"GO TO"....DRACO, Ursa Minor and Cepheus
Dithering in the Domain of the Dangling Celestial Dragon...
by: Clay Sherrod
In this SIXTH constellation guide installment, "GO TO DRACO, Ursa Major and Cepheus"- of our constellation study guides for GO TO telescope users - we will explore a fabulous selection of fine nebulae, some unusual galaxies and some very nice and often overlook double and multiple star systems that are ideal for all telescopes. As will all of our "GO TO GUIDES", this guide begins with a "start" of an easy GO TO to the bright star THUBAN, in the long and meandering constellation of DRACO and then proceeds through the many WONDERFUL interesting objects within reach of YOUR telescope, not only in Draco, but the surrounding constellations of Ursa Minor (yes, there is something to see there) and Cepheus! This sixth Guide encompasses Draco - a "dragon" or sometimes imagined as a "water dragon" - , Ursa Minor - the "lesser Bear" - and Cepheus - a very kingly "King" and husband of philanderer Cassiopeia. From bright, beautifully-colored and complex multiple star systems, to very challenging planetary nebulae, there are discussions along the way to tell you what to expect from each telescope size and type. All objects will be discussed with exact descriptions of what the viewers with any telescopes should expect to see...and what to NOT expect to see!
As in all Guides, useful magnifications for EACH GO TO object are discussed for certain telescopes, what type of night and conditions are needed to see certain details, double stars that can be resolved in each telescope model, and much, much more. It is your complete GUIDE for your deep sky observing pleasure and a very handy tool for use at your next star party!
Needless to say, it WILL put your GO TO telescope to work for you in a most efficient and enjoyable way!
I hope you will enjoy these comprehensive ASO GUIDES to "Touring the Constellations" which will features the most prominent constellations, complete with diagrams, charts and illustrations. Please let us hear from you with summations of YOUR observations through these constellation tours!
The constellation of DRACO (pronounced "DRAY-co") is a large, winding and meandering string of stars that pretty much fills the high northern skies of spring and summer. The slithering dragon has been of much greater significance in history than we see it today, particularly in the mysticism of the Egyptian times of the Great Pyramids and Pharaohs.
The skies of 5,000 years ago were noticeably different than they are today; yes, the "fixed stars for the most part were right where we know them to presently be, but the EARTH itself was tilted to a slightly different vantage point....an aspect of "precession" that is a result of the Earth's axis pivoting over a long period of time, like a wobbling toy top. As it does, the axes of the Earth - both north and south - will point to different parts of the sky.
That's right....Polaris has NOT always been our "north star." Boy Scouts of ancient Pharocian Egypt would have to learn another way of reckoning "north" than by the bright dipper stars Duhbe and Merak.
Indeed, ancient skywatchers - the Priests - of Egypt about 3,000 B.C. were much aware that the not-so-bright star THUBAN was the "north star" of those skies long ago. The diagram above demonstrates the constellations of Draco, Ursa Major and Ursa Minor as they appear to "move" (actually it is the Earth that is wobbling and pointing differently, not the constellations) and hence rotate the honor of hosting the "Pole Star" in this past 5,000 years.
Interestingly, in "only" 15,000 MORE years, this precession will have continued until the brightest possible "north star" ever will be in position....the brilliant white VEGA, in the constellation of Lyra!
The designation of a DRAGON, or "water dragon" to Draco is due probably to two aspects: 1) its brighter stars meander through the sky in stringlike fashion that can easily be imagined as the long neck and tail of the dreaded creature; and 2) more importantly is the ancient legend of the Nile of which a "dragon" is very important to the people of Egypt.
The Nile river - and hence all rivers pretty much - was life-giving to the ancient Egyptians, its springtime floods providing the irrigation necessary to sustain crops for the growing population. The clouds of the brilliant late spring and summer Milky Way were envisioned by these people as a great celestial river, along which the SUN GOD RA would ride in a boat on a daily course through this great river. His head was the mighty sun which shone in full brilliance and majesty when directly overhead. In the Egyptian hieroglyph below you can clearly see RA in the center of the river boat, wearing the brilliant sun atop his (its) head. The identities of the other curious features (except the stars surrounding the boat) are unknown.
