Auroras of 28 Feb 2019 from Sodankylä iCCD

Last night we had one of the best aurora events of the season 2018-2019. Here is the movie from SGO iCCD camera with 1 minute resolution. Each minute image is composition of the three adjacent images with different filters for green (557.7nm), blue (428.8nm) and red (630.0nm) emissions.

1min resolution movie of 28Feb-1Mar 2019 from SOD iCCD camera.

Sodankylä magnetogram 26.2.-4.3.2019. The enhanced geomagnetic activity caused by high speed stream from coronal hole continued until 2 Mar.

Start of the Northern Lights Season

Click on map for better resolution.

Almost three weeks after the summer solstice, we start to get questions regarding when the Northern Lights can be seen again after the Polar Day. The answer depends on where you are: the further south you are, the earlier it will get dark enough.

How dark does it need to be? Our scientific cameras operate when the Sun is at least 10° below the horizon. However, if there are particularly bright Northern Lights, you might be able to see them already earlier.

The map above shows the days on which the Sun will be at least 10° below the horizon in Finland. Be aware, however, that due to summer time (daylight saving time), the darkest time of the night is around 01:00h in Finland.

Note further, that our scientific cameras will not necessarily be back on location on the first day that it is dark enough. Their annual maintenance might well delay the schedule.

Map and text: Thomas Ulich, SGO.

Northern Lights 31st January / 1st February 2017

[Helsingin Sanomissa 7.2.2017: "Revontulet sykkivät mystisesti" -artikkeli SGO:n ja Japanilaistutkijoiden välisestä tutkimusyhteistyöstä.]

Last week beautiful northern lights were seen across large parts of Northern Finland and Scandinavia. Already early in the evening after 19:00 EET (17:00 UTC), the lights appeared and by 21:00 EET the sky was filled with what we call "pulsating aurora". This form of aurora displays large patches of diffuse green light, which are flickering at various speeds, some flicker very fast. Pulsating aurora is very much a topic of active research, and our Japanese colleagues just launched the ARASE (ERG) satellite to study these specific lights from space. These efforts are combined with optical studies on the ground, and just in time for last week's northern lights, a special high-speed camera was installed at SGO, which can take up to 100 photos of the aurora per second!

From Sodankylä, four films of the aurora during the night of 31st January / 1st February have recently been published, two of which are from SGO:

The video above was made by taking all of the images of the regular all-sky camera of SGO, which are black-and-white images taken through filters for the auroral green, red, and blue lines, and combine these to create RGB (false) colour images. Images are taken every 20 seconds, and thus the video linked above is a time-lapse of the whole night, which is just 1min 30 sec long. (©2017 by SGO)

The video linked here is a result of a collaboration between SGO and Site-Eye Ltd., UK. Site-Eye have installed two long-term time-lapse cameras at SGO, one looking at the sky at a northerly direction, the other looking west across the river Kitinen. This video combines images from both cameras. (©2017 by SGO and Site-Eye Ltd)

The video above was taken by SGO's Thomas Ulich, who placed a camera looking almost straight up, with a slight tilt towards the south. This is the best direction to see what is called the auroral corona, a display, where the auroral rays all seem to originate from the same point in space. This is, however, just a result of perspective: the rays are in fact parallel. Images taken over 9 hours at a rate of four photos per minute were combined into a time-lapse film of about one minute duration. (©2017 by Thomas Ulich, see his blog post)

In the final video of this series, which was taken by SGO's Esa Turunen using a fish-eye lens to cover as much sky as possible, you can see the shapes of pulsating aurora especially well. They are patches drifting across the sky and flickering at the same time. The images were taken at a rate of approximately one per second. (©2017 by Esa Turunen)

Please note that in all videos linked here, the flickering of the aurora is aliased by the number of time per minute the images were taken as well as by the frames-per-second rate of the final time-lapse films.

Northern Lights Season has started!

The photo above was captured last night (24th August 2016, at 21:00 UTC (00:00 EEST) by one of the time-lapse cameras we operate jointly with Site-Eye Ltd, UK. The night sky is still too bright at the latitude of Sodankylä to get good contrast, but the season has definitely started. The scientific auroral all-sky camera will return in the near future for real-time monitoring. In the meantime, the time-lapse camera can be used for a look to the north from Sodankylä.

Photo: Site-Eye/SGO, text: Thomas Ulich.

April Aurorae

   

Recently, we reported about a new long-term time-lapse project at SGO. Today, we have received the summary video of the Northern Lights in April. The video above works best in full screen and high definition.

Also, we now have live feeds from the time-lapse cameras to SGO's web pages, which allow you to check the current weather conditions in real time. The images are updated once per minute.

As an example, here's what our river camera sees at the moment. You see both images on on their dedicated live-feed page. Enjoy!

Text: Thomas Ulich; image and film: Site-Eye Ltd.

Northern Lights

It's been very cloudy this past month, with few clear nights. Often we saw in our instruments that there must have been brilliant lights on the other side of the clouds, but on the ground there was no chance to see anything. Then, on Wednesday evening (2nd December), there were gaps in the clouds and for a brief moment the lights appeared...

With this photo we wish all of you a very good weekend, and those of you in Finland a very good Independence Day on 6th December, when Finland will turn 98. Hyvää Itsenäisyyspäivää!

Photo: Thomas Ulich.

Aurora pictures 09.09.15

A couple of nights ago, a geomagnetic storm sparked very bright and dynamic aurora over Sodankylä, which lasted for most of the night. Here are a couple of pictures taken from behind the local airport.

At first, it was a bit cloudy, but soon enough the sky became perfectly clear and it was possible to fully enjoy the live show. It went really crazy around 01:00 LT, with very bright pinkish displays below the green arcs, pulsating aurora and dancing structures.

Photos: M. Grandin.

All-sky operations started with night time thunder storm

Last night was first observation night with the camera capable to observe the Northern Lights at SGO site station. The observation time is about 4 hours. Instead of the Northern Lights we captured lightning strokes, which is really rare in Sodankylä this time of year when the nights are dark. Past couple weeks has been warmest weeks of the past summer. This ended with cold front travelling over Sodankylä forming heavy thunder shower. The long exposure allowed multiple lightnings in the same frame. The present solar wind conditions provides good change to capture the Northern Lights in the coming night! Other SGO imagers are now in calibration and will be in operation after calibration.

Lightning strikes in UCL Colour image at SGO.

Northern Lights Season has started

The first northern lights of the season have been spotted as far north as Sodankylä last night. This has raised the question on when it is dark enough to see them. The northern lights are comparable in brightness to the stars: if you can see the stars, you would see also northern lights, even if the contrast against the bright sky is still very low.

In more definite terms, for the night to be dark enough, the Sun should be some 8°–9° below the horizon. For our scientific all-sky cameras, the limit is -10° solar elevation for at least a couple of hours. This means that it is turned off in mid-April, and could be deployed in autumn as early as late August, but in practice this depends on operational matters, since all cameras are recalibrated and serviced every autumn, which is a collaborative effort with colleagues from other institutes.

In order to give you an idea when the aurora season starts at various latitudes in Finland, we have computed the time of sunrise and sunset as well as the start and end of civil, nautical and astronomical twilight. These are plotted below in "length-of-day/night" diagrams (click to enlarge) for the locations of Utsjoki, Sodankylä, Oulu, Jyväskylä, and Helsinki. The green line in those plots refers to the -10° elevation limit of the auroral camera. These diagrams are explained in somewhat more detail in our article about the Polar Day.

Twilight refers to the time when the Sun is below the horizon, but it is not completely dark. Civil twilight refers to the Sun being between the horizon and -6° elevation. During civil twilight, observations of stars and aurora are possible only using special equipment. When the Sun is between 6° and 12° below the horizon, we speak of nautical twilight, and when the Sun is between 12° and 18° below the horizon we call it astronomical twilight. Once the Sun reaches -18° elevation (18° below horizon) we have complete darkness. Note that this does not happen in Utsjoki before mid-September. But even in Utsjoki, the northern lights season will start in about a week.

Happy aurora hunting!

