2012 DA14 Flyby

Here is a new video showing range and spectrum estimates using the latest ephemeris and correctly calculated round-trip times and Doppler shifts. Now there is no significant range deviation, but the frequency deviation persists. The bandwidth is narrowed down during the video, as the speckle induced spikes gradually decrease.

LBA aerials in the snow

Wow! It is Friday again.

This time last week, we were in the midst of preparations for the 2012 DA14 fly-by, and reeling from the news of the spectacular (and sobering!) Chelyabinsk meteor event. It has been a tumultuous time, but the team have risen to the challenge, being first to disassociate the two events, get the initial trajectory for the meteor and make the first rudimentary size estimates. Then, we had a brilliant run on the EISCAT radar allowing us to obtain some high-accuracy data on the asteroid 2012 DA14. To everyone in the team — and all of you who have supported us — well done and thank you!

And, of course, in amongst all of this, our trusty KAIRA facility has continued to record all-sky radio images and pursue the riometry and radio-astronomy work. Operations as per normal, of course!

So, for our photo-Friday, we'll leave the heady world of asteroids and impacts for a moment and insert a series of serene photographs from the Low-Band Antenna (LBA) array at Kilpisjärvi.

Have a nice weekend!

Photos by D. McKay-Bukowski

Dash-cam astronomy

One of many YouTube-posted videos. A GPS- or GLONASS-set
clock would have provided accurate time information though and
location and direction would have also helped us enormously.

The recent Chelyabinsk event demonstrated the power of distributed sensors for reconstructing incidents after the event. With cheaper and cheaper consumer electronics, miniaturisation, lower power requirements and the increasing distribution of these systems across the world, it is clear that we are entering a new era of Earth (and sky!) observation.

So, what is needed?

Firstly, there is the image itself. This is now widely available with resolutions and linear-responses far exceeding anything that astronomers could only dream of a few decades back. Generally speaking, there is no need to "flat-field" images or remove artefacts. The dynamic range continues to improve as well, making them increasingly sensitive to relatively faint events.

Then there is time. Most of these systems now have built in clocks which can stamp the image with the date and time. Although may have this information on the associated image files, it is embedding the information visually within the image that then allows others to derive useful scientific information. Some require manual date and time setting, which is subject to error and inaccuracy. Better still is a system which synchronises to satellites (GPS, ГЛОНАСС/GLONASS, etc.).

Which brings us on to position. Knowing the view point of the observation is also an extremely useful piece of information. It was the association of  Chelyabinsk videos with known land marks that made it possible for us (with no local knowledge whatsoever) to find references and therefore establish positional information. Again, by embedding this information visibly in the image it removes the need for the camera user to post this meta-data separately (thus saving time, making it easier and also reducing risk of errors).

Direction is also a useful piece of information and can supplement information, especially if other records of the event are scarce. For our own assessment of the Russian meteor, it certainly would have helped in the early stages (when were we trying to dis-associate the meteor with 2012 DA14), although later data helped clear this up. In some cases, this can be done by hand. If lucky, it may even be able to be solved automatically (such as with the astrometry.net project).

Image scale is the final thing that lets us work out the reference frame. This is especially important in wide-field images, which often have large amounts of pin-cushion distortion.

Whether dash-cams, all-sky cameras, CCTV, or from the hand-held devices of quick-reflexed users it is inevitable that there will be a rise in the quantity and distribution of sky data. No doubt, the ubiquity of computing, the influence of social internet media and a growing awareness of the public will contribute to a very new and fascinating era of incident astronomy.

Echos still received at 300000 km

The quest to analyze and understand the data continues. I've done one full analysis pass over the whole low sample rate data and we get echos almost all of the time. We have short gaps in data when we cannot observe the echos due to transmitter pulses blocking our receiver (We transmit 2 ms of coded pulse every 16 ms).

Last measurement of the campaign at Feb 16th at 8 UT, when the rock was already 300000 km away from us! We could have still continued as we were still getting a signal. 

To start validating our analysis routines, I've sent a few range and Doppler measurements to NASA. Let's see how well our results fit.  

Understanding the terms

Asteroids? Or Small Solar System Bodies?
(Image: Wikipedia)

Over the past few days, there has been a bit of confusion over the difference between the Chelyabinsk event (a meteor) and the 2012 DA14 flyby (a small asteroid)

How we classify the objects in our Solar System is defined by the International Astronomical Union (IAU). In 2006, they voted on a modification to the system previously used. This resulted in the nomenclature that scientists now use today.

Starting with the largest, the objects are:

Planets must orbit the sun, must have achieved "hydrostatic equilibrium" (that is, they are more or less round) and have "cleared the neighbourhood of its orbit". In other words it must be the dominant gravitational force in that orbit area. There are currently 8 recognised planets around our Sun (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune).

