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Monthly
Messier Star-Hop; April #3 "Lasciate ogni speranza voi ch'entrate!" Part II Like our trip last month into the heart of the Virgo and Coma clusters, we'll begin in the constellation Leo and use the galaxies M87, M84 and M86 as our guide. We'll then jump off to the galaxies M58, M59, M60, M89, and M90. Galaxy-Hop
#1. M86 to M89 (NGC 4552) Reiterating last month's Star-Hops, the secret to star-hopping in the realm of galaxies is that you don't star-hop with stars! You star-hop with galaxies! Once again; depending on the size of your scope, you'll often find more galaxies in your field of view than you find stars. Of course this also means you need to have GOOD STAR CHARTS!! As a minimum, consider using a copy of Sky Atlas 2000. However, you'll be much better off using Uranometria or a set of custom printed finder charts generated by one of the many excelent personal computer based astronomy programs now available.
So how to get started? Where to begin? Once again, find the constellation Leo which this month, culminates (crosses the zenith or gets as high as it ever does) on the 15th at about 10PM. From the star Denebola, Beta Leonis, extend a line east-southeast to the star Vindamiatrix, Epsilon Virginis, in the constellation Virgo. You'll find the M84 and its close companion, M86, at the midpoint between these two stars. As a side trip, note the giant elliptical galaxy, M87, is only a little more than 1 degree east-southeast of M84 because we'll use it to get started with our galaxy-hopping. Like before,
this is where the fun really starts. As with last month, we'll be using
M86 as our starting point for our journey to this month's galaxies.
Take time getting comfortable finding M86 as it is very easy to
get lost galaxy-hoping in the fields of myriad galaxies in Virgo
and Coma Berenecies. At this point, be sure you know how large
the field of view in your telescope's eyepiece is. For comparison purposes,
the distance between M84 and M86 is about 17 arcminutes.
The distance from M86 to M87 is about 1.3 degrees, or a
little more than 3 times the distance between M84 and M86.
Take time to determine the size of your field of view in order that you
know how far you are moving when you transvere star and galaxy fields
when observing through your eyepeice. This is probably the easiest way
to work your way through the galaxy fields of Virgo and Coma,
so familiarize yourself with the technique. Do you know the field of view
of your favorite eyepeice? If not, take time to find out before tackling
these galaxy-hops. If not obvious
already, there are many galaxies in this area. In the figure below, for
simplicity, I've excluded all galaxies dimmer than 11th. As a general
rule, the Messier galaxies are brighter than the surrounding galaxies,
so you shouldn't have too much trouble finding your way during the Galaxy-Hops
to follow. Remember, if you get lost, you can always start over at M86. Galaxy-Hop #1. M86 to M89 (NGC 4552). Starting at M86, our first hop enroute to M89 is the giant elliptical galaxy, M87. As stated earlier, M87 is about 1.3 degrees southeast of M86. Assuming a 1 degree field of view in my favorite eyepeice, I'd only have to move about 2 fields of view southeast of M86 to arrive at M87. From M87, M89 is about the same distance away to the east-northeast, once again, about 2 fields of view away. Even in large telescopes at medium magnifications, this galaxy appears small, but diffuse, so pay attention when you are in the proper field of view. Its halo is relatively uniform in brightness except for the edges which fade rapidly. At high maginfication, the nucleus is much more pronounced with mottling around its edges. Galaxy-Hop#2. M89 to M90 (NGC 4569). M90 is much more readily visible than M89 which can be difficult to find at times. M90 is about 40 arcminutes, or about 2/3 of a degree to the northeast of M89. Assuming a 1 degree field of view in your eyepiece, you'd only have to move one field of view northeast to find M90 from M89. In a large telescope at medium magnification, M90 has an oblong halo with a compact core. Bright, but not overly so and oriented northeast to southwestwith a halo of uniform density. At high power the halo remains very uniform with a stellar nucleus. Galaxy-Hop #3. M89 to M58 (NGC 4579). Return now to M89 which will serve as our jumping off point to M58. From M89, M58 lies about 54 arcminutes (not quite 1 degree or 60 arcminutes) to the southeast. In a large telescope at moderate power, M58 appears similar in size to M89.The nucleus is visible and seems to predominate halo which fades rapidly at its edges. At high power, the nucleus is prevalent, but not bright, with some mottling around edge as it extends into halo. Galaxy-Hop #4. M58 to M59 (NGC 4621). Continuing from M58, M59 is about 1.1 degrees to the east-southeast. In a large telescope a medium power, M59, M60 and several other galaxies are in the same field of view. The Messier galaxies are generally brighter than the other galaxies in the field so its easy to pick out the Messier galaxies. M59 appears as a mostly round object with predominant nucleus in halo. At high power, the nucleus becomes more visible, but still predominates halo. Galaxy-Hop #5. M59 to M60 (NGC 4649). Continuing from M59, M60 is a little less than 1/2 degree to the east-south east. As before, there are many galaxies in the field of view. Concentrate on the brighter galaxies and you'll typically be focusing on Messier galaxies. |