Lapland Ice Lanterns

At this time of year, Lappish Ice Lanterns (Jäälyhty in Finnish) are lovely way to decorate paths and outdoor areas around homes. The lanterns are made of ice with a candle and are easy to make. First, you need a bucket. Anything will do, but a plain 10-litre plastic bucket is ideal.

Standard buckets. Just what you need to make the Lappish ice lanterns. Well, that and a cold climate, of course! The exact size is not critical, but these ones hold about 10 litres. (Photo: D. McKay-Bukowski)

This is then filled up with water, leaving a few centimetres to the top (the exact distance is not important, but you just don't want it completely filled). The bucket is then put outside in the snow.

Because it is quite cold at this time of year (typically –15 to –30 degrees C), the water in the bucket will freeze. The bucket should be left out for 4 to 8 hours (depending on the temperature). What is needed is that the water only part freezes. When half frozen, you are left with an "ice bubble" (frozen around the outsides, but still liquid in the centre). That is when you need to bring it back indoors. Note that you should never let the ice completely freeze. It will expand and crack the bucket!

Next, you put the bucket in the sink, upside down. Let some water run over the outside: the ice will slowly start to melt and, with a loud bang, the ice will fall out of the bucket into the sink. Let some water then run onto the top (which was originally the bottom of the bucket). It will melt through the ice and create a hole.

Then tip the ice over and let the remaining water drain out. This leaves an ice shell with a hole in the top.

Tipping the water our of the lantern. Because of the way this one froze, it now has a very thick base. Your hands tend to get very cold doing this! Also, be careful as the wet ice is very slippery too. (Photo: D. McKay-Bukowski)

These ice lantern shells can then be taken back outside. Carefully place a lit candle in it and there you go!

A completed Lapland ice lantern. (Photo: D. McKay-Bukowski)

And that is the lantern!

The ice will protect the candle flame from the wind and the frosted ice will make it beautiful to look at. Because the ice will freeze slightly differently each time, the individual lanterns will all be subtly different. Also, you can colour them, but using not plain water, but the left over water from cooking beetroot or tinted with the dregs of pots of tea.

Some more Lappish ice lanterns in the snow. The two on the left were tinted with some coffee grounds when they were froze, to give an amber-brown tint to the ice. We have several here jsut for decoration and some to illuminate the path to the front door. (Photo: D. McKay-Bukowski)

Of course, in the spring, these lanterns will melt away (but don't forget to clean up the remains of the candles!)

Winter solstice 2012

Another year is almost done and today is the winter solstice. It is also a Friday so, in the tradition of pretty photographs for the end of the week, here is one for that... at the winter solstice too.

Winter solstice at SGO. (Photo: D. McKay-Bukowski)

The photograph was taken looking across the antenna fields; not at KAIRA, but at the Sodankylä Geophysical Observatory. Of course, being in the Arctic the sun does not rise above the horizon, but it is only just below it, giving a strange ethereal twilight above the snowy landscape.

Have a nice weekend (and winter solstice too!)

Routine display of all-sky images

For those of you who have been wondering about the strange plots on the right-hand side of our weblog page, here is the explanation.

These are all-sky radio images, taken using KAIRA. Our array is capable of imaging the entire sky instantaneously. In some ways, you can think of it as a fish-eye lens for radio astronomy. Because of the typical observation mode, we can taken these images regularly and put them on the web for everyone to see. In fact, we are the only LOFAR-based station that we know of that does this on a regular basis. Typically, the images are updated every 9 minutes or so. Here's a recent example:

Along the top of the image is the date (top left) and time (top right). The times are given in Coordinated Universal Time (UTC). Along the bottom are some details of the observation. The "mode" is the "RCU mode" (RCU = Receiver Unit) which specifies which filters are being used and which antenna array is selected. Typically, this is Mode=3 for our low-band antenna array observations. "Sb" is the subband (or receiver channel). Each receiver unit splits the signal up into 512 subbands which are sampled and processed. These all-sky observations are only one subband. The equivalent frequency of this subband is shown at the bottom right.

