Active heating effect detected by the KAIRA riometer

Just a little update to our broad-band riometer studies (see previous posts on this topic here and here). 

We have manipulated the cosmic radio noise flux through the ionosphere! Buhahahaaa!

Ionospheric opacity for the radio waves depends on the electron temperature of the plasma, or more precisely, on the electron-neutral collision frequency. The electron temperature (and the collision frequency) can be increased artificially by using powerful radio-waves sent from the EISCAT Heating facility. Because the ionospheric opacity is altered, the effect should be visible, in principle, in the riometer data measuring the cosmic radio noise propagated through the heated region. This effect, however, is expected to be relatively small, especially if the riometer beam doesn't overlap the heated volume perfectly.

In our statistical study (Kero et al., 2007), we summed together all the IRIS riometer data during the heating experiments carried out between 1994-2004 in order to see this change, which turned out to be even smaller than expected theoretically. More recently, Senior et al., 2011 were able to measure the same effect within single experiments by using a high spatial resolution imaging riometer with more optimal geometry. Their effect was also found to be significantly smaller than expected by the theoretical model.

Obviously, we wanted to try this with our KAIRA riometer, and we did, please have a look:






















In the figure above, the cosmic radio noise power ratio between heating on and off is plotted in dB as a function of frequency. This is done for two KAIRA beams, the red one pointing towards the heated volume and the blue pointing vertically. The effect is again very small (surprise!), but still clearly there, and not visible in the vertical reference beam. Good. This is the first broad-band riometer measurement of the active heating effect and hopefully it will provide the final answer on what the heck is wrong with our heating model!

Have a nice Easter!
 

VLBI with KAIRA, LOFAR and the LWA

As we write this, KAIRA is carrying out its first VLBI experiment. We are recording 122 beamlets from RCU mode 4 (LBA, but with 30-80 MHz filters). The subband statistics, beamlet statistics and antenna cross-correlation files are being recorded, but it is the raw beamlet data that is significant here, as it can be used to correlate with the other VLBI stations involved. This particular experiment, organised by Olaf Wucknitz, is being done together with LOFAR stations Effelsberg (DE601), Jülich (DE605), Onsala (SE607) and the LWA in the United States. The map shows the location of these sites:

Sites used in this VLBI experiment. (Background map: ESRI/Penn)

Although this is not the first international experiment with KAIRA, it is the first with recorded raw beamlet data and, therefore, our first attempt to get radio interferometric fringes. Although this is a very ambitious project, if we do manage to get this to work it will be a major technical success.

Updates:

03:26 UTC — In the end, DE605 did not take part. DE601, KAIRA and the LWA reported in okay. No news yet, from SE607.

05:49 UTC — SE607 have now reported it. Their observations went well too.

European Space Expo: June 2013, Ireland

We have been advised by our I-LOFAR colleagues that the European Space Expo will visit Dublin and Cork in Ireland in June 2013. This is a spectacular travelling exhibit that shows how space and its applications provide benefits to Europe. There will be lots of exciting activities surrounding the Space Expo visit, including space-related workshops for kids, an Irish space industry event, public talks, and lots more.

The Space Expo highlights the critical role of space and space-based technologies to Europe. In Ireland, there is an active space science and astronomy research community who have worked with the European Space Agency for many decades. What’s more, there are now over 40 Irish companies working with ESA on everything from telecommunications, to materials, to remote sensing of our oceans.

Of course, this will be a fantastic opportunity for I-LOFAR to raise awareness of their project and garner more support.


Expo Link: http://www.astrophysics.ie/?p=778

Expo Video: http://www.youtube.com/watch?v=FjmIUQAU5Jw

I-LOFAR site: http://www.lofar.ie/

KAIRA presentations at Dalfsen

Just one of the KAIRA talks.

We've now had the Single-Station meeting at Dalfsen, following the Science workshop. The meeting has been extremely well attended, with all the big names in the field present. The fact that several critical meetings have been combined has certainly helped. There is the science workshop, the board meeting, the single-station meeting and the International LOFAR technical operations meeting).

The KAIRA project has also been well-represented at the meeting. In total, there have been five KAIRA presentations made so far, with one more scheduled for tomorrow. They include:

— Scintillation Studies: Updates and New Perspectives
— KAIRA Construction and Commissioning,
— RCU 357 mode observations
— KAIRA Riometry and Incoherent Scatter Radar
— KAIRA outreach
— KAIRA station operations update


It's not over yet (we have the International LOFAR Telescope Technical Operations meeting in the morning), but so far it has been a highly productive meeting with lots of new and interesting science, engineering and ideas!

