[vsnet-chat 276] Re: Mira

[Fraser Farrell <fraserf@dove.net.au>]

G'day Dave (and vsnetters...),

On 1997-04-26 dave@telf-ast.demon.co.uk said:
   >However, rather than providing Northern visibility data alone, the
   >two observations from the appended table closest to conjunction are
   >by Southern observers;
   >latest...   1913 Apr 15   C J Westland
   >earliest... 1932 May 11   R C Shinkfield

And here are the full details of that early observation from the late
Reg Shinkfield's actual notebook:

1932 May 12 05:35 local time (UT+9.5hours)
1932 May 11 08:05 GMT (=UT)
JD 2426839.
instrument = binoculars  (I think Reg used 8x42s ?)
mag 3.5
sky = 1  (good)
class = 1 (good)

Reg's written comment is "low".  He was observing from home (inner
suburb of Adelaide) during an era when the streetlights were turned off
after midnight.  Adelaide had a population well below 300,000 in those
days; the high cost of electricity and the stringencies of the
Depression would have kept early morning light pollution well down.

According to GUIDE 5.1, Mira was at an altitude of 6.1 degrees and
azimuth of 89.7 degrees.  The corresponding values for the Sun are -17.7
and 80.1 degrees, so Mira was above the Sun in an almost astronomically
dark sky.

However, local geography - the Adelaide Hills - would have helped darken
the sky a bit more.  From Reg Shinkfield's suburb they dominate the
eastern view and rise to an average 4-5 degrees above the theoretical
horizon. A maximum at the time of conjunction definitely helped, but
having a 600 metre high wall of rock to hide the rising Sun for those
few extra moments seems to make the difference!

An opportunity exists to beat Reg's record during the next couple of
weeks - when a bright Mira emerges from conjunction.  Those of you who
have a well-positioned mountain to the east are favoured to win this
contest  (go for it, Michael! :)


cheers,
Fraser Farrell

http://vsnet.dove.net.au/~fraserf/   email: fraserf@dove.net.au
traditional: PO Box 332, Christies Beach, SA  5165, Australia

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp