Andromeda Galaxy's near-zenith transit

Event Date: November 9th

Time: 9:35(.51) PM

Brief

   Here is an interesting fact about Andromeda and the namesake galaxy: the transit times of them are only a little over 2 1/2 minutes apart.  The constellation, using its most "center" spot, transits at the time above, while the galaxy does so at 9:33(.17) PM.  Therefore, if you look up the transit time each evening of the galaxy, it helps locate the center of the constellation, which will be seen very high up near the galaxy.  Here they are labeled, on both sides of Zenith.

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

Detailed

   As I have mentioned earlier this fall, the constellation and galaxy are far enough north that we see them very high, with respective declinations of 41º 22' 43"/59", just 16 arc-seconds apart, and with RA's obviously, nearly identical in difference as the hour angle.  Although I cannot mark the constellation's center, do not let the stick figure deceive you, as it is further from the center than the galaxy, by far.  At these declinations, we see the two on the northern side of the sky all night long.  By saying that, it means that when the two rise, they do so in the northeast, "arc" gradually and then quickly in the sky; they halt near the eastern azimuth mark, and then come back to the northern azimuth before that.  With the image above, it is hard to see this, or perhaps imagine it.  However, if using an alt-az telescope, you can get to know the local path of the constellation and galaxy.  At the times when the two are quite high yet not at transit, these will be when the altitude is increasing at its fastest, yet the azimuth does not change.  The same holds true for transit, when the azimuth changes at its fastest, and the altitude does not change briefly.  Your telescope, if an alt/az go-to, will adjust for this, yet keep the stars and galaxy tracking if your telescope is very level to the ground.