Let's go galaxy hunting! The harbinger of Spring constellation Leo The Lion is prominent above the eastern horizon in mid March during normal observing hours (8-10 PM MDT). It's well situated for long exposure astrophotography because it will continue to rise and drift a bit south as the night wears on. And...it's chock full of galaxies! We are going to concentrate on only 2 galaxies and 2 galaxy clusters this month. I'll showcase others in April's issue.
We'll start with NGC 2903, a bright elongated slightly tilted from face-on barred spiral galaxy. It has two major spiral arms extending from the ends of its central barred structure. This galaxy should be relatively easy to see in 8" telescopes or larger in a dark sky location. It photographs well in visible light using total exposure times under five minutes. It's 25 million light years away and is large for it's distance at 12x6 arc minutes.
Next, we'll hang around the bright alpha star Regulus to find what is the closest object cataloged in this star map, but also the hardest to find! That's because Regulus is so bright, you have to move your telescope so the star's glare is outside the field of view. Leo 1 or UGC 5470 is a dwarf spherical shaped satellite galaxy of our own Milky Way. It is 820,000 light years away and is thought to be the farthest of the 11 known dwarf galaxies orbiting our home galaxy. You have to move about 12 arc minutes away from Regulus and up the "backward question mark" that forms Leo's front paws and head to reach Leo 1. It's almost the same angular size as NGC 2903, but about two and a half times dimmer because it has no new star forming regions to light it up. This may be a bit too challenging for backyard telescopes as Leo 1 wasn't discovered until 1950 and the equipment used to find it was the 48 inch Schmidt Camera at Mount Palomar Observatory. Still, with today's superior optics and sensitive CCD cameras available to amateur astronomers it's possible to image this ghostly galaxy. Stay tuned!
We'll continue to move down Leo's body about half way to his tail to find what I call, "The Other Triplet." It consists of 3 galaxies that should fit in the field of view of 8" or larger telescopes. Scopes smaller than 8" may show them, but with no detail. They'll look like three out of focus stars. M105 is the brightest of the three at magnitude 9.2 but it's small because of it's distance at 42 million light years.
The Leo Triplet is last on the list. This galaxy cluster consists of two Messier objects (M65 and M66) as well as a rather long (14x4 arc minute) third companion that Charles M failed to add to his famous list. Perhaps it's because NGC 3628 is a bit dimmer or that Messier was in a hurry observing this cluster. He should've seen it as these 3 galaxies would've fit in the eyepiece field of view of his telescope during the night he discovered M65 and 66 in the year 1780. It's interesting that a contemporary of Messier, William Herschel (discoverer of planet Uranus), received Charles' famous catalog of celestial objects and, no doubt, used it to "scoop" Messier with his discovery of NGC 3628 in the year 1784. It seems William H didn't have time or was not as well organized as his sister Caroline who did the cataloging for Herschel's celestial discoveries. Caroline's work later became the NGC (New General Catalog) that astronomers like me still reference frequently today. Thanks, Caroline!