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Astronomical Observatory and Planetarium, Varna, Bulgaria
Special thanks to the National Astronomical Observatory - Rozhen for their help
and to Nadezhda Lyubomirova
for translation in English
EUROPEAN EDUCATIONAL PROGRAMME  "CATH A STAR "

PROJECT: Constellation Ursa Majo r
 
1. Introduction
2. Historical information
3. Passport of the constellation UMajor:
stars, double stars and Messier Objects
4. How did scientists receive the information               
5. Our observations of Ursa Major:
Visual Observations
CCD observstions
6. Comparison between UMajor  and UMinor               
7. Exercise: Orientation using Ursa Major
8.  Conclusion


Secrets of Ursa Major

1. Introduction : The object whose sky secrets we will show is the oldest and the most famous constellation on the night sky- Ursa Major. The popularity of this never going down constellation is caused by its character figure, its nearness to the Northern pole and the numerous interesting astronomical objects in it. This constellation is a star guide - if we start from this object looking at different directions, we can find many constellations on the night sky.
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2. Historical information :
The constellation in past:                       
This constellation has a very long and interesting history.
Many civilizations over the centuries have attached their own particular interpretations and meanings to this area of the sky. What we call the Big Dipper is only part of a much larger area of the sky, the constellation of Ursa Major, or "Great Bear". The ancient Greeks called this constellation "Arktos", a word meaning "bear", which is where our word "Arctic" comes from
these stars were associated with their positions in the  Northern sky. The Greek myth about Ursa Major says that Hera, Zeus's wife, was jealous of Zeus's affections toward a maiden named Callisto, and so Hera turned Callisto into a bear, and Zeus then placed Callisto and her son, Arcas (who became the Little Dipper, Ursa Minor) into the sky.
The constellation Ursa Major contains the group of stars commonly called the Big Dipper. The Big Dipper is not a constellation itself, but an asterism, which is a distinctive group of stars. According to some Native American legends, the bowl of the Big Dipper is a giant bear and the stars of the handle are three warriors chasing it.
The constellation is low in the sky in autumn evening sky, so it was said that the hunters had injured the bear and its blood caused the trees to change color to red.                                                     
Although the whole of Ursa Major is difficult to see without very dark skies, the Big Dipper is one of the most recognizable patterns in the  northern sky. In other cultures it was identified as a wagon or cart, a plow, a bull's thigh, and (to the Chinese) the government.
Bulgarians call this constellation the "car" or the "cart" and have a very interesting tale about it.
The seven stars of the Big Dipper have in the past been associated with the chariot of various legendary heroes and gods. For the Welsh it was King Arthur's chariot, while Germanic tribes called it Thor's chariot. The Vikings saw Odin's chariot. The Big Dipper is also commonly refered to as "The Plough" in English tradition. You can use the Big Dipper as a convenient guidepost to find other important stars in the area: the end stars of the Dipper's bucket point to Polaris, and the arc of its handle leads to Arcturus (in fact, an easy way to remember this is "follow the arc to Arcturus"!) Remember, if you use this method to find Polaris for your first time, don't expect to be led to a brilliant star! Polaris is surprisingly dim!
    In ancient England, Ursa Major was King Arthur's home and was called Arthur's Chariot.  The Irish named Ursa Major after one of their early kings, calling it King
    David's Chariot.  And in France it was the Great Chariot.
3. Passport of the constellation:
Abbreviation : Uma
Genitive : Ursae Majoris
   Position of the sky sphere: Right Ascension: 10.67 hours Declination: 55.38 degrees
Visibility : Visible between latitudes 90 and -30 degrees
Best visibility: Best seen in April (at 9:00 PM). Ursa Major,   There are many interesting stars and Messier objects in this constellation.
   There are many interesting stars and Messier objects in this constellation.
We will show the most important information for the most interesting (according to us) objects from the treasures of Ursa Major. 
In this constellation there are 42 double stars, 11 galaxies and 41 variable stars!!!
In a clear night without Moon in this constellation it can be seen around 130 stars but only 20 of them are brighter than 4 magnitude. When observing the stars from the Constellation Ursa Major it is very useful to be known the magnitudes of these stars. They are:
Stars                                                  Magnitudes
DUBHE (Alpha UMa)                         1.79
MERAK (Beta UMa)
PHEGDA (Gamma UMa)                  2.44
MEGREZ (Delta UMa)                       3.31
ALIOTH (Epsilon UMa)  -                   1.77
MIZAR (Zeta UMa)                              2.27
ALKAID (Eta UMa)                             1.86
Talitha (Iota UMa)                                3.14
Tania Borealis (Lambda UMa)          3.45
Tania Australis (Mu UMa)                   3.05
Alula Borealis (Nu UMa)                     3.48 
Alula Australis (Xi UMa)       
Muscida (Omicron UMa)
Muscida (Pi 1 UMa)
Muscida (Pi 2 UMa)                            3.36   
ALCOR (80 UMa)
Psi    UMa                                             3.01
Very interesting double star is formed from the stars Alcor and Mizar.
Alcor and Mizar, are a visual double found in the handle of the Big Dipper. Easily seen with the naked eye - if you have good vision - this famous double star was often used by American Indians as a test of visual acuity. Try it out for yourself. In a telescope, you will see that not only are Alcor and Mizar a pretty double on their own, but Mizar in itself is also a double star, making this a triple star. Alcor and Mizar, however, are visual binaries, meaning that this is a chance arrangement of these stars in the sky. Mizar and its visual companion, however, are a true double star system. Mizar is again a spectroscopic binary, but its closer companion cannot be seen with an optical telescope.
In this constellation there are 42 double stars, 11 galaxies and 41 variable stars.     
Messier                 Type                      R.A.                Dec.                Mag.                  Size
M40                        Dbl                       12h 20.0         58d 22            9.0                      49"
M81                       Galaxy                   9h 55.6           69d 4              8.5                      21' X 10'
M82                       Galaxy                   9h 55.9           69d 41            9.5                      9' X 4'
M97                       Planetary Nebula 11h 14.8         55d 1              12.0                    202" X 196"
M101                     Galaxy                  14h 3.3           54d 22             8.5                      22.0'
M108                     Galaxy                  11h 11.6         55d 41             11.0                    8' X 1'
M109                     Galaxy                  11h 57.6         53d 23             11.0                    7' X 4'
Short description of Messier objects:

