Theta 2 Orionis 

Paolo Morini
Star: Theta 2 Orionis
Date & Time: 07 Dec 1998, approx 22 UTC 
Seeing:  8 <1-10 Seeing Scale (10 best)> 
Location of site: San Romualdo, a little village in the country near Ravenna – Italy. 
Site classification: Suburban 
Sky darkness: 5  <Limiting magnitude> 
Telescope: Takahashi FS102 
Magnification: 52x (15.4 Swarovski eyepiece)
 
 
Star: Theta 2 Orionis
Date & Time: 06 Dec 1999, 23:15 UTC 
Seeing:  5 <1-10 Seeing Scale (10 best)> 
Location of site: San Romualdo, a little village in the country near Ravenna – Italy. 
Site classification: Suburban 
Sky darkness: 5  <Limiting magnitude>
Temperature -1ºC 
Telescope: Takahashi FS102 
Magnification: 164x (Takahashi LE5)
   		 Clearly seen the three components in the same field of Theta1. Without any diagonal and looking for position angle, no doubt about the identification of this stellar system. No coloration was registered. 
 
 
 
 
 
 
 

A well-spaced triple star 
 

 
Chuck Layton
Star: Theta 2 Orionis
Date & Time: Dec.19, 1998, 05:30 UT 
Seeing:  5 <1-10 Seeing Scale (10 best)> 
Location of site: Tacoma (WA) 
Site classification: --- 
Sky darkness: 4.6  <Limiting magnitude> 
Telescope: 20cm f/6 Eq. Newtonian 
Magnification: 122x 		 Observed Colorations of Components: A - white, B - blue white, C - white. 
Other comments:  A triple made spectacular by its nearness to M42 and the Trapezium 

 

 
Dave Mitsky
Star: Theta 2 Orionis 
Date & Time:  1/19/99  03:45 UT 
Seeing: 6 <1-10 Seeing Scale (10 best)>.
Transparency: ~ 4 
Location of site: ASH Naylor Observatory (http://www.msd.org/obs.htm) 
near Lewisberry, PA 
Site classification: Rural 
Sky darkness: < 5.0 <Limiting magnitude> moonlight 
Telescope: 17" f/15 classical Cassegrain 
Magnification: 118x, 202x, 249x		 Still another widely separated triple star in the midst of one of the most spectacular regions of the heavens, the Orion Nebula (M42).  The position angles were estimated at approximately 90 degrees. 

 
Ilario Melandri
Star: Theta 2 Orionis 
Date & Time:  
Seeing: 5 <1-10 Seeing Scale (10 best)> 
Location of site: Italy, Ravenna, San Romualdo, Lat 44 32’N Lon 12 08’E
Elevation: 0 m
Site classification: Rural 
Sky darkness: 5.5  <Limiting magnitude>
Temperature: -0.5C 
Telescope: 150 mm f/15 achromatic refractor 
Magnification: 140 x (eyepiece Plossl Clavé 16 mm)


 

 
Tomás Vazquez
Star: Theta 2 Orionis 
Date & Time: 16/12/1999, 21:46:35 TU 
Seeing: 4  <1-10 Seeing Scale (10 best)> 
Location of site: 37 24 N. 5 58 W. Sevilla, Spain 
Site classification: Urban 
Sky darkness: 3 <Limiting magnitude> 
Telescope: Celestron C8” D:203mm. f/6,3 
Magnification: CCD Camera 

 		 Observation method: CCD Camera. 
Integration time: 15 seconds 
Reading CCD software: LUCAS 1.1 
Treatment software: LAIA 3.1g 
Image Position: North up, East left. 

In this image from M42, you can see Theta 1 Orionis (The Trapezium) and finally Theta 2 Orionis located towards SSE. 

Theta2 is a really open triple star and we can almost speak about an alignment of stars. The brightest is located West with a magnitude of 5.4. Then a second component appears shining at magnitude 6.4 located 52” apart with a PA of 92º and finally a third component of 9 magnitude located 129” apart from the main component with a PA of 99º. All components are giant blue. 
 

 
Randall Heckman
Star: Theta 2 Orionis 
Date & Time: 12/26/99 at 2:50 UT 
Seeing: 4 
Location of Site: Heckman Observatory 
40 37' 10" N and 99 03' 50" W 
Site Classification:  Rural 
Sky Darkness (Limiting Magnitude):  5 
Telescope:  8" Orion Dob 
Magnification: 120x 
 		 Separation (Clear or Toughing): Clear 
Magnitude Comment: Seem to agree with quoted values. 
Color Comment: All white to blue white. 
General Comment: Easy to find. 
 
