[AZ-Observing] Re: Sun Spot

Jack wrote:
>When observing sunspots, I notice that the longer one looks at the disk in 
>a
>given session, the more spots appear that can be counted.

This is not at all uncommon.  One of the reasons Rosie sees more sunspots 
than I do is because she takes her sweet time looking.  As always, the more 
you look, the more you see.  Jeff's suggestion of a dark hood is useful.  
Believe it or not, it IS mostly a matter of dark adaptation and not as much 
seeing.

>How long does it take anyway (in minutes) for a sunspot to form, i.e. go
>from invisibility to sufficient size to see with a given aperture?

Sunspots can form in real time.  Changes can be seen in as few as a couple 
minutes.  Bob Goff showed me how you can watch changes in a light bridge 
across a large spot at GCSP.  I've seen active regions develop spots before 
my eyes, (wow, lookitthat!), once or twice, but the spots are quite small at 
first.  (The ring-shaped feature I had a sketch of at the last SAC meeting 
is an example.)  Only after an hour or so usually do they really register as 
spots.  (An active region can be seen as an uneven colored disturbance on 
the surface, usually at the limb, but anywhere when the seeing is good.)  As 
far as aperture goes, my 4.5" F/4.5 solar scope worked well for large spots, 
but we definitely saw smaller ones with the C8 and a Thousand Oaks filter.  
The new 6" F/4.5 does a great job at 60X or sor, too.
  H-Alpha is a whole different category.  As long as you can stand being 
under a dark hood, the more amazing the view becomes!
>
>How large a spot can be obscured by the usual bad seeing that suddenly 
>laxes
>out?

The granularity visible on the Sun during good seeing in white light, 
(convection cells), are measured at around 500 to 1000 miles across, being 
about .5 to 1 arcseconds as seen from Earth.  Super cells seen in H-Alpha 
and Calcium-K are 1000 to 5000 miles across-nearly as large as Earth.  We've 
seen spots come and go in seeing that were, I'd say, 2000 miles across.  It 
just depends.  Mornings are best for viewing the Sun, between 9 and noon.  
After that, the air gets crummy.

>I'm using 125X, 80 mm full aperture, Baader film filter. Please do not 
>refer
>me to some source, I just want to know if its a phenom you (solar observers
>on this list) ever noticed, frequently or infrequently, and have to watch
>out for.

I have noticed some of the smaller spots being less distinct with my Baader 
film.  You might add an orange or deep yellow filter to your EP.  It helps a 
lot with contrast.

Steve and Rosie Dodder
sdodder@xxxxxxxxxxx
Visit my web site at http://www.stargazing.net/Astroman

_________________________________________________________________
Take off on a romantic weekend or a family adventure to these great U.S. 
locations. http://special.msn.com/local/hotdestinations.armx

--
See message header for info on list archives or unsubscribing, and please 
send personal replies to the author, not the list.

Other related posts: