[AZ-Observing] Re: I split Sirius tonight
- From: "Richard Harshaw" <rharshaw2@xxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Sun, 17 Feb 2008 06:54:27 -0700
That "blue" effect in the companion is called the Perkunje Effect (I think).
It is basically the idea that a faint companion star often appears to have a
bluish tint dues to how our eyes work (or don't work!). In my logs, there
are dozens of faint companion stars that to me looked bluish.
Dick H
-----Original Message-----
From: az-observing-bounce@xxxxxxxxxxxxx
[mailto:az-observing-bounce@xxxxxxxxxxxxx] On Behalf Of Steve Coe
Sent: Saturday, February 16, 2008 11:39 PM
To: amastro@xxxxxxxxxxxxxxx
Cc: az-observing@xxxxxxxxxxxxx
Subject: [AZ-Observing] I split Sirius tonight
Howdy all;
After trying to split Sirius for the past several years, I did it tonight.
My backyard observatory has a newly installed Nexstar 11 GPS. I have always
appreciated the excellent optical performance of this SCT. And tonight it
proved it once again.
It is a somewhat hazy night in Phoenix Arizona and we have often found that
to be the nights of best seeing. I would certainly say that is true this
evening. At first I spent some time on the Moon and found that powers of
233X and 280X were very useful. There was lots of detail in and around
Sinus Iridium and by 10 PM Sirius was just about right on the meridian, so I
thought I would give it a go.
I had trouble finding a good point of focus and then I tried moving the
scope so that Sirius was out of the field at 375X, focusing on the stars in
that field very carefully and then returning Sirius to the center of the
view. This method worked right away, because I saw a star about 10
arcseconds from the brightest star as soon as I looked into the 7.5mm
Lanthanum eyepiece. The star was just outside the bright disk of Sirius and
it appeared off blue, but I am certain that is a contrast effect, with
Sirius, for crying out loud!
I took a moment and moved the scope a little bit to determine an estimated
position angle of the companion star I was seeing. That turned out to be
easy since the star is dead east of Sirius A. I had not looked at any
source of information about the position since I wanted to only know that
once I had seen a companion. So, I came in the house, searched the Internet
and found that sure enough the companion, Sirius B, is indeed at a PA of 85
degrees or so.
I am very happy after being patient for several years as Sirius B pulls away
from Sirius A so that I could split it. It is nice to plan an observation
and then have it come true.
Clear Skies to us all;
Steve Coe
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