ARRL Propagation Bulletin No. 0034

SB PROP @ ARL $ARLP034

ARLP034 Propagation de K7RA

ZCZC AP34

QST de W1AW

Propagation Forecast Bulletin 34  ARLP034

From Tad Cook, K7RA

Seattle, WA  August 25, 2017

To all radio amateurs

SB PROP ARL ARLP034

ARLP034 Propagation de K7RA

All solar indicators rose over the past week (August 17 to 23), with

average daily sunspot number increasing from 15.3 to 39.9, and

average daily solar flux from 72 to 84.6, compared to the previous

seven days.

Predicted solar flux is 79 on August 25, 80 on August 26, 78 on

August 27 to 30, 75 on August 31, 78 on September 1 and 2, 75 on

September 3 to 7, 80 on September 8, 85 on September 9 to 14, 88 on

September 15 and 16, 90 on September 17 to 22, 85 and 80 on

September 23 and 24, 78 on September 25 to 29, 75 on September 30

through October 4, 80 on October 5, and 85 on October 6 to 8.

Predicted planetary A index is 8 on August 25, 5 on August 26 and

27, 8 on August 28 and 29, 10 on August 30, 18 on August 31 to

September 1, 14 on September 2, 5 on September 3 to 7, then 10 and 8

on September 8 and 9, then 5 on September 10 to 12, 25 on September

13, 30 on September 14 and 15, then 25, 8, 10 and 6 on September 16

to 19, 5 on September 20 to 25, then 12, 24, 18 and 14 on September

26 to 29, 5 on September 30 through October 4, and 10 and 8 on

October 5 and 6 and 5 October 7 and 8.

And now from our correspondents in Eastern Europe:

“Solar activity forecast for the period August 25 to August 31, 2017

Activity level: mostly low

X-ray background flux (1.0 to 8.0 A): in the range A8.0 to B4.5

Radio flux (10.7 cm): a fluctuation in the range 75 to 95 f.u.

Events: class C (0 to 5/day), class M (0 to 4/period), class X (0/period),

proton (0/period)

Relative sunspot number (Ri): in the range 11 to 80

Martina Exnerova

RWC Prague, Astronomical Institute, Solar Dept., Ondrejov, Czech

Republic

Geomagnetic activity forecast for the period August 24 to August 31, 2017

Quiet: Aug 26 to 29

Unsettled: Aug 24 and 25, 30 and 31

Active:    Aug possible Aug 31

Minor storm: 0

Major storm: 0

Severe storm: 0

Geomagnetic activity summary:

Currently, an active episode has been recorded.  At the Budkov

observatory, the local K-index did not exceed level 4.

Thursday, August 24, we expect at most unsettled conditions.  Next

day, Friday, August 25, we expect geomagnetic activity decrease to

quiet to unsettled level.

Quiet to unsettled conditions are predicted for the rest of forecast

period.  At the end of August, active episode is possible about

August 31.

Tomas Bayer

RWC Prague

Institute of Geophysics of the ASCR, Prague

Department of Geomagnetism

Budkov observatory (BDV)”

Did you witness the eclipse on Monday?  I found a group of my

neighbors gathered on the street corner after 1700 UTC, and they had

one of those taped-together box arrangements for projecting the

image.  We were in Seattle, north of the band of darkness that

spread over northern Oregon.  Someone drove by with a box of those

special safe eclipse glasses, and they worked very well.

Reports from friends who travelled to Madras, in Eastern Oregon’s

Jefferson County reported that in the middle of the totality band

they saw the sky go totally dark, and stars illuminated the sky.

Scott Craig, WA4TTK of Nashville, Tennessee sent this, along with a

link to eclipse photos he took:

“Thought you might like these.  They are photos of Monday’s eclipse

taken here in Nashville.  I took them and keep looking at them

because I find them fascinating.”

http://ift.tt/2vp9oBH

For more information concerning radio propagation, see the ARRL

Technical Information Service at

http://ift.tt/1bXLmvi.  For an explanation of

numbers used in this bulletin, see

http://ift.tt/1bXLlHQ.

An archive of past propagation bulletins is at

http://ift.tt/1bXLlHS.  More good

information and tutorials on propagation are at http://k9la.us/.

Monthly propagation charts between four USA regions and twelve

overseas locations are at http://ift.tt/1cYhR1b.

Instructions for starting or ending email distribution of ARRL

bulletins are at http://ift.tt/1cYhR1d.

Sunspot numbers for August 17 to 23, 2017 were 30, 41, 33, 44, 43,

48, and 40, with a mean of 39.9. 10.7 cm flux was 76.7, 80, 86.8,

86, 87.1, 90.2, and 85.1, with a mean of 84.6.  Estimated planetary

A indices were 29, 21, 31, 22, 11, 23, and 25, with a mean of 23.1.

Estimated mid-latitude A indices were 20, 20, 23, 21, 13, 16, and

17, with a mean of 18.6.

NNNN

/EX

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