pi Gem - an colorful after-work double winter double 

Finder: http://members.csolutions.net/fisherka/astronote/finder/Gem_piStarHops.jpg

pi Gem, currently favorably positioned (J074731.20+332512.0) for 41N 
op's, is visible in small refractors after sunset from urban light 
polluted skies.  The Belmont Society Colorful Double Star List 
describes pi Gem as "orange/bluish triple" with an AB separation at 21" 
and the third at 92."  The primary of this colorful multiple is a v5.3 
M0III star approximately 172 parsecs distant. The pi Gem multiple at ~ 
172 parsecs at G186.76+25.54 lies about 25 parsecs beyond the 
anti-galactic center end of our Local Bubble. 

Current CCDM data on pi Gem (CCDM 07475+3325, STF1135) are: 


C Pa  Sep  mag 
A          5.3 
B 214 21.0 11.4 
C 341 91.9 10.4 


There does not appear to be a Sixth Orbit Catalogue plot for this 
multiple system. 

pi Gem is about 3 degs north east alf Gem.  A courtesy star hopping 
finder chart is provided at: 

http://members.csolutions.net/fisherka/astronote/finder/Gem_piStarHops.jpg

pi Gem can be star-hopped or right-angle swept by starting at alf Gem. Using an eyepiece that approximates a 1 deg TFOV, find HR2936 (HD 61295), a v6.2 F6II, star about 1 deg north east of alf Gem. From HR2936, there are two right angle sweeps to pi Gem. 

The first right angle sweep involves going 2 eyepiece FOVs east of HR2936, then north in declination 1 1/2 eyepiece FOVs.  The second right angle sweep route involves sweeping in north declination about 4 eyepiece FOVs to omi Gem - the first unmistakeable bright v4.9 F3III star on a north dec sweep from alf Gem. Then sweep east two 1 deg eyepiece FOVs, and then south one eyepiece FOV until an apparent, but unmistakeable, two color double is seen. For some reason, I found the longer route through omi Gem easy to execute with an alt-az mount. 

Once the position is mentally fixed, pi Gem can be direct swept to using a 3 deg 1x dot finder.  Center the scope alf Gem and use bet Gem as a intermediary reference line.  Estimate where the edge of the 3 deg finder intersects alf-Gem-bet-Gem reference line at about a 60 degree angle. Direct sweep to that location.  Odds are pi Gem will be somewhere in a 1 deg TFOV eyepiece view. 

In a small alt-az 60mm refractor under urban Bortle class 8 mag 3.0 light-polluted urban skies at 22x, pi Gem retains its nice orange/blue color, albeit washed out.  At 47x and 78x, the increased size of diffraction disk of the M0III primary brought out more of its redish color. 

I did not detect the v11.4 C component under these light-polluted conditions. I did not have the position angle (PA) reference for the third C component at the time of viewing and could not definitely confirm its location among the options within the star field. A Schaefer limiting magnitude computation for these light pollution conditions indicates the TLM for this small refractor is at or near the v11.4 of the C component, so it may have not been visible under those light-pollution conditions seen and small aperature used. 

All-in-all, this was a nice 15-20 minutes of easy after-work viewing. The temperatures last night were not so oppressively low as in prior winter nights at 41N. 

Prepared 3/2006 K. Fisher fisherka@csolutions.net