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!

Range deviations

Ok. After a pretty intensive day, I just couldn't stop fiddling around with the data. I started looking at our data at the closest approach. I sparsely looked at our low resolution data during the first three hours at 1 minute intervals to see if there was any difference with the ephemeris. Each spectrum is calculated in individual decoded pulses of length 1950 microseconds and 16 ms IPP. The length of the spectral window is 2 seconds. And indeed there seems to be a nearly 5 km difference, which can be used to refine the orbital elements of the asteroid. The power fluctuates a lot, which is due to speckle. The spectrum width due to speckle reduces as a function of range.

During the next few days there will be much more results to come. We picked up the asteroid on the radar at about 20:12 UT and continuously received echos until at least 4 UT.

Update: 18/2/2013: I clarified some of the radar processing parameters and added more explanation. 

Coherent integration image

Here is a 20 second coherent integration at 02:23 UTC.

We can detect a ~ -6 km error in along track range, and a 1.5 Hz error in Doppler.  

DA14 Measurements Running Smoothly

EISCAT Tromsø tracking of asteroid 2012 DA14 is running smoothly.

Haystack joined tracking at 22:00 UT and Goldstone joined at 00:10 UT. All three radar facilities are now tracking DA14. EISCAT will continue until 08:00 UT.

We got a confirmation that Haystack has observed DA14!

Update: Goldstone confirms observation of DA14!

Update

We picked up DA14 at around 20:12 UTC and continued seeing echos in our real-time analysis until around 22:00 UTC. The asteroid was right on track and is now about 114 000 km from us already, receding with a relative velocity of about 6.3 km/s.

More sensitivity is to be expected in our post analysis, but you'll have to wait a couple of weeks for our final data. 

First results

Asteroid 2012 DA14 EISCAT low resolution real-time analysis range agrees within 2 km to ephemeris at around 20:20 UTC.

EISCAT PINGS ASTEROID 2012 DA14

First radar pings of asteroid 2012 DA14 recorded at EISCAT Tromsø appr. 20:15 UT!

After some tuning of the system, the real-time analysis was running appr. at 20:45 UT.

We celebrate the first European ping of an asteroid! First real-time analysis results in the pictures below!

We continue the measurements until 08:00 UT Sat 16 Feb! Work on the real-time analysis and pointing accuracy will keep us busy through the night!

Observing Team

Some asteroid 2012 DA14 observing team members:

Observer in charge: Researcher Juha Vierinen from Sodankylä Geophysical Observatory, Finland

Observer 2: Researcher Lassi Roininen from Sodankylä Geophysical Observatory, Finland

Observer 3 (sitting): Mike Rietveld, EISCAT Scientific Association, Norway
Observer 4 (front): Jussi Markkanen, EISCAT Scientific Association, Finland

EISCAT Engineer on duty: Erlend Danielsen, EISCAT Scientific Association,  Norway

Co-located Observer / Meteor Trajectory Expert: Derek McKay-Bukowski, Sodankylä Geophysical Observatory & Chilbolton Observatory, UK

Radar is Running - Testing and Calibration

EISCAT Tromsø switched on 18:00 UT. At the moment, final testing and calibration before the asteroid DA14 flyby.

Tracking asteroid 2012 DA14 starts 20:00 UT!

Transmission test is ok (see photo)!

Size estimates for the Chelyabinsk event

There are several sets of video footage with audio. Just a few examples include:

• http://www.youtube.com/watch?v=N8Z3giHwcYg
• http://www.youtube.com/watch?v=LS3yFNjiVT8
• http://www.youtube.com/watch?v=xPe9uOGOhkg

The have audio blasts at various intervals. What is unknown, however, is their location with respect to the incident vector of the meteor. There is one super-loud explosion which is followed by various minor secondary noises. This is somewhat confused by echoes, local noise (e.g. falling debris), microphone noise, etc. These follow for many seconds after the main event.

The blast is not the meteor hitting objects, but rather the shock wave from the air burst. The meteor explodes during re-entry due to thermal stress. Essentially the surface of the meteor is super-heated due to friction against the atmosphere during re-entry. The interior, however, will still be extremely cold.

Relying only on reports, and in the absence of any confirmed finds of fragments, we can only estimate the composition. However, it is more likely to be a stony meteor based on the explosion and statistical likelihood, given the populations of this size of small object in the solar system.

There are no reliable reports of craters. The smoke trail burns out at high altitude, and while fragments may certainly have reached the ground, these will be at terminal velocity free fall (and also relatively cooler). The smoke trails indicate that the air-burst was occurring several kilometres up in the atmosphere.

The initial impact angle (on the atmosphere) will be around 50 degrees. This is based on the radiant location and the distance from zenith (earth travel direction). There is still a good degree of uncertainty in this, though, due to lack of precise information about the incoming orbit. There is a large error associated with this though and it remains a weak point in our findings. Impact velocity is probably 25 km/s. This is based on fact that the earth is moving at about 20 km/s and the impact is coming from the sun-side.

Based on these assessments, particularly audio shock information, and correlating damage reports, we can revise our estimate to make it larger than our first estimate.

Again, we must stress that the associate errors with these estimates remain large, but we are probably looking and initial object size of 10 to 20 metres across.

We will continue to provide updates and we continue to process the information that we have.

Difficulty estimating size

In addition to the question of the meteor trajectory, we have been trying to estimate the size of the object. This is extremely difficult as there are a large number of parameters that can affect the result of any impact.

Of course, for the Chelyabinsk event, we are trying to work backwards, based on reports, video footage, and any other data we can obtain. In the excitement of the moment, we need to bear in mind that some reports can be exaggerated in the excitement, so it is necessary to be cautious.

The result of the impact can be affected by the size and density of the object. How it is formed (and how it fractures) can be significant. Video footage from some angles suggests that the object split into two roughly equal parts (based on smoke patterns). There have been suggestions of fragments (and even a crater!), but we don't have any details. When confirmed, this will be critical in not just size estimates, but also in improving our estimate of the trajectory.

The velocity of the object is also of importance. Faster moving objects will do more damage. Therefore, for an equivalent explosion, a slow-moving fragment would be comparatively bigger than one that was fast moving. The movement of the Earth through the Solar System means that "near dawn" events may be compounded by the "head-on-collision" effect. Again, as our knowledge of the trajectory improves, so too will our impact parameter set.

As more data comes to hand, we will continue to revise our information and will post something when we can.

However, the Chelyabinsk event is certainly much smaller than the 2012 DA14 asteroid.

Are 2012 DA14 and the Chelyabinsk meteor related?

This morning, there was a spectacular meteor event over the city of Chelyabinsk, unfortunately resulting in damage and injuries. Of course, with the increasing attention around the asteroid 2012 DA14, this event has immediately sparked the question if the two are related.

They are not.

The reason that we can discount the possibility of the two being associated in any way can be reduced to the following reasons.

Firstly, we need to look at the trajectories. The asteroid 2012 DA14 is approaching from the south. It will slingshot past the Earth and continue rising to the North.

However, the Chelyabinsk event is coming from a different direction. The city is at 55°09′N 61°23′E and the event radiant (the position of origin of the meteor) is above and to the left of the rising sun.

Early appearance of the meteor.

General trajectory.

This puts the meteor origin/radiant at approx. RA 22h and Dec +10.

UPDATE at 10:25 GMT: Revised estimate is now approx, RA 22h Dec +20°

UPDATE: Improved radiant estimate.

Piecing this together is difficult, as video footage does not always come with an associated position. Angle and direction needs to be calibrated from nearby objects (buildings, people, etc.) and using these are ways of estimating scale. Also, we do not always know the location of the observer, which introduces additional uncertainty. Fortunately, as more footage is being posted, we are getting a better estimate of the origin of this meteor.

However, even with the uncertainty, this is still in a COMPLETELY different direction.

Also, we can consider the timing of the events. The closest approach of 2012 DA14 will occur at approximately 19:24 UTC. The Chelyabinsk event occurred at about 9:20 am local time... which is 03:20 UTC. (UTC is Coordinated Universal Time, and provides a common time-zone to allow the comparison.)

If we consider the difference, it is approximately 18 hours. The asteroid is travelling at approximately 8 km/s and, if the Chelyabinsk object was related, it would have required a deep space velocity of about the same. Even if the two were related, this would put the two objects some half a million km apart.


In any case, the two events are not related.

This is just a VERY unusual coincidence.

Media Info on DA14 Tracking

During the asteroid 2012 DA14 flyby, media can contact observers 20:00-08:00 UT.

Researcher Juha Vierinen +358 40 482 7774, juha.vierinen'at'sgo.fi  (Observer in Charge)
Researcher Lassi Roininen +358 40 482 7773, lassi.roininen'at'sgo.fi

Other members of the observing team are Jussi Markkanen, Erlend Danielsen and Arild Stenberg from EISCAT Scientific Association.

Updates of the observations will be posted in Kaira blog and Twitter!

Getting ready

Yesterday I was working on my coherent integration algorithm in anticipation of today's run. This is the first time I've used this code, so I anticipate some real-time coding today. I can also use my space debris coherent integration code, but this is intended for shorter integrations, as it doesn't have ephemeris corrections.

The folks at EISCAT (Roger, Stian, Guttorm, Arild and Erlend) also replaced a piece of cracked waveguide to reduce arcing. After this, we tested our measurement program again and did some pointing checks on radio stars with Jussi. I believe we are as ready as we can be with the radar experiment now.

