Propagation News – 15 October 2023

We had a period of low geomagnetic disturbance last week, which allowed the upper HF bands to shine. There were lots of reports of DX being worked on the 10m band as the Kp Index sat mainly in the ones and twos, with a maximum of Kp 3.33 for one three-hour period on the 9 October.

The Solar Flux Index, or SFI, also remained in the 150s and 160s, hitting a maximum of 166 on the 9 October. All in all, these were very good conditions for high-band DXing, especially at this optimum time in the calendar.

As promised last week, let’s take a look at HF paths from the UK to the W8S Swains Island DXpedition in the South Pacific. The good news is that operations are in full swing and are being spotted daily on the DX Cluster.

At a distance of approximately 9,500 miles from the UK on the short-path, and 15,300 miles on the long-path, it’s quite a distance for signals to traverse. The short-path beam heading you need to select is a polar path at 350 degrees, and for long-path 169 degrees.

The best openings to Swains from the UK start on the 20m band from about 0630UTC. As the morning progresses, move up in frequency until you get to the 10m band around 1000 to 1100UTC. This path should remain open until 1500 or 1600UTC, at which point you can drop down to the 12, 15 or 17m bands.

Long-path openings may be a lot weaker, with a short opening on the 15m band from 0600 to 0800UTC. Then move to the 12 or 10m bands from 0700 to 0900UTC. There may also be a long-path evening opening from 1800 to 2000UTC on the 17 and 10m bands. The above predictions are for SSB and CW. You may find FT8 openings extend these times a little.

For more details, and to compute your own predictions, see VOACAP.com or Proppy

This weekend, ending today the 15 October, may see some geomagnetic disturbances due in part to a coronal hole. But, as long as we don’t get any coronal mass ejections, this should settle after the weekend.

The Solar Flux Index is predicted to remain in the 150s with a maximum Kp index of two. If this turns out to be true, we should have a good week of DX hunting to come.

VHF and up

The coming period of weather offers many changes, and it looks as though we have said goodbye to the warm air, with low pressure controlling events.

Just a gentle reminder to keep an eye on your antennas as this time of year can produce surprisingly rapid developments of deep low-pressure systems with associated strong winds.

Early next week, a temporary high returns to give you a chance to give those antenna supports and guys a once-over while winds are light, and leave the potential Tropo until the evenings and overnight.

Incidentally, this new high is essentially a cold air high, so may not be as productive as the recent Tropo of the week just ending.

The new high will probably hang around until midweek when it should migrate north to allow an easterly wind across the south. This will probably bring some showery rain along the east coast. It’s possible that we may have some rain scatter from these showers.

Meteor scatter is always good in October, with high random meteor rates and a number of small showers. Most notable of these is the Orionids Meteor Shower which peaks on the 22 October and is active until the 7 November with an average zenithal hourly rate of around 20.

Of course, aurora is also worth keeping in mind if you get any spare time!

For EME operators, Moon declination is negative and falling all week, reaching minimum on Friday 20 October with corresponding shortening Moon windows. As we are now past apogee, path losses will continue to fall.

144MHz sky noise starts very high with the annular eclipse on Saturday 14 October. The following week sees it moderate, increasing to a high of over 2000 Kelvin on Thursday.

Category: GB2RS Propagation News