Mu Canis Majoris

 
Eddy O’Connor
Star: Mu Canis Majoris
Date & Time: January 7th, 2001
10 p.m local; UT +10
Seeing: 5 <1-10 Seeing Scale (10 best)>
Transparency: 8 <1-10 Seeing Scale (10 best)>
Temperature: 20ºC
Location of site: Terara, New South Wales, Australia
150º.38 E, 34º.52 S
Site classification: Suburban-rural
Sky darkness:  No Moon. 
Telescope: 8" Newt. F9
Eyepieces: 25mm K, 12.5 mm Ortho
Magnification: 73x, 146x
Harshaw Scale: 3 <1-5; 1 best> 		 This is Canis Major's eye, which can only be spotted as such by people in the Southern lands by hanging upside down like bats and wishing that those Arabian astronomers had occasionally steered their camels to the southern parts of Africa before drawing their confusing maps.

Comments: This is a Deep yellow star set in a triangle of fainter stars and just split at X144.
 
 
 

 

 
William Schart
Star: Mu Canis Majoris
Date & Time: 21, January, 2002
From 10:00 pm CST.
Seeing: ~ 6 <1-10 Seeing Scale (10 best)>
Location of site: Killeen, TX, USA.
Site classification: Suburban
Sky darkness:  <Limiting magnitude>
Temperature: ~ 50ºF
Telescope: Celestar 8" SCT
Magnification: 80x, 120x and 200x 

 

 A brilliant yellow star. At low power I thought that I could get an occasional        elongation; however at high power I never was able to get a clean split, just        elongation.
 
 
 
 
 

 

 
Steve Bodin
Star: Mu Canis Majoris
Date & Time: 4 Feb 2002, 01:00-02:30 local
Seeing: 4-5 <1-10 Seeing Scale (10 best)>
Location of site: Silverdale Wa, USA 47N,123W
Site classification: deep burbs
Sky darkness: 5.0 due to hi-cirrus clouds <Limiting magnitude>
Telescope: Celestron 8 SC
Eyepiece: 3x Barlow, 24mm koenig, 19mm televue widefield
Magnification: 250x, 315x
 		 This is a very nice double, primary is orange, secondary blue. Very striking contrast. However, difficult in the 5/10 seeing and low altitude at 47N Lat.  Surrounded by 3 fainter blue stars in a triangle pattern. Almost looks like a mini-cluster. Recommend to put on my 'must observe' list.
 
 
 

 
 
 
Ron Bee
Star: Mu Canis Majoris
Date & Time: 02/19/02
Seeing: --- <1-10 Seeing Scale (10 best)>
Location of site: Alpine, California, USA
(elev. 2000ft)  
Site classification: Semi-Rural
Sky darkness: 4.0 <Limiting magnitude>
Telescope: 102mm Tele Vue 102 APO refractor 
Magnification: 22x, 73x, 110x, 146x, 176x, 220x, 293x. 
 		 The 7-day old moon shines brightly but shrouded with haze.  I couldn't even see the mag 5.3 Mu Canis Majoris!. Nor could I see theta Canis Majoris (probably got swallowed up by the clouds).  In fact, the sky is so bad I had to locate Mu using a detailed printed star chart and my 40mm Pentax XL (22x) finder eyepiece to match the star pattern! The steady was average.

I couldn't believe it; I could see the companion at only 73x (12mm TV Radian) and the separation is supposedly 2.8"!  Umm, maybe these TV Radian eyepieces are made of photon razer blades ;-).  At 110x, I could see that Mu was trapped inside a triangle of stars: mag 10.2 star GSC 5392:2311, mag 10.5 star GSC 5392:963, mag 11.9 star GSC 5392:1355.
 
The secondary is clearly brighter than these stars.  At 146x, almost got a clean split.  Clean split at 176x; Mu vibrated sometimes.  Secondary appears greenish blue color and is dimmer than at 146x.  220x was maximum tonight and Mu starts to vibrate unacceptably due to seeing. Secondary is now noticably dimmer than 3 stars forming triangle, possibly because of the haze from light scattering due to clouds surrounding Mu.
   
293x proved too much but I could still see the secondary!. As my experience has now indicated, those 3 GSC stars got brighter as magnification increases until about 176x and maintained it brightest at even 293x!  I'm pretty sure the view would have been fantastic if the sky were clear ;-).
   
The secondary appeared round and never pin pricked at 110x through 293x.

Mu's color is yellowish bordering orange.  At first it threw me off because there are quite a few variable stars nearby. I didn't have to check the chart because their colors are deep red, some ruby!

Later, I checked with the web and Mu is supposed to be a quadruple star system.  Umm, I saw only two.  Does anyone know what's the other two's magnitude and separation data?

+ -------------------------- +
Reply by Jim Jones:
Actually it looks like a five star system as follows.  
STF 997 AB  5.00/7.05  2.8"/343d
STF 997 AC  5.1/10.4   86.9"/228d
STF 997 AD  5.1/10.6  105.7"/062d
Gal 416         7.5/12.0  14.9"/163d

Companions C and D haven't been reported since 1912. I think that Gal 416 is really a companion of STF 997 B.