Andromeda Galaxy transits high

Event Date: October 8th
Time: 12:43(.02) AM


Brief

   The time of this journal is less than 5 hours after yesterday's.  Then, I showed the galaxy rising, and here, I will show it transiting...looking north!  For lots of our stars and constellations, we face south at transit, even if close to zenith.  However, with a declination of 41.4º, more than 3 degrees better than a declination that puts an object at zenith as seen from our latitude, Andromeda's local path never puts it on the south side of the sky.  When it reaches transit, its azimuth value decreases very fast in value, during the last several seconds.  Before talking about that, let's show it at transit, about 86.4º high.

Detailed

   When a fixed celestial body--whether a star or deep sky--transits with a declination that puts it south of zenith, it picks up movement in azimuth gradually.  However, when having a declination that puts it north of zenith, that means that at some point during its rise, it stops moving north to east, is briefly stationary, and gradually starts moving the other way, from east to north.  While this is gradual at first, it can get fast in a hurry, during the last seconds before transit.  By showing the celestial grid and taking out the alt-az one, we can see how north the galaxy is, with the gridline closest to the galaxy tracing out a parallel local path of it.  Looking at the image, the left and right sides about the same altitudes as Polaris near the center of the inner circle, are approximately where the galaxy stops moving east in azimuth and back towards the north, while rising.

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