[Prev][Next][Index][Thread]
Re: (meteorobs) Plotting: Three Stooges Method
At 09:36 PM 9/4/99 -0400, you wrote:
>Hello All,
> As part of my continuing education in meteor observation, I
>have slowly been working my way into plotting. I must admit, never have
>I found anything that seemed so deceptively simple to be so
>confoundingly frustrating. A typical attempt . . .
> Thanks in Advance, Kim S. Youmans
==================================================
The angle covered by any "fixed-length" device will be entirely dependent
on the distance from your eye (your arms length and mine will yield
differing results - trig) and that will vary from measurement to
measurement because we don't always hold out our arm in the same way.
Whatever device you use will have to be tailored to you or it will be of no
use in terms of accuracy. I have a large plexiglass sheet formed to a
spherical surface that is held 1.25 meters from my eye and engraved with a
grid of 5 degree increments. The distance of 1.25 meters allows me to
focus at infinity and still read the grid. The plex is edge-lighted
causing the grid lines to show as fine, red lines. The whole affair is
attached to a rigid reclining chair that has been carefully aligned
east-west. A bit more complicated than normal meteor observers require,
but very accurate.
It also pays to memorize certain things for the sake of aiding in your
measurement of angular distances:
SUMMER SKY:
Star pairs degrees sep.
Vega-Deneb 23.85
Vega-Altair 34.46
Deneb-Schedar 37.99
Deneb-Algenib 53.47
Altair-Algenib 64.27
Capella-Almach 34.24
Polaris-Dubhe 28.71
Etc.
SteveH's suggestion regarding using a string is a particularly good one and
one heck of a lot cheaper than my plex. If you use it carefully and
practice holding it the same way (as close as you can) every time it will
serve quite well.
Another handy tool is a radio tuned to those boring time signals along with
your tape recorder. I use a child's toy, a "clicker," to mark times on the
tape and with the time signal you can get quite accurate times. You can
also state your observation verbally and play it back later to get rid of
the Alzheimer's quotient (which in me is quite strong).
J.
To UNSUBSCRIBE from the 'meteorobs' email list, use the Web form at:
http://www.tiacdot net/users/lewkaren/meteorobs/subscribe.html
References: