Theta 1 Orionis 

Clich Here to go to our Addendum 2000-2001
 
 
William L. Schart
Star: Theta 1 Orionis 
Date & Time:  November, 26th, 1998 
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: 32x, 48x, 120x 
 
 
Star: Theta 1 Orionis 
Date & Time: 12/25/98 10:45 pm CST using a micrometer reticle: 
Seeing: 7 <1-10 Seeing Scale (10 best)> 
Location of site: Killeen, TX (Lat 31 N, Elev 600 ft) 
Site classification: Suburban 
Sky darkness: 5 <Limiting magnitude> 
Telescope: Orion 6" Dob 
Magnification: 98x 
 
 
Star: Theta 1 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) 		 I had not yet officially observed these for the "33 Doubles in Orion" project, so I started this evenings observing with this. Even in low power, it was obvious that this is a multiple star system. At 48x, all 4 stars are visible and at high power all four are clearly visible. No color other that white was apparent to me. Much 
detail was visible in M42, with dark lanes. 
 
 
 
 
 
 
 
 

Pa and separations measured as follows: The closest pair had a separaton of 6", the next 2 pairs both measured at 17" and the widest pair was 20'. PA of one 
diagonal was 270 degrees, and the other diagonal was 175 degrees. 
 
 
 
 
 
 
 
 
 
 

I was able to capture the 4 brightest members with my AstroCam. Separations, measured from a created double exposure: 
A-B, 9”; A-C, 12”; A-D, 21”. PAs, A-B, 35d; A-C, 134d; A-D, 95d. These agree well with published figures. 

 

 
Paolo Morini
Star: Theta 1 Orionis 
Date & Time: 07 Dec 1998, 23:15 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) - 164x (LE5 eyepiece) - 205x (LV4 eyepiece) 
  

 
Star: Theta 1 Orionis 
Date & Time:6th Dec 1999 , 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> 
Temperature -1?C 
Telescope: Takahashi FS102 
Magnification: 164x (LE5 eyepiece)
 

 Very fine image of the Trapezium. I thought to have seen for a minute the E component of the Trapezium, of 11 mag, at 164x without prism. My friend Ilario who is a very skilled observer, failed to see it. We tried again at 205x with the mirror diagonal, for a better comfort – nothing. 
We tried again at 164x without diagonal – nothing. 

At home I find the position of E in the Burnham Celestial Handbook : it was in the exact position I saw my star and were I told my friend to look for : so I saw it 
(?!). What do you think about? 
 
 

The Trapezium, an exciting vision, no matter if you have seen it a thousand times before. 
 

 

 
Chuck Layton
Star: Theta 1 Orion 
Date & Time: Dec.19, 1998, O5:00 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: 36x, 122x		 Observed Colorations of Components:  All stars appear white except  A which appears brilliant blue white. 

Other comments:  Spectacular field!  This quad lies embedded within the beautiful green swirls and tendrils of M42.  Theta 2 is well within the field. 
 

 

 
Luis Argüelles
Star: Theta 1 Orionis 
Date & Time:  January, 6 th, 1999 - 22:50 UT 
Seeing:  2-3 <1-10 Seeing Scale (10 best)> 
Location of site: Oviedo - Spain. (Lat 43.23 N, 5.51W, Elev 250 m.) 
Site classification: Urban 
Sky darkness: 2.5-3 <Limiting magnitude> 
Telescope: Televue Ranger refractor. 
Magnification: 48x (10mm Eudiascopic)		 Components A,B,C and D are all clearly visible, although component D, due to a really bad seeing “comes and goes”. This is also the reason that it’s 
impossible to go higher in magnification, but this observation demostrates that “entry-level” double star observing is even possible with:  1. Bad seeing, 2. 
Small instruments, and 3. Bad observing site (from inside the living room of my home). Anyway, I allowed the living room to cool to balance the difference in 
temperatures from inside and outside the house. 

Under these observing conditions the observed coloration is the same for all 4 components: white-blue. 
 

 

 
Dave Mitsky
Star: Theta 1 Orionis 
Date & Time: 1/19/99 02:48 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> 
Telescope: 17" f/15 classical Cassegrain 
Magnification: 118x, 202x, 249x, 381x		 Perhaps the most famous of all multiple stars and better known as the Trapezium, this group of hot young stars is actually part of an open cluster in the making.  Stars A through F were resolved. 
 

