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Date: 10 Jul 2007 22:46:20
From: mitch
Subject: sunspot numbers
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http://www.spaceweather.com/
Here the sunspot number is given as 20. At 150 X's
the most I could muster was maybe 12.
How do they come up with 20?
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Date: 13 Jul 2007 12:48:57
From: Johnny Borborigmi
Subject: Re: sunspot numbers
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On 2007-07-10 18:46:20 -0400, "mitch" <mitch@nospam.com > said:
> http://www.spaceweather.com/
>
> Here the sunspot number is given as 20. At 150 X's
> the most I could muster was maybe 12.
Back WAY off the power. Try 40-50 times. Also how long have you been
solar observing? It takes awhile to get your solar eyes. Like it does
to get your night time observing eyes.
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Date: 13 Jul 2007 12:47:25
From: Johnny Borborigmi
Subject: Re: sunspot numbers
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On 2007-07-10 18:46:20 -0400, "mitch" <mitch@nospam.com > said:
> http://www.spaceweather.com/
>
> Here the sunspot number is given as 20. At 150 X's
> the most I could muster was maybe 12.
>
> How do they come up with 20?
If they're using the AAVSO formula it's GX10+NXK
G=Number of groups
N=number of spots
K=K Factor
I was a sunspot observer for the AAVSO solar Division for 8 years. Made
over 1,000 observations.
Haven't done it in a long time though....
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Date: 11 Jul 2007 23:17:30
From: canopus56
Subject: Re: sunspot numbers
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On Jul 10, 4:46 pm, "mitch" <m...@nospam.com > wrote:
> http://www.spaceweather.com/
> Here [the Boulder] sunspot number is given as 20. At 150 X's
> the most I could muster was maybe 12.
> How do they come up with 20?
The modified Swiss method referred to by David originated in the 1840s
from Swiss astronomer Rudolf Wolf. The basic formula is:
R = k( 10g + f) where
R is the sunspot number
f is the number of spots observed and depends on the observer's
apeture and counting methods
g is the number of sunspot groups on the Sun
k is a personal observing coefficient that adjusts an individual's use
of different apetures and magnifications to an arbitrary standard
When Wolf began in the mid-1800s, he used an 8 inch apeture at 64x. As
the originator of the standard, his personal observing coefficient is
1.00. The successors to his system changed the counting system, and
modified the observing coefficient to 0.60.
Observatories from around the world report a daily sunspot number
using the modified Zwiss system to the international clearinghouse at
the Solar Influences Data Analysis Center in Belgium. http://sidc.oma.be/index.php3
Because g or groups is a factor it is possible to have one visible
sunspot on the surface of the sun (in let's say 8 or 10 inches of
apeture at 64x) and a sunspot number of 11. 5 spots in 5 group would
have a sunspot number of 15, but those same 5 individual spots spread
across the Sun's surface would have a sunspot number of 55.
In otherwords, the counting system is a little artibrary and will not
necessarily correspond to the number of sunspots that you would see
with 4, 6, 8 or 10 inches of apeture.
In its current form, the index is called the International Sunspot
index.
In the U.S., NOAA uses a modification of the Swiss formula that gives
a higher result than the International Sunspot Index, called the
Boulder index.
Spaceweather.com suggests a rough rule of thumb: divided the sunspot
index by 15 for an estimate of the number of individual spots that you
might see at low power.
Your description of using 150x is probably why you are counting many
more sunspots than the index for that date would imply.
Either ramp back your magnfication until your counts are similar to
those reported in the daily Boulder or International indices or keep
your mag at 150x after observing for a few solar cycles, compute your
personal k factor.
Looking at the spaceweather.com SOHO image for 7/11/2007 and the
reported sunspot index of 28, I count two groups and a total of 9
individual sunspots, or an index of 29 - which is consistent with the
Boulder index.
- Canopus56
References:
Bhatnagr, A. and Livingstone, W. 2005. The Fundamentals of Solar
Astronomy. World Sci. Publ. pp. 213
Spaceweather.com sunspot index page
http://spaceweather.com/glossary/sunspotnumber.html
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Date: 10 Jul 2007 19:10:50
From: David Knisely
Subject: Re: sunspot numbers
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mitch posted:
> http://www.spaceweather.com/
>
> Here the sunspot number is given as 20. At 150 X's
> the most I could muster was maybe 12.
>
> How do they come up with 20?
That is not necessarily the true number of spots on the sun but is a
result of a formula based on a number of factors. Spaceweather.com (as
questionable as it is), gives an explanation of how the Boulder Sunspot
number (modified Zurich Sunspot number) is arrived at. Depending on the
aperture, you might be seeing anywhere from 10 to 20 individual umbrae
in the current active region (NOAA 10963). Clear skies to you.
--
David W. Knisely KA0CZC@navix.net
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/
**********************************************
* Attend the 14th Annual NEBRASKA STAR PARTY *
* July 15th-20th, 2007, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************
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Date: 12 Jul 2007 00:38:03
From: David Parkin
Subject: Re: sunspot numbers
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Well, looking at the picture, I came up with 19 - maybe you should look
again.
>> Here the sunspot number is given as 20. At 150 X's
>> the most I could muster was maybe 12.
>>
>> How do they come up with 20?
--
**************************
Dave Parkin
Swansea - Wales - UK
**************************
Keep Wales tidy, dump your rubbish in England.
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Date: 12 Jul 2007 02:32:24
From: mitch
Subject: Re: sunspot numbers
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"David Parkin" <david.parkin53@ntlworld.com > wrote in message
news:LJeli.34384$KE1.11371@newsfe1-win.ntli.net...
> Well, looking at the picture, I came up with 19 - maybe you should look
> again.
>
Baloney..
I like Dave's answer better
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