M-81 - A large and beautiful spiral galaxy. It has a bright core with a stellar nucleus, and spiral arms can be seen, especially with avert vision. 
M-82 -A peculiar galaxy is. It has slightly tapering ends, and a great amount of mottling across its length can be seen. The southern edge appears flatter, and it seems to be "pinched" near the center on this side.
M-97 - The Owl Nebula. This large planetary nebula is almost 3' in diameter, and appears as a gray puff of light, slightly brighter in the center. At times, especially with averted vision, the "eyes" of the owl can be seen as two slightly darker spots.                
M-101 - A large face-on spiral galaxy with low surface brightness. It is about 7' in diameter, with a brighter core surrounded by an envelope that sometimes can be seen to be spiral arms.                 
M-108 - This galaxy has an evident central bulge, a stellar nucleus, and tapering ends. The western end appears to be tapered more than the eastern end, and dark markings are seen along its northern edge. 
M-109 - It has faint stellar nucleus. Spiral arms can be seen leading to the north and south. 
NGC 2841 - A very pretty galaxy, with a sharply brighter core and stellar nucleus. Dark markings can be seen, especially east of the nucleus. 
NGC 3079 - Fascinating. Broadly concentrated to the center with pointed ends. At times, the ends appear curled: the north end to the west, and the south end to the east.      
NGC 3631 - Large and impressive, this galaxy is roughly circular and 5' in diameter. The core is about 1' in diameter and has a stellar nucleus. Averted vision shows arms spiraling from the north to the east.                         
The constellation Ursa Major now :

We know that stars are at different distance from us. Some of the stars in Ursa Major are found at huge distances. Bur for us, the observers on the Earth, they are projected at one and the same place
And in future:

Stars have their own movement that can be established after 20-30-year observation. The average movement of all stars that can be seen with naked eyes is less than 0".1 (arc second) for one year. Because of this velocity we cannot see how the appearance of  the constellation changes.  But if we could travel in time and went in future after 50 000 years, we would see that the constellation will be much more different.            
4. How did scientists receive the information :  All objects from this constellation have been studied by astronomers since ancient times. Ancient astronomers measured the brightness of the stars in it and determined their coordinates on the sky. Thanks to observations with telescopes wore and more objects were found. Using spectral analyses astronomers explored all visible stars and received information about their temperature, spectral class, physical characteristics, chemical composition, etc. Astronomers observe and explore galaxies in this constellation. Projects for searching for supernova in  the galaxies in Constellation Ursa Majoris are very interesting. The space telescope Hubble works over observational programmes that include objects from this constellation as well.
5. Our  observations of Ursa Major:
Visual observations:
We observed all stars from this constellation Ursa Major that are brighter than 6m. In the telescope the double star Mizar and Alcor was very interesting. This constellation is one of the most important and we used it for searching for other stars and comparisons, as it is show in the exercise. We observed the objects with naked eyes, with binocular 10x50 and with a small school telescope.
We learned to measure arc distances between the stars in Ursa Major. We used these arc standards to determine distances between many other constellations. For us it was very useful to learn the distances between the stars in the constellation because we can use them for comparisons during our observations of meteors and comets.

CCD observations:
We received our CCD observations of stars from Ursa Major and the galaxy M101. The observations were made with CCD ST8 with 50/70 Schmidt telescope in NAO-Rozhen-Astroschool in June 2002.
.        Aliot                                                         Benetnash                                                      Dubche
        Megrez                                                       Merak                                                           Mizar

Galaxy M101
The images are made in V filter.