 
Orlon Petterson
Star: Theta 1 Orionis 
Date & Time: 12/02/99, 9:30UT to 14:00 UT 
Seeing: 9 
Location:  Staveley, ~80km SW of Christchurch, New Zealand. 
Instrument: 102mm f/9.8 refractor 
Sky darkness: 6 - 6.5  <Limiting magnitude> Didn't actually make a definitive measure but the sky was dark and the transparency really good. 
Magnification: 50x, 208x 		 50x clearly shows 4 components and the surrounding nebula, when magnification was increased to 208x still only saw the 4 components.  Where did the rest go? 

 
Orlon Peterson, Marilyn Head, Giles Reid and David Downing
Star: Theta 1 Orionis 
Date & Time: 13/02/99, 10:00UT to 14:00 UT 
Seeing: 7-8 got better as night progressed 
Location:  Staveley, ~80km SW of Christchurch, New Zealand. 
Instrument: 102mm f/9.8 refractor 
Sky darkness: 6 - 6.5  <Limiting magnitude> Again didn't actually make a definitive measure but the sky was dark and the transparency really good. 
Magnification: 208x		 Back again this time armed with a little more information on where to find the faint 5 and 6 stars of the Trapezium.  At 208x I was able to make out these 2 stars.  I now realise why I missed them the first time, one is close to Theta Ori1 and I must have dismissed it as part of the airy disc and the other is almost lost against the surrounding nebula.  Perhaps a warning label should be added for those :-) 

 
Ilario Melandri
Star: Theta1 Orionis 
Date & Time: 6/Dec/1999 – 23.08 UTC 
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: Theta1 Orionis 
Date & Time:  December, 16, 1999 21:45:10 UT 
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 

 		 Observing Method: CCD ST-4 Camera 
Integration time: 2 seconds 
Software used (reading/treatment): Lucas 1.1 / Laia 3.1g 
Image Position: North up, East left 

Located within the Orion nebula, we can see in this image this four-components system (for medium and small instruments). In order to capture this image, I first made a take from M42 and then I selected the Trapezium area, using a 2X Zoom. 

In this multiple system, the brightest component is C with 5.6 magnitude followed by A (6,7), D (6.8) and B (8,2) all the stars are type O or B low. 

Star     Separation    A.P. 
CA       13”              312° 
CD       14”              61° 
CB       17”              342° 
AB       8,7”             32° 

In the Trapezium there are 2 components more that requiere superb optics and really dark skies: one has magnitude 11, located 4” apart from component C and other of magnitude 11.5-12 located towards East. 
 

 
Randall Heckman
Star: Theta 1 Orionis 
Date & Time: 12/26/99 at 2:27 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): All components clear 
Magnitude Comment: Magnitudes agree with quoted values 
Color Comment: All white to blue white. 
General Comment: I could not see the E and F components. I have rarely been  able to view these.
 
 
 
 

 

 
Richard Harshaw
Star: Theta 1 Orionis [Trapezium; 41 Ori; STF 748; ADS 4186; SAO 132314] 
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): 0225 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, high haze approaching from the SSW 
Telescope: Celestron C-8 
Eyepiece: Celestron Micro-Guide (160x) 		 All of the separations and position angles appear to be fixed. 

I made five pairs of separation and PA measures using the Micro-Guide and got the following averages:  AB 9.2" in PA 35; AC 14.5" in PA 241; and AD 17.6" in PA 342. This might have been a good system to use the Micro-Guide and Barlow on to get a little better spread for the PA 
baseline on the AB pair. 

What an awesome system! The area is rich, of course, with the Orion Nebula and dozens of doubles within 3 degrees of here. 

I noted colors of White, White, Blue, and Blue. 

The 7.9m star has an 11.5m companion 4" away in PA 122. Try for it next time you are in the area! 

There is also an E star of 11.1m 4" from A in PA 351. It is an extreme challenge for a good night, and was impossible to see tonight. 

Christian Huygens first saw the pair in 1656. 