Occasionally, the great RA would be overtaken and devoured in this journey by a huge Water Dragon and the bright sun would disappear from sight (this was the solar eclipse in case you are wondering). But much to the credit and strength of mighty RA, the sun would ALWAYS pop forth and emerge from the belly of the great Water Dragon.
At any rate, the importance of this star - THUBAN - in the "water dragon" is even more compounded when we consider that it appears that the Great Pyramid of Khugu at Gizeh - the most perfect giant structure in the world - was constructed in such a way that a shaft in the pyramid is aligned precisely to Thuban on or about 2,830 B.C. The precision of this alignment of this incredibly narrow and extremely long shaft with what was then the Pole Star appears to be anything but coincidental.
In our GO TO Guide, we also look at the few objects in Ursa Minor, the "lesser bear" to its huge and perhaps more interesting "greater bear", Ursa Major.....and to the realm of King Cepheus, home of the original and world-famous first Cepheid variable star!
The click-on chart shown below can be downloaded to a file on your computer, resized in that file and printed as a complete star reference chart for these three constellations. Each of the reference numbers apply to the concise listing of objects found following. The outlines that portray Draco can easily be imagined into the shape of our slithering water dragon....on the other hand, much imagination is required to see a "lesser bear" in Ursa Minor and more so a "king" in Cepheus.
Just for the record, Cepheus discovered - or suspected in some mythology - his beautiful and young wife CASSIOPEIA as having some illicit dealings with the handsome, strong and heroic PERSEUS. In a fit of jealous rage and resentment, King Cepheus banished the Queen eternally to the sky, strapped in her heavenly throne and perpetually encircling the pole, as the desperate Perseus follows in pursuit in the exact opposite part of the sky. Looking at a star chart or planisphere reveals quickly that, no matter how hard the poor chap tries....he will NEVER catch up with the shackled Cassiopeia.
And....watching the merry-go-round of love from afar: King Cepheus.
Click for full size version
YOUR DRACO / URSA MINOR / CEPHEUS CONCISE DIRECTORY
There are 14 objects in this constellation GO TO tour; all are in reach of every telescope. Yet each telescope will demonstrate uniquely different and challenging aspects of the objects. In addition to the 14 finest objects, there are literally hundreds of wonderful double stars that are visible in most telescopes as well as many fainter globular clusters (check your AutoStar library for "ngc" listings!), stars of curious colors and motion.
As will all of our GO TO TOUR GUIDES, I continue to recommend good a good star atlas and/or chart/or computer sky program which lists the finest objects constellation-by-constellation; if you cannot access any of these objects (or those that are not listed in this TOUR), you can access directly from coordinates - Right Ascension (RA) and Declination (DEC) of any known object via the AutoStar. You merely need to hold down your MODE key on the AutoStar for three (3) seconds and the RA and DEC coordinates appear for the telescope. Merely press "GO TO" and the cursor appears prompting you to enter the Right Ascension of the object if it is NOT listed among the objects in the AutoStar library; once the RA is entered, press "Enter" and the cursor once again prompts for the Declination coordinates (these coordinates for epoch 2000) are found in all good observing guides). Once those are entered, merely press "GO TO" once again and your computerized telescope will slew to the position of the object!
The following constellation guide to objects at the end of this TOUR will describe all the details of each object and provide specifics as to visibility of that object in YOUR telescope aperture.
The constellation tour star chart provided above (click on and print to size, above) will get you started, as it demonstrates the relative positions of all objects in this "tour" to the conspicuous stars outlining the distinct figures of our three constellations of this TOUR.
Following is a concise directory of the complete 14-object list for your "GO TO TOUR" of Draco, Ursa Minor and Cepheus; you may wish to find the majority of the objects from the AutoStar library (for example, you can merely pull up Messier 102 by going to "Object/Deep Sky/Messier Object/M-102....enter....GO TO" or...if you want to experiment and be a "better AutoStar user", try entering the following coordinates (provided in the list directly following) as described under MODE above.