New radio galaxy discovered

The International LOFAR Telescope has made a new announcement regarding one of their discoveries. Their press-release states that a team of astronomers led by Dr. George Heald (ASTRON) has discovered a previously unknown gigantic radio galaxy using the International LOFAR Telescope (ILT). The discovery was made as LOFAR conducted its first all-sky imaging survey: the Multifrequency Snapshot Sky Survey (MSSS). Using early MSSS images, the astronomers have identified a new, huge source that represents material ejected from the center of the galaxy tens to hundreds of millions of years ago, and now stretching across millions of light years of intergalactic space. If this newly discovered galaxy were visible by eye, it would be larger than the full moon. The MSSS survey is still ongoing, and hopes to discover many new sources like this one.

The new giant radio galaxy (pale blue). Inset the power-source
at the centre of the huge structure. Image: ASTRON

The new galaxy is a member of a class of objects called Giant Radio Galaxies (GRGs). GRGs are a type of radio galaxy with extremely large physical size, suggesting that they are either very powerful or very old. LOFAR’s extreme sensitivity to large objects like this one, combined with its operation at low frequencies that are well suited to observing old objects, make it a powerful tool to find new GRGs like this one.

The centre of the new GRG is associated with one member of a galaxy triplet known as UGC 09555. The central galaxy is located at a redshift of z=0.054536, or 750 million light years from Earth. The central radio source was previously known and has a flat radio spectrum, typical of giant radio galaxies.

LOFAR’s MSSS survey is a concerted effort to image the entire northern sky at very low radio frequencies, between 30 and 160 MHz (wavelengths from 2m to 10m). The primary aim of the survey is to perform an initial shallow scan of the sky, in preparation for deeper observations yet to come.  

Source: ASTRON

LOFAR Science Meeting in Dalfsen

Dalfsen, de Westermolen.
Image: Michiel Verbeek

The LOFAR science meeting, will be held this week (19-22th March 2013) in Dalfsen, Netherlands. The first two days will be for science with the overall LOFAR network. Then there will be a day dedicated specifically to single-station science with LOFAR stations. Finally, the last day will be the technical operations meeting, to discuss issues with the running, maintenance, upgrade and enhancement of the LOFAR systems.

This will be the first meeting of the International LOFAR Telescope since formal operations began last year. There will be over 100 attendees at the meeting, making it a very exciting event.

KAIRA will be strongly represented on the single-station day, as this is our primary mode of operations. It will also be a great opportunity for us to show-case some of our initial results and outline our plans for the future work.

This is a fantastic chance to bring more attention to the science results already coming out of LOFAR, and the fact that full operations are now happening. No doubt there will be a number of significant discoveries and results announced during the next few days, and we'll be reporting them here and on twitter (@KairaProject) when we can.

Link:  http://www.astron.nl/lofarscience2013/

CME predictions

Whenever a CME goes off, it is possible from some of the data received from different solar observatories (especially the space-based ones) to predict the path of the ejected material. As part of our update on this particular event (which is of particular interest to us as we will be observing it!), we have included some simulation results from


The following is from the Naval Research Laboratory Solar Physics Branch

H3DMHD predict CME (March 15, 2013, 06:54: COR2A/B) driven shock will arrive at Earth at 00UT on March 17, 2013.

Estimated speed of CME from COR2 of STEREO-A/B is ~1000 km/s.

Source region of this CME located at N09W02.



Here are some links to the animations from the simulation results.


CME_20130315_1000km_N09W02/D_S7_1000km_N09W02.gif
CME_20130315_1000km_N09W02/V_S7_1000km_N09W02.gif
CME_20130315_1000km_N09W02/V_W0_1000km_N09W02.gif
CME_20130315_1000km_N09W02/D_W0_1000km_N09W02.gif

Thanks to RAL Space for bring these to our attention!

Coronal Mass Ejection

We may be in for a bit of a solar storm soon. A recent coronal mass ejection (CME) has been predicted as being on a direct impact with the earth, sometime in the next 24 hours. As a result, we could be in for some interesting auroral displays. Certainly KAIRA will be operating throughout this time as part of its ongoing riometry project. We also hope to obtain some EISCAT data too.

We know about CMEs typically from solar observatories. Although the material that is ejected from the sun is moving extremely quickly, it still can take a couple of days to reach the earth.

A recent coronal mass ejection (CME). Image: LASCO C2 / SOHO.

LASCO (Large Angle Spectrometric Coronagraph) is a camera on the SOHO spacecraft. It uses a block (occulter) to obscure the sun itself, thus allowing the camera to be more sensitive to the fainter material that is streaming out as part of the solar wind. The size of the sun's disc is indicated by the white circle.The radial line features are coronal streamers. The blast of material is the coronal mass ejection and it can be seen being expelled away from the Sun. This image shows the inner solar corona up to 8.4 million kilometers (5.25 million miles) away from the Sun.

We will post up more information as the weekend goes on to report on anything interesting that we find!

Link:  SOHO website

CME to coincide with KAIRA/EISCAT observations?

