- Double Stars (UMa) -

And (32) Cep (13) CVn (4) Her (13) Mon (1) Sex (2)
Aql (9) Cet (1) Cyg (19) Hya (4) Oph (1) Tau (11)
Ari (8) CMa (1) Del (2) Leo (19) Ori (8) Tri (4)
Aur (27) Cnc (10) Dra (8) Lib (1) Peg (16) UMa (24)
Boo (12) Com (8) Equ (5) LMi (6) Per (18) UMi (1)
Cam (10) CrB (4) Eri (1) Lyn (18) Psc (7) Vir (6)
Cas (17) Crv (1) Gem (19) Lyr (8) Ser (2)

41 Lyn (**)

Name: 41 Lyn, S598
Type: **
Constellation: UMa
Coordinates: 09h28m39.99s / +45°36'06.50"

Components:
m1 m2 ρ θ Year
AB 5m5 7m8 69.7" 160° 2017
This star has the designation 41 Lyn but is assigned to UMa. At the time, when Flamsteed numbered the stars, the constellation boundaries were not exactly defined. Another example is 10 UMa, which is located in Lyn today.

Robert Zebahl
B 8x40, Bortle 7, NELM 5m0, SQM-L 19.2
Fairly well split with fainter component.

67 UMa (**)

Name: 67 UMa
Type: **
Constellation: UMa
Coordinates: 12h02m06.80s / +43°02'44.30"

Components:
m1 m2 ρ θ Year
FOR1 AB 5m2 6m7 274.4" 62° 2015
ARN5 AC 5m2 8m5 375.9" 25° 2015
FOR1 AD 5m2 8m9 363.2" 268° 2015
Robert Zebahl
B 8x40
2020-04-05: The pair AB stands out immediately and shows itself in beautiful colors: A white-yellowish, B slightly orange. Almost at right angles to pair AB component C is visible as a faint star at a slightly smaller distance. I did not pay attention to the even fainter component D.

55mm f/9.1, 27x
2020-04-05: Components A, B and C easily visible with decreasing brightness. I did not consider component D. A: white-yellowish, B: pale orange. I liked the view in the 8x40 binoculars better.

BU 1077 (**)

Name: BU1077, alpha UMa, 50 UMa, Dubhe
Type: **
Constellation: UMa
Coordinates: 11h03m43.84s / +61°45'04.00"

Components:
m1 m2 ρ θ Year
AB 2m0 5m0 0.8" 342° 2017
AC 2m0 7m2 370.0" 205° 2015

../images/binary-star-orbits/BU1077-AB-orbit.jpg

Robert Zebahl
70mm f/5.7, 22x
AC: 2020-04-07: Very wide, uneven & inconspicuous pair. A appeared white-yellowish, for B I could not detect any color.

STF 1258 (**)

Name: STF1258
Type: **
Constellation: UMa
Coordinates: 08h43m25.41s / +48°51'41.90"

Components:
m1 m2 ρ θ Year
7m7 7m9 10.0" 330° 2017
Robert Zebahl
70mm f/5.7, 22x, Seeing 3/5
Easy to separate at 22x, similarly bright components at moderate distance. At 57x very small difference in brightness noticeable. The components appeared slightly orange and white-bluish, with the color changing from one component to another. A very strange effect, which I observed several times.

STF 1275 (**)

Name: STF1275
Type: **
Constellation: UMa
Coordinates: 08h51m26.19s / +57°31'38.10"

Components:
m1 m2 ρ θ Year
AB 8m7 8m9 1.9" 198° 2019
Robert Zebahl
70mm f/5.7, 100x
At 100x and 150x not permanently split. Components very close together.

STF 1306 (**)

Name: STF1306, sigma 2 UMa, 13 UMa
Type: **
Constellation: UMa
Coordinates: 09h10m23.53s / +67°08'03.30"

Components:
m1 m2 ρ θ Year
AB 4m9 8m8 4.3" 348° 2016
AC 4m9 10m3 197.8" 148° 2003

../images/binary-star-orbits/STF1306-AB-orbit.jpg

Robert Zebahl
70mm f/5.7, 100x, Seeing 3/5
AB: Companion almost permanently visible as elongated, non-condensed brightening of the first diffraction ring of the primary component at the correct position angle.

STF 1315 (**)

Name: STF1315
Type: **
Constellation: UMa
Coordinates: 09h12m45.94s / +61°40'32.70"

Components:
m1 m2 ρ θ Year
7m3 7m7 24.9" 27° 2017
Robert Zebahl
70mm f/5.7, 22x, Seeing 3/5
Medium bright double star, easy to separate with attractive distance and slight difference in brightness. Together with 16 UMa in one field of view. The brighter component appeared slightly orange, the fainter one showed a hint of blue. However, the colors of the components changed over time. At 57x similar view.

