Eta Geminorum 

Bill Reinehr
Star: Eta Geminorum 
Date & Time: Jan 12, 2001 -  03:30 UTC  
Seeing: 8 <1-10 Seeing Scale (10 best)> 
Conditions: moon just breaking horizon, instant dew, very steady. 
Location of site: Pflugerville, Texas, USA  (30 degrees N.) 
Site classification: Suburban  
Sky darkness: 3.9 <Limiting magnitude>  
Temperature: 42º F. 
Telescope: Vixen 80mm Fluorite, f/8  on Custom D altaz mount  
Magnification: 299x (6mm Vixen Lanthanum & 2.8x Barlow) 
 
I'd like to say I split this but I'm not rock solid sure. There was something (a microbe?) lurking in the 1st diffraction ring at about the right PA. The split (if there was one) was clean. The primary appeared yellow to me, no color in the microbe. 
 
Difficult. Skymap Pro V.7 lists the separation as 1.71 arcsec. 

 
 

 
 

 
 
Tim Leese
Star: Eta Geminorum 
Date & Time: 13 January 2001( 21:00 UT ) and 
14 January 2001 (21:45 UT ) 
Seeing: 6  <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: Clear and cold with drifting high haze. 
Telescope: 200mm f/6  Newtonian scope  mounted 
over a Vixen GP mount (manual slow motion). 
Any Quoted PA or SEP using Celestron micro guide (CMG) 
Magnification: X60, X120, X240 X322 
  
  
 
Observations: 13-Jan-2001 
I first observed this star using X120 magnification and to my eye a yellow orange colour was detected. I was unsure but thought I could just observe a mote attached just above the preceding edge of the primary star. 
 
Steadily increasing the magnification to X360 and X480 it became very difficult to observe the companion but I thought I could see it in odd seconds of steady air within the glare of the primary star. 
 
As the images were boiling and bobbing about at this high magnification I tried the use of an apodising  filter made from a series of fine wire mesh masks as in my observation of Alpha Gem. In addition, I experimented with a hexagonal mask also. Using the masks helped me to observe the companion at the high magnifications but patience and persistence prevailed in the end with an unmasked view, using a magnification of X240, eventually producing the best view.  In the moments of steady air the companion was seen to pop in and out of the glare of the primary star. No measures attempted. 

Observations: 14-Jan-2001 
Returning to this star and using a magnification of X240 I confirmed my previous observation with the companion being observed at the same PA. The view using X120 was steadier and the companion was seen during odd seconds of steady air.  Using X60 a beautiful yellow star was observed but to spot the close companion, with this telescope and conditions would be wishful observing for me, I think. 
 
Ambience. 
A couple of nights in a row of clear weather in the UK providing the opportunity to empty the nesting spiders out of the scope. The frost soon crisps up the ground under foot on both nights. All quiet with only the company of a visiting fox and of course the chocoholic stray cat. ^..^ 
 

 
 
Susan Delaney
Star: Eta Geminorum 
Date & Time: 2001-01-31, 02:00 - 03:00 UT 
(21:00 - 22:00 EST) 
Seeing: 4 <1-10 Seeing Scale (10 best)>. 
Transparency: 7/10 
Temperature: 31º F (-5º C) 
Location of site: Fairfield, CT, USA  
Site classification: Suburban   
Sky darkness: ~ 5 <Limiting magnitude> 
Telescope: Discovery 10" DHQ f/5.6 Dobsonian 
Eyepieces and Magnification: 7.5mm Plossl (190x), 12.5mm Plossl (115x) 
 
190x revealed a golden primary accompanied by a smaller yellowish companion. 
 
 
 
 
 
Eddy O'Connor
Star: Eta Geminorum 
Date & Time: Saturday, February 3rd 2001 
10-11 p.m. local, UT +11. 
Seeing: 6 <1-10 Seeing Scale (10 best)> 
Transparency: 4/10 
Temperature: 20ºC 
Location of Site: Terara, New South Wales, Australia, Long.150.38 degrees; South 34.52. 
Site Classification: Suburban 
Sky darkness: 4-5 <Limiting magnitude> 
Moon: Moon 10 days old. Calm 
Instrument: 8" Newt. F9 and 16" Newt. F5 
Magnification: 72x, 126x, 144x, 288x 
Eyepieces: 25mm K, 12.5 mm , 6mm ortho, 18mm Celestron Ultima 
Harshaw Scale: 1 (1-5, 1 best) 
 
I had failed to split this on two previous occasions. With seeing only fair tonight I tried powers of X72; X144 and X288 with no results. This is a fine deep yellow star at an altitude of just 32º at the time of observation. I turned to the 16" and used a 18mm Celestron Ultima giving a magnification of X126. The improvement in light was considerable but the image was not sharp. My efforts at adjustment resulted in my breath fogging up the eyepiece. 
 
Suddenly a dimmer but lighter star appeared just clear of the primary and travelling across the field in a Western direction. Could this be it? I refocused and by then the fogging on the lens had disappeared and so too had the 
companion star. I breathed on the eyepiece(!). The primary dimmed and 
the companion star reappeared! Why had I never come across this human 
filter before? Patents pending! 
 
 
 
Ilario Melandri
Star: Eta Geminorum 
Date & Time: 2 February 2001 ? 19.05 UTC 
Seeing: 6 <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: 3.5 <Limiting magnitude> 
Temperature: -2ºC 
Telescope: 150 mm f/15 achromatic refractor (lens by Romano Zen, Venice). 
Magnification: 250 x (eyepiece OR 9 mm) 
 
 
 
 
 
 
John Anderson
Star: Eta Geminorum 
Date & Time: February 9, 2001, 20:00 
Seeing: 6-8, fluctuating <1-10 Seeing Scale (10 best)>. 
Temperature: 35ºF 
Location of site: Woodinville, WA, USA 
Altitude: 540 feet. 
Site classification: Suburban   
Sky darkness: ~4 <Limiting magnitude> 
Telescope: Takahashi FC-76 
Eyepieces and Magnification: 200x (9mm UO Ortho with Televue 3X barlow). 
 
Star: Eta Geminorum 
Date & Time: February 12, 2001, 21:00 
Seeing: 7-8 <1-10 Seeing Scale (10 best)>. 
Temperature: 38ºF 
Location of site: Woodinville, WA, USA 
Altitude: 540 feet. 
Site classification: Suburban   
Sky darkness:  <Limiting magnitude> 
Telescope: Jaegers 6" f/10 Achromatic Refractor 
Eyepieces and Magnification: 300X, 375X, 500X (5mm, 4mm, 9mm with 3X barlow). 
 
During moments of good seeing the airy disks were just touching. Both components were dim but appeared white. 
 
If the separation is truly 1.5", this is the first time I have reached Dawe's limit in any scope. 
 
 
 
 
 
 
 
 
Lovely golden primary, bluish secondary, cleanly split. Best at 375X. I purchased the Jaegers to tide me over while I waited for a 6" Astro Physics. With this kind of performance maybe I will just get a Chromacor and save big $$$. 
 
 
 
Tom Teague
Star: Eta Geminorum 
Date & Time: 2001 February 13 (20:45UT) 
Seeing: 5 <1-10 Seeing Scale (10 best)>. 
Location of site: Chester, England 
(53 11 08N; 02 51 39W) 
Site classification: Suburban  
Sky darkness: 4.5 <Limiting magnitude> 
Telescope: 63mm Zeiss Telementor refractor 
Magnification: x168, x210 
 
I was unable to see the comes, although the seeing was rather poor. Couteau recommends an aperture of 162mm for this pair.  Burnham goes further and suggests 12 inches. Observations by other members of this group show that this is unduly pessimistic. Of course, the pair has slightly widened since Burnham wrote his Celestial Handbook. 

I have a feeling that with high power, when the variable primary is at or near minimum brightness, and in excellent seeing, it may well be possible to glimpse the comes in my 63mm Zeiss as a faint 'bump' on the primary. 
 

 

 
 
Thad Robosson
Star: Eta Geminorum 
Date & Time: 2/12/01  02:00UT (2/13) 
Seeing: 7~8 <1-10 Seeing Scale (10 best)> 
Transparency: 3/10 
Location of site: Phoenix, USA 
33º 32.674N, -112º 08.029W 
Site classification: Decidedly Urban 
Sky darkness: -- <Limiting magnitude> 
Temperature: In the mid 60's (F) 
Telescope: 90mm ETX MakCas 
Eyepieces: Vixen Lanthanum 10 and 15mm, 
Meade super wide 32 and 20mm. 
Magnification: 250x 
 
Had good diffraction rings, and suspected a little knot in one of the rings, but at wrong PA. I know that there's been some confusion about this one...Is there something I need to know that I didn't pick up on in an earlier discussion?  I pushed up to 250x with no results. 
 
Ambiance: Traffic noise, airplane noise, city noise.  All tuned out after about 5 minutes. 
 

 

 
 
Rafael Benavides
Star: Eta Geminorum 
Date & Time: 15 - February - 2001 (21 h 00 m UT) 
Seeing: 8 <1-10 Seeing Scale (10 best)>. 
Location of site: Posadas (Córdoba), Spain 
37º 48' N - 5º 08' 30" W  - 100 mts altitude 
Site classification: Suburban 
Sky darkness: 5.6 <Limiting magnitude> 
Temperature:  11ºC 
Telescope: Helios 120 mm f/8.3 achromatic refractor 
Eye Pieces: Plossl 10 mm, Microguide 12.5 mm, 2x Barlow, diagonal prism, 3x Barlow 
 
It is indispensable to have a good seeing. For example, on 12 February the seeing was 6 ( 1-10 scale) and I could not split this star. A few days later (15th February) the sky was very clear, I attempted again. Increasing the magnification to 315x and 500x it became to observe the companion, but at this high magnification the view was trembling and unstable. The colours noted were orange for the primary and pale blue greenish for the secondary. 
Rating: 3 
 

 

 
 
Giuseppe (Pino) Bandini
Star: Eta Geminorum 
Date & Time: 8 February 2001 - 22.24 UTC 
Seeing: 6 <1-10 Seeing Scale (10 best)> 
Location of site: Ravenna, Italy. 0 mts Altitude 
Site classification: Urban  
Sky darkness: -- <Limiting magnitude>  
Temperature: 11ºC 
Telescope: Celestron 8 
Magnification: 125 x (Plossl 16 mm)
Note: quite difficult to split.