Elusive Galaxies

M33 by Filip LolićIn a previous story I covered some galaxies that you can see reliably even under washed-out skies. Unfortunately some relatively bright galaxies that amateurs everywhere know and love are particularly susceptible to the effects of even modest light pollution. If you live in urban or suburban areas, you can spend hours looking for these without success. To save you this frustration, I’ve prepared a list of famous galaxies that are very hard to see in washed-out skies. You can treat this as a list of galaxies to avoid, or if you prefer, consider it a challenge list for observing under washed-out skies....
(Photo of M33 by Filip Lolić.)

Galactic no-shows

These galaxies are relatively bright and quite famous. Under dark skies, they are easy to see with small telescopes, and modestly sized telescopes will often show structure. But for a variety of reasons, if you add some light pollution, these galaxies just disappear.

M51, the Whirlpool Galaxy

M51 by Rick ArendtM51 is a beautiful, face-on spiral galaxy that is spectacular in dark skies. But in even mildly washed-out skies, M51 vanishes. In 4.0-4.5 magnitude skies with M51 near zenith, using a 10 inch (250mm) Dob I consistently need averted vision to see a small, faint smudge corresponding to M51’s core. On nights with outstanding transparency, I have caught a glimpse of NGC 5195 (M51’s companion), again using averted vision. But both are at the edge of visibility and they are certainly not anything I can show my friends or neighbors. I’ve never been able to see M51 using my 4.25 inch (100mm) scope in washed-out skies. So if you try M51 in light-polluted skies, count yourself lucky to see even a faint smudge. (Photo of M51 by Richard Arendt.)

M33, the Triangulum Galaxy

M33 by Hunter WilsonAt magnitude 5.7, M33 is the second brightest galaxy visible from earth, but its large size translates into relatively low surface brightness. As a result M33 is pretty much invisible in light-polluted skies. I have only been able to see M33 from my front yard once, and that was using my 10 inch (250mm) Dob on a night of spectacular transparency, with M33 almost directly at zenith. Even then, it was an incredibly faint haze visible only using averted vision and because I knew exactly where to look. That same night M33 remained invisible with both a 4.25 inch (100mm) scope and 7x50 binoculars. (Photo of M33 by Hunter Wilson)

M101, the Pinwheel Galaxy

M101 by Robert PriceM101 is roughly half the size of M33 but also about two magnitudes fainter than M33, so it shares M33’s low surface brightness. Like M33, M101 is essentially invisible under washed-out skies. I’ve managed to see M101 twice from my front yard using a 10 inch Dob, but both times it was a major effort to pick out the exceedingly faint hazy spot that was M101. I’ve never been able to see M101 in the 4.25 inch Newtonian or with binoculars from my light-polluted front yard (although M101 is visible in both from dark-sky locations). (Photo of M101 by Robert Price.)

M110, satellite to the Andromeda Galaxy

M31 and M110 by Rick ArendtThe Andromeda Galaxy (M31) and one of its satellite galaxies (M32) are among the easiest galaxies to see from urban areas. On photos, M31’s other bright satellite galaxy, M110, looks nearly as bright as the others, but in reality M110 is very hard to see from washed-out skies. On nights of very good transparency with M31 near zenith, I can usually see M110 in my 10 inch (250mm) Dob thanks to a detailed star-map that shows me exactly where to look. But it is a struggle every time. In light-polluted skies I have never been able to see M110 with the 4.25 inch (100mm) scope, even when M32 was readily apparent. (Photo of M31 and M110 in the lower right by Richard Arendt.)

M65, M66, & NGC 3628, the Leo Triplet

M65 and M66 by Rick ArendtIn my light-polluted skies, the central core regions of M65 and M66 are visible on transparent, moonless nights with a 10 inch (250mm) Dob, but they show up as faint smudges of gray that novices are unlikely to see. NGC 3628 is essentially invisible in my washed-out skies unless conditions are near-perfect. So even with a telescope of moderate aperture don’t expect to see a triplet—you’ll see a very faint doublet at best. With a 4.25 inch scope none of these three galaxies is visible from urban skies. (Photo of M65 and M66 by Richard Arendt.)

NGC 4565

NGC 4565 by Rick ArendtUnder a dark sky, NGC 4565 is not only the most beautiful of all the edge-on spiral galaxies, but is in fact one of the most spectacular sights to see with a telescope. Its needle-like shape and central bulge are clearly visible even in my 4.25 inch (100mm) scope. On the other hand, in urban/suburban skies, you’ll be lucky to even see NGC 4565. It’s totally beyond the reach of my 4.25 inch Newtonian. On reasonably transparent nights, NGC 4565 is just visible in my 10 inch (250mm) Dob using averted vision. The narrow profile comes through using averted vision, but even that isn’t very distinct. (Photo of NGC 4565 by Richard Arendt.)



Washed-Out Galaxies

Thanks for this inside story. Have seen m-81, m-82 and m109 through a 4.25 incher and an 8." Have yet to try in my new 10".