STF 1318 (**)

Name: STF1318
Type: **
Constellation: UMa
Coordinates: 09h13m38.79s / +46°59'25.30"

Components:
m1 m2 ρ θ Year
7m8 9m5 2.4" 228° 2018
Robert Zebahl
70mm f/5.7, 133x, Bortle 6, SQM-L 19.4
Separated with clear difference in brightness. The faint companion is slightly outside the first diffraction ring of the primary component.

STF 1321 (**)

Name: STF1321
Type: **
Constellation: UMa
Coordinates: 09h14m22.79s / +52°41'11.80"

Components:
m1 m2 ρ θ Year
AB 7m8 7m9 17.0" 98° 2018
AC 7m8 14m5 145.7" 64° 2010
AD 7m8 11m9 136.4" 129° 2015

../images/binary-star-orbits/STF1321-AB-orbit.jpg

Robert Zebahl
70mm f/5.7, 22x, Bortle 6
AB: 2020-04-11: At 22x pretty wide pair with equally bright components. Striking colors: slightly orange & white-bluish, but it was a bit difficult to assign the colors to the components. At 44x slightly better color perception.

STF 1331 (**)

Name: STF1331
Type: **
Constellation: UMa
Coordinates: 09h20m46.02s / +61°20'58.40"

Components:
m1 m2 ρ θ Year
AB 8m5 8m7 0.9" 153° 2017
AC 8m5 11m6 13.5" 186° 2015
AD 8m5 14m5 19.4" 117° 2015
AE 8m5 9m8 139.1" 223° 2015
Robert Zebahl
152mm f/5.9, 180x, Bortle 6, SQM-L 19.4
2020-04-13: The wide pair AE is already visible at 22x with a significant difference in brightness, but quite inconspicuous. A appeared white-yellowish, E rather orange. The close pair AB appeared immediately elongated at 129x, partly visible as '8'. At 180x, AB was just separated with a fine black space between them. The faint C component was only visible with averted vision. Best view at 180x. The even fainter D component was out of range.

../sketches/2020-04-13_stf1331.jpg

STF 1350 (**)

Name: STF1350
Type: **
Constellation: UMa
Coordinates: 09h34m19.56s / +66°47'42.30"

Components:
m1 m2 ρ θ Year
AB 8m3 8m3 10.2" 249° 2015
AC 8m3 9m2 131.0" 216° 2015
Robert Zebahl
152mm f/5.9, 100x, Bortle 6-, SQM-L 19.1
At 22x, all three components are already visible, with A & B still standing quite close together. Component C is less prominent. At 69x and 100x, the pair AB shows a nice color contrast: The eastern component mostly appeared in a slightly shiny orange, while the other component appeared more white-bluish. During the observation, however, the colors changed between both components. At the time of observation, the pretty bright comet C/2019 Y4 Atlas was also in the same field of view - a great scene! Note to the sketch: The positions of the stars to each other do not exactly match, also the alignment of the pair AB to C.

../sketches/2020-03-18_stf1350_c2019_y4_atlas.jpg

STF 1351 (**)

Name: STF1351, 23 UMa
Type: **
Constellation: UMa
Coordinates: 09h31m31.57s / +63°03'42.50"

Components:
m1 m2 ρ θ Year
AB 3m6 9m2 22.7" 267° 2015
AC 3m7 11m8 107.4" 232° 2015
Robert Zebahl
70mm f/5.7, 22x
AB: 2020-04-07: Well separable with a significant difference in brightness, where the companion appearing only as a tiny star close to the primary component. The primary component itself appeared bright and rather whitish.

STF 1415 (**)

Name: STF1415
Type: **
Constellation: UMa
Coordinates: 10h17m50.61s / +71°03'38.90"

Components:
m1 m2 ρ θ Year
AB 6m7 7m3 16.6" 168° 2018
AC 6m7 10m8 153.3" 13° 2015
Robert Zebahl
70mm f/5.7, 22x
AB: 2020-04-07: At 22x immediately noticeable as double star, medium bright with rather small difference in brightness. A appeared whitish, B slightly orange, partly brownish. At 44x similar color impression: A white-bluish, B slightly orange.

STF 1505 (**)

Name: STF1505
Type: **
Constellation: UMa
Coordinates: 11h05m41.23s / +62°37'01.50"

Components:
m1 m2 ρ θ Year
AB 8m9 10m6 8.2" 312° 2015
AC 8m9 12m0 217.7" 177° 2015
Robert Zebahl
70mm f/5.7, 80x, Bortle 6, NELM 5m0+
AB: 2020-04-14: Easy split with pretty dim companion.

