Struve 1937

Steve Bodin
Star: Struve 1937
Date: 10 June 2006
Time: 11pm to midnight
Seeing: 3/10
Transparency: good
Location of site: Mattawa Wa, USA
46.7N,119.9W
Site classification: Rural
Conditions: 60F, no wind, dry
Sky darkness: limiting mag 4.5 due full moon
Telescope: Meade 16 inch LX200GPS UHTC
Eyepieces: not used
maging: DX8263SL video camera at f10 and f20
Magnification: app. 600x, 1200x
eta CrB Had to try this a favorite. I have watched about half of its orbit over the years. Had a devil of a time even seeing any sign of a double. Searched through 600 video frames and found 12 that looked like a pair. I know that it has been close for a few years, but I, for some reason thought that it was widening again. Not true, WDS 6th Orbit catalog calculation for last night was 0.494 at 130.8 deg PA. The project data is from some years ago. Measured, 0.48 sec at 134 deg PA from that poor stack of kidney bean shaped stars!
 



      

Steve Bodin
Star: Struve 1937
Date: 25 June 2006
Time: 11pm to midnight
Seeing: 5-6/10
Transparency: good
Location of site: Mattawa Wa, USA
46.7N,119.9W
Site classification: Rural
Conditions: 79F, no wind, dry
Sky darkness: limiting mag 6.5
Telescope: Meade 16 inch LX200GPS UHTC
Eyepieces: not used
maging: DX8263SL video camera at f30
Magnification: app. 1800x

 eta CrB Supplement to previous observation. this time the seeing was better and the pair was obvious the whole time that I observed. Measurement, 0.51 sec at 125.9 deg PA.


  
       

Wolfgang Vollmann
Star: Struve 1937
Date: 2006 July 26
Time: 21:00-24:00 UT
Seeing: 5 <1-10 Seeing Scale (10 best)>
Transparency:  clear
Location of site: Vienna, Austria
Site classification: Suburban
Conditions:
Moon:
Sky darkness: 4.5 <Limiting magnitude>
Telescope: 130/1040mm refractor
Camera: SBIG ST237A CCD
Exposures: 6 or 12 x 10 seconds for astrometry. Distance/PA measurement was done with these images also except where noted (bright stars need shorter exposure times of 1 sec or less)
Image measurement: astrometry with Astrometrica software and UCAC2 or USNO B1.0 catalog (see http://www.astrometrica.at); with exact focal length and image orientation I measured distance and PA with AIP4WIN software. I took means of measuring all my images for a star. There is a scatter of 0.2 arcsec in separation and 0.2 deg in PA. Scatter in PA is much larger if the stars are very close. Note: All images have north up
Eyepieces: n/a
Magnification: n/a

STF1937 = WDS 15232+3017

Eta CrB is a very close double star of short period which is very interesting to watch using high magnification. With my CCD camera at prime focus I could observe only two faint wide companions, C and D. Star C is probably optical since it has quite different proper motion from AB in the WDS catalog.

C is north of bright AB (up) D is northeast of bright AB (upper left
Measures: STF1937AB-C: year 2006.57 / distance 73.7 arcsec / PA 358.7 deg STF1937AB-D: year 2006.57 / distance 217.7 arcsec / PA 41.0 deg

 
   
      
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