Sky & Telescope - April 2020 - 43

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Binocular Highlight by Mathew Wedel

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WHEN TO
USE THE MAP

Late Feb
Early Mar
Late Mar
Early Apr
Late Apr

Midnight
11 p.m.
11 p.m.*
10 p.m.*
Nightfall

*Daylight-saving time

omething that alarms me as an observer is
just how much sky I haven't looked at carefully yet. In particular, I've spent far too little time in
the far southern sky, especially the winter and early
spring constellations. I tend to think of the tail end of
Canis Major, the Big Dog, as being pretty far south,
but that constellation ends more than 10° north of
Omega Centauri, which I observe every year in the
late spring. So there's no real barrier to my observing
down south, it's just a mental block.
The constellation Puppis, the stern of the celestial ship Argo Navis (see S&T: Mar. 2020, p. 22), is an
especially rewarding hunting ground for binocular
observers. One of my favorite "deep south but not
really" objects is the open cluster NGC 2546. The
cluster lies 3° northeast of Zeta (ζ) Puppis, squarely
along the center of the Milky Way. At sixth magnitude,
NGC 2546 is fairly bright, although it may be a challenge to figure out where the cluster ends and the rich
background star field begins. The cluster sprawls over
a full degree of sky, so even in binoculars it shows
plenty of detail, with a band of brighter stars running
from southeast to northwest.
Another degree to the northeast you'll find a
gaggle of bright stars, including q and r Puppis and
the double star OS Puppis. These are all foreground
objects compared to NGC 2546, lying between 90
and 1,000 light-years away, compared to 3,000 lightyears for the cluster. And as long as you're in the
neighborhood, have a look back at Zeta Puppis and
see if you can detect any color. The star is a 2.2-magnitude O-type blue supergiant, vastly brighter and
more massive than our own Sun. I hope you enjoy this
saunter into more southerly skies.
¢ MATT WEDEL will be mining his celestial blind

spots for observing fuel for years to come.
sk yandtelescope.org * APRIL 2 02 0

43
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Sky & Telescope - April 2020

Table of Contents for the Digital Edition of Sky & Telescope - April 2020
