Orionidy sú spolu s Eta Aquaridami jedným z dvoch rojov spojených s Halleyho kométou. Prach, ktorý kométa zanechala pozdĺž dráhy, vstupuje do zemskej atmosféry rýchlosťou približne 66 km/s. Pre vizuálneho pozorovateľa je to astronomický zážitok, pre rádioamatéra pracujúceho meteor scatter (MS) zdroj ionizovaných stôp vo výške okolo 100 km, od ktorých sa dajú odraziť signály na 50, 144 a 432 MHz.
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Activity period and peak in 2026
The swarm is active from October 2 to November 7. According to several sources, the maximum in 2026 falls on the night from October 21 to 22. The activity is gradual and lasts longer than a month, so it makes sense to observe several nights before and after the maximum.
In some years, the frequency can reach 50 to 70 meteors per hour, but for 2026, don't count on that. The quoted value of 10 to 20 per hour is the upper limit for dark skies; it will obviously be lower in the vicinity of cities.
Radiant and visual observation
The Radiant lies in Orion about 10° from Betelgeuse, in a northerly direction. Orion rises high in the autumn sky in the second half of the night. It is recommended to observe between midnight and dawn, roughly between 1 and 5 in the morning.
The first quarter moon cancels the faint meteors because it is a waxing moon that sets in the early morning hours. The best part is therefore the part of the night after its sunset, before dawn.
You don't need binoculars or special equipment to observe. Choose a place with minimal light pollution and an unobstructed view, lie down and watch the whole sky, not just Orion. Meteors near the radiant have shorter trails. Sight adapts to the dark in about 30 minutes.
Meteor scatter: prečo to funguje
A meteor entering the atmosphere ionizes the track in the E layer at an altitude of approximately 100 km. It can be tens of kilometers long. Most reflections belong to the underdense type: short, sharp and quickly fading echoes from meteors invisible to the naked eye. Less frequent overdense reflections can last tens of seconds, but they come from meteors that are already visible to the naked eye. More power helps: doubling (+3dB) extends underdense echo by about 1.4 times and overdense by about 4 times.
For the radio amateur, this leads to a practical conclusion about the bands. MS works better at lower frequencies because both signal strength and echo duration decrease with increasing frequency.
Reach and geometry
The practical range of MS is up to 2350 km, but the longest and strongest reflections come at a distance of around 1000 km. The optimal partner distance is 1000 to 1600 km, while the chances of a QSO at 1000 km are 5:1 to the chances at 2200 km. The largest number of usable echoes is given by the geometry in which the radiant is at an altitude of 45° and an azimuth of 90° on the route between the stations. Radiant directly above or on the route gives few usable reflections. Most of the reflections from sporadic meteors come from "hot points", elliptical regions near the straight line. At a distance of 1000 km, a shift of about 13° to one side or the other is ideal.
For the Orionids, the best times (UT) are given according to the direction of the route: SW–NE 00 to 02 UT, E–W 02 to 06 UT and SE–NW 06 to 08 UT. It is a very practical aid: if you are looking for a partner in the west, plan to operate between 02 and 06 UT. You can also use Meteor Scatter Planner US8AR.
Modes and procedure of the first QSO
The original high-speed CW (HSCW) was replaced in the WSJT program by FSK441 mode and then MSK144 with a transceiver in SSB. Pay attention to the time: the clock must be set to UTC, otherwise you broadcast to the neighboring period and interfere. Synchronization to ±0.01 s is recommended.
Today, MSK144 is commonly used in WSJT-X. According to HamSCI, it has a period of 15 s and a message length of 73 ms that repeats for the entire period. The meteor shows up as a fast spike in the Fast Graph window and decoding usually follows immediately. HamSCI recommends the following settings: Mode MSK144, Decode DEEP, Tx F Tol 200 Hz, Rx 1500 Hz, T/R 15 s, receiver AGC off, audio meter noise level 30 to 40 dB and a wide USB filter around 3000 Hz. Frequency accuracy must be better than 200 Hz. With low activity, one QSO can last half an hour or more.
Which affects the number of usable bounces
The swarm flow is not the only source of reflections. Sporadic meteors peak around 6 a.m. local time, and fall is the best time of year, while spring afternoons are the worst. The Orionids therefore fall into a period when the sporadic contribution is increasing. Swarm maxima have the advantage of predictability compared to sporadic bounces, so you can plan the operation in advance with your partner.
The aurora borealis also reduces the range of reflections. It can reduce the signal on a 1200 km route by approximately 87% on 50 MHz, 83% on 70 MHz and 40% on 144 MHz at maximum. In case of unusually weak activity, it is worth checking the geomagnetic situation before you start looking for a fault in the antenna system. On the contrary, short head echoes with a Doppler shift of 12 to 76 kHz and a typical duration of around 100 ms occur in meteors with a very low inclination of the path to the atmosphere, and higher frequencies reflect them more often.
V čase maxima rojov môžu byť meteor scatter frekvencie veľmi preplnené. HamSCI preto odporúča, aby susedné stanice na tom istom pásme používali rovnaké párne a nepárne časové sloty, inak sa navzájom rušia. Ak je na pásme len bzučanie v celom prijímacom slote, ide podľa HamSCI zvyčajne o vzdialenú stanicu cez troposférické šírenie alebo E-Skip, alebo o lokálnu stanicu v nesprávnom slote, nie o meteor.
Equipment and coordination with a partner
About a 4-element yagi antenna and 20 W is given as a minimum for QSO. During sporadic activity, he recommends at least 100 W and a 9-element yagi. HamSCI states that 100-500W directional antennas are suitable, but a 100W dipole can also work. Don't overload the PA as the FSK441 behaves like FM in terms of power.
Make the connection agreement through the DX cluster and the ON4KST chat. For the first attempts, it is recommended to try the Perseids in August, but the Leonids in November are also suitable swarms.