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December 8-9, 2004: Double stars in Auriga, Orion and Gemini

On the nights of December 8 and 9 2004 I observed some double stars in Auriga, Orion and Gemini. The seeing and transparency was not very good (4 out of 10) on these nights. Even the big clusters in Auriga, M 36, M 37, and M 38 where no real fun to observe, but for looking at some double stars, it was proved to be OK. I observed from my own backyard (visual limiting magnitude 4 on these nights) using my TAL 200K, an 8-inch Klevtzov-Cassegrain mounted on the EQ6, and the Argo Navis Digital Telescope Computer.

I used most of my observing time for making field drawings of each double (or multiple) star. I sketched the double star components together with some field stars that where visible through the eyepiece. I did not include all stars that where visible in the field of view. I always tried to plot bright stars and stars that form patterns that are easy to recognize, like a triangle, semi-circle, a row of stars etc. This helps identifying a double star when you compare the sketches with a printed star chart or star atlas.

Later that week I compared my field drawings to maps I generated with SkyTools 2. This software prints not only the field-stars very accurate, but it also plots the components of double and/or multiple stars in the correct position angle to one another. It was great fun to recognize the star-patterns I drew at the telescope, and it was even better to see that I got the position angles right in most cases.

With the help of the printed maps and the field sketches I created final versions of the sketches, all in the same orientation. South at the top and east to the left, like the way I see them through my telescope. I did not add any stars from the printed maps into the sketch! All stars on the sketches come from the original field sketches. I only corrected the orientation, and tried to get all position angles as correct as possible.

This was the first time ever I observed and sketched double stars for a few hours on two consecutive nights, and it was fun. Not only to make the sketches but also to try and recognize the different colours (observing star colours is very subjective!) and try to estimate the difference in magnitudes between the different components of a double/multiple star. A real joy for visual observing.

Below you find the sketches I made with the reports and basic data. They are arranged by RA and DEC. The brightest component of the double/multiple star is always at the centre of the sketch. The postion-angles are oriented as follows: 90° is East, 180° is South, 270° degrees is West and 0° is North (so 359° is almost North).

Enjoy!



Omega Aurigae

Rigel

1: Omega Aurigae (Σ616)

Observed on December 9 2004. RA 04h.59m, DEC +37°53'. The bright magnitude 5 A-component of Omega Aurigae is yellowish-white. At the postion-angle of 359° lies the magnitude 8 B-component. The separation between both stars is 5.4". I cannot tell the colour of the B-component. It looks like a faint white point of light. The eyepiece used is a 20mm Vixen Lanthanum, magnification 100x and a true field of view of 28.75'.




2: Rigel or Beta Orionis

Observed on December 8 2004. RA 05h.15m, DEC -08°12'. The bright magnitude 0.1 A-component of Rigel is a blazing bluish white star. For the first time ever I spotted the magnitude 6.8 B component at the postion-angle of 202°. The separation between both stars is 9.4" I cannot tell the colour of the B-component. The bright light of the A-component makes it very hard to tell the colour of it's companion. This was a difficult couple to split, but with a 10mm Vixen Lanthanum eyepiece, giving a magnification of 200x it was clearly visible. The true field of view is 15'.

14 Aurigae


Struve 698

3: Σ653 or 14 Aurigae A-C pair.

Observed on December 8 2004. RA 05h.15m, DEC +32°31'. The magnitude 5.1 A-component of Σ653 is also part of another double, 14 Aurigae A-B pair. The A-component is yellowish. On both nights I could not detect the magnitude 11.1 B component of 14 Aurigae, that can be found at a position angle of 352° and is separated by 11.1".

At the postion-angle of 226° lies the magnitude 7.4 C-component of 14 Aurigae, that forms Σ653 together with the A-component. The separation between both stars is 14.6". The C-component looks blue-white. The eyepiece used is a 15mm Vixen Lanthanum, magnification 133x. The true field of view is 22.5'.

4: Σ698

Observed on December 9 2004. RA 05h.25m, DEC +34°51'. The magnitude 6.60 A-component is yellow-orange. At the postion-angle of 345° lies the magnitude 8.7 B-component. The separation between both stars is 31.2". The B-component is too faint to detect any colour.