The stars are lettered (A, B, C, etc.) not in the normal order of brightness, but in order of right ascension. The four main stars were the ones seen by Huygens and his followers, but F. Struve, in 1826, discovered a fifth star, b (sometimes called E), as noted above. John Herschel discovered E (sometimes called F) in 1830. Beyond an 8" scope's reach, there is also a G star (found by Clark in 1888 with the 36" Lick telescope) and H (found in 1888 by Barnard). 

The Hubble Space Telescope has revealed that the space surrounding the Trapezium is actually a dense and brand-new star cluster. (The Trapezium itself is only about 23,000 years old.) Most of its stars are just too faint for earth-based telescopes, and a high percentage are variables (still approaching the Main Sequence). 

The A star is a spectroscopic binary with a period of 65.43233 days. It is also an infra-red source. 
The B star is also a spectroscopic binary (6.4705 day period), as is D. 
C was once thought to be a spectroscopic binary, but now it is believed that material falling into it is responsible for the "fake" binary spectrum. It is also an infra-red source. 

The entire system is part of the Ori OB1 Association. 

Measurements of 1990: 
5.1m (O7) primary 
7.9m companion at 8" in PA 31 
5.5m (O) companion at 13" in PA 241 
6.7m companion at 17" in PA 342 
 

 
Thad Robosson
Star: Theta 1 Orionis 
Date & Time: 12-30-99,  3:00 to 6:30 UT (12-31-99 UT) 
Seeing: 4-5   <1-10 Seeing Scale (10 best)> 
Location of Site:  Carbondale, IL, USA 
Site Classification: Suburban/near rural 
Sky darkness: 4.7 using "stars counted in the area of" method, (Taurus)   <Limiting magnitude> 
Telescope: 8" f/6 Newt on Dob mount  (soon to be split ring  :-) 
Magnification: 46x, 87x, 174x 
 

 

 All 4 were quite distinct at 46x, and the "E" comp. at 87x.  At 
174x tube currents were troublesome.  The nebula was quite extended to the E, with much detail available.  No hint if the "F' comp. 
 
 
 
 
 

 

 
William L. Schart
Star: Theta 1 Orionis 
Date & Time: 1/9/00 11:00 PM CST 
Seeing: 7 <1-10 Seeing Scale (10 best)> 
Location of site: Killeen, TX (Lat 31 N, Elev 600 ft) 
Site classification: Suburban 
Sky darkness: 4.5 <Limiting magnitude> 
Telescope: Orion 6" Dob. 
Magnification: 48x, 72x, 120x		 The four main members of the Trapezium, are clearly visible at 48x. The 3 brightest members appear white while the fourth appears blue. Higher powers did not reveal any of the other members of this group and due to time constraints, I did not attempt any  measurements.

 
Patrick J. Anway 
Star: Theta 1 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; white with  perhaps some blue. At 34X not positive, but with averted vision and maybe a  little imagination appeared to be. I recall splitting these with my 50mm f/11 Zeiss and a Vixen 12mm .965" ortho at 45X. They are truly a sky wonder and I never grow tired of the view. 
 
 
 
 

 

 
Orlon Petterson
Star: Theta 1 Orionis 
Date & Time: 12/01/2000, From ~10hr UTC to 11:30
Seeing:  4-7, improved as the evening progressed <1-10 Seeing Scale (10 best)> 
Location of site: Christchurch, New Zealand  
Site classification: Suburban 
Sky darkness:   <Limiting magnitude> 
Telescope: C102HD f/10 refractor  
Magnification: 28x 50x 100x 208x		 4 main trapezium stars visible at all used magnifications, seeing too poor  to locate 5 and 6th stars. 
 
 
 

 

 
Philippe de Jocas 
Star: Theta 1 Orionis  
Date & Time: January 22, 1h00-7h300 UT 
Seeing: 3-4 <1-10 Seeing Scale (10 best)>.
Location of site: Ottawa/Hull, Canada
Site classification: Suburban 
Sky darkness: 4.5 <Limiting magnitude>
Temperature: -25C 
Telescope: 6" f5 newtonian
Magnification: 40x		 Theta Ori's group (1&2) is for me always a grand sight, a more flamboyant version of the last two, easy to see at 40x, with M43 barely visible, washed out but moonlight and city lights.

