globular clusters' transits

Event Date: February 6th

Time: 4:44(.16)/7:43(.08) AM

Brief

   I have spent the last two days looking--and magnifying--M3 and M13.  This evening, I will show each one at transit, as both are at northern declinations not far from zenith.  M3 is a hair under the 28º mark for declination, so can be seen at or very near zenith from the southern US and other countries of similar latitude in Africa and Asia.  As for M13, it is 36.4º north, and seen at or near zenith at central US latitudes.  Those viewing in very northern Africa and southern Europe have the opportunity to see it at its highest.  Even if several latitudes away from these aforementioned declinations, viewers will still get several hours to see them well.

   Taking a look below, I first show M3 along the meridian, followed by M13.  The grids for altitude/azimuth, as well as celestial are overlapping, with the latter emphasizing the clusters seen north of the celestial equator.

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

Detailed

  As seen from the second time [of day] listed at the top of this entry, it is after Sunrise and therefore, we will not see the cluster transit in enough darkness for about another two months.  It can still be seen in about half that time in twilight, which will start earlier each day and last a little longer.  After all, we are getting closer to that time of year when the Sun rises over a minute earlier each morning.  While that may not be the best news for deep sky viewing, the next several months are promising for M13.  During most of the spring, it is up all night along.  While the nights shrink further time-wise, the hours that we still have with enough darkness, will let us see M13 rise in the northeast during the evening, and then seen very high during later weeks in the spring and early summer.

   Getting back to M3, which often falls in the popularity shadow of more "sparkly" M13, it is still worth looking at, as shown yesterday.  Try to catch it getting higher in the east each evening at the same time, before it transits.  Since it is a few degrees further north than the Sun, it gradually curves upwards from the horizon.  Remember what I have said, about celestial bodies and deep sky: the more north, the smaller the circular path around the celestial pole.  The celestial circle of M3, about 8.4º further north, is smaller than that of M13 and therefore, also above the horizon for more time each day.