Andromeda Galaxy: left...or right?

Event Date: January 7th

Time: 7:33(.59) PM

Brief

   I showed the Andromeda Galaxy yesterday transiting during twilight.  As the sky quickly darkens looking high and in the northern half of the sky, the galaxy slowly descends as a result of its declination and our rotation.  Since Andromeda's declination is a few degrees larger in value than our latitude, it sets north of zenith instead of south.  As a result, its azimuth changes extremely quickly during the last few minutes before and after transit.  Although we will not think much about this with our eyes, it is something that go-to altitude-azimuth telescopes have to have programmed successfully into their databases to work correctly to track such northern bodies/objects.  To learn more about go-to telescopes and see what some of them look like, take a look at this link.  In the meantime, take a look at the image below, with the (alt)itude/(az)imuth not celestial grid included, as opposed to showing the celestial one.  Using the az info that I gave earlier, can you figure out why I chose the precise time above?  Hint: I mentioned including the alt/az grid for a good reason!

click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   Here is the answer to the question wrapping up the brief, for if you don't know it:

At the time above, the Andromeda galaxy "switched direction", so to speak, in az.  That is, after transit it moved north to west, and then started moving back towards north after remaining stationary in az at a particular coordinate.  At each transit, celestial bodies further north than our latitude transit at 0º az twice.  Those with less of a northern declination value than our latitude, transit on the south side of zenith,  It is quite abstract to explain, yet can be believed.  In my case, I used the software to help me understand it better, and even that can be tricky!  To understand this better, take Polaris as an example, which makes a tiny circle from our perspective each day around the north axis.  For this to happen, Polaris needs to stay north, and cannot go far north and east.  Therefore, its az changes slowly, yet dramatically during transit time.  Of course, we cannot have the star get as far west (270º) or too far east (90º) and we never do.  The smaller than range of az, as a result of a higher declination value, the smaller the circle of rotation.