Meteor Camera

Southland Astronomical Society Meteor Camera

In 2023 October, the society joined the New Zealand section of the Global Meteor Network, by installing a meteor camera at Sandy Point. It is number NZ0025.

There are now four of these cameras in Invercargill. The orange coloured dot shows ours. And there are two on Stewart Island.

Each evening after sunset they turn on and record 25 images per second of the night sky, then turn off just before sunrise. The Raspberry Pi (RPi) computer connected to them then processes these images into a series of sky images, a time lapse video and several analytical diagrams Including a Radiant Map. Then the data is uploaded to a computer server at the University of Western Ontario in Canada, where it is further processed with similar data from the roughly 1000 other cameras around the world.

You can access our camera’s imagery via this link:

https://globalmeteornetwork.org/weblog/NZ/NZ0025/

This will give you further links to the various nights the camera has been operating. You will have to scroll down to the bottom to get the latest night.

To see all of New Zealand’s cameras’ images on the latest night, use this link:

https://globalmeteornetwork.org/weblog/NZ/index.html

Scroll down to the station you want and click on ‘- Latest Successful Calibration’. The other three

Invercargill stations are NZ0003, NZ000N and NZ000P.

This is a fairly typical view of the meteors captured in a night. This was from our camera on the 9th November 2023. The RPi has filtered out all the satellites and other non-meteor objecrs (such as moths!) and most stars. The star trails left here show that the camera is pointing a little west of north. The field is 90° wide and 45° high. (It would take eight of these to cover the whole sky.)

There are 41 meteors here. Six of them come from known meteor showers. The others are just ‘sporadics’ of unknown origin. Shower meteors come from swarms of debris left in space from comets. They are named for the star constellation they appear to be radiating from. On this night there were Southern Taurids, Northern Taurids, and Omicron Eridanids.

It is more important than ever, now, to know when and where meteoroids are in space. Expensive space craft and satellites are vulnerable.

Meteoroids, Meteors and Meteorites. What’s the difference?

While still in space these pieces of rocks, or just pebbles, are called meteoroids (like asteroids which are much bigger).

When they fall through our atmosphere, they heat up from air friction and leave the bright trail we call a meteor.

Larger ones can survive the fall and land as debris on the ground. This is called a meteorite.

A bright meteor is often called a Fireball. These are the ones most likely to end up as a meteorite. This is the second reason for the Global Meteor Network.

Our camera caught this fireball on 14th October 2023, early in the evening. It was only the fourth night that it had been operating.

The NZ meteor network was developed largely by the Geology Department of the University of Otago. They want to get hold of a freshly fallen meteorite so as to analyse it without it having been contaminated by laying on the ground for a long time. Only nine meteorites ever been found in NZ. Our fingers are crossed for the tenth! This is a much cheaper way of collecting the Solar System’s primordial material, than sending a spacecraft to collect it from a comet or asteroid and then return it to Earth. A meteorite search was made in August 2022.

Even if you don’t have a camera, if you see a fireball you can contribute to this Citizen Science programme by reporting it on https://fireball.nz.imo.net/members/imo/report_intro

The alpha Capricornids meteors in space in relation to the inner planets.

(https://www.meteorshowers.org/view/Alpha-Capricornids)

The showers that your meteor camera detects is displayed on your Radiant map. Select your station from

https://globalmeteornetwork.org/weblog/NZ/index.html . The one below is from NZ0003 on 2023 March 18 th .

It covers the whole sky, night and day, showing a total of 145 meteors, 142 of them being sporadics (not belonging to a known meteor shower) and 3 eta Virginids (EVI). They are plotted in ecliptic coordinates. The path of the Sun during the year is known as the ecliptic; and it is inclined to our equator. (In astronomy, the ecliptic coordinate system is more conveniently used for representing the apparent positions and orbits of Solar System objects.)  At the top of this map you see (sol = 357.16° and sol = 357.54°). This is the position of the Sun at the beginning and at the end of the night observing run: it is of course, on the other side of the Earth during our night! The arrow shows its position on the map. And this is why all the meteor tracks are at the sides of the map. That is where our night was.

The vertical scale is degrees away from the ecliptic.

The Radiant map below is four months later, 2023 July 21 st .

This shows six meteor showers detected on an all-night clear sky. There were 81 sporadic meteors, 25 alpha Capricornids (CAP), 19 Southern delta Aquariids (SDA), 18 eta Eridanids (ERI), 10 Northern June Aquilids (NZC – nothing to do with New Zealand!), 4 July Pegasids (JPE) and 4 July xi Arietids (JXA). Greek letters are often used in the naming of showers. Again, the arrow shows the position of the Sun on this night.

https://celestialscenes.com/cmn/streams.php is a useful site for identifying the three letter designations of meteor showers. 

From the Global Meteor Networks webpage https://globalmeteornetwork.org/data/ you can see summaries of shower plots. For example, near the end of 2023 July, this was displayed;

Note that for this plot, the center is at 270°, rather than 0° as in the previous ones. 270° is the direction that the Earth is moving towards, so it would be expected that the meteors; velocities would be highest (yellow) here.

A Meteorite Search

During the night of 28th August 2022, a fireball was caught by several cameras in Southland and Otago. This is the image caught from northern Southland.

By trangulating the images of this fireball from a number of cameras, the landing site for the meteorite was calculated to be west of Outram.

Search parties on two successive days tramped over rough farmland but could not find the meteorite. It was a good exercise for future searches. Many children were called in to help, so it became a rather festive occasion.