 
Jim Brownfield
Star: Theta 1 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, 75x
 
 
Star: Theta 1 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 		 47x showed trapezium, at 75x glimpsed star E at 11.1 mag, but couldn't see star F at any power 
 
 
 
 
 
 
 
 
 
 
 

showed all 4 stars at 28x 

 
John M. Ryan
Star: Theta 1 Orionis (Trapezium) 
Date of Observation: 30/01/00 23:00UT 
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 of four main components. 
Magnitude Comment:Magnitudes go up in succesion like a graph. 5,6,7,8 in accordance with the data. 
Color Comment:All four components seem white to me. 
General Comment: It is always a joy to return to the trapeziun in M42. Need a bad night not to split this group. It was getting late and cold so I did not spend much time trying to squeeze out the components E and F. These much dimmer components were not available. I have never seem them so I have some searching to do with much higher magnifications in the future. 

 
Bill Reinehr
Star: Theta 1 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, 91x, 183x, 256x 		 Split at 29x. No luck on the E component at any power. I've had glimpses of it before but not on this occasion. Have never spotted the F component with this aperture. 
 

 

 
Jay Zimmerman
Star: Theta 1 Orionis 
Date & Time: 02/06/2000, 0415 UT 
Seeing: 7 <1-10 Seeing Scale (10 best)> 
Location of Site:  Carbondale, IL, USA 
Site Classification: Suburban/near rural 
Sky darkness: 5.0  <Limiting magnitude> 
Telescope: 97mm, f7 apo 
Magnification: 26.7x 
 

Star: Theta 1 Orionis 
Date & Time: 02/08/2000, 0245 UT 
Seeing: 8-9 <1-10 Seeing Scale (10 best)> 
Location of Site:  Carbondale, IL, USA 
Temperature: 30°F (-1.11°C) 
Site Classification: Suburban/near rural 
Sky darkness: 5.3  <Limiting magnitude> 
Telescope: 97mm, f7 apo 
Magnification: 192x, 256x, 384x 
 

 Easy at 26.7x. The area in the immediate vicinity of the Trapezium was dark and free of nebulosity, but I could not detect components E and F.  Colors: A, C, and D = white to blue-white; to me, B always seems to have a warmer tint. 
 
 
 
 
 
 
 
 
 
 

Owing to exceptionally steady conditions early in the evening, the E component of the Trapezium was visible at 192x (8mm EP + barlow). The view at 192x was better than at 256x or at 384x so the atmospherics, while very good, were not calm enough to support a really massive push of the optics. E winked in and out of visibility but could be spotted at least 75 percent of the time. AV was not needed. 

Color: blue.  This was my first sighting of E, but I'll bet it's been there all the time!  I also note from today's reports that Bill Becker saw E at nearly the same time.  It was a good night all the way from Casper to Carbondale. 

 

 
Bill Becker
Star: Theta 1 Orionis 
Date of observations: Feb. 8, 2000, 
Location of site: Casper, Wyoming Elev. 5200' 
Site classification: Suburban 
Seeing: 6 <1-10 Seeing Scale (10 best)> 
Sky Darkness: 5 <Limiting magnitude> 
Telescope: Quantum 4 Maksutov 
Magnification: 149x 
 		 I'm finally posting this multiple as I was able to glimpse the E star between A & B. The 3 brighter stars(C, D & A) appeared blue-white, B seemed to be a violet maybe? no color in the E star, just glad I saw it. The winds were, for the most part, missing tonight and the seeing of 7 was chosen because the images were very steady both in and out of focus. 
 
 

 

 
Jordi Viver
Star: Theta 1 Orionis 
Date & Time: 19/02/2000, 10:00 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: Can’t see de fourth component 
General coments: The famous “Trapezium” 
 
 
 
 
 

 

 
Tim Leese
Star: Theta 1 Orionis 
Date & Time: 19-Feb-2000, 1900-2330 UT.
Seeing: 5/6  <1-10 Seeing Scale (10 best)> 
Location of site: Cheshire. UK
53° 15' N –2º 33' W 
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, x240
 

Star: Theta 1 Orionis 
Date & Time: 25-Feb-2000, 1930-2350 UT
Seeing: 4-5  <1-10 Seeing Scale (10 best)> 
Location of site: Cheshire. UK
53° 15' N –2º 33' W 
Site classification: Suburban 
Sky darkness: 3-4 <Limiting magnitude> 
Conditions: High haze, slight breeze. 
Telescope: 200mm f/6  Newtonian scope  mounted over a Vixen GP mount (manual slow motion).
Magnification: x120, x240

 Split into 4 stars( trapezium) at x48 and x120. x240 observe stars E and F also (star F with averted vision) This is the first time I have seen stars E & F. 
 