Length of Day/Night at Utsjoki (click for larger image)

Length of Day/Night at Sodankylä (click for larger image)

Length of Day/Night at Oulu (click for larger image)

Length of Day/Night at Jyväskylä (click for larger image)

Length of Day/Night at Helsinki (click for larger image)

See also: Polar Day.

Polar Day Ahead!

The nights are getting brighter, and we are rapidly approaching the Polar Day, when the Sun does not set anymore for many weeks. The All-Sky Camera of SGO requires that the Sun has set at least 10° below the horizon before it will start up to take images of the night sky and the aurora if there's any. On Friday, 24th April, the Sun will not set below –10° elevation, and thus the camera operations have now been stopped for the summer. The next time the Sun goes low enough in the night is on 19th August. Thus from our auroral camera's point of view, the Polar Day is about to start, and it will last for 117 days!

Please note that for operational reasons, SGO's All-Sky Camera will not be immediately available from 19th August onwards, but of course we try to make the real-time images available as soon as feasible.

The image above (click to get a larger version), shows the light conditions in 2015 for the location of our All-Sky Camera. On the horizontal axis there are key dates for this year. On the vertical axis are the number of hours of darkness. Yellow refers to daytime, i.e. the Sun is above the horizon, and in the middle of the year, there are some 44 days when the Sun does not set at all here. The darkest blue refers to the time when the Sun is 18° or more below the horizon. This is considered total darkness.

The remaining shades of blue refer to the twilight: the lightest blue represents civil twilight, when the Sun is between 0° and 6° below the horizon, i.e. the time just before sunrise or after sunset. The next darker blue with the green line refers to nautical twilight when the Sun is between 6° and 12° below the horizon. The green line shows the limit for the All-Sky Camera, when the Sun is 10° below the horizon. The remaining shade of blue refers to astronomical twilight when the Sun is between 12° and 18° below the horizon.

The green line goes to zero (no darkness anymore) on 24th April and rises again on 19th August. In the middle of winter, the Sun remains for more than 16 hours low enough for our camera to operate.

Furthermore, we can see that just around winter solstice, the Sun does not rise at all during four days. However, it is not totally dark thanks to the prolonged civil twilight time and usually bright, snow-covered land.

Graphic and solar data: Thomas Ulich.

Northern Lights on 25th March 2015

On the evening of 25th March, 2015, we once again saw nice Northern Lights above Sodankylä. First it looked like it might end soon, then some clouds came in, it was a situation when it is not quite clear whether or not it's worth to stay outside and take photos. The solution: take a camera timer, set it to one frame per 15 seconds, keep the camera running pointing in some reasonable direction, and keep finger crossed. Then warm up inside and be ready to rush out if there's something happening.

After some 90 min and 360 photos, there was enough material for a time lapse film. Click the photo to watch it.

Photos and film: Thomas Ulich.

Last night...

Last night the Northern Lights were active again, but this time, unlike the previous night, the sky was clear. Here's a photo from early on, at 22:23 h (local time), i.e. 19:23 UTC.

The activity continued through most of the night, even increasing to a total of 600 nT (fullscale) storm, which must have been visible over most of Finland and Scandinavia.

When you look at our real-time magnetogram, like the one above, always look for sharp drops in the X component (red). Large changes in short time mean that the Northern Lights are most active and beautiful, and you shouldn't be looking at the computer, but at the sky. The trick is to anticipate the moment and be ready to run out right away... Good luck hunting for the Northern Lights!

Photo: Thomas Ulich (8s, 400ISO, f/1.4)

Aurora pictures 22.09.14

Last night was pretty active around Sodankylä, geomagnetically speaking. The northern light appeared around 22:00 local time and lasted for several hours. It was mostly of the pulsating kind, which is very fascinating yet not particularly impressive on pictures. Still, here are a few ones.

