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Sky Hunting with Small Refractors - October, 2010


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#1 MistrBadgr

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Posted 24 October 2010 - 06:06 PM

Sky Hunting with Small Refractors – September, 2010

Sorry this is so late.  Work load has been getting in the way again.  This is a busy time.

I write this in Microsoft Word and copy over to the posting editor.  Things look pretty jumbled and I try to correct it.  The final thing posted looks jumbled.  Therefore, I only did one thing to one of the headers and then stopped, thinking that maybe it will end up looking better posted if I leave things alone.  Hopefully, this will not look like scrambled eggs.

Once again, for October as with September, there are eight items from the Astronomy League’s Double Star Club List. Three of them are in Capricorn, which is in the Southern part of the sky from my back yard, and two in Cygnus, more overhead.  The rest are spread around in Delphinas, Cephus, and Pegasus.

The two globular clusters with magnitudes over 8 are not visible with a lot of light pollution, even with a big scope.  It would take a really dark sky for a small scope to see them.  I am including them more for educational purposes.  You might look them up on line to see pictures of them.

The descriptions and how to find these will follow as continuations.

October Double Stars:

Item                                            R.A.                Dec.             Mag.             Sep.    P.A

31 Cygni                                20h 13.6’        +46d 44’          3.8, 6.7            107”    173d
                                                                                                        4.8            337”    323d
Alpha Capricornus                20h 18.1’        -12d 33’            3.6, 4.2            378”    291d
Beta Capricornus                    20h 21.0’        -14d 47’          3.4, 6.2            206”      267d
Gamma Delphinas                  20h 46.7’        +16d 07’          4.5, 5.5            9.6”      268d
61 Cygni                                21h 06.9’        +38d 45’          5.2, 6.0            28”        146d
Beta Cephei                            21h 28.7’        +70d 34’          3.2, 7.9            13.3”    249d
Struve 2816                            21h 39.0’          +57d 29’        5.6, 7.7            11.7”    121d
                                                                                                      7.8              20”      339d
Epsilon Pegasi                        21h 44.2          +09d 52’          2.4, 8.4            142”    320d

Object     R.A.   Dec. Mag. Size Constellation

Globular Clusters:

M-71/NGC 6838                    19h 53.6’        +31d 43.0’        8.3        6.1’      Sagitta
M-55/NGC 6809                    19h 40.0’        -30d 58.0’        7.0        19’        Sagittarius
M-75/NGC 6864                    20h 06.1’        -21d 55.0’        8.6        6.0’      Sagittarius

Open Clusters:

M-29/NGC 6913                    20h 23.9’        +38d 32.0’        6.6        7.0’      Cygnus                                 
Collinder 399 (Coathanger)    19h 25.4’        +20d 11.0’        3.6v      60’        Vulpecula
                         
Nebula:

M-27/NGC 6853                      19h 59.6’      +22d 43.0’        7.6        8.0’      Vulpecula

Thanks,

Bill Steen

#2 MistrBadgr

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Posted 24 October 2010 - 06:08 PM

I should not have messed with that one header.

#3 MistrBadgr

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Posted 28 October 2010 - 05:03 PM

Sky Hunting with Small Refractors – October, 2010  (continuation 1)

October Double Stars:

Item                                            R.A.                Dec.             Mag.             Sep.    P.A

31 Cygni                                20h 13.6’        +46d 44’          3.8, 6.7            107”    173d
                                                                                                        4.8            337”    323d

From the information above, which comes from the Astronomy League’s list, I thought this was a triple star.  Actually, going by what the Night Sky Observer’s Guide says, it is a quadruple star system.  Unfortunately, the B star is not visible to amateur telescopes.  Therefore, for us, it is a triple star system. With the dimmest magnitude being 6.7, all three stars should be visible to small telescopes.  The challenge will be to identify them as being together as one system.  The D star is about five and one half arc minutes away from A.

To find this one, look for Deneb, the brightest star in the Northern Cross or Cygnus the Swan.  From my back yard, at this time of year, Cygnus is pretty much over head.  Deneb is the tip of the northwestern leg of the cross or the tail of the swan.  Then, look for delta, which is almost due west of Deneb.  It forms the tip of the northeastern wing if the swan.  31 Cygnus is about half way between these two and slightly to the North.  30 Cygnus is located very close to 31 and is toward the northeast.  Due North is 32, shich is about as bright as 31.  31 is also known as Omega 1 and 32 as Omega 2.  I am not sure what the deal is with that naming.  Possibly, someone thought they were part of a multiple star system themselves.

Alpha Capricornus                20h 18.1’        -12d 33’            3.6, 4.2            378”    291d

Now we will turn our gaze more to the South, at least from my back yard.  Capricornus is the sea goat.  I am not quite sure what a sea goat is, but Capricornus is supposed to be one.  This constellation is east of Sagitarius and looks more like some kind of bowl to me, or almost a right triangle with the square corner to the South.  Alpha Capricornus is really to bright stars relatively close together on star charts and is designated Alpha 1 and Alpha 2.  These are actually located off the tip of the right corner of the “bowl.”

All we can see of this with a small telescope is just Alpha 1 and 2.  However, each one of these is itself a four star system.  The problem is that the brightest after the two primaries is magnitude 9.2.  Therefore, with a small refractor, the likelihood of seeing anything bewises the main two is pretty slim.  However, we can certainly try and be pleased if we can see any of them.

