Struve 1558 

Richard Harshaw
Star: Struve 1558 
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): 02:00 – 04:10, March 31, 2000, 
LT:  20:00 - 2210, March 30, 2000 
Site classification: suburban 
Sky conditions: 
Seeing: 4 to 8 out of 10. (This night there was high, thin haze in the sky, which in this part of the world normally means superb seeing, still air and the ability to push a scope to its theoretical limits.  But this time, the sky was turbulent, despite the fact that a front had passed by two days ago, and the back sides of fronts tend to be quiet here.  So the seeing varied greatly, from a deplorable 4-- 
stars that looked like breathing sponges-- to 8, crisp Airy disks and partial diffraction rings.  And this change could take place in as little as five seconds!  Frustrating experience!) 

Transparency-- 4 out of 10 
Limiting visual magnitude-- 3.5 
Temperature:  40 F 

Telescope: Celestron C-8 
Eyepiece: 7.4mm Plossl with Barlow (708 x) 
 

 A:  9.0 mag, G5 
B:  9.0 mag 
C:  9.0 mag 
AB:  1.3" at 162 PA (PA increasing) 
AC:  44" at 280 PA (PA increasing) 

First measures: 
AB:  in 1828, 1.3" @ 158 
AC:  in 1829, 43" @ 276 
Measures listed above (1.3", 44") are the 1956 set. 

This pair was too close for use of the Micro-Guide for measurements, so only visual impressions are reported. 
 
All three were white.  C was a cinch at 163x, of course.  But AB were 
very difficult.  At times, I could only get a figure 8.  At other times 
(brief moments), a clean split. 
 

 

 
 
 
Alessandro Bertoglio 
Star: Struve 1558
Date & Time: April, 25, 2000, 21.25 UT
Seeing: 8 (Pickering A) 
Location of Site: Turin - Italy  
Site Classification: urban 
Sky darkness: 4 - 4.5 <limiting magnitude>  
Telescope: 120mm, f=1800mm achromatic refractor
Magnification: 185x - 257x (Meade PL 9.7 mm, Vixen LV 7 mm)		 Component  A, Yellowish-white color
Component  B, Yellowish-white color
Component  C, White color