Struve 750 

Craig M. Carver
Star: Struve 750 
Date & Time:  11/28/98  0100 LT 
Seeing:  5 <1-10 Seeing Scale (10 best)> 
Location of site:  Randalman, NC  (Lat 36.07, Long 79.79, Elev. 500 ft) 
Site classification: Rural 
Sky darkness:  5.1-5.3  <Limiting magnitude> 
Telescope: 6" Maksutov 
Magnification: 257x 		 This is embedded in the open cluster NGC1981 and is the northern-most star in a chain of 5 stars.  With this scope I needed 257x to split the two white stars. 

 
Chuck Layton
Star: Struve 750 
Date of Observation:  Jan. 11, 1999 
Time of Observation:  0610 UT 
Seeing (1 - 10, 10 best):  5 
Site classification: Suburban 
Limiting Mag. (naked eye):  4.8 
Instrument:  20cm f/6 Eq. Newtonian 
Magnification:  177X 		 Observed Colorations of Components:  Both components appear pale white. 
Other comments:  Close pair but easily split.  Interesting pale to grayish white colors. 

 
Dave Mitsky
Star: Struve 750 
Date & Time: 2/4/99 02:53 UT 
Seeing: 6 <1-10 Seeing Scale (10 best)>
Transparency:  ~ 6 
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, 324x		 Another binary in Orion that is a member of an open cluster, Struve 759 was a close split at 118x.  This star makes up the northeast corner of the M (erect view) that NGC 1981 resembles.  The primary was white and the comes had a bluish tint. 

 
Ilario Melandri
Star: Struve 750 
Date & Time:  
Seeing: 3  <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: +2C 
Telescope: 150 mm f/15 achromatic refractor 
Magnification: 140 x (eyepiece Plossl Clavé 16 mm)

 

 
Randall Heckman
Star: Struve 750 
Date & Time: 12/30/99 at 2:50 UT 
Seeing: 5-6 
Location of Site: Heckman Observatory 
40 37' 10" N and 99 03' 50" W 
Site Classification:  Rural 
Sky Darkness (Limiting Magnitude): 3.5 
Telescope:  8" Orion Dob with 6" aperture mask 
Magnification: 160x 
 		 Separation (Clear or Toughing): Clear 
Magnitude Comment: Secondary at least two magnitudes dimmer. 
Color Comment: White. 
General Comment: The sky had turned hazy and the seeing improved 
substantially. 
 
 
 
 

 

 
Richard Harshaw
Star: Struve 750 [ADS 4192] 
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): 0350 on 12/31/99 
Site classification: suburban 
Sky conditions: 
seeing-- 8 out of 10 
transparency-- 8 out of 10 
limiting visual magnitude-- 5 
Temperature: 41 F 
Telescope: Celestron C-8 
Eyepiece: Micro-Guide (160x) with 2.48x Barlow (397x total) 		 I made five sets of measurements with the Micro-Guide illuminated reticule eyepiece and got an average of 4.3" at PA 57. (If you want the measurements themselves, reply to this posting.) This pair was difficult to measure as it is at about the practical limit of the Micro-Guide with my scope and Barlow. 

I noted colors of White and White. 
The star is a member of the Ori OB1 Association and rotates at 140 kps. 

Measurements from 1940: 
6.6m (B2IV) primary 
8.5m companion, 4" at PA 60 

 

 
Thad Robosson
Star: Struve 750 
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: 87x 

 

 Clearly double at 87x.  Comp. seen as blue 
 
 

 

 
Bill Becker
Star: Struve 750 
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 		 Much closer pair similar in separation to Castor. Primary seen as white, no color for companion. Best seen in 4" at 149x. 
 
 

 

 
William L. Schart
Star: Struve 750 
Date & Time: 1/9/00 10:31 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 		 Easily located in a group of stars that forms the top part of the “sword.” There are 3 stars in a flat triangle, this is at the uppermost end. Also, there is a nearby Y-shaped asterism that almost directly points to this pair. Couldn't split at lower powers, barely split at 72x in momentsx of good seeing, clearly split at 120x. 

Both members appear blue. A very tight pair only a few seconds apart and the secondary is quite faint. For these reasons I did not attempt a measurement. 
 

 
Steve Ott
Star: Struve 750 
Location of site: Millersburg, KY 
Date of observations: Jan 9, 2:30 - 4 UT 
Site classification: Suburban 
Sky darness: ~ 5.5 <limiting magnitude> 
Seeing: 5 (scale 1-10) 
Telescope: 94 mm f/7 apo refractor 
Magnification: 220x 		 Brighter than Struve 712, but not as pretty. Separation seen well at 220X. Colors unremarkable. 
 