bright star - THUBAN(alpha Draconis) - R.A. 14h 03' / DEC + 64 37 - Magnitude: 3.6
great double star - Mu Draconis - R.A. 17h 04' / DEC + 54 32- Magnitudes: 5.5 & 5.5
tough triple star - KUMA - R.A. 17H 31'/ DEC + 55 13 - magnitudes: 4.9(2) AND 7.1 (2)
TEST for LX 90 - 20 Draconis - R.A. 16h 56' / DEC + 65 07 - Magnitudes: 7.1 & 7.3 (tough
one of the closest doubles - ADS11632 - R.A. 18h 43'/ + 59 30 - Magnitudes: 8.9 & 9.7
galaxy - Messier 102 (ngc5866) - R.A. 15h 05' / DEC + 55 57 - Magnitude: 10.8
planetary nebula - (ngc6543) - R.A. 17h 59' / DEC + 66 38- Magnitude: 8.5
OBJECTS OF INTEREST IN URSA MINOR:
north star - POLARIS - R.A. 01h 59'/ DEC + 89 02 - Magnitude: 2.1(v)
reference star - KOCHAB - R.A. 14h 51' / DEC + 74 22 - Magnitude: 2.0
OBJECTS OF INTEREST IN CEPHEUS:
nice double - Beta Cep (ALPHIRK) - R.A. 21h 28' / DEC + 70 20 - Magnitudes: 3.3 & 8.0
famous variable! Delta Cep - R.A. 22h 27' / DEC + 58 10 - Magnitude: 3.9 to 5.1 (5.37 days)
star cluster - (ngc188) - R.A. 00h 39' / DEC + 85 03 - Mag.: 9.3
large open cluster - (ngc6939) - R.A. 20h 30' / DEC + 60 28 - nice, 80 stars
diffuse nebula - (ngc7023) - R.A. 21h 01' / DEC + 67 58 - Magnitude: 7.2
A VISUAL GUIDE TO OUR OBJECTS IN THIS CONSTELLATION SELECTION -
Object 1 - Bright Star THUBAN (alpha Draconis)
From the Arabic, this magnitude 3.7 star is actually a translation of the name (Dragon) of the entire Draco constellation. The easiest way to locate Thuban is look for the brightest star almost exactly one-half way from the bowl of the "little dipper" (use the star Kochab) to the famous double stars Alcor and Mizar at the "crook" of the handle of the "big dipper." other than its history of 5,000 years past, the star is most uninteresting other than the fact that it MAT be slightly variable, fluctuating between 3.7 and 4.2 (maybe) and is also known to be a spectroscopic binary (a double star that cannot be visually resolved, but shows to distinct spectral "fingerprints" with a spectroscope).
Object 2 - Very Easy Double Star - Mu Draconis (ERAKIS)
This double star - at a separation of 3.2" arc - is an easy target for all of our scopes. In the smallest telescopes high magnifications (about 50x per inch minimum) are required to split this pair. Look for two EQUAL magnitude stars (5.1 each) aligned in a nearly precise north-south orientation. It makes a nice average brightness double for the 4- to 6-inch at about 100x. About 14" arc distant is a third small and faint (13th magnitude) companion that MAY be glimpsed with the 8" scope on a very steady and very dark night at about 220x magnification. Averted vision is required to see this companion." This companion star is a very small dwarf star, less than 180 times dimmer than our own sun.
Object 3 - KUMA (ADS 10728) very wide an interesting quadruple system
Okay, now that I've gotten you attention, the main TWO stars are very wide apart - some 61" arc, larger than Jupiter appears at the same power you observe these twin magnitude 4.9 stars! Thus, they are extremely easy in even the smallest scope at low power. However, that being said, there are two MORE companions to this interesting group, now nearly due north of the bright pair. At magnitudes 7.2 and 8.2, and only about 1.2" arc from one-another, the pair can first be seen as one object close to the brighter stars; THEN increase the magnification on the 6- to 8-inch scopes until resolution is achieved. Even though both scopes can clearly resolve at this level, it is not so easy as it might seem.
Object 4 - 20 Draconis - A very tough double star resolution test for 6- and 8-inch telescope!
This one is tough, and like the object below (Object 5), you will be required to enter the coordinates manually to access it. At magnitudes 7.1 and 7.3, be sure that you have the correct image (it will look like one star at low power) centered in the scope prior to trying to resolve. There are a LOT of 7th magnitude stars in this same area! Once there, begin increasing power on the 6-inch; at about 220x, you should begin to see some clear dark separation in these two stars. Save your time with the smaller scopes....it can't be done.
