Stockton Astronomical Society
Valley Skies - December 1999 Issue
Constellations:
Cetus
Gen: Ceti
Abb: Cet
Dec: -25.2° to +10.2°
RA: 23h 55m to 3h 21m
Area Covered: 1231 square degrees
Cetus is Latin for "whale," but throughout history it has been viewed as a monster. More often than not this constellation is pictured as a "Sea Monster". The sea monster is generally depicted with paws, a large rearing head and a long scaled tail. Cetus lies in an area of the sky known as The Sea, along with Pisces, Capricornus and Aquarius.
Cetus is visible in the evening sky from September through January, and is at it’s highest point at about 8:00 P.M. in early December. The stars in the fall evening sky are relatively faint, making the constellations in this area much harder to find. A case in point is trying to follow the stars in Pisces, most of which are 4th and 5th magnitude.
To find Cetus look for the reddish star Aldebaran in Taurus and the bright, blue-white star Fomalhaut in the constellation of Piscis Austrinus, located low in the southeast. Cetus can be found in the open area between these two stars and just a little to the south. Even though Cetus is the fourth largest constellation in the Northern Hemisphere, all of its stars are rather dim so you will need your planisphere to pick it out.
Cetus is an ancient constellation that dates back to the 2nd and 3rd millennia BC. The Sumerians and Babylonians saw Cetus as the mythical dragon Tiamat. Tiamat was the god of chaos and legend tells the story of Enlil doing battle to bring order to the world. To do this he gathered all the winds and as Tiamat attacked with her mouth open Enlil forced the wind inside so that Tiamat couldn’t move. Enlil then cut Tiamat in half; one half he flattened out to form the Earth and the other half he allowed to remain full of the winds to form the sky.
In Greek mythology Cetus was the monster released by Poseidon to ravage the coastal areas of King Cepheus’s land after Queen Cassiopeia bragged about being more beautiful than the Sea Nymphs.
The Greek poet named Aratus described the constellation in his poem on astronomy, "Phaenomena," which he wrote during the 3rd century BC. It was later that the Romans saw it as a whale and gave the constellation its present name.
Exploring in Cetus
We will start out this month with a very special star, Mira (68 Omicron Ceti). Mira was the first known variable star (a variable star is a star that changes brightness as viewed from Earth). Mira was discovered by a German astronomer David Fabricius in 1596. His studies determined that Mira has an 11-month cycle (331 days), during which it changes from 2nd magnitude to magnitude 10.1. It also appears to get redder as it gets dimmer.
Move your scope so that Mira is at the southwest edge of your finder and you should have 75 Ceti just inside the northeast edge. Adjust your scope so that 75 Ceti is just to the east of center to find a group of three galaxies, NGC's 955, 941 and 936. NGC 936 is the brightest one of the trio at magnitude 10.1 and it is paired with the dimmest, NGC 941, at magnitude 12.4. Both of these galaxies are rather large and tilted more face-on to us, so their light is spread over a large area, making them a bit hard to hit. I think I just got lucky with NGC 955 because I found it first and it was easier to see than the other two.
Continue northeast until 75 Ceti just leaves the southwest edge of your finder and you should have Delta Ceti in your field of view. At this point you have NGC 1068 (M77), plus NGC's 1055, 1073, 1090 and 1087, all in the area of your finder. NGC 1090 and NGC 1087 are right on the east-southeast edge of the finder.
M77 is located about 1° southeast of Delta Ceti. This is the only Seyfert galaxy on Messier’s list and from my books I really expected more than what I found. Seyfert galaxies have very active nuclei and are potent emitters of radio waves, very similar to the much more distant quasi-stellar objects called quasars. The nucleus of M77 is extremely bright and if you don’t spend some time using averted vision, you will miss the spiral arms surrounding it. Moving just under 1° north from M77 you will find two stars sitting above a 10.6 magnitude edge-on spiral galaxy, NGC 1055. NGC 1055 is pretty faint, but careful examination will reveal a dust lane cutting through its central region.
Move to the midway point between Mira and Zeta Ceti to find NGC's 788 and 779. These two galaxies are located northwest of this center point and you will need at least 8" of aperture to catch them as they are both very faint. NGC 779 is the brighter of the two and the farthest to the northwest. NGC 788 is very hard to find and appears more as a fuzzy star than a galaxy.
Continue on to Zeta Ceti to find NGC 681 less than 1° to the west. Although this galaxy is pretty faint, it does have a nice dust lane running through the nucleus. From Zeta Ceti jump west-northwest over to Theta Ceti then northeast a little over a half of a finder scope field to find NGC's 584, 596 and 615. With a wide field 32mm eyepiece I can get two of these three galaxies in the same field of view. All three are evenly spaced and close to the same magnitude. NGC 596 has a faint tail extending out from the main structure, making the nucleus appear off center.
Return to Theta Ceti then continue southwest through 31 Eta Ceti and Phi3 Ceti. With Phi3 Ceti just outside the east-northeast edge of your finder you should have NGC 246 in your eyepiece. NGC 246 is a large planetary nebula with a faint ring structure. I found this planetary nebula without a filter but, until I used the filter, at least one person at Highway 4 thought that I had a lot more imagination centered in the field than a nebula.
Before I close, I would like to take you on one last hop. Use your Telrad to move just under two thirds of the distance between Beta Ceti and Alpha Sculptoris and just to the right to find NGC 253, the Sculptor Galaxy. It is very bright and inclined 12° to our line of sight. This is a fantastic galaxy and well worth spending some time on.
This month I have hit most of the objects located mainly along the spine of Cetus and a quick dip into Sculptor. There are many more galaxies and galaxy clusters in this area that are well worth looking for.
Happy Star Hopping...Eric
Copyrighted © 2000 by Stockton Astronomical Society
Lasted Updated: 11/24/2000
http://www.stocktonastro.org/Newsletter/CON_Cetus.html