 
 
 

 

 
Richard Harshaw
Star: Theta 2 Orionis [43 Ori; SI 16; ADS 4188; SAO 132321] 
Location of site: Northern Kansas City, Missouri (USA) 
94d 30m west longitude, 39d 15m north latitude 
980 ft above Mean Sea Level 
Date of observations (UT): 0215 of 12-30-99 
Site classification: suburban 
Sky conditions: 
seeing-- 6 out of 10 
transparency-- 8 out of 10 
limiting visual magnitude—5 
Temperature: 44F, calm 
Telescope: Celestron C-8 
Eyepiece: Celestron Micro-Guide (160x) 		 I made five pairs of separation and PA measures using the Micro-Guide and got the following averagers:  AB 53" in PA 93; and AC 131" in PA 98. 

This is the heart of the Orion Nebula, and only a few minutes east of the famous Trapezium. The field is overwhelming here! 

I noted colors of White for all three stars. 

Star A is a spectroscopic binary with a period of 20.96722 days and an infra-red source. It weighs in at 20 solar masses, with the companion at just over 14, making it one of the most massive binaries known. It is thought that perhaps this star is the X-ray source 3U0527-05 and that the star may be a collapsed one. 

Measurements of 1937: 
5.0m (O9Ve) primary 
6.5m (B1V) companion at 53" in PA 92 
9.1m companion at 129" in PA 97 

 

 
Bill Becker
Star: Theta 2 Orionis 
Location of site: Casper, Wyoming Elev. 5200' 
Date of observations: Jan.6,2000 5:35UT 
Site classification: --- 
Sky conditions: 
Seeing: 4 
Transp.: 4.5 
Telescope: Quantum 4 Maksutov 
Magnification: 85x & 149x 		 Nice string of stars: Primary seen as white, B star seemed blue-white, no color seen in 9th mag c star. Easy at 85x. 
 

 

 
Patrick J. Anway 
Star: Theta 2 Orionis 
Date & Time: January, 9, 2000  03:00 UT 
Seeing: 7 <1-10 Seeing Scale (10 best)> 
Location of Site: Munising Michigan USA 
Site Classification: Rural 
Sky darkness: 5.8 limiting magnitude 
Sky condition: No moon; high clouds 
Temperature: 14*F   -10*C 
Telescope: Zeiss Telementor 63mm, f/13.3 on equatorial mount 
Magnification: 47X, 34X (Vixen 18mm & 25mm orthoscopics) 

 

 All four main components split cleanly at 47X and 34X; white/white-blue.  Not as inspiring as their neighbors, but still a nice system. View of both systems together was lovely. 
 
 
 
 

 

 
William L. Schart
Star: Theta 2 Orionis 
Date & Time: 1/12/00 9:07 pm CST
Seeing:  8 <1-10 Seeing Scale (10 best)> 
Location of site: Killeen, TX (Lat 31 N, Elev 600 ft) 
Site classification: Suburban 
Sky darkness: 4 <Limiting magnitude> 
Telescope: Orion 6" Dob. 
Magnification: 98x  
 

Star: Theta 2 Orionis 
Date & Time: 2/9/00 7:50 pm CST
Seeing: 6 <1-10 Seeing Scale (10 best)> 
Location of site: Killeen, TX (Lat 31 N, Elev 600 ft) 
Site classification: Suburban 
Sky darkness: 4 <Limiting magnitude> 
Telescope: Orion 6" Dob. 
Magnification: 300? (Astrocam)

 A wide spaced triple system near M42. Separation AB = 49”, AC = 73”, BC = 113”.  PA AB = 90, BC = 100, AC = 110. 
 
 
 
 
 
 
 
 
 
 
 

Captured in same image as theta 1. Separations: A-B, 49”; A-C, 125”. PAs: A-C, 94d, A-C, 99d. 

 

 
Jim Brownfield
Star: Theta 2 Orionis   
Date & Time: 26/01/2000, 6:30 p.m.- 11:30 p.m. EST 
Seeing: 3 – 5 (improving) <1-10 Seeing Scale (10 best)>.
Location of site: Huntsburg, Ohio, USA
Site classification: Suburban 
Sky darkness: 6 mag., could see ST 855, going to 5th mag. star Rho  <Limiting magnitude>
Other observing conditions:  83% humidity, 16 degrees F. with 12" snow on ground going to 84% humidity, 4 degrees F.
Telescope: 13.1"/F4.5 Dobsonian, with 5" aperture mask for the brighter pairs
Magnification: 47x