Revontulia nähty ja lisää varmaan tulossa

Perjantaiset revontulet (Kuva: Markku Inkilä www.facebook.com/airphotolapland)

Keskiviikkoinen auringon X1.6-tason röntgensädepurkaus, joka siis liittyi koronan massapurkaukseen, tömpsähti maahan perjantaina alkuillasta. Shokkiaallon saavuttua magnetosfääri puristui kasaan. Observatorion magnetogrammissa mittasimme noin 400 nanoteslan muutoksen parin tunnin aikana. Revontulet tulevat näkyviin kun ionosfääriin tulee ionisaation takia voimakkaampia virtoja. Tämä näkyy magnetogrammin X-komponentin muutoksesta. Lisäksi ns. Bz-komponentin pitää olla negatiivinen. Sopivaa yhdistelmää revontulia varten saatiin odottaa melkein puolille öin. Silloinhan ne rävähtivät taivaalle. Markku Inkilä saikin napattua oheisen kuvan Inarin kunnassa. Lisää Markun kuvia näet täältä!

Lauantai-illan tullen saatamme nähdä lisää revontulia! Sääennuste näyttää ihan kohtuulliselta, joskin Bz-komponentti on vääränmerkkinen. Toivotaan siis sen muuttuvan!

Aurora pictures 12.09.14

Although the beginning of the night was not very promising, the sky being almost overcast, I managed to take a few pictures of the northern light this night. 

The sky started to clear up around 23:45 and some activity could be guessed behind the clouds.

As the last clouds were drifting from the western horizon towards Sodankylä, a diffuse aurora appeared in the south.

Around 1:15, a proper arc finally showed up, offering gorgeous displays of green and purple.

A few minutes later, a quite active arc appeared in the north. Unfortunately, it lasted only for a couple of minutes.

Slightly tired and feeling cold, I decided to stop hunting a bit after 2:00. Finally, this night's displays were not as impressive as I had hoped, but they were still worth staying up to enjoy them.

Revontulia luvassa!

Lähde: http://sdo.gsfc.nasa.gov/

Auringosta välähti äsken voimakas X1.6-tason röntgensädepurkaus, joka luultavasti liittyy ns. "koronan massapurkaukseen". Suomeksi sanottuna tämä tarkoittaa komeita revontulia 2-3 päivän kuluttua, kun auringosta sinkoutuneet hiukkaset saavuttavat maan.

Tässä on kuitenkin pari muuttujaa. Hiukkastuulen mukanaan kuljettama magneettikenttä saisi mielellään olla maan magneettikentälle vastakkaissuuntainen. Reaaliajassa tätä pääsee pääsee jännäämään suoraan satelliitista: punaisella piirretyn Bz-käyrän soisi siis olevan negatiivinen, jotta auringosta tulevat varatut hiukkaset pääsisivät tunkeutumaan maan magnetosfääriin aiheuttamaan revontulia.

Toinen mutta matkassa on tietysti mahdollinen pilvisyys, mutta juuri nyt ennuste ei näytä ihan toivottomalta sekään.

Eli peukut pystyyn ja seurataan tilannetta!

Revontulikausi alkanut

Kaikki SGO:n revontulikamerat mukaanlukien Abiskossa oleva EMCCD-kamera, on nyt toiminnassa ja kuvaavat taivasta auringon laskusta nousuun. Ensimmäisen havaintoviikon aikana revontulet oli tunnistettavissa Sodankylän kameran kuvista yhtä yötä lukuunottamatta, tosin parina yönä reposet oli pilviverhon takana. Kamera kuvaa taivasta kolmella eri suotimella sekä ilman suodinta. Näyttävin show oli sunnuntain ja maanantain välisenä aamuyönä, jonka kuvista koostettu elokuva on alla.

Tällä hetkellä Sodankylässä kamerat aloittaa kuvaamisen puoli yhdentoista jälkeen illalla, jolloin kuvat alkavat myös päivittyä SGO:n www-sivuille ja mm. AurorasNow!-sivustolle. Kyseisillä sivuilla päivittyy revontulen vihreän valon aallonpituuden (557.7nm) suotimella otettu mustavalkoinen kuva. Loppuviikosta kuvassa alkaa näkymään myös kasvava kuu, joka vaikeuttaa heikkojen revontulien havainnointia paljaalla silmällä.

Briefly in English:

All SGO imagers are now in operation after EMCCD imager at Abisko station was started in the end of the last week. Auