SN2005cs Visual Observation Report (M51 Supernova)

On saturday, July 9 2005 I managed to visually observe
supernova SN2005cs in M51.

Actually, we may have observed SN2005cs without
knowing it a week before under better conditions using my
20 inch f/5 dobsonian. At the time I wasn't aware of
this supernova but I did have a good time observing
M51 with other family, friends and fellow club members on
July 1. That night was the best night for transparency
that I personally have seen so far in several months.
The weather has been awful here in Missouri for months now.
The spiral arm detail in M51 was fairly obvious with
direct vision that night. It was only after coming
home and seeing references to SN2005cs notices posted
such as this one

Special AAVSO MyNewsFlash July 1, 2005" 1325+47B
SUPERNOVA 2005cs IN NGC 5194 (M51)

found at

http://www.aavso.org/publications/newsflash/sp23.shtml

that I realized that I had a chance to visually
observe this supernova. I managed to make it out to my
sister's property again in the country again on Saturday,
July 9 for a try at visually picking up this
supernova. Beforehand I had printed out various images
of SN2005cs and M51, such as the one you can find at
this link:

http://www.aavso.org/tmp/ngc5194-tb.png

which I didn't find as useful as images like the ones
posted at

http://www.supernovae.net/sn2005/sn2005cs.html

In particular, I found that white stars on black
background images like the one at the link below to be
very useful if printed out on a large scale so I could
see the SN marker in this image without using a lot of
(red) light while at the eyepiece:

http://www.theastronomer.org/superno...050702_mwa.jpg

SN2005cs had a web page devoted to it by that time
that had magnitude measurements and curves done by
various observers indicating that it was around
magnitude 14.5 in visible bands:

http://www.astrosurf.com/snweb2/2005/05cs/05csCurv.htm

http://www.astrosurf.com/snweb2/2005/05cs/05csMeas.htm

http://www.astrosurf.com/snweb2/2005/05cs/05csHome.htm

I have to point out that this observing site is
turning into a typical suburban light polluted
location which seems to be getting worse during the
last 3 years or so that I've kept the 20 inch out
there. You probably don't need a 20 inch to observe
this supernova - there are many 16 inch scopes out
there that should be able to do it from a darker site.
See

http://www.go.ednet.ns.ca/~larry/astro/maglimit.html

for an online calculator for limiting magnitudes that
takes into consideration several factors.

At this site, about half the sky shows stars down to
about magnitude 6, with much of the rest of the sky
washed out by lights from nearby towns of Eureka and
Washington. On top of that, my sister's neighbor has 2
recently installed bright lights on their garage
facing directly at my sister's property which they
have little if any interest in turning off. However,
by selecting spots near my sister's house itself I can
block the light from these two obnoxious sources so
that I can see a large chunk of the sky without glare
problems. Despite these drawbacks it is the place
where I've been doing most of my deep sky observing
because of it's convenience - it is only 45 minutes
from my urban home and I can observe all night without
worrying about driving afterwards or unloading the 20
inch.

I arrived there around sunset, setup the 20 inch,
turned on it's primary fan and shortly before
astronomical twilight ended I began observing M51.
Once I was starting to dark adapt, I began by using a
26mm Nagler (98X, 0.839 degree true field, 5.2mm exit
pupil) in the 20 inch. I could see some of the other
foreground stars in the M51 field, but the spot where
Sn2005cs is supposed to be didn't show anything
obvious other than one of M51's HII regions in that
part of the galaxy, even with averted vision. I tried
moving the scope back and forth across the field,
concentrated on my breathing but that didn't seem to
help. I changed to a 17mm Nagler (149X, 0.549 degree
true field, 3.4 mm exit pupil) But still no luck at
first.

But after a bit more time and getting more dark
adapted I could occasionally see a faint star like
object in the right position using averted vision.
Then I tried seeing what effect LPR filters had. I
brought an Orion Ultrablock and a Lumicon Deep Sky
Filter with me and both made it just about impossible
to see anything at all as far SN2005cs goes, which
isn't too surprising - filters will generally make
things appear dimmer - light pollution AND
astronomical objects, though the effect is (hopefully)
weaker for the latter. They did help a little in
contrast when observing M51 itself, though.

I played around with the filters for a good 30 minutes
or more and after finally satisfying myself that they
weren't really helping at all with respect to Sn2005cs
I removed them and went back to the 17mm Nagler
without any filters. By this time I had completely
become dark adapted and had no problem seeing SN2005cs
with direct vision at times and could consistently see
it with averted vision in the correct position. Going
back and forth from the eyepiece to my printed images
was not a problem by this time using the dimmest
setting on my red light held a foot or so away from my
large scale maps.

Wow! An exploding star in another galaxy flashing in
and out of my vision...

Recent Sky & Telescope article - featuring an
astounding amateur image of M51:

http://skyandtelescope.com/news/article_1544_1.asp

Other web pages for SN2005cs at

http://www.supernovae.net/sn2005/sn2005cs.html

http://www.supernovae.net/supernova.html#2005cs

Good article for novices (and others) on the Secrets
of Deep-Sky Observing at

http://skyandtelescope.com/howto/vis...ticle_78_1.asp

K. Michael Malolepszy
St. Louis Astronomical Society