 
 
 
 
 
 
 
 
 

Trapezium stars seen at x120 and x240 but unable to see stars E and F this time. ( Nebula looks brighter ) 
 
 
 
 
 
 

 

 
Eddy O'Connor
Star: Theta 1 Orionis 
Date & Time: Friday, Feb 25th 2000, local times 9.30 p.m. 
Seeing: 9 <1-10 Seeing Scale (10 best)>
Location of Site:  South Coast New South Wales(E150.37;S34.52), Australia 
Site Classification: Suburban near water. 
Sky darkness: 5, no Moon <Limiting magnitude> 
Telescope: Meade 90mm 
Magnification: 260x 		 4 brightest stars easily seen with fifth star in the system just visible, North of E. No discernible difference in colours of main four - florescent white. 

Ambience: Much barking of dogs, street noises and car doors. Several mag 3 satellites passed over the zenith; one blue-white flashing object passed rapidly in the Northern sky. My viewing companion feels it was too fast for a plane - I am not a UFO believer - he would like to be! :) 

Some years back I saw six stars comfortably in the trapezium at low power with a home-made 12" glass, but have since only detected 5 in 25X100 large binoculars. Hartung reckons the dimmer 11 mag. 5&6 may have been much fainter in the past as the keen-eyed Hershels did not detect them. Burnham gives them at mag. 11 and separation 4". Why do I so easily spot number 5 but not number 6? Interestingly, a friend the same night from a nearby location spotted only number 5 in a 90 mm Takahashi. 
 

 
G.E.O.D.A Group
Star: Theta 1 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 = 17.5-16.4-21.9; PA = 60-312-343 
 
 

 

Addendum 2000-2001

 
 
Bob Hogeveen
Star: Theta 1 Orionis 
Date & Time: December 18, 2000, 23:00 UTC 
Seeing: -- <1-10 Seeing Scale (10 best)>.
Location of site: Annen, The Netherlands (53 N, 6 E)
Site classification: Village-backyard 
Sky darkness: 4.3 <Limiting magnitude>
Conditions: Lot of moisture in the air
Temperature: 0° C
Telescope: Celestron CG-11 
Magnification: 112x 		 The sight of M42 around Theta-1 (and 2) Ori is overwhelming with this scope. As this is my first M42/Trapezium-observation with the CG-11 I am a bit distracted from the stars towards the nebula. 

The 6 brightest stars of Theta-1 are all easily visible at 112x. I tried a OIII filter on the nebula, but I liked the overall view of nebula + stars without filter better. It is a fantastic view, this multiple star embedded in this nebula. Theta-1 definitely rating 1 among doubles, M42 definitely rating 1 among DSO's. 

 

 
Thad Robosson
Star: Theta 1 Orionis 
Date & Time: 22, January, 2001
Seeing: At best a 7, but went down to
4 in places <1-10 Seeing Scale (10 best)>.
Definately did not support the higher 
powers necessary for this project. A 
moderate wind was a big factor/problem. 
Location of site: Eagle Eye, in the lovely
Harquahala Mts., Arizona
33 43.787n, 11317.765w. Elev 1,800ft
Site classification: Rural
Sky darkness:  <Limiting magnitude>
Temperature: about 40°F 
Telescope: 8" f/6 (1200mm) on a
dob mount.
Eyepieces: Mostly Vixen. 10 and 15mm 
with 2x and 5x barlow combo's. 		 I'm not sure about which ones were the E and F, but here's an obs anyway. 
E is at PA 100° from the A comp. and F is at an est PA of 315°, with F being 
considerably further away. 
 
 
 
 
 
 

 

 
William L. Schart
Star: Theta 1 Orionis 
Date & Time: 
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: Celestar 8” SCT
Magnification: 78x, 120x, 203x 		 At high power I occasionally thought I might have glimpsed the 5th and 6th members of the Trapezium. However, I wouldn’t swear to it. The nebula was a spectacular backdrop for this.