Delta Cygnus 

Ilario Melandri
Star: Delta Cygnus 
Date & Time: 06/07/2000 – 23.18 UT 
Seeing: 4 <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: 4 <Limiting magnitude> 
Temperature: 21C 
Telescope: 150 mm f/15 achromatic refractor (lens by Romano Zen, Venice). 
Magnification: 140 x (eyepiece Clave Plossl 16 mm) 
Notes: fantastic!! 
Bill Reinehr
Star: Delta Cygnus  
Date & Time: July 21, 2000, 2000 05:00 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: 4.1 <Limiting magnitude>  
Temperature: 82F 
Telescope: Vixen 80mm Fluorite, f/8  on Custom D altaz mount   
Magnification: 142x (9mm Vixen Lan & 2x Barlow), 183x (7mm Pentax XL & 2x Barlow) 


Split but not cleanly at 142x, a clean split at 183x. Pretty tough. I've tried and failed to split it on evenings when the seeing was not as good. No color noted. 
William L. Schart
Star: Delta Cygnus 
Date & Time: 7/24/00 11:28 pm CDT 
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, 120x, 240x
Suceeded in splitting this tonight at 240x. The conditions were pretty good, which probably helped. I used both the hex mask and no mask in conjunction with my barlow. I think it was better without the mask. At 120x, nothing was doing without the mask; with the mask I got a bit of a notch but no separation. 
Richard Harshaw
Star: Delta Cygnus 
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): 03:30 on 26 July, 2000 
Site classification: suburban 
Sky conditions
Seeing--  6 out of 10, but highly variable 
Transparency--  6 out of 10 
Limiting visual magnitude-- 4.0 
Telescope: Celestron C-8 
Eyepiece: 10 mm Ortho + Barlow, 516x, with mask 
Magnitudes: 2.9 (B9 III), 6.3, 11.9 
Sep/PA's: AB = 2.4" + / 225 -. AC = 66" / 66. 
Year of last measurement: 1997 
Distance (light years): 171 
Luminosity (in suns): 168 
Eyepiece and magnification: 10 mm Ortho + Barlow, 516x, with mask 
Colors noted: W, B, bW (But Webb saw G and W for A, B.) 
The B star was very difficult to see. It sat on the second diffraction ring, hence the use of the mask. 
The pair was discovered by W Herschel in 1783. First measure (1830, F. Struve): 1.9" / 41. Van Biesbroeck obtained 1.6" / 288 in 1911. 
Espin found a faint comes at 130" @ 64. It was in fact a double (11.5m and 12.5m, 2.6" @ 310). 
Its orbit takes 827.6 years (Baize, 1973). 
Star A is a spectroscopic binary that rotates at 149 kps. It is also an infra-red source. 



Luis Argüelles
Star: Delta Cygnus 
Date and Time: 30, July, 2000, 21:28 UT
Seeing: 7 <1-10 Seeing Scale (10 best)>
Sky darkness: 3.0 <Limiting magnitude>
Transparency: 5-6
Temperature: 16C, light breeze
Location of site: Quintueles, near Gijón, Spain
Site classification: Suburban  
Telescope: Vixen 102M, 4" achromatic refractor 
Eyepiece(s): Eudiascopic 5mm and 2x Celestron Barlow Ultima
Magnification(s): 200x, 400x
A really tight double from the same observational family as Antares in
Scorpius. The primary is rather bright (magnitude 3) and there is a
“delta-magnitude” of 3.5 with respect to the other component. With the
observing conditions in this night this star is a challenge to split,
althought I get it at 200x when a “seeing” of 7 comes, but the secondary
vanishes when it goes lower.

Using the Barlow and the Eudiascopic 5mm eyepiece I feel some problems
because the wind moves the telescope (I must adapt my wood surveyor’s tripod for my GP) and only during short moments I clearly see two stars in Delta.
400x seems to be the “upper limit” of my refractor.

Coloration is appreciated at 200x as orange and blue, and it’s even more
easy to appreciate it defocusing slightly the telescope. I find Delta easier
to split than Antares, but not for a big difference in observing efforts.



John M. Ryan
Star: Delta Cygnus 
Date of Observation: 1/08/00 22UT  
Location of Observation: Ciudad Rodrigo, Salamanca, Spain 
40º 36' N, 6º 32'W, Elev. 800 Meters 
Seeing: 5 to 6 (1 - 10, 10 best) 
Transparency: 6 Misty  
Limiting Mag. (naked eye): 3.5  
Site classification: Urban 
Instrument: Meade 8"SCT 
Magnification: 286X (7mm Ortho) and 400X (5mm Ortho) 
Separation (Clear or Touching):Clear 
Magnitude Comment: The comes was much dimmer in comparison. 
Color Comment: Both white 

General Comment: Could not separate the double until I boosted the magnification to 286X and then it was just coming clear. At 400X the comes was sitting small and very pretty just outside the glare of the primary. Until the double star separation my two orthos were just sitting in the case but they sure are handy now. 

