The Daytime Omicron Cetids meteor shower
Key facts
- Peak
- around 20 May
- Active
- early May to early June
- Rate at peak (ZHR)
- weak on radio; a few seen by eye from the tropics
- Speed
- about 39 km/s
- Radiant
- Cetus (close to the Sun in the sky)
- Parent body
- Unknown
Dates shift slightly from year to year. This year's peak is in the events calendar.
The Daytime Omicron Cetids are a late-May daytime shower, discovered by radar and occasionally glimpsed by eye just before dawn from tropical and southern sites.
The radiant. The radiant lies in Cetus, the Whale, close to the star Mira, Omicron Ceti, a famous variable star that brightens and fades over about eleven months. In late May this part of the sky is only a few tens of degrees west of the Sun, so it rises shortly before sunrise.
Discovery. The shower was found by radar in the mid-twentieth century, when astronomers in Britain and Australia began using radio techniques to study meteors by day.
Visual sightings. A few Omicron Cetids have been reported by visual observers in the tropics and the southern hemisphere, where the radiant rises a little earlier relative to the Sun at that time of year. Such meteors appear as long earthgrazers low in the east. There are too few to calculate a reliable rate, but they show the shower is real.
How active is it? Radio results vary, and some long-running programmes have found no clear activity in recent years. The meteoroids arrive at medium speed, about 39 kilometres per second.
The parent. No parent body has been identified.
What to expect. From the UK, nothing by eye: the radiant rises in the bright twilight of late May. By radio, a modest rise in echoes around 20 May.
How to observe. Radio is the practical method. Tropical observers can also try a short watch low in the east in the hour before dawn around 20 May, stopping well before sunrise. Any meteor seen should be noted with its time, brightness and direction.
Viewing tips
- Use a radio receiver to follow the shower through late May.
- From the tropics, watch low in the east in the hour before dawn.
- Look for long earthgrazers skimming the horizon.
- Stop well before sunrise and never look towards the Sun.
- Record times and directions of any meteor you see.