SB PROP @ ARL $ARLP017

ARLP017 Propagation de K7RA

ZCZC AP17

QST de W1AW

Propagation Forecast Bulletin 17 ARLP017

From Tad Cook, K7RA

Seattle, WA April 26, 2013

To all radio amateurs

SB PROP ARL ARLP017

ARLP017 Propagation de K7RA

Solar activity quieted this week. The average daily sunspot number

declined nearly 23 points to 90.6. Average daily solar flux values

were down nearly 13 points to 109.1. The most active day was April

24, with a planetary A index of 19 and mid-latitude A index of 15.

But that is still quite moderate activity. The average daily

mid-latitude A index was the same this week as last, 4.9.

The predicted solar flux is 120 on April 26-29, 125 on April 30

through May 1, 130 on May 2-3, 125 on May 4-5, 120 on May 6, 115 on

May 7-8, 120 on May 9-11, 115 on May 12-13, 110 on May 14-15, 105 on

May 16-18, 110 on May 19 and 120 on May 20.

The predicted planetary A index is 12 on April 26, 5 on April 27

through May 4, 8 on May 5, 5 on May 6-18, and 8, 12, 12, 15, 12 and

5 on May 19-24.

F.K. Janda, OK1HH predicts the geomagnetic field will be quiet to

active April 26, quiet to unsettled April 27 to May 10, quiet to

active May 11-12, and quiet to unsettled May 13-19.

The Australian government's Ionospheric Prediction Service issued a

geomagnetic disturbance warning at 0503 UTC on April 26. Increased

geomagnetic activity is expected due to a high speed solar wind

stream from a low-latitude coronal hole. Minor storm levels are

possible. Active to minor storm levels are expected April 26, and

unsettled to active levels are expected April 26-27.

See http://www.ips.gov.au/. You can go to

http://www.ips.gov.au/mailman/listinfo/ to subscribe to their alert

messages.

Bob Logan, NZ5A lives in Manor, a tiny town in central Texas. On

Sunday, April 14 at 2032 UTC he was surprised to work HC2UA

(Ecuador) on 6 meter CW. Bob ran 4 watts with a Flex 1500. The

antenna was unusual, an 80 meter inverted vee with the center at 35

feet, fed with ladder line and an HF antenna tuner, which Bob says

"is not designed to tune 6 meters, but it does!" He also worked them

at 2043 UTC on SSB, although they were not able to copy his report.

"Quite exciting for me!" says Bob.

Jeff Hartley, N8II of Shepherdstown, West Virginia wrote on April

19: "10 and 12 meters have been quite poor with the recent solar

activity decline, but 15 and lower continue to delight with 20 open

to western EU and the middle East thru most if not all of their

night. There were tremendous signals on 10 meters from south central

and SE EU during the recent flux in 140s, the best days being April

10th and 11th.

"The highlight of propagation was working VK9CZ (Cocos-Keeling) on

10 CW easily around 1400 UTC and hearing JAs around 2230-2330 UTC on

10 one night with one JA QSO. I had a run of JAs on 12 meter SSB

with the loudest over S9."

Scott Bidstrup, TI3/W7RI sent an article about a study with a pair

of sounding rockets to see if turbulence in the E-region of the

ionosphere at sunset could serve as a warning of disturbance in the

F-layer an 1-2 hours later. Read it at

http://phys.org/news/2013-04-rocket-mission-disrupts-radio.html.

NASA has a new video of the Sun showing three years of continuous

images. In that time, if the Sun rotates relative to Earth about

every 27.5 days, then this video should show 398 rotations of the

Sun, in less than 4 minutes. Watch it at,

http://www.nasa.gov/mission_pages/sdo/news/first-light-3rd.html.

If you would like to make a comment or have a tip for our readers,

email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL

Technical Information Service web page at,

http://arrl.org/propagation-of-rf-signals. For an explanation of the

numbers used in this bulletin, see

http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past

propagation bulletins is at

http://arrl.org/w1aw-bulletins-archive-propagation. 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://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL

bulletins are at http://arrl.org/bulletins.

Sunspot numbers for April 18 through 24 were 86, 101, 101, 76, 83,

95, and 92, with a mean of 90.6. 10.7 cm flux was 105, 99.4, 104.9,

109.3, 112.9, 117.5, and 114.7, with a mean of 109.1. Estimated

planetary A indices were 3, 2, 4, 3, 4, 7, and 19, with a mean of 6.

Estimated mid-latitude A indices were 2, 1, 2, 3, 5, 6, and 15, with

a mean of 4.9.

NNNN

/EX