Object 5 - ADS 11632 - One of the closest double stars to Earth
Being so close to the Earth - only 11.3 light years - this star pair has moved an incredible 30" arc (2/3 the size of Jupiter) in the last 30 years! This is a very interesting pair of red dwarf stars of magnitude 8.7 and 9.7 separated by about 12" arc. This distance is adequate for a clean "split" with the 3-inch and larger scopes, but the relative faintness of them makes this a very tough target and a true observer's test in the 3-inch (and sometimes in a 4-inch). You MUST use your ENTERED COORDINATES AND GO TO on this one....hold down "Mode" for three seconds until you see the RA and DEC coordinates of where you are pointing with the sky program and press "Enter." Then type in the RA as the cursor prompts and once done again press "Enter"; then type in the DEC coordinates. Once complete, hit "Enter" again, and the telescope will take you there!
Object 6 - Messier 102 (ngc5866) - A very nice and unusual galaxy
Although known as "Messier 102" this object was likely NOT seen by Messier and not originally part of his list; several additions were made after his list was published of objects that more modern astronomers "thought" that Mr. Messier should have seen (or perhaps "did" see) and thus they felt it necessary to add them to his famous list of 100. Messier 102 is an object worth attempting to locate. At magnitude 10.8 or so, it is one of the most difficult galaxies on the Messier list, but it is so small that its brightness is "compacted" into a more brilliant center. In photographs, this object looks like a "flying saucer" seen from the edge, as can be seen in the beautiful Lick Observatory photo below. Because of its concentrated brightness, it is possible to see this galaxy and a bit of this shape even in the 4-inch telescope at about 120x....the "UFO shape" is clearly evident in the 6-inch and larger telescopes at about the same magnification. This faint object is just on the verge of visibility to the smaller telescopes at best will appear as a very faint out-of-focus star.
IN URSA MINOR.....
Object 8 - Our "North Star" POLARIS (alpha Ursa Minoris)
What can I possible add to the already voluminous accounts of this otherwise uninteresting star? Right now, it just happens to be our north polar star (see above), or otherwise it would be a very often-overlooked medium bright star will little to offer casual observers. But that has not stopped civilizations throughout history from building great temples, churches, monoliths to its honor. Indeed, in earlier times, Polaris was known as "Al Kutb Al Shamaliy", or the northern spindle and signified the beacon toward mighty Mecca. For observers today, Polaris IS a wide double star and one worth taking a look at! It is listed on your sky program, so why not? Have you ever done a GO TO to the object you usually use for home position alignment? I doubt it. The brighter member of the Polaris pair is a variable Cepheid (see discussion below) of magnitude 2.3 normally. The faint 9th magnitude companion of Polaris is a whopping 19" arc distant, about due west of Polaris itself. It is really worth a look, as this tiny star in the 6-inch is a distinct BLUE COLOR and quite a nice contrast to the brighter star. Use medium (about 75x) magnification for the best look for color and contrast.
Object 9 - Our famous KOCHAB (beta Ursa Minoris)
About 3,000 years ago, Kochab was very near the north celestial pole, so it has shared this honor with Thuban and Polaris. This star is referenced here because it has become somewhat "famous" with telescope users from the increasingly used "Clay's Kochabs's Clock method of accurate portable telescope polar alignment first published right here on ASO; the Kochab Clock is available from the ASO Home Page TABs at top; use it: you will love it!
Object 10 - Nice Double Star - a great test for small telescopes - ALPHIRK (beta Cephei)
Here is an excellent challenging double star for small APO refracting telescopes. Alphirk (also spelled "ALFIRK") is relatively bright (magnitude 3.1) star with a fainter 8th magnitude companion some 14" distant, nearly due west from the brighter star. It is an interesting object that will require about 100x in these scopes to see the fainter star. In the 4-inch it is a very nice low power target, but loses some of its beauty in larger instruments. It might bear looking at regardless, however when you know an interesting aspect of this very bright "newer" star. At a distance of 930 light years, it has an actual luminosity that - if it were located by Earth at the same distance as our sun....it would OUTSHINE it by 4,000 times!
Object 11 - Delta Cephei - the "granddaddy" of the "Cepheid Variables"
By nature of its light changes of ONLY 3.6 to 4.3 magnitude and its AVERAGE brightness of only 3.6 or so, this star should be relatively uninteresting. However, you can literally set you clock by the variations in light of Delta Cephei, with its precise pulsating period of 5.366341 days!
