Sky & Telescope - April 2025 - 22

Observing Challenge
Night of 110 Messiers
Globular cluster
Diffuse nebula
Galaxy
Open cluster
Planetary nebula
A CELESTIAL RACE TRACK This map shows the distribution of Messier objects across the spring night sky. Those near the dusk and dawn
horizons are the most challenging to observe. Note the dense concentration of galaxies in the Leo and Virgo regions (near the map's center) and the
clusters and nebulae that dot the summer Milky Way on the left side.
Join the Club
Many deep-sky observers have run Messier marathons, but
the " Club of 110 " remains rather small. While it's not hard
to see 80 to 90 Messiers in one night from many locations,
there are a handful of objects that are particularly tricky. History
has it that the first to try a Messier marathon were a trio
of Pittsburgh, Pennsylvania, amateurs. Ed Flynn logged 98
objects with a 6-inch reflector on the night of March 24-25,
1977, only to be superseded by Tom Hoffelder who tallied 101
the following night. Hoffelder's record held until April 11-12
that same year, when Tom Reiland made it to 103. Renowned
comet hunter Don Machholz (who sadly passed away in
2022) was another early participant. To this day he likely
remains the most prolific marathoner of all, with more than
50 attempts to his credit. His 2002 book, The Observing Guide
to the Messier Marathon, is highly recommended to anyone
interested in Messier, his catalog, and the marathon.
It wasn't until 1985, however, that Gerry Rattley and Rick
Hull managed to complete the first full marathon on March
23-24 that year. Both used 10-inch telescopes and reached
110 within an hour of each other. Rattley and Hull observed
from Arizona and California, respectively. They were significantly
farther south than their predecessors, demonstrating
that latitude is also key to completing a marathon. You can't
do 110 at any time or from any place!
Messier compiled his catalog from France, at a latitude of
49° north, so his objects are concentrated on the northern
celestial hemisphere. Many can be viewed from much farther
south, but to catch them all during a single night, you have to
be north of +10° latitude. Too far north, however, and you'll
miss the most southern ones. For example, M7, the beautiful
open cluster near the tail of Scorpius, is practically unobservable
poleward of 53° north.
Between latitudes 40° to 50° north (comprising the
northern U.S., southern Canada, and most of central Europe),
22 APRIL 2025 * SKY & TELESCOPE
a full Messier marathon is possible only theoretically, as three
objects (globular clusters M30 and M55, and the aforementioned
galaxy M77) are extremely difficult to catch.
For some, the idea of running a marathon is to simply
record as many objects as possible from a given location,
even if catching all 110 isn't possible. One of us (Ronald)
pioneered European marathons from 49° north in Bavaria,
Germany, where he logged 103 objects in 1993. In 2001
Arto Oksanen and Harri Hyvönen completed the first digital
Messier marathon when they imaged 82 objects on CCD from
Finland, more than 60° north.
But despite these accomplishments, the sweet spot for
a full Messier marathon is about latitude 25° north; however,
anywhere between 10° and 35° north will work. This
means the southern continental U.S. is marathon territory,
as well as Hawai'i, the Caribbean, and even the southern tip
of Japan. For European observers, the Canary Islands are the
best place to go. On La Palma we were at 28° north - close to
the ideal latitude!
Our Marathon Night
Even if you're at an ideal location and have set up your
telescope on the optimum date, a successful marathon
requires planning. You have to observe the objects in the
right order to have the best chance at seeing all 110 of them.
For our attempt, we created a list (see page 23) that sorted
the objects into one-hour slots corresponding to the optimal
observing time. Such a script is especially useful during the
stressful evening and morning hours, when time is tight and
the right sequence is crucial.
On our marathon night, we set up our main instrument
- a 10-inch Dobsonian reflector - but since many Messiers
are fairly bright, we also use 15×56 binoculars, 2×54 opera
glasses, and of course our naked eyes. In effect, we are doing
four parallel marathons at the same time.
Dusk
Dawn
S&T ILLUSTRATION

Sky & Telescope - April 2025

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