Dwarf Planets are the next category. These orbit the sun and have achieved hydrostatic equilibrium, but they have not cleared the neighbourhood of the orbit. At the moment the IAU recognises five dawrf planets (Ceres, Pluto, Haumea, Makemake, Eris), although more are likely to be added to the list as we discover them or as other unclassified objects are evaluated.

There there are the Small Solar System Bodies. Essentially, this is everything that orbits the sun, that is not in the first two categories. So this includes comets and asteroids.

Comets are typically made of ice and dust. Their distinguishing feature is that they  have a coma or tail. This is caused by solar radiation vapourising volatile material.

And then the others are asteroids; chunks of inert rock.

There are a few terms around which have been used in the past, but are no longer recommended by the IAU. Examples include "minor planet", "meteoroid" or "planetoid".


2012 DA14 and the Chelyabinsk meteor were both asteroids and, thus, small solar system bodies. The difference is that 2012 DA14 missed the Earth during the recent flyby, whereas Chelyabinsk did not. This brings us to meteors and meteorites.

When an object enters the Earth's atmosphere, the friction of the entry can sometimes be sufficient to heat it to cause it to give off light. This visible "streak across the sky" is a meteor. Particularly bright ones are often referred to as fireballs.

This heating usually causes the object to burn up completely. Thus, it never reaches the ground.

However, if the object survives the burning in the atmosphere, and survives the impact as well, then it is called a meteorite.

The Chelyabisk event is definitely a meteor. At present there are searches being carried out to try to find debris on the ground, with some candidates having been collected. This is an on-going effort and no doubt more news will come from this during the next few weeks.

However, the bulk of the original object was destroyed on entry and, as yet, no substantial fragments have been found on the ground. Thus it continues to be referred to as the "2013 Russian Meteor" for the time being. However, that may change!

References

• http://www.iau.org/
• http://solarsystem.nasa.gov/
• http://en.wikipedia.org/wiki/2012_DA14
• http://en.wikipedia.org/wiki/2013_Russian_meteor_event

Inverse Days 2013 with a special emphasis on the mathematics of Planet Earth

10-13 December 2013, Sodankylä and Inari, Finland

Organised by Markku Lehtinen, Lassi Roininen, Samuli Siltanen 

inverse-problems.org/id2013

Sodankylä Geophysical Observatory is organising the 19th Inverse Days in 10-13 December 2013. Two events will be organised:

• 10 Dec 2013, Sodankylä, A thematic day mathematics with applications in geospace and atmospheric research.
• 11-13 Dec 2013, Inari, Traditional Inverse Days will be held in Sámi Cultural Centre Sajos in Inari.

A special theme of Inverse Days 2013 is the mathematics of Planet Earth, a project managed by UNESCO. The conference themes will be organised around mathematical inverse problems relevant to Planet Earth, such as seismic inversion, remote sensing, underground prospecting and climate change. International experts will be invited, as well as international press.

Examples of relevant research themes include:

1. Forest characterisation based on airplane-borne laser scanning data
2. Ionosphere imaging using radar measurements
3. Ozone layer monitoring based on satellite-borne stellar occultation data and tomographic reconstruction
4. Climate studies with statistical uncertainty quantification
5. Asteroid shape analysis based on light-curves
6. Nonlinear seismic inversion

The main meeting will be held in an arctic location in Inari (68°54'27.26" N, 27°0'47.68" E), honouring the local Sámi culture and emphasising the growing importance of the Arctic. Conference venue is the Sámi cultural centre Sajos.

Sámi cultural centre Sajos and the Aurora Borealis

Inverse Days is the annual meeting of the Finnish Inverse Problems Society. It is part of the activities of Finnish Centre of Excellence in Inverse Problems Research. In recent years, Inverse Days have gathered together an international crowd of roughly 100 scholars.

The Finnish Inverse Problems Society coordinates a wealth of activity in inverse problems research in the fields  of mathematics, physics, computer science and astronomy. One of the major funding sources is our Finnish Centre of Excellence in Inverse Problems Research funded by the Academy of Finland.

Request for data — other meteor events?

We are now investigating reports of other events that might be related to the Chelyabinsk Meteor. Although we have discounted the possibility of any relationship between the Chelyabinsk event and 2012 DA14, there are several other reports that we are looking into.

Another bolide? And is it related to the Chelyabisk event? (Image: proufu,ru, LINK)

The above image is from a single dash-cam report from the Bulgakovo Ufimsky District (Russian: Булгаково Уфимского района). The time for this was approx. 19:43 of 11-Feb-2013, placing it well before the Chelyabinsk event. Irregularities in the video, and discrepancies with the event suggest that it may be a hoax.

However, if you know of additional supporting (or discrediting) evidence for this or other events, you can let us know either by posting a comment below, via Twitter @KairaProject or by contacting the project directly. Many thanks!