Around the edge of the plot are the cardinal points (North, East, South, West). Although it might seem that East and West are incorrect, this is actually what you expect when you look up. Imagine lying on your back, looking up. If North is above your head, then East is on your left and West to the right. This is also what you see on conventional star maps.

Because the images are regularly updated, you can watch the radio sources change position with time. The sequence below shows four images, separated by approximately one hour each. As you can see, the position of the radio objects move. This is because the Earth is rotating in the opposite direction. As a result, they appear to be moving around the north celestial pole.

The amount of time it takes for the sources to complete one full circuit is one sidereal day (approx. 23 hours 56 minutes). This is due to the mix between the rotation of the Earth and the orbit of the Earth around the Sun. This also means that for a given time of day, the radio sky will appear at a different position at different times of the year.

Have a very log periodic christmas!

An X-polarized X-mas tree of the future.

With the holidays approaching, the folks at MIT Haystack decided to decorate. This year the Christmas tree is a bit more special than usual. This one can sense radio waves as it doubles as a prototype antenna for SKA. The antenna is developed by Cambridge University for the SKA project and was just recently set up at MIT Haystack so that it can be tested with future receivers developed in the RAPID project.  On the background you can also see the steerable and zenith pointing MIT Haystack ISR antennas.

The lonely road

Roads in Lapland are often long and straight, with very little traffic. Today's photograph shows one such stretch of road between KAIRA and SGO. And with no traffic, it is very easy to stop and wander out into the middle of the road to take such a photograph!

The road to SGO. (Photo: D. McKay-Bukowski)

Have a nice weekend!

New KAIRA pages

Some of you will no doubt have noticed, but we now have some new pages linked directly through the web log. Above the web log text, you'll see links to general information about the project and also the technical specifications.

The technical specifications list the capabilities of the instrument... very useful for scientists who are thinking of making use of our facility!

KAIRA as a multi-frequency riometer

Photo: Carl-Fredrik Enell

"My name is Malefia Sinor, I’m a student in Lappeenranta University of Technology, in where I am doing a masters thesis in collaboration with Sodankylä Geophysical Observatory. My topic is to search for a parameterized model for the D-region electron density to be used in a multi-frequency riometer data analysis.

"Riometer (relative ionospheric opacity meter) is an instrument used to measure the cosmic HF radio noise absorption that is taking place in the D-region ionosphere (50-90 km). Traditionally, riometers measure the cosmic radio noise only at one or two single frequencies, typically around 40 MHz. Depending on the amount of ionization, the radio signal is absorbed when it passes through the ionosphere. The ionosphere is the partially ionized region of the Earth’s upper atmosphere. It extends from about 60 km to 1000 km. The absorption takes place mainly in the lowest part of the ionosphere, due to collisions between the free electrons and neutral particles.

"KAIRA instrument turns out to be a unique riometer, because of its capability to measure a wide range of different HF frequencies in multiple narrow beams. The multi-frequency capability is the one which makes it possible to invert the electron density since the height profile of the refractive index of the plasma depends on the radio wave frequency for a given electron density profile.

"To share experience and to get an idea about my work, I traveled to Sodankylä. When I arrived, the weather was -20oC (or more), which is for me very cold, I never imagined this kind of weather and I almost couldn’t survive from it for the first time, but peoples at SGO were very helpful. For the last week, I have had an opportunity to attend to the Finnish EISCAT campaign in Tromsø, Norway. After we drove for several hours from Sodankylä to Tromsø, we finally arrived to the EISCAT site. It was ecstatic to see the control room and the receiver when the radar equipments were introduced to us. I’m enjoying my stay on the site, seeing the magical white mountains and the sparkle of the northern lights, and gaining experience of the space physics research in practise."

Winter's day

Today's photograph shows the best light levels that you can expect at this time of year.

The KAIRA site. (Photo: D. McKay-Bukowski)

Signs of winter

Just a nice photograph to finish the week. This one is of the sign as you head past the custom station. In the distance is Saana Mountain.

