 70-mm refractor.

1948 Installed Celestron Lens&Filter kit Ploessl 6mm and kit 2X Barlow and successfully split the companions E Lyrae E1A and E Lyrae E2A. 

Smaller, of course,
but about like this

05 November 2021

1955 Chasing epsilon Lyrae.

2011 Chasing epsilon Lyrae.

Celestron 70-mm AstroMaster with 8mm Celestron Ploessl and 2X Barlow.

Note that northern members are touching. Western pair definitely separated. I tried the 6mm with 2X Barlow but it was just too hard to fight with the pan-tilt camera mount.

PREVIOUSLY ON NECESSARY FACTS

 

Focus on Georg-Simon Ploessl 

Product Review Celestron AVX Mount and Tripod 

Galileo and Saturn: Epistemology, not Optics 

Observing with NASA: An Open Platform for Citizen Science 

Below the fold.

Open the Jump to see all of the notes that I took 31 October to 05 November 2021.