I also gave a few radio interviews and today there will be a few more. Derek apparently also gave one radio interview in the UK. Out of all my radar measurements, this has by far generated the most attention. I believe this is the first European radar measurement of an asteroid -- let's hope there are more to come.

NASA is updating their ephemeris a few times per day. They are up to solution #48. The uncertainties have dropped significantly any more in the last days, but our beam width is 0.5 degrees, so a 300 arc second 3-sigma in the ephemeris isn't a problem for us. I updated my energy to noise calculations to show values at 10 seconds of integration.

By some strange coincidence, a beautiful and a bit scary meteor was spotted this morning in Russia. I'd be interested to see what kind of a trajectory astronomers can deduce from the dash cam videos posted on youtube (there are plenty of them, as every russian seems to have one). Click the links if the videos don't work in embedded mode.

DA14 European and US Radar Schedules

Three large-scale research facilities will track asteroid 2012 DA14 with radars. The asteroid will be first observable in the European sector and later in the American sector. Tentative schedules are:

EISCAT (Tromsø, Norway) will track Feb 15 20:00-08:00 UT.

Haystack (Massachusetts, USA) will track Feb 15 22:00-08:35 UT.

Goldstone (California, USA) will track Feb 16 00:10-08:35 UT. Goldstone will continue Feb 18, 19 and 20.

Asteroid will not be observable at Arecibo radar in Puerto Rico.

Asteroid diameter is estimated within a factor of two of about 50 meters! Radar observations will give refined estimates on the size and shape!

Tracking Starts Friday 20:00 UT

24 hours till the first ping of asteroid 2012 DA14! EISCAT Tromsø is now calibrated and secured to track the flyby of DA14.

We will post updates both in the Kaira blog as well as in Twitter during the DA14 flyby from the EISCAT control room (see photo).

Latest photo from the radar prior to DA14 flyby

With a glimmer of sunshine against the mountain tops, and an impressive view, 2012 DA14 observer Lassi Roininen took a moment to take this fantastic photograph of the UHF radar dish at the EISCAT facility at Tromsø, Norway.

EISCAT UHF radar dish and transmitter and control buildings. (Photo: Lassi Roininen)

The event is getting closer, and it's getting exciting. The team are ready and the system is calibrated and set to go.

Radar system used for 2012 DA14 observations

The EISCAT facilities near Tromsø (Norway) include a radar there which operates at 931 MHz. This is what the team will be using for their observations of 2012 DA14.

The dish is 32m in diameter and is fully steerable. The radar power is provided by klystron technology and coded radar pulses are transmitted towards the asteroid 2012 DA14.

Using timing, pulse-decoding and all the other required calibration techniques, the faint echoes that are received from the asteroid can be interpreted to discern critical parameters about the fly-by.

Events of this kind are not common and there is a lot of work to be done to prepare the system for the observations. The team is working flat-out to ensure that everything is in order, calibrated, tested and ready for the pass.

Photo: D. McKay-Bukowski

Pointing calibration for the 2012 DA14 event

In order to carry out the observations of 2012 DA14, we must carefully check the radar pointing calibration. Remember that this asteroid will fly past quite quickly, so it is essential to check that the alignment is correct.

To do this, we plot the anticipated asteroid trajectory. We then search for radio calibration sources (point-like radio "stars") that are in the sky and work out when they would cross the asteroid trajectory.

The trajectory of the asteroid, as seen from the EISCAT-UHF.site. The circles are the locations on that trajectory where bright radio calibration sources pass. These will be used to carry out the pointing accuracy calibration tests ahead of the actual observations. (Plot by J. Vierinen)

We then can observe these sources as they are in that position. Because these are the anticipated positions of the asteroid, we can check to make sure everything is ready for the critical observations.

Latest update on 2012 DA14

 Work is continuing in preparation for Friday's radar observations. The next step for us is preparation of the calibration for the radar ahead of the observations.

Also, an article in Swedish about our team's project has just been posted.

Radar från Tromsø håller koll på asteroiden 2012 DA14. 

Link to article

2012 DA14 Uutiset

Asteroidin harvinaista ohilentoa seurataan SGO:n ja NASA:n yhteistyössä



(English summary below)

Asteroidi 2012 DA14 ohittaa 15. helmikuuta maapallon pinnan erittäin läheltä, 27 700 kilometrin päästä. Sodankylän geofysiikan observatorion tutkijat Juha Vierinen ja Lassi Roininen mittaavat ohilennon aikana Norjan Tromssassa sijaitsevalla EISCAT-järjestön suurtehotutkalla asteroidin ratakehitystä, pyörimistä ja muotoa.

Asteroidin Maan painovoimakentässä muuttunut rata pystytään tutkamittauksilla määrittämään erittäin tarkasti, ja täten uusi rata voidaan ennustaa. Mittaukset on suunniteltu yhteistyössä Tampereen teknillisen yliopiston professori Mikko Kaasalaisen ja EISCAT-järjestön fyysikko Jussi Markkasen kanssa.