 

 
Orlon Petterson
Star: Struve 750 
Date & Time: 10:00 - 12:00 UT 20/01/2000
Seeing: 3 <1-10 Seeing Scale (10 best)> 
Location of site: Christchurch, New Zealand  
Site classification: Suburban 
Sky darkness: 5 <Limiting magnitude> 
Telescope: C102HD f/10 refractor  
Magnification: 50x, 83x, 100x
 
 		 Clear night with a warm light NW breeze, near Full Moon, but with seeing like looking up from the bottom of a swimming pool.  Occasional hint of companion to NE at 100x, but seeing very poor making it difficult to be certain. 
 
 
 
 

 

 
Philippe de Jocas 
Star: Struve 750   
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: 120x
 		 Struve 750 required 120x to become the pretty double completing this neat three stars row.

 
Jim Brownfield
Star: Struve 750 
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 		 split at 47x 

 
Daniel Rodríguez
Star:Struve 750 
Date & Time: 1/30/2000, 23:45 (UT) 
Seeing: 5 <1-10 Seeing Scale (10 best)> 
Location of site: Jerez de la Frontera, SPAIN, elev. 24 m 
Site classification: Urban 
Sky darkness: 4  <Limiting magnitude>
Temperature: 9C 
Telescope: Celestron G8 (8” SCT f/10)
Magnification: 119x, 203x (Celestron Plössl 17mm, 10 mm)
 
 		 Easily split at 119x, best seen at 203x. Due to the observing site conditions no colors were apreciated. Nice double star, the components are close enough to be splitted without problems but you can’t see the secondary component at low powers (50x) so it is a surprise when you split them. 
 

 
John M. Ryan
Star: Struve 750 
Date of Observation: 2/02/00, 22:45UT
Location of Observation: Ciudad Rodrigo, Salamanca, Spain 
40º 36' N, 6º 32'W, Elev. 800 Meters 
Seeing: 6 to 7, fog began to degrade seeing (1 - 10, 10 best)  
Site classification: Urban
Limiting Mag. (naked eye): 5
Instrument: Meade 8"SCT 
Magnification: 167x, 286x 		 Separation (Clear or Touching):Clear Split 
Magnitude Comment: Bright A component with dimmer B component. Data shows 6 & 8. 
Color Comment:The colors both seem pale blue to me. I seem to see more pale blue stars when other observers see these as white. 
General Comment: After spending much time with the close double of 42 Ori this was much wider at 4.3 arc seconds so there was no problem to split this double. I guessed a positional angle of about 70 to 80º for this double. The date shows 60º. However I am aware that the position of my eyepiece or the telescope was not aligned to correctly determine the PA. My near project is to get the Celestron microquide eyepiece and the protractor to correctly ascertain the positional angles. 

 
Jay Zimmerman
Star: Struve 750 
Date & Time: 02/08/2000, 
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: 80x, 160x 		 Clean split at 80x. Colors: A = white; B = white (maybe). 
Under current conditions (actually pretty good) this one needed high magnification. Even at 160x the pair looked closer than I would have predicted from the published mag. and separation numbers. 
 
 
 

 

 
Bill Reinehr
Star: Struve 750 
Date & Time: February 14, 2000, 02:00  UTC
Seeing: 8  (very still) <1-10 Seeing Scale (10 best)>
Location of site: Pflugerville, Texas, USA  (30 degrees N.)
Site classification: Suburban 
Sky darkness: 4 <Limiting magnitude> 
Temperature: 65 F 
Telescope: Vixen 80mm Fluorite, f/8  on Custom D altaz mount  
Magnification: 29x, 58x, 91x		 Cleanly split at 91x. No colors noted. 
 
 
 
 
 
 

 

 
John Clemmer
Star: Struve 750 
Date & Time: March 6/2000 1930 EST  
Seeing: 7, quite steady <1-10 Seeing Scale (10 best)>
Location of site: Priceville, Ontario, Canada
W80 41'41"  N44 10' 40"
Site classification: Rural 
Sky darkness: 6+/10ths 5th mag. if I'm lucky tonight <Limiting magnitude>
Telescope: Televue Pronto
Magnification: 95x 
 		 clean w/ 5xBarlow + 26mm, 95x 

 
G.E.O.D.A Group
Star: Struve 750 
Date & Time: 10-III-2000, 19:00-21:00 UT
Seeing: 7.5 <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: 3 <Limiting magnitude> 
Telescope: Meade 10" LX-200 SCT
Magnification: 200x		 Published measures are the mean of two observations made from two different observers.

d =  6.0; PA = 61