The sign to Kilpisjärvi. (Photo: D. McKay-Bukowski)

Have a nice weekend!

Snow trench

Another photograph of the snow conditions on the site. This one is the path we manually dug through the snow to get to the RF-container and Barracks. At the time this photograph was taken (a couple of weeks ago now), the trench was about 70cm deep. No doubt this will fill up again very quickly.

Snow trench at KAIRA (Photo: D. McKay-Bukowski)

Kaira Local Pipeline

Today we decided to release the code for our local processing pipeline that we have been working on. We didn't have time to invent a fancy name for it, so just decided to call it the KAIRA Local Pipeline (KLP). You can download it from here: http://www.sgo.fi/~j/klp-1.0.tar.gz. The 1.0 release contains three simple processors: file recorder (to store beamlet data on disk), average power recorder (for e.g., interplanetary scintillation measurements), and a null processor that does nothing (for performance testing the udp packet processing).

While there already exists at least one program (PELICAN) with similar capabilities, we wanted a program that is very simple and allows users get going without learning how to use a larger framework. If you need a sophisticated highly configurable object oriented framework for processing LOFAR data, you should probably be considering PELICAN. If you want something simple and ANSI C based, with minimal supporting utilities and configuration files, you might want to check out KLP.

The hardware needed to run KLP is the similar to what one would have for running ARTERMIS (the pulsar processing pipeline developed at Oxford) or any other local processing pipeline on a LOFAR station. At KAIRA we currently only have one Linux PC with a quad gigabit ethernet interface. This quad gigabit ethernet is connected to the four data lanes coming out of the four RSPs that output the beamformed beamlets. For our current purposes, one machine is enough, but in the future, it would also be possible to install KLP on a Linux cluster and use, e.g., MPI for interprocess communication.

Two possible hardware configurations to run the LOFAR local processing. 

As already said, the software architecture is very simple. There is one process for each lane and there are two threads that work in parallel on the incoming data. The first thread reads the udp packets coming in from the LOFAR RSP, parses them and puts them into a double buffer. Another thread waits for the double buffer to flip and once this happens, it then calls the klp_proc() function that processes the contents of the buffer. All of the underlying threading and synchronization is hidden away from the user, who only has to implement klp_proc().

The software architecture detailing all of the inner workings of KLP. The way to implement your own processing is to define klp_proc() and klp_init() and link it with klp_core.c.  

Mounting snow

Snow levels at KAIRA continue to deepen. Additionally, there is significant drifting in places, which results in raised mounds of it. So far, the arrays are holding up well. There is uniform distribution on the LBA ground planes and snow on tope of HBA tiles is barely exceeding 5 cm due to natural clearing by the wind sheer.

Snow build-up between the LBA mausoleum and the HBA array. (Photo: D. McKay-Bukowski)

The road goes ever on and on...

Just a nice photograph to finish the week. As I was recently driving along the stretch of road towards Karesuvanto, the sun peeked through the clouds for just long enough to stop and take this photograph. But there is not much sun left up here these days...

The midday sun in late Autumn. (Photo: D. McKay-Bukowski)

Have a nice weekend!

Cable joins

Inside the mausoleum, we found that there had been considerable snow build-up. This may be a contributing factor to the failed join (and that was precisely what it turned out to be). Here are some photographs of the situation as we found it and the problem cable.

Snow of the cables in the mausoleum. (Photo: D. McKay-Bukowski)

The culprit. A loose ground connection, possibly caused by a misseated o-ring. (Photo: D. McKay-Bukowski)

The path to the mausoleum

Despite the service to the aerial, we were still having problems with RCU #84 (Aerial #42, X-polarisation). The next most likely source of the problem would be the cable join. This means opening up tyhe LBA mausoleum (where the excess lengths are located and the joins are placed).

The LBA mausoleum. (Photo: D. McKay-Bukowski)

Getting to the mausoleum is easy. However, opening it up was quite a challenge in the cold conditions.