STF 1520 (**)

Name: STF1520
Type: **
Constellation: UMa
Coordinates: 11h16m04.03s / +52°46'23.40"

Components:
m1 m2 ρ θ Year
6m5 7m8 12.4" 344° 2017
Robert Zebahl
70mm f/5.7, 44x
2020-04-08: At 22x pretty tight, uneven pair. A appeared orange, B did not show any clear color. At 44x, A appeared yellowish-orange, B silvery grey, partly grey-bluish.

STF 1523 (**)

Name: STF1523, xi UMa, 53 UMa, Alula Australis
Type: **
Constellation: UMa
Coordinates: 11h18m10.90s / +31°31'45.00"

Components:
m1 m2 ρ θ Year
AB 4m3 4m8 2.1" 155° 2019

../images/binary-star-orbits/STF1523-AB-orbit.jpg

Robert Zebahl
55mm f/9.1, 83x, Bortle 6-, SQM-L 19.1
2019-02-09: Already seen as '8' at 83x. At 125x the overlapping of both Airy disks was visible, but also a slight difference in brightness.

../sketches/2019-02-09_xi_uma.jpg

70mm f/5.7, 100x, Bortle 6
2018-02-18: Very close together with similar brightness. At first glance seen as an '8', looking closer I partly split both components. Similar view also at 128x.

70mm f/5.7, 133x
2020-03-15: Splendid sight! Beautifully separated with almost touching diffraction disks. The rather small difference in brightness was well visible. The diffraction rings of both components coalesced.

102mm f/11, 160x
2020-03-16: Awesome! Bright with lovely, subtle diffraction rings. The distance between both components is a smaller than the diameter of the diffraction disk of the fainter component.

120mm f/5, 168x, Bortle 6, SQM-L 19.1
2018-02-14: Well split with slight difference in brightness.

152mm f/5.9, 129x, Bortle 6, NELM 5m0+
2019-02-06: Well split with visible difference in brightness. The colors of both components appeared equal.

STF 1559 (**)

Name: STF1559
Type: **
Constellation: UMa
Coordinates: 11h38m49.11s / +64°20'49.40"

Components:
m1 m2 ρ θ Year
6m8 8m0 1.9" 328° 2017
Robert Zebahl
70mm f/5.7, 133x, Bortle 6, NELM 5m0+
2020-04-14: Two clearly visible, slightly touching diffraction disks. The fainter companion appeared somewhat more diffuse. Occasionally the double star appeared separated.

../sketches/2020-04-14_stf1559.jpg

STF 1561 (**)

Name: STF1561
Type: **
Constellation: UMa
Coordinates: 11h38m44.90s / +45°06'30.30"

Components:
m1 m2 ρ θ Year
AB 6m5 8m2 8.9" 247° 2017
AC 6m5 9m5 176.8" 90° 2015
AD 6m5 7m6 718.2" 76° 2015
AE 6m5 12m1 60.7" 338° 2015

../images/binary-star-orbits/STF1561-AB-orbit.jpg

Robert Zebahl
70mm f/5.7, 44x
AB: 2020-04-07: At 22x separated. The fainter companion is still very close to the primary component. At 44x beautiful sight with a clear difference in brightness. A: slightly yellowish, B: pale bluish.

STF 1579 (**)

Name: STF1579, 65 UMa
Type: **
Constellation: UMa
Coordinates: 11h55m05.74s / +46°28'36.60"

Components:
m1 m2 ρ θ Year
AB-C 6m7 8m3 3.8" 40° 2017
AB-D 6m7 7m0 62.5" 114° 2018
Robert Zebahl
B 8x40
AB-D: 2020-04-05: Immediately conspicuous in the field. Medium bright double star with slightly uneven components. Western component AB appeared slightly orange, component D tended to be bluish.

55mm f/9.1, 83x, Bortle 6-, SQM-L 19.1
2019-02-09: AB, C & D easy to split, but the faint C component only appeared as a tiny star. To the south there is the brighter D component.

../sketches/2019-02-09_65_uma.jpg

55mm f/9.1, 27x, Bortle 6-, SQM-L 19.1
AB-D: Easy to separate with large distance and very small difference in brightness. The D component showed a bluish tint, the lighter one (AB) a slightly yellowish tint. At higher magnification also the faint C component is visible.

STF 1603 (**)

Name: STF1603
Type: **
Constellation: UMa
Coordinates: 12h08m07.07s / +55°27'50.70"

Components:
m1 m2 ρ θ Year
7m8 8m3 22.5" 85° 2018
Robert Zebahl
70mm f/5.7, 22x
2020-04-07: At 22x quite apparent double star in rather poor surrounding. Nice separation with little difference in brightness. Primary component appeared slightly orange, companion grey-bluish. At 44x similar view in color appearance.