It looks like we may be up for some interesting solar activity soon. And, as luck would have it, we have dual KAIRA/EISCAT observations scheduled for that time. A perfect opportunity to test some of our new riometry experiments.

Here is one of the first reports we received. And it really looks like the BBC's Shipping Forecast, no?

SUBJ: IPS DAILY SOLAR AND GEOPHYSICAL REPORT
ISSUED AT 2330UT/15 MARCH 2013 BY IPS RADIO AND SPACE SERVICES
FROM THE AUSTRALIAN SPACE FORECAST CENTRE
SUMMARY FOR 15 MARCH AND FORECAST FOR 16 MARCH - 18 MARCH
STATUS INDICATORS SOL:** YELLOW **   MAG:** RED **     ION: ** YELLOW **
-----------------------------------------------------------
1A. SOLAR SUMMARY
Activity 15 Mar:  Moderate

Flares    Max     Fadeout    Freq.  Sectors
  M1.2    0709UT  possible   lower  Mid East/Indian

Observed 10.7 cm flux/Equivalent Sunspot Number for 15 Mar: 123/76


1B. SOLAR FORECAST
             16 Mar             17 Mar             18 Mar
Activity     Low to moderate    Low to moderate    Low to moderate
Fadeouts     Possible           Possible           Possible
10.7cm/SSN   120/72             120/72             115/66

COMMENT: Solar activity has been Moderate with a long duration 
M1 flare from region AR1692(N09E06) peaking around 07UT. A halo 
CME was observed in association with this event in SOHO/LASCO 
coronagraphs. Combined with STEREO coronagraph imagery, analysis 
suggests that the main part of the CME appears to be directed 
to the east and north, however a significant amount of the material 
is likely directed towards the Earth. This is expected to arrive 
late on the 16th of March or early on the 17th UT. A weak shock 
was seen in the ACE solar wind data just before 05UT on the 15th 
of March, most likely the arrival of the CME observed on the 
12th of March. The solar wind speed peaked just below 500 km/s 
before diminishing to around 450 km/s. The IMF Bz component went 
as low as -10nT for less than an hour before swinging northward 
for the remainder of the day. More significant solar wind speeds, 
potentially up to around 800 km/s, are expected following the 
arrival of the CME observed on the 15th. Solar activity is expected 
to be low to moderate for the next 3 days, with some chance of 
further M class flare activity.

Sun pillar

The Arctic skies are one of the most beautiful things about living so far north. Apart from the spectacular aurorae, there are numerous optical effects that you get from having ice crystals in the air. We have written about parhelia on several occasions now, but today's article discusses a different ice-related phenomenon... sun pillars. These are formed from reflected sunlight from flat ice crystals. The light can either be internally reflected or even reflected off the external surface.

The more general phenomena are light pillars, which can form from any light source. All that is required are the light, the ice crystals and a sufficiently dark background so that the contrast is sufficient to see the reflected light. Sun pillars are those specifically formed from reflected sunlight. They are usually easiest to see at sunset as the sun dips just under the horizon.

A faint sun pillar seen near Muonio. Photo: D. McKay-Bukowski

But as we mentioned, any illumination source could form a pillar. It is possible to see them from artificial light sources light street lamps or car headlights. And it is even possible to see them from other natural sources of light such as the moon or bright planets.

Have a nice weekend!

ERIS 2013

Registration for the 2013 European Radio Interferometry School – ERIS 2013 — is now open. This is the Fifth European Radio Interferometry School and it will take place in Dwingeloo (The Netherlands), in the week of 9-13 September 2013.  ERIS will provide a week of lectures and tutorials on how to get scientific results from radio interferometry. Topics covered include:

• Calibration and imaging of continuum, spectral line, and polarization data
• Low frequency (LOFAR domain), cm-wave (e-MERLIN domain), decimetre-wave (HI/OH domain), high frequency (ALMA/IRAM domain), and very long baseline interferometry
• Extracting the information from astronomical data and interpreting the results
• Choosing the most suitable array and observing plan for your project

A preliminary programme is posted on the ERIS webpage: http://www.astron.nl/eris2013/programme.php

Participants are expected to bring fairly recent Linux or MAC o/s laptops with tens GB disk space. Instructions for installing data reduction packages and downloading data will be provided nearer the time of the event. Most examples will be drawn from m-, cm-, and mm-wave instruments such as LOFAR, WSRT, JVLA, EVN, e-Merlin, and ALMA.

Registration will be open until April 1st 2013, although the conference organisers say that the event is likely to be very popular and that people should register as soon as possible to secure a place. http://www.astron.nl/eris2013/registration.php

Link: http://www.astron.nl/eris2013/

Nordic Physics Days 2013

The Nordic Physics Days will be held in Lund, Sweden on June 12-14, 2013. The Department of Physics at Lund University will host the conference in cooperation with the Nordic Physical Societies. The meeting is the third in a series of meetings in which the first was held in Copenhagen in 2009 and the second in Helsinki 2011. The meeting will consist of plenary lectures, parallel sessions and poster sessions. The Nordic Physics Days is a conference both for researchers and teachers in physics.

