Sky and Telescope - June 2016 - 31

ROGELIO BERNAL ANDREO / CC-BY-SA-3.0

generally isn't as transparent. On the other hand, I was
working with a lot more aperture. I used my 32-inch f/4
reﬂector to view the remnant's eastern nebulosity with
the same 3.5-mm eyepiece at 929×. Just southeast of
a ﬂattened triangle of 17- to 18th-magnitude stars, the
fragment tipped north to south. It was several arcseconds wide and between 15-20″ in length. This location
is just east of the position shown on the POSS-II red
plate, a change in position that correlates with the SNR's
expansion rate of ~0.2″ per year as calculated by van den
Bergh. My friend Tim Parson conﬁrmed the observation.
On that night and again a few nights later with the same
equipment, the SNR was seen quite well with averted
vision and, at times of good seeing, was on the edge of
direct vision. Tycho G was easily seen in the 32-inch.

Take a Shot At It
If you're interested in observing supernova remnants,
you may ﬁnd it helpful to start with brighter and closer
objects, then work toward fainter members like SNR
1572. An excellent resource, updated regularly, is Dave
Green's Catalogue of Galactic Supernova Remnants
from Cambridge University (mrao.cam.ac.uk/surveys/
snrs/). Images of SNRs in professional journal articles
can be correlated with POSS-II data to determine visibility. Messier 1, the Crab Nebula in Taurus, is one of
the best training targets; at magnitude +8.1, it's easily visible about 1°° northwest of Zeta (ζ) Tauri with a
small scope or binoculars. The challenge with M1 is to
view the 16th-magnitude pulsar energizing the nebula.
Similarly, IC 443, the Jellyﬁsh Nebula in Gemini, is a
large and beautifully detailed structure, oﬀering hours
of reward for careful observers. It contains a neutron star
on its southern end that's plowing through nebular gas,
leaving an observable wake.
After whetting your optical appetite on these targets,
more diﬃcult fare awaits. Objects for advanced observers
include Simeis 147 in northern Taurus, near the Auriga
border. This 200″ remnant is diﬀ use, with only several
of its brighter fragments visible. Cassiopeia A is surprisingly accessible, and it has been seen in a 9.25-inch
scope by veteran observer Bill Gates. In its quadricentennial year, I observed several of the fragments of Kepler's
SNR (1604) in Ophiuchus with my 25-inch scope at
454× without a ﬁlter. But I recommend observers of
SNRs try diﬀerent ﬁlters, particularly the O III. Having
a ﬁlter slide that allows rapid switching between ﬁ lters
enhances the view and improves the chance of recovering these faint objects.
Lastly, don't give up if you don't capture your prey
on the ﬁrst attempt. For objects at the edge of visibility,
sky conditions are critical. I keep a list of "challenge"
targets for periods of excellent seeing and clarity, and
in unusual cases have pursued objects for over a decade
before they succumbed to diligence. Visually observing

SUPERNOVA SPAGHETTI With careful planning, the ﬁlamentary structure of the supernova remnant Simeis 147 can be
teased out of the starﬁeld in northern Taurus.

historical supernova remnants is rewarding on many levels. Their study can take us back in time to delve more
deeply into the context of their occurrence, and they
show how unexpected ﬁndings can push science and
understanding forward. Technical observing obstacles
hone skills that create a desire to seek new goals, extend
visual limits, and encourage others to pursue challenging targets.

Nothing Ventured, Nothing Gained
Over my three decades in this hobby, my rate of visually
recovering diﬃcult objects has risen greatly. I've learned
that with persistence and planning, many objects previously considered invisible through a telescope can be
seen. I've experienced satisfaction in these moments
when an observation oﬀers a sense of being part of an
event spanning centuries of time. In the case of SNR
1572 we have, through a shared love of the sky and careful documentation, a connection with one of the great
observers of the past. Maybe someone four centuries
from now will ﬁnd fresh value in the remains of this
elusive star. ✦
David Tosteson has been an amateur observer for over 30
years. His main interest is observing rare and unusual deepsky objects, including quasars, black-hole phenomena, and
distant galaxy clusters. When he's not working as a family
practice physician just north of St. Paul, Minnesota, traveling to regional star parties and solar eclipses with his wife
keeps him busy.
Sk yandTelescope.com June 2016

https://www.mrao.cam.ac.uk/surveys/snrs/ https://www.mrao.cam.ac.uk/surveys/snrs/ http://www.SkyandTelescope.com

Sky and Telescope - June 2016

Table of Contents for the Digital Edition of Sky and Telescope - June 2016