Star: Theta 2 Orionis 
Date & Time: 1/29/00, 3:30 UT - 10:00 UT 
Seeing: ) 3 improving to 4 <1-10 Seeing Scale (10 best)>.
Location of site: Huntsburg, Ohio, USA
Site classification: Suburban 
Sky darkness: 4.5 (limiting magnitude)
Other observing conditions: 14 degrees F dropping to 6 degrees F, 92% humidity
Telescope: Meade 80mm/ f11
Magnification: 28x, 45x

 split at 47x 
 
 
 
 
 
 
 
 
 
 
 

needed 45x to find 9.1 mag star, then could see it at 28x along with the 6.5 mag component 

 

 
John M. Ryan
Star: Theta 2 Orionis 
Date of Observation: 30/01/00 23:10UT
Location of Observation: Ciudad Rodrigo, Salamanca, Spain 
40º 36' N, 6º 32'W, Elev. 800 Meters 
Seeing: 7 to 8. Best so far this new year based on the Luis Arguelles method (0 - 10, 10 best)  
Site classification: Urban
Limiting Mag. (naked eye): 5
Instrument: Meade 8"SCT  
Magnification: 80x, 167x		 Separation (Clear or Touching):Clean Split 
Magnitude Comment:Various magnitudes seen in accordance with the data. 
Color Comment:All three components tend to be white. 
General Comment:Theta 2 can be seen in the same FOV as the trapezium (theta 1) but can't compare in beauty with Theta 1. This is a group of three wide components of various magnitudes. I suppose they are in mutual garvitacional attraction but they seem to be separated at great differences to have much of an effect on each other. 

 
Bill Reinehr
Star: Theta 2 Orionis 
Date & Time: February 3, 2000, 03:00  UTC
Seeing: 7  <1-10 Seeing Scale (10 best)>
Location of site: Pflugerville, Texas, USA  (30 degrees N.)
Site classification: Suburban 
Sky darkness: 4 <Limiting magnitude> 
Temperature: 42 F 
Telescope: Vixen 80mm Fluorite, f/8  on Custom D altaz mount
Magnification: 29x		 A very wide triple. Easily seen in the same low power field as Theta 1. All three components seen at 29x. 
 
 
 
 
 

 

 
Jay Zimmerman
Star: Theta 2 Orionis 
Date & Time: 02/08/00, 0300 UT 
Seeing: 8 <1-10 Seeing Scale (10 best)> 
Location of Site:  Carbondale, IL, USA 
Site Classification: Suburban/near rural 
Temperature: 30°F (-1.11°C) 
Sky darkness: 5.3  <Limiting magnitude> 
Telescope: 97mm, f7 apo 
Magnification: 13.3x 		 Very wide, nearly linear triple with diminishing magnitudes from west to east.  Colors: A=B=C = white. 
 
 
 

 

 
Jordi Viver
Star: Theta 2 Orionis 
Date & Time: 19/02/2000, 10: 10 UT 
Seeing: 6 <1-10 Seeing Scale (10 best)> 
Location of Site: Vic (Spain) 41º55’N, 2º19’E 
Elev. 570m 
Site Classification: Suburban 
Sky darkness: 4.62 <Limiting magnitude> 
Temperature: 7ºC 
Telescope: Celestron C8 
Magnification: 162x, 321x 		 Separation: Easy localization and separation. 
Catalog data: Guide 7.0: vM 4.91, 6.02, 8.46, D(A-B)52.4” PA 94º, D(A-C)2.1’, PA 98º. 
 
 
 
 

 

 
Tim Leese
Star: Theta 2 Orionis 
Date & Time: 19-Feb-2000, 1900-2330 UT.
Seeing: 5/6  <1-10 Seeing Scale (10 best)> 
Location of site: Cheshire. UK
Site classification: Suburban 
Sky darkness: 3 <Limiting magnitude> 
Conditions: High haze, very cold and frosty, sky clearing later but full moon. 
Telescope: 200mm f/6  Newtonian scope  mounted over a Vixen GP mount (manual slow motion).
Magnification: x48, x120		 Observe SE of Theta1 in same field of view with M42/M43 nebula also. 
 
 
 
 

 

 
G.E.O.D.A Group
Star: Theta 2 Orionis 
Date & Time: 8-III-2000, 19:00-21:00UT
Seeing: 6.5 <1-10 Seeing Scale (10 best)> 
Location of Site: Manises, Valencia, Spain. GPS coordinates: 39º 29' 36" N, 00º 27' 56" W.
Site Classification: Urban-Suburban
Sky darkness: 4 <Limiting magnitude> 
Telescope: Meade 10" LX-200 SCT
Magnification: 200x		 Published measures are the mean of two observations made from two different observers.

d = 63.5-152.2 ; PA = 91-97