KAIRA VHF-altitude angles

One of the primary experiments for KAIRA is to observe incoherent scatter from the EISCAT VHF transmitter near Tromsø, Norway. In order to do this, the digital beam of KAIRA needs to be correctly pointed to intersect the correct volume of the ionosphere. To assist experimenters in planning this, the following graph can be used to estimate the centre elevation for a given altitude. Click on the graph to see the enlargement.

KAIRA pointing elevation angles to intersect at specific altitudes
above the VHF transmitter near Tromsø. (Graph: J. Vierinen)

Please note that depending on the observing frequency, the beamsize can actually be quite large, spanning many degrees.

Ode to the coffee machine

Our trusty double nozzled source of energy.



ODE TO THE COFFEE MACHINE


First there was a big bang
Then galaxies formed and
upon one planet
around a small sun...


There was a land, where
the sacred beans did grow
Ethiopia, (or Kenya or Peru)
We don't care!


Oh wondrous artefact
thou takest our beans,
gently roasted,
meticulously ground.


With the pure spring water
Clear and copper free
highest pressure
near to boiling


And thou blasts the water
and the sacred beans
together as would a
particle accelerator


Elemental magic
Air, earth, fire and coffee
The drink of power
Sleeps bane


The rites performed
in the graveyard shift


And thus extracts
the nectar of the gods
the beverage of the scientists
the fuel of the equations


We pause, as we who sip thy acrid concoction
feeling the rush of the blood and
palpitations of the heart
encouraged and inspired


We are brave now
ready to face another day
another boring meeting
another line of code

Photo by J. Vierinen, text by J. Vierinen and D. McKay

Digging down to the ground plane

One of the tasks for the recent site maintenance visit was to do some tests and replacement on LBA aerial #42. To gain access to this, we needed to dig out the snow, down to the ground plane.

LBA aerial L42 (Photo: D. McKay-Bukowski)

The fiery mountain

On the day of the E3D site visit to KAIRA, we were treated to a spectacular sight. Just as we'd finished lunch, we came out to see the last blink of the setting sun catch the snow-covered Saana Mountain in its entirety. All other parts of the landscape were in shadow and gloom and only the mountain was illuminated by the amber rays of the setting sun. Sadly, the tiny little camera in the mobile telephone will not do this justice, but hopefully you get just a small idea of the beauty of the fiery mountain.

Saana, near Kilpisjärvi, Finland. (Photo: D. McKay-Bukowski)

Have a nice weekend!

LBA aerials in the snow

Today's photograph shows part of the Low-Band Antenna (LBA) array . As you can see, we have a good covering of snow over the entire field. Fortunately, there is no ice build-up on either the posts or the wires.

The LBA field at KAIRA. Click on the image to see an enlargement. (Photo: Esa Turunen)

E3D visit to the KAIRA site

Last week we hosted a small visit to the KAIRA site by some of the EISCAT_3D project team. The main objective was to show the site the new EISCAT director and explain the significance of our project and demonstrate its capabilities.

Staff and visitors at the KAIRA site. (Photo: Esa Turunen)

We didn't move, but the photographer certainly did! (Photo: Esa Turunen)

Aurora over the E3D meeting

During the EISCAT_3D "all-hands" meeting, we were treated to some mostly-clear skies and a bit of auroral activity too.

Some of the delegates at the E3D "all-hands" meeting. Photo: Esa Turunen

EISCAT 3D meeting in Kiruna

KAIRA is linked to the EISCAT_3D project. As a result, we are participating in this week's "All-Hands" meeting, which is being held at the Swedish Institute for Space Physics. This is where the EISCAT headquarters is also located. It is a great opportunity to get the team together to talk about the upcoming work in the project and to review the current situation.

The photograph shows Craig Heinselman talking about recent developments on another phased array radar system.

Craig Heinselman at the EISCAT_3D meeting. Photograph by Esa Turunen.

Craig will be taking over as Director of EISCAT in 2013. We all look forward to working with him.

RFI on the horizon

We are now taking routine all-sky images with KAIRA, 24 hours a day. These are great as not only are we building up a fantastic data archive, but we are starting to get a good feel for some of the features.

In this image, there is a strong source on the south-eastern horizon. It is so bright that it saturates out all the other sources in the sky.

No doubt this is some RFI (Radio-Frequency Interference). It is possible to recover the data, but these require a reasonable amount of work. In the case of fast-burst RFI, sometimes it is easiest just to flag it (i.e. note it, but otherwise ignore it) and move on.

Snow laden branches

Just another wintry photograph to end the week. 

Have a nice weekend. (And stay warm!)

LBAs in the snow

At the moment, we have a few engineers on site to carry out maintenance work and continue with some of the general site work that needs to be carried out. They also took a few photographs and one of them is featured on today's web log post.

Looking south-southeast across the KAIRA LBA array. (Photo: M Postila)

An unexpected party

We don't normally get reindeer in around the institute. A few reindeer fences should put stop to them wandering through. However, our experiences at KAIRA indicate that one should not rely 100% on a reindeer fence and that there will always be occasions when these lovely creatures turn up for a party.

So, sure enough, the other day we did have a small herd wander in... I've no idea how they managed it! The first I heard of it was the doleful clanging of the bells that a few of them are wearing. They then spent a couple of hours digging through the snow trying to get at the left over grass from the past summer.

Reindeer at the EISCAT 32m dish at Sodankylä. (Photo: D. McKay-Bukowski)

The source of the clanging noise. (Photo: D. McKay-Bukowski)

Snow posts

The Sunday before last, a great lorry rumbled through Tähtelä and put sticks into the ground along the side of the road. Yes, sticks. These turned out to be just eco-friendly snow-posts, to mark where the roads are before the snows set in (which they did soon after!).

The thin stick in the foreground is the snow post. I guess you just need to know what to look for.

Freezing fog

The other day we had a freezing fog come through. These are wonderful, as they leave the trees — especially the deciduous ones — covered in a thin "fur" of ice crystals. A few more of these, and even the conifers will be ghosts in twilight shadows.

Ice on the trees in Tähtelä. (Photo: D. McKay-Bukowski)

The Finnish State Flag

Today's photograph features the Finnish State Flag flying beside the EISCAT 32m dish at Sodankylä. Finland has quite a few "flag days", when it is customary to fly the national flag. This particular photograph was taken on 24th October 2012, and the flag had been hoisted for United Nations day.

The EISCAT 32m dish and the Finnish State Flag, 24-Oct-2012. (Photo: D. McKay-Bukowski)

Link

• Flag days in Finland

Test LBA system at Pittiövaara

The original plan was to build 96 LBA aerials at KAIRA. That plan was altered because of ground stability considerations, limited signal processing and some other interesting ideas. So, although we've installed 48 aerials at KAIRA, the remainder will be used for other tests and experiments.

At the moment, we've installed four of these aerials at Pittiövaara, a small field station not far from the main institute at Sodankylä. These are being used to test a new digital signal processing concept being developed by SGO.

One of the test aerials at the Pittiövaara site. (Photo: D. McKay-Bukowski)

Of course, at KAIRA, being much further into the Arctic you would never get trees like this!

LOFAR observations of Virgo A

Today, ASTRON announced some stunning new results of the radio galaxy Virgo A (also referred to as Vir A, M87, etc.) along with a great image taken by the International LOFAR Telescope:

This false colour image shows the galaxy M87. Optical light is shown in white/blue (Credits: SDSS), the radio emission in yellow/orange (LOFAR). At the centre, the radio emission has a very high surface brightness, showing where the jet powered by the supermassive black hole is located. Credits: Francesco de Gasperin, on behalf of the LOFAR collaboration.

From their press release...

Using a brand-new radio telescope, astronomers have produced one of the best images ever made at the lowest frequencies of giant bubbles produced by a super-massive black hole. The observations were performed at frequencies ranging from 20 to 160 MHz which are normally used for communications by {aeroplane} pilots. The picture shows what looks like a giant balloon filled with radio emitting plasma, which exceeds the size of an entire galaxy.

