ARRL

ARRL Propagation Bulletin ARLP056 (2001)

SB PROP @ ARL $ARLP056
ARLP056 Propagation de K7VVV

ZCZC AP56
QST de W1AW  
Propagation Forecast Bulletin 56  ARLP056
From Tad Cook, K7VVV
Seattle, WA  December 31, 2001
To all radio amateurs 

SB PROP ARL ARLP056
ARLP056 Propagation de K7VVV

Thanks to K9LA for writing last week's bulletin while I was
vacationing in New York City. One of the highlights of my visit was
watching the new star show at the Hayden Planetarium in the Rose
Center for Earth and Space at the American Museum of Natural
History. See http://www.amnh.org/rose/haydenplanetarium.html and
http://www.amnh.org/rose/index.html for more information.

This bulletin was prepared Sunday night to update the solar and
geomagnetic data.

Average daily solar flux was up nearly 34 points for the December 20
through 26 period, compared to December 13 through 19. Solar flux is
predicted at 250 for December 31 and January 1, 245 for January 2,
and 255 for January 3 and 4.

A coronal mass ejection on December 28 was not directly aimed at
earth, but caused a rise in geomagnetic activity on December 30.
Planetary K indices rose as high as 4. The planetary A index is
predicted at 20, 15 and 10 for December 31 and January 1 and 2.

WD4NIT asked about the holographic technique used for detecting
sunspots on the sun's far side. You can read a very interesting
explanation of helioseismic holography on NASA's web site at
http://spaceweather.com/glossary/farside.html .

We get email occasionally asking for more information on some of the
terms used in this bulletin. This has been covered from time to
time, and you can find a large list of old bulletins on the ARRL web
site at http://www.arrl.org/w1aw/prop/ .

A recent explanation was in Propagation Forecast Bulletin ARLP038,
available at that same URL. The propagation chapter in any recent
edition of the ARRL Handbook is also an excellent resource.

Sunspot numbers for December 20 through 26 were 171, 215, 234, 220,
176, 246 and 290 with a mean of 221.7. 10.7 cm flux was 221.1,
234.3, 242.8, 254.6, 274.5, 258.8 and 267.8, with a mean of 250.6,
and estimated planetary A indices were 5, 11, 8, 7, 19, 8 and 7 with
a mean of 9.3.
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/EX