STF 1695 (**)

Name: STF1695
Type: **
Constellation: UMa
Coordinates: 12h56m17.64s / +54°05'58.10"

Components:
m1 m2 ρ θ Year
AB 6m0 7m8 3.9" 281° 2017
AC 6m0 12m3 131.7" 139° 2015
Robert Zebahl
70mm f/5.7, 57x, Bortle 6-
AB: Easily separable, but still quite close together with a relatively large difference in brightness. The companion appeared only as a tiny star.

STF 1830 & STF1831 (**)

Name: STF1830 & STF1831
Type: **
Constellation: UMa
Coordinates: 14h16m08.47s / +56°42'45.70"

Components:
m1 m2 ρ θ Year
STF1831 AB 7m2 9m6 5.8" 138° 2017
STF1831 AC 7m2 6m7 112.2" 219° 2017
STF1831 CD 6m7 13m1 112.1" 116° 2016
STF1830 CE 6m7 9m3 138.0" 245° 2016
STF1830 EF 9m3 10m3 10.6" 312° 2017
STF1830 EG 9m3 12m2 35.2" 81° 2017
Robert Zebahl
B 8x40
STF1831 (AC): 2020-04-05: Fairly wide pair with slight differences in brightness and color. C appeared slightly orange, A on the other hand slightly bluish. Comparatively bright double star, which gives a nice view.

55mm f/9.1, 27x
STF1831 (AC): 2020-04-05: Moderate difference in brightness. C: pale orange, A: subtle blue.

70mm f/5.7, 57x, Bortle 6
2020-04-11: At 22x the components AB, C, E & F are well visible and widely separated. E & F are comparatively faint. The C component in the middle appeared white-yellowish, AB rather white with a slight tendency to blue. At 57x, the pair AB with a clear difference in brightness can be easily split. An altogether rewarding and unusual multiple system.

../sketches/2020-04-11_stf1830_stf1831.jpg

VBS 18 & CSN7 (**)

Name: VBS18 & CSN7, WX UMa
Type: **
Constellation: UMa
Coordinates: 11h05m27.65s / +43°31'38.70"

Components:
m1 m2 ρ θ Year
VBS18 AB 8m8 14m6 32.0" 125° 2017
CSN7 AC 4m8 7m5 7.3" 168° 2003
Robert Zebahl
70mm f/5.7, 100x, Seeing 3-4/5
AC: 2020-03-31: Not identifiable at magnifications between 22x and 100x. WX UMa (component A?) is a variable (b14m2-16m53) and probably too faint.

zeta UMa (**)

Name: zeta UMa
Type: **
Constellation: UMa
Coordinates: 13h23m55.42s / +54°55'31.50"

Components:
m1 m2 ρ θ Year
STF1744, 79 UMa, Mizar AB 2m2 3m9 14.4" 153° 2017
STF1744, Mizar & Alcor AC 2m2 4m0 707.7" 72° 2017
SMR4 AD 2m2 7m6 492.8" 102° 2017
Robert Zebahl
B 8x40
AB: 2020-04-05: Even with tripod not separable.

70mm f/5.7, 10x
AB: 2020-04-12: Observation from city with a 70/400mm ED refractor, for which I made aperture masks from 10mm to 60mm. Goal was to find the minimum magnification for a successful split.

70mm: At 12.5x no separation of the components possible due to outshining. Grey filters brought a slight improvement, but again no separation or elongation was visible.

60mm: At 12.5x slight outshining of the companion, clearly elongated and almost separated.

50mm: At 12.5x the companion was almost outshined. A separation was just possible.

40mm: At 12.5x both components appear finely separated from each other.

30mm: At 10x not clearly separable due to outshining, but clearly elongated. At 12.5x then quite easy to separate with a fine star rendition.

20mm: At 10x the companion is still clearly visible, but quite close to the primary component. At 12.5x best view under the used apertures with a very fine rendition!

10mm: At 10x the companion appears very faint. Separation possible, but extremely tight. At 12.5x reasonably well separated.

70mm f/5.7, 22x, Bortle 6
AB: 2020-04-11: At 12x no separation possible, because the bright primary component outshines the companion. At 22x clearly separated, but still quite close together.

102mm f/11, 28x
First pastel sketch (Pitt pastel by Faber-Castell) of a double star on black paper, where also the halos were sketched around the stars. The stars themselves were redrawn with an Edding (Edding 1500, Soft Pastel white). The sketch shows the components A to D.

../sketches/2019-08-14_mizar_alcor.jpg