If you are interested in observing this star (naked eye only....there is nothing to be gained by using a telescope to estimate brightness changes) you can download and save the file the following link for a chart of Delta Cephei; merely save it to file, resize and print off the chart which shows a wide field of view and many comparison stars suitable for comparing through Delta's entire cycle. Link to this chart at:
https://www.aavso.org/apps/vsp/ . Note for these charts, simply type in the NAME of the variable at top to generate your choice of chart.
This huge yellow giant "K" type star was first discovered as variable by John Goodricke in 1784 and is perhaps the "most watched" variable outside of Algol. These stars are now quite common and have been found to actually GROW and SHRINK in size, accounting for their apparent magnitude variations. With periods of merely a day to some 50 days, the Cepheids can be used for incredibly accurate gauges for determining distances to objects in space, merely by their apparent brightness and their periods of variation. I highly recommend to all observers to take the time to reference these interesting stars and read of their history and usefulness in modern astronomy.
Object 12 - "Ancient" Galactic Cluster - ngc188
Located only 4 degrees SSE of Polaris, this very distant (5,000 light years) galactic cluster may well be on the order of 24 BILLION years old, one of the oldest known. The nature of its stars suggests that it is more similar to the GLOBULAR CLUSTERS, like Messier 13, than to the loose and younger "galactic star clusters". IMPORTANT NOTE: if this estimation of the age of this cluster is, indeed accurate....it makes it perhaps the OLDEST known object, not just in our own galaxy....but in the entire UNIVERSE.
With 6- and 8-inch telescopes, this cluster is impressive, appearing as a "dusting" of tiny stars just at the threshold of visibility. Only a few of the brightest of its yellow giant stars can be detected. At magnitude 9.1 and covering a large 15' (one-half moon diameter) of sky, this object is too faint for small telescopes and is a quite difficult object even for the 4-inch. With the 6- and 8-inch scopes at very low magnification, it is an awe-inspiring sight, with the faint stars around the edge of M-62 glowing clearly and the bright cluster suspended in the starry field.
Object 13 - Guess what...ANOTHER galactic cluster: ngc6939
This is yet another star cluster, but this one is much richer in stars (at least that can be seen) and not so distant as ngc188 above. There are about 80 stars in this cluster, most of which are visible in this VERY tight (only 5' arc) cluster with the 8-inch at medium-high power. At about 125x in the 4- and 6-inch scopes this cluster can reveal about half that many. this cluster is beyond the reach of smaller telescopes.
Object 14 - Diffuse Reflection Nebula - ngc7023
This is a rather large but overall very bright (magnitude 7.3) nebula due southwest of Alphirk. Because it is spread out so much (over 18' arc of sky - "2" Jupiter's), it requires a VERY dark sky to see this in all scopes. Use as low a power as possible and do not attempt to observe unless sky conditions are almost perfect. Low powers and very wide field reveal a very interesting and memorable field of stars..
WANDERING ABOUT....YOUR NEW "USER OBJECT" IN CEPHEUS
This brief GO TO Tour of Draco, Cepheus and Ursa Minor has taken you into one of the many "void" areas that seem to not have a rich display of astronomical delights. But remember....all the cosmos should delight you! THIS USER OBJECT is not even part of our TOUR this time! It's like a Christmas surprise, and the COLOR is quite appropriate for such an occasion as well. We are going to load as your next AutoStar User Object:
"Herschel's Garnet Star" - R.A. 21h 42' ; DEC + 58 33. Magnitude 3.7-5.0 (variable). Here are the details on this remarkable star. It is a variable with MULTIPLE superimposed periods, and thus the true period is NOT known. It is an incredibly "late" highly evolved giant star and very, very red! Hence "Garnet Star". You will be thrilled with this star at low to medium power, appearing as a ruby in the sky! This is a gem for all of our telescopes, so load this one up!
LET'S LOAD THE "GARNET STAR" AS A USER OBJECTS! You could not find any more appropriate and interesting subject to add to your growing "User Object" library.
On AutoStar, go to: "Select/Object [enter] and scroll down to "user object" [enter]. Now enter the coordinates listed above for the "Garnet Star". Under "description" put in a nice title for it ...be creative with your brief description.
Good observing and explorations of the wonderful world of deep space!
Arkansas Sky Observatory
Conway / Petit Jean Mountain