Myöhemmässä ohilennon vaiheessa asteroidi tulee Amerikan sektorin tutkien näkyviin. NASAn tutkijat pystyvät käyttämään EISCAT-tutkalla mitattuja arvoja hyväkseen ja jatkavat asteroidin mittaamista suurtehotutkillaan loppuohilennon ajan.

Asteroidin läpimitta on noin 50 metriä. Asteroidin voi havaita maanpinnalta kiikareilla tai kaukoputkella, mutta paljaalla silmällä asteroidia ei erota.


English summary

Of the 15th February, asteroid 2012 DA14 will pass very close (27,700km) to the Earth. Finnish researchers Juha Vierinen and Lassi Roininen from Sodankylä Geophysical Observatory will measure the fly-by from the EISCAT radar facility in Tromsø, Norway. The observations will accurately measure the change in the orbit, as well as rotation and shape parameters.This sophisticated experiment has been designed in cooperation with Professor Mikko Kaasalainen from the Tampere University of Technology and Jussi Markkanen from the Finnish EISCAT station at SGO.


Web link

Press-release (Finnish language)

2012 DA14 radar parameters

EISCAT pointings for the asteroid pass. Based on the energy to noise ratio, we estimate that we can observe until 01:00 UT before losing signal. The vertical lines indicate when the different radars start observing (solid=EISCAT, long dashes=Haystack, short dashes=Goldstone).

Right now I'm doing some programming to allow EISCAT to track the asteroid during the pass. This will involve translating NASA Horizons ephemeris tables into pointing commands that are given to the radar -- possibly involving offsets. With recent observations, the errors are getting smaller and smaller, which increases the chances of hitting the target. Luckily our radar is so small, that the 0.1 degree 3-sigma errors are already much less than the 0.5 degree antenna beam width.

As you can see from the figure above, the asteroid will appear from the East and then head approximately towards zenith. The target will be fast, but not even close to the limits of the tracking speed of the radar. I've estimated the radar cross-section by assuming it is 0.1 times that of a metallic sphere with a diameter of 50 meters. I've estimated the energy to noise ratio based on a 0.1 second coherent integration time and a 12.5% duty-cycle (the maximum that EISCAT can do).

As for coding, I intend to use 200 different codes with a 10 us baud length and the EISCAT maximum 2 ms pulse length. This is to allow a real-time analysis, but still leaving quite many phase transitions for high resolution analysis. I'll be sampling at 10 MHz, which covers the 7 MHz receiver bandwidth at EISCAT. 

Current status at KAIRA

An expedition has gone from the institute up to the EISCAT facility at Tromsø, Norway, to carry out radar observations of this weeks near-miss fly-by of asteroid 2012 DA14. On the way, the team passed the KAIRA site... still happily and reliably observing! Here is the photograph showing the site conditions.

KAIRA site, as of 10-Feb-2013. (Photo: Lassi Roininen)

Like the asteroid and earth, the photo was taken during a "near-miss" drive-by. The vehicle passed within a couple of hundred metres of the site, but there was no risk of collision! ;-)

2012 DA14 Flyby

The asteroid 2012 DA14 will zoom past our planet on the 15th of February at about 20 UT. What makes this even special, is that it passes us really close, about 28000 km from the surface of Earth. Keep in mind that the satellites  that broadcast satellite tv are at about 36000 km. You can see some fun facts about the asteroid on the youtube video prepared by NASA above.

The fact that this asteroid is passing us so close, means that we have a chance of measuring it with the EISCAT UHF incoherent scatter radar. We also happen to be approximately on the same side of Earth as the asteroid will pass, which will allow us to measure it very close to its nearest point. With some luck, next week we will have radar echos of the asteroid show you. 

Gloaming

Just a nice photograph to end the week. We hope you all have a nice weekend!

Arctic twilight. (Photo: D. McKay-Bukowski)

Snowmen

Okay, not from real snow... these little guys were made of white chocolate, desiccated coconut, currents and chips of candied orange.

Some (temporarily) surviving snowmen. (Photo: D. McKay-Bukowski)

Aerial photograph of KAIRA

Our colleagues at EISCAT_3D have posted on their weblog an article about the first high-resolution aerial-photograph of the KAIRA site.

The author (Thomas Ulich) wrote:

" We just learnt that the MapSite of the Finnish National Land Survey (Maanmittauslaitos) has updated aerial photography from the Kilpisjärvi area where the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) is located. The images were taken in late summer 2012, and astonishingly one can just about make out the 3m x 3m ground planes of the LBA aerials in the circular area south of the HBA tiles. "

Also in their article is a link to the high-resolution image of the KAIRA location on the MapSite directly. Note that the images are copyright of the Finnish National Land Survey.