Jim Jones
Star: Delta Cygnus 
Date & Time: 0520 UTC, August 3, 2000  
Seeing: 6 <1-10 Seeing Scale (10 best)> 
Location of site: Lake Oswego, Oregon, USA  
Site classification: Suburban 
Sky darkness: 4.5 <Limiting magnitude>  
Telescope: 8 inch LX50 SCT 
Eye Piece(s): 18mm Radian/2X Ultima (Between OTA and diagonal) 
Magnification: 336x 
Visible periodically between diffraction rings. Comes and goes but clearly visible. Also visible at 224x but not as often. No color noted. Est PA 230d without insturments. 
Rich Tyson
Star: Delta Cygnus 
Date & Time 8/6/00, 2:08 UT 
Seeing: 6 <1-10 Scale (10 best)>  
Location of site: Robert Mosses State Park, 
Long Island, New York. 
40º 71N, 73º 30W 
Site classification: Suburban 
Sky darkness:  5.0 <limiting magnitude> 
Telescope: 10" reflector 
Magnification: 253x 
A difficult star to split. Both stars appear blue/white in color. Secondary Star had a hint of yellow to it. 


Tom Teague
Star: Delta Cygnus 
Date & Time: 2000 August 11, 23:00 UT 
Seeing: 8 <1-10 Seeing Scale (10 best)>. 
Location of site: Chester, England (53 11 08N; 02 51 39W) 
Site classification: Suburban  
Sky darkness: 4 (Moon present) <Limiting magnitude> 
Telescope: 63mm Zeiss Telementor refractor 
Magnification: x140, x210 
This is one of those unequal pairs on which a small refractor can outperform a larger reflector or catadioptric instrument. 

Not difficult x210 - comes held constantly with a/v.  Both components seem yellow to me. 

Comes also seen x140, but with difficulty - held with a/v for several seconds at a time, but not continuously as with the higher power. 

I have observed this pair many times in the past.  In my experience, seeing conditions are absolutely critical for a good view, regardless of aperture.  Accurate focusing is also critical.  If the focus is less than perfect, the diffraction rings may appear slightly too bright, and you will then be lucky to detect the comes as a localised brightening of the inner ring, if at all. 

In my 215mm f/5 Newtonian, this pair is not significantly easier than in the little Zeiss. 

Tim Leese
Star: Delta Cygnus 
Date & Time: 11/12 Aug 2000 (21:00UT- 01:00UT) 
Seeing: 6-7 <1-10 Seeing Scale (10 best)>  
Location of site: Cheshire. UK 
Site classification: Suburban  
Sky darkness: 3, moon ( low in sky ) <Limiting magnitude>  
Telescope: 200mm f/6  Newtonian scope  mounted over a Vixen GP mount (manual slow motion). 
Any Quoted PA or SEP using micro guide 
Magnification: X60, X120, X240 
Nothing doing at X60 for this system. Using X120 I could 
just see the secondary popping in and out of the view just to one side of a diffraction spike! 
A magnification of X240 was needed to get a complete split with the primary seeming to be a white colour and  the secondary being off white. 




Cor Berrevoets 
Star: Delta Cygnus 
Date & Time: 13 august 2000, 23:20 MET / 21:20 UTC 
Seeing: 6 <1-10 Seeing Scale (10 best)>  
Location of site: Ritthem, The Netherlands, EU 
Site classification: Rural  
Sky darkness:  ~4 <Limiting magnitude>  
Temperature : 20 C 
Telescope: Intes Micro 603 150/1500 (MCT) on CG-5 mount with dual-drive. 
Magnification: 10 and 15  mm with 2.4 Intes Barlow (240 - 360x)  
Due to some tube-currents the split was difficult earlier in the 
evening. But at 23:00 most of my Mak-plague had gone and at 240x I could see a hint of the secondary (disturbance) in between the 2nd/3rd 
diffraction zone. At 360 it was easy split, the secondary showed up like 
a small brightened knot near to the 3rd diffraction ring. I did see no 




Patrick J. Anway 
Star: Delta Cygnus 
Date & Time: August  18, 2000  - 03:00 UT 
Seeing: 7 <1-10 Seeing Scale (10 best)> 
Location of Site: Munising Michigan USA 
Site Classification: Rural 
Sky darkness: 6 <limiting magnitude> 
Sky condition: Moon just below east horizon; no clouds 
Temperature: 50*F   10*C 
Telescope: Vixen 102/1000 f9.8 refractors on 
equatorial mount 
Eyepiece: Vixen 6mm orthoscopic (with Lumicon OIII & UHC filters) 
Magnification: 166x 
I used Vixen 4" and a 6mm ortho,  for 166X and a clean split using the nebula filters. With the OIII filter the primary was a deep red and the brightest component; the secondary was an off-white with perhaps a hint of blue. 

Using the UHC I found the secondary more obvious and while the primary remained a deep red, the 
secondary became sky blue and was definitely the brightest of the two. At this power without the filters, I was unable to pick the secondary out of the glare of the primary.