[ATM] Need help: Where's spica?

[Douglas S Angle]

I did some surveying, and used Polaris and Spica to orient my 
measurements.  I thought it would be easy from there to convert to 
azimuth, and therefore find true north to a fairly high precision.  I then 
fired up Cartes du Ciel to do the conversion.  It's not clear how it 
handles daylight savings time, so I cross checked against Desktop 
Universe.  That's where my troubles began. 

For example, DU with daylight savings turned on, gives azimuth of 164d 41m 
for Spica.  CdC doesn't have a daylight savings setting, but using an hour 
earlier gives the same siderial time (12:23:12), but then yields azimuth 
of 161d 31m for Spica.  Further, the rise, set and transit times are 
different by about 5 minutes between the two programs. 

I specifically used star positions to give me accurate directions, but now 
I have a discrepancy of 3 degrees in the calculated positions!

In summary, from these measurements, how do I get the 3 Azimuth values?
Location 44d 25m 42s N          76d 23m 28s  W
Polaris 21:42   Eastern Daylight time
Polaris 22:06 
Spica 22:13:43 

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