The eyepiece used is a 20mm Vixen Lanthanum, magnification 100x. The true field of view is 28.75'.

26 Aurigae

Sigma Orionis

5: 26 Aurigae (Σ1240)

Observed on December 9 2004. RA 05h.38m, DEC +30°30'. The magnitude 6 AB-component (too close to split for amateur telescopes with a separation of 0.2") is yellow. At the postion-angle of 267° lies the magnitude 8 C-component of this easy double. The separation between both stars is 12.4". The C-component is too faint to detect any colour.

The eyepiece used is a 32mm Televue Plossl, magnification 62.5x. The true field of view is 46.4'.

6: Sigma Orionis

Observed on December 8 2004. RA 05h.39m, DEC -02°36'. All components of this multiple star look bluish-white. The magnitude 3.8 AB-pair (not split) forms a nice triple with the D- and E component. The magnitude 7.5 D-component lies at a position angle of 84°. The separation between both stars is 12.9". The magnitude 6.5 E-component lies at a position angle of 61°. The separation between the AB pair and the D-component is 42.6". The trio can be found at the centre of the sketch with the D-component just to the east of the bright AB pair and the E-component a little to the east-northeast of the D-component. The magnitude 11.4 C-component was not detected. This faint member of this multiple star system lies at a postion angle of 238° of the bright AB-component.

To the west of Sigma Orionis you see three stars, two close together and one a little more to the north. This trio forms the multiple star system Σ761.

The eyepiece used is a 20mm Vixen Lanthanum, magnification 100x. The true field of view is 28.75'.

Nu Aurigae

Delta Aurigae

7: Nu Aurigae

Observed on December 9 2004. RA 05h.51m, DEC +39°09'. The magnitude 3.97 A-component is bright yellow-orange. At the postion-angle of 206° lies the magnitude 9.5 B-component. The separation between both stars is 54.6". The B-component is too faint to detect any colour.

The eyepiece used is a 12mm Vixen Lanthanum, magnification 166x. The true field of view is 18'.

8: Delta Aurigae

Observed on December 9 2004. RA 05h.59m, DEC +54°17'. The magnitude 3.72 A-component of this triple star is yellow-gold. At the postion-angle of 271° lies the magnitude 9.7 B-component. The separation between both stars is 115". At a position-angle of 67° lies the magnitude 9.7 C-component. The separation between the A- and C-components is 197" Both B- and C-components are too faint to detect any colour. In the sketch above, the B compenent lies to the west of the bright A-component and the C-component lies to east-northeast of the A-compnent at about 8 O'clock.

The eyepiece used is a 15mm Vixen Lanthanum, magnification 133x. The true field of view is 22.5'.

Struve 872

Otto Struve 147

9: Σ872

Observed on December 8 2004. RA 06h.15m, DEC +36°09'. The magnitude 6.9 A-component of this very fine double is is yellow. At the postion-angle of 217° lies the magnitude 7.1 B-component. The separation between both stars is 11.3". The B-component is seems too faint to detect any colour, but at 287x it still not looks white. I think I see some bluish or purple colour, but maybe thats just imagination. It remains hard to see colours in most stars.

The eyepiece used is a 20mm Vixen Lanthanum, magnification 100x. The true field of view is 28.75'.



10: OΣ147

Observed on December 9 2004. RA 06h.34m, DEC +38°05'. The magnitude 6.6 A-component of this triple star is yellow. At the postion-angle of 73° lies the magnitude 10 B-component. The separation between both stars is 43.2". At a position-angle of 117° lies the magnitude 10.6 C-component. The separation between the A- and C-components is 46.3" Both B- and C-components are too faint to detect any colour. In the sketch above, the B and -compenents both lie to the East of the bright A-component. The three components form a beautiful triangle in the eye-piece.

The eyepiece used is a 15mm Vixen Lanthanum, magnification 133x. The true field of view is 22.5'.

Castor

11: Castor

Observed on December 8 2004. RA 07h.34m, DEC +31°53'. The magnitude 1.9 A-component is bright white. At the postion-angle of 68° lies the magnitude 2.9 white B-component. The separation between both stars is 4". This is the first time I split this beautiful double.

The eyepiece used is a 12mm Vixen Lanthanum, magnification 166x. The true field of view is 18'.






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