Parallel sessions are arranged by expert committees in astronomy/astrophysics, atomic and molecular physics, bio- and softmatter physics, nuclear physics, particle physics, nano physics and solid state physics. Additional sessions will be arranged by expert committees in education, women in physics and physics and society. A panel discussion on large facilities will be arranged during the first evening.

The deadline for submission of abstracts is 15^th March 2013.

For more information, visit the Nordic Physics Days website at: http://www.fysik.lu.se/english/npd2013/

Best wishes, Juha!

Juha Vierinen.

This week, we have said goodbye to our Observer-in-Charge at KAIRA... Juha Vierinen. It is difficult to understate how fortunate we have been to have had Juha with the project. He has been working with us right since the start and has been critical to the success of the facility at so many levels.

Last year, Juha successfully defended his PhD thesis: "On Statistical Theory of Radar Measurements". As is typical, most recently completed PhD students take the opportunity to do some post-doctoral research at a different institute, usually in a different country.

Sodankylä Geophysical Observatory has agreed to let him go (temporarily, mind!) to MIT Haystack observatory in the United States. A major coup for them!

Of course, the remainder of the KAIRA team will carry on (doubly hard now) and we hope to continue working with Juha over the coming years as we start publishing our results. Still, his presence in the group will be sorely missed. Rarely does one find someone so enthusiastic, generous and very, very bright.

So, on behalf of the entire KAIRA team, we wish you all the best, Juha. Thanks for everything that you have done and we hope to see you again soon.

Hölökynkölökyn!

KAIRA IPS/ISS data

Recently, KAIRA data featured on the ASTRON/JIVE picture of the day:

KAIRA data of Cygnus A showing scintillation. Image: Richard Fallows, ASTRON.

Richard Fallows, who used the KAIRA facility in September 2012 wrote:

The scintillation of point-like radio sources is a well-known phenomenon which arises from the diffraction and refraction of light due to density variations in the line of sight between the source and the observer. Usually, scintillation occurs due to one or more distinct regions in the line of sight: the interstellar medium (InterStellar Scintillation, ISS), the interplanetary medium (InterPlanetary Scintillation, IPS) and the Earth's ionosphere (Ionospheric Scintillation, IoS). This talk will focus on the latter two cases. IPS has been used for many years to probe the solar wind. As a remote sensing technique, it is capable of being used to provide global measurements of solar wind speed and estimates of density on a regular basis, thus complementing the single-point measurements from spacecraft. Different analysis techniques can be used to probe the solar wind: tomography from many measurements is used to provide a global picture of solar wind density and speed, while in-depth analysis of single observations can be used to observe different solar wind streams and Coronal Mass Ejections in the line of sight. The wide bandwidth of LOFAR is opening up new perspectives in the study of scintillation in the near-space environment, with recent advances in the field of ionospheric scintillation. The evolution of scintillation from weak to strong scattering regimes has been directly observed in dynamic spectra. Scintillation arcs, seen previously in two-dimensional power spectra from interstellar scintillation observations, have been noted for the first time using observations of ionospheric scintillation. This offers new methods of studying the plasma structures giving rise to the scintillation. 

Well done Richard on getting such good results!

In order to observe simultaneously at all frequencies from 30 up to 250 MHz, KAIRA needs to make use of RCU-357-mode. This is where different sets of antennas are used to cover the different frequencies. By making clever use of the selection (to optimise the beam patterns) and being very careful in the activation sequence (to avoid tripping circuit breakers), it is possible to cover such a wide range.

Reference: http://www.astron.nl/dailyimage/main.php?date=20130228

A Night of Northern Lights

Last night the Northern Lights appeared early above Sodankylä. The western horizon wasn't even completely dark yet. Here is a short time-lapse film spanning of this fantastic night of observations with the All-Sky Camera of the Sodankylä Geophysical Observatory (SGO), Sodankylä, Finland.

The film covers the night of 1st/2nd March 2013.

The all-sky camera uses a fish-eye lens with 180° field of view pointing vertically up. It takes grey-scale images through filters of green, blue and red. The green image is taken every 20 seconds, the red and blue images are taken once per minute. These images are then overlaid to make an RGB (false-)colour image. The blue and red images are recycled to cover those green frames, for which there's no red or blue data. This sometimes results in blue lights being out of place. But this is a small price to pay for the overall colour effect.

Enjoy!

By the Kitinen

Another nice photograph to end the week. This one was taken near the river-side at Sodankylä Geophysical Observatory.

Kitinen riverside. (Photo: D. McKay-Bukowski)

Have a nice weekend everyone!