6. Comparison:
Let's compare the constellation Ursa Major with the only one constellation that has almost the same shape - Ursa Minor.
              UMajor                                                                                       UMinor                          
They have many similarities : the figure of stars, the nearness to the Northern pole and the fact that the constellations can be seen during the whole year above the horizon, their enormous role for orientation of the four cardinal points, participants in a common legend,
Differences: different area on the night sphere - Constellation Ursa Major is situated in a huger area on the sky, in Ursa Minor all seven basic stars from the main figure are faint, while in Ursa Major the main stars are very bright, there are many Messier objects and a cluster of galaxies in UMa.
7. Exercise: Orientation using Ursa Major
Ursa Major is one of the most well known constellations in the heavens. It contains the famous grouping of stars known as the Big Dipper, which is often the first group of stars learned by people in the northern hemisphere. Several other "firsts" are associated with this constellation; the star Mizar was the first double star to be discovered through a telescope (1662), the first star to be photographed (1857), and the first star to be identified as a spectroscopic binary (1889).
Also, the star Xi UMa was the first binary star  to have its orbit calculated (1828). As Ursa Major lies away from the obscuring dust of the Milky Way, many galaxies are visible in its confines, and several of these are large and bright in amateur instruments due to their relative  closeness. A whole night's observing can easily be spent in this large constellation.
This exercise will show us how we can orient for the cardinal points during the night and how to find many constellations using Ursa Major as a start point.
Task1 : Orientation for the cardinal points.
We find the constellation Ursa Major. We continue the distance between the last 2 stars from the quadrangle and enter 5 times this distance. We reach the Polar star that always shows north. We stand with face towards it. In front of us is North, behind us- South, right- East and left- West

Task2: Aim - Cassiopeia
To find the constellation Cassiopeia, locate the second star in the handle of the
"Big Dipper" and Polaris.  Connect a line through this star from Ursa Major through Polaris.  This will point you through Polaris and on to a "W" or "M"shaped constellation.  This is "the queen," F Cassiopeia. The stars of Cassiopeia are not excessively bright. This will make Cassiopeia a difficult constellation to locate.
Task3: Aims - Regulus from Leo
To find the star Regulus and the constellation Leo, locate the two inner most stars of the cup of the "Big Dipper."  Connect a line through these stars extending from the bottom of the "Big Dipper."  This line will point to the bright star Regulus in the constellation Leo.  Regulus is the twenty-first brightest star we see at night.  It is eighty-three (83) light years away from Earth and is seventy-five (75) times brighter than the Sun.       

Task4: Aim -  Alrai and Cepheus                                              
To find the star Alrai and the constellation Cepheus, locate the two end stars in the cup of the "Big Dipper." Connect a line through these two stars. This will point to the star Polaris. Continue through Polaris and onto Alrai. Alrai marks the point of the constellation Cepheus. This star is not all that bright, but Cepheus is not known for its bright stars. Cepheus was an important constellation in Greek mythology. He was the King of Ethiopia (not present day Ethiopia). This constellation is entangled in mythology with Andromeda (his daughter), Cassiopeia (his queen), Cetus (the monster), Pegasus (helped Perseus), and Perseus (saved Andromeda)
Task5: Aim -  Pollux and Gemini

To find the star Pollux and the constellation Gemini, locate the stars in the cup of the "Big Dipper." One star that will help you to find Pollux is the star that joins the cup and the handle together. Connect a line from this star through the center of the cup to the bottom end   star. Continue on this line until you run into the bright star Pollux.  Pollux is the seventeenth (17) brightest star in the night sky and the fifteenth (15) closest star to our solar system at forty (40) light year's away. Pollux forms one of the two heads of the "twins," Gemini.  Castor forms the other head of the "twins."


8. Conclusion: the introduction to constellations is the first and the most important step when people start studying the sky. Most of the people know only one constellation - Ursa Major. But few people know how interesting and beautiful are the objects in the Constellation Ursa Major. We think that the constellation Ursa Majoris justified our interest. This constellation turned to be one of the most interesting: with many exciting legends that are very important for orientation on stars. All voyagers, all pilots and astronauts start their teaching in navigation with this main constellation. In our project we show not only Ursa Major -a guide for learning other constellations but and many double stars, planetary nebulae and galaxies. We are sure that the introduction to the night sky should start exactly with Ursa Major. This well cause bigger interest in the night sky and will show the richness and variety of astronomical objects in the Universe.

References:
Myths and legends for the constellations, Angel Bonov, 1976
Encyclopedia for children, Moskva, 1999
http://www.corvus.com/con-page/spring/uma-01.htm
http://www.allthesky.com/constellations/ursaminor/constell.html
http://www.starrynight.com

For contacts:
Group:

Kostadin Aleksandrov
Alexander Borisov
Nikolai Ivanov 

Leader:
Veselka Radeva, Astronomical Observatory, Varna, Bulgaria
radevi@mail.varna.techno-link.com
The students are from the Astronomical courses in the Astronomical Observatory and Planetarium "N.Kopernicus"-Varna