Beta Capricornus                    20h 21.0’        -14d 47’          3.4, 6.2            206”      267d

Very near and slightly to the South of the Alpha system, is Beta, the western corner star of the “bowl.”  Beta also has one more star not listed in the Astronomy League’s list.  It is 9.0 magnitude, is a little farther away from the A star than is the B.  It is located roughly southeast of A while B is located almost due west.

Gamma Delphinas                  20h 46.7’        +16d 07’          4.5, 5.5            9.6”      268d

Delphinas, the dolphin, is a very small constellation located South of Cygnus, the swan.  It is almost directly South of Deneb.  It is also northeast Altair, Alpha Aquila.  (Remember Deneb, Altair, and Vega making up a triangle?

I can see how someone thought this looked like a dolphin.  There are four stars that make a diamond shape with the long direction running northeast to southwest.  From the Southwest end, there are a couple stars that make up a tail that curves off to the South.  The tail is a little longer than the long dimension of the diamond.  None of the stars are as bright as Altair, or really anywhere close to that bright.  From my red zone back yard, I can just barely make them out if I look close with my eyes.  They show up very well in binoculars.

The star we are looking for is the point of the kite away from the tail.  The two stars will look oriented east and west.  With a separation of 9.6”, they should be easy to spot with your 25 or 26mm eyepiece.  The two stars are supposed to be yellow and green.  You will probably need to be under very dark skies to see the colors with a small telescope.  However, I might be surprised.

61 Cygni                                21h 06.9’        +38d 45’          5.2, 6.0            28”        146d

Now, let us go back to Cygnus again.  This star pair forms a parallelogram with Deneb, the bright star, Gamma, the middle bright star, and epsilon, the bright star forming the wing to the southeast.  Look at the direction from Gamma, along the wing line, to Epsilon.  Then go up to Deneb and travel in that same direction, the same distance.  Or, start with Epsilon on the wing (not the tip which is Zeta) and go in the same direction and distance as from Gamma to Deneb.

61 forms a triangle with two other stars, 65 and 67.  Both of those stars show to be brighter than 61.  61 is the western-most of the three.  At over 30 arc seconds, you should be able to easily distinguish the pair with your 25 or 26mm eyepiece.  These two stars are supposed to be reddish-orange, if you can see the color.  They are oriented on a northwest-southeast line.

Beta Cephei                            21h 28.7’        +70d 34’          3.2, 7.9            13.3”    249d

Cepheus, the king, is located North of Cygnus and east of Draco.  Alpha and Beta Cephei are relatively bright stars that form a North-South line about half way between Deneb and Polaris, the North Star, and a little to the east.  Beta is the dimmer of the two at magnitude 3 and is the Northern of the two.  The secondary or B star is magnitude 7.9.  It will be very dim compared to its primary.  The two should look relatively close together with your 25 or 26 mm eyepiece.  B should be roughly southwest of A, but directions in that part if the sky can be deceiving and the stars move slowly.

Struve 2816                            21h 39.0’          +57d 29’        5.6, 7.7            11.7”    121d
                                                                                                      7.8              20”      339d
This system actually contains four stars, but one of them, the B star, we will not be able to see.  I tend to get my directions mixed up this far North.  With the A star being only magnitude 5.6 and the other two a little brighter than 8, I expect this one to be difficult to locate.  Possibly, I will be wrong.  But, I do expect it to be a challenge.

Remember Alpha and Beta Cephei mentioned above.  Alpha, again is the southern one of the two.  To the southeast of Alpha, are two bright stars, Zeta and Epsilon that are close together and form one corner if the constellation.  Go about two-thirds of the way from Alpha to Zeta, the closest of the pair, and make a right turn toward the southwest and go about one-third of the distance from Alpha to Zeta. On the way of this last leg, you will pass Mu, off the line a little bit.  Mu, Hershel’s Garnet Star, is about half way to Struve 2816.  When you get to the right spot, there will be two stars showing that are separate systems, but both show to be double stars.  2816 is the brighter and farther of the two.  The other system is Struve 2819.  At magnitudes of 7.5 and 8.5 and a separation of 12 arc seconds, you may be able to see both stars, just barely, in the same field as 2816.  Both are in front of what I think is a nebula, IC 1396.  I have not looked at these stars as I write this, but there may be a dim open cluster behind these two.  Any stars in that cluster should be much dimmer than either of the Struve systems.

Epsilon Pegasi                        21h 44.2          +09d 52’          2.4, 8.4            142”    320d

From Cepheus, we head almost straight South to Pegasus, or at least the western edge of it.  On the way southward, you will see Deneb.  If you draw a line from Deneb to Zeta Cygnus, the southern wing tip star, and then follow that line about another equal distance, you should see Epsilon.  It is also the “Hoof” star of the Southwestern leg of Pegasus.  To the east and somewhat North of Epsilon, you should be able to see the great square of Pegasus, four bright stars that almost form a square.

I am not sure what the deal is, but Epsilon does not show up as a double star in either the Night Sky Observer’s Guide or in the Pocket Sky Atlas.  The Astronomy League’s list shows this as a double star, with the second star at Magnitude 8.4, 142 arc seconds away.  That is over two arc minutes separation.  If it can be seen, this secondary star should be roughly northwest of the primary.  With the primary having a magnitude of 2.4, seeing the secondary may be a challenge.  If it can be seen, it will be because of its great distance from the primary.

Well, that is the double stars in the list for this month.  I found the first three last night and will go for some more in a few minutes.

I hope you have as much fun as I am with these.  I hope to post on some of the other October objects soon.

Best Regards,

Bill Steen




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