Refer to the full press-release in the links section below for details.

Links

• ASTRON press release
• Article on VirA (M87)

Winter welcome

Well, in the past few weeks Winter has been arriving. In fact, things are moving faster than we can keep up with this web log (... so much to do!). In any case, here are some of the first Winter scenes from Sodankylä Geophysical Observatory for the season.

View from the EISCAT building. (Photo: D. McKay-Bukowski)

A wintry scene along the road through Tähtelä. (Photo: D. McKay-Bukowski)

Observing tips #3 — Starting/stopping KBT experiments

KBT (KAIRA Background Task) as an observing system for scheduling and running pre-designed scripts. The following is the instruction set for getting KBT observations started.

Starting KBT observations

1.  Be organised and log in to KAIRA01 at least 30 mins in advance, thus checking that you have a password, etc.
2. When you have been allocated the telescope, you will receive an e-mail from someone (usually the previous observer). 
3. When you get the "it's all yours now" e-mail, log in to the LCU.
4. Double check the system is reset and ready to use. To do this, type:
   
   %  swlevel
   
   You should see "Currently set level is 0" and all processes are down. If not, get help.
5. Check the current experiment with kbt.
   
   %  kbt --status
   
   It should be STOPPED. If not, get help.
6. Change the experiment to yours.
   
   % kbt --list
   % kbt --experiment=rio3_v45z
   
7. Start the experiment
   
   % kbt --start
   
   Your experiment is now starting. Note that it takes 2 minutes to fully start. Eventually, you will get your prompt back.
8. Your experiment is now running. You should check that it is recording data files. First, use kbt to find where the data is going:
   
   % kbt --variables
   
   Look for "datapath".
9. Use "ls" to inspect the datapath and check that the data is being recorded.If all is going well, there is no need to give the system further attention until the observations are over.

Stopping KBT observations

1. Stop your observations with KBT.
   
   %  kbt --stop
   
   Note that this might take a little while.
2. Double check that the system is reset and ready to use for the next observer. To do this, type:
   
   %  swlevel
   
   You should see "Currently set level is 0" and all processes are down. If not, get help.
3. Then, and this is VERY IMPORTANT, send an e-mail to the next observer with a CC to lofar-obs to inform the observing team that you are finished.

That's it! You should now consider exporting your data.

Arctic skies

Just a nice image to finish the week. Enjoy...

The Arctic sky, looking southwest past the KAIRA HBA array. Photo: D. McKay-Bukowski.

Freezing over

We took these photographs are the Sodankylä Geophysical Observatory recently. With theonset of the Autumn, the temperatures are dropping rapidly and winter will soon be upon us. And, of course, the water in the area is starting to freeze over.

First crystals forming in the puddles. (Image: D. McKay-Bukowski)

The Kitinen River starting to freeze over. (Image: D. McKay-Bukowski)

VHF upgrade at SGO — Part 3

And finally, the new receiver is installed on the 32 m antenna.

The new prime-focus, VHF feed. (Photo: D. McKay-Bukowski)

VHF upgrade at SGO — Part 2

Today work started on replacing the sub-reflector with a VHF prime-focus feed.

The crane (right) prepares to suspend the old sub-reflector, while the mobile platform allows the workers to get in close. (Image: D. McKay-Bukowski)

VHF upgrade for the EISCAT antenna at SGO

Due to the encroachment of radio-frequency interference (RFI) it was decided to convert the two EISCAT remote stations to operate at VHF frequencies. This is great news for KAIRA as it gives us some long baselines at the common frequency. Of course we've mentioned Sodankylä before; this is where the host institute is located.

At SGO, there is a 32m antenna (which used to have a UHF receiver). This is now being converted to a VHF system. The new receiver and feed can be seen in the lower left of the photograph.

The final image shows a close-up shot of the new system. It will replace the sub-reflector addionally converting the dish to a primary feed. Here, it is still on the trailer as it was brought over from Kiruna, Sweden.

The conversion is due to take place on 23rd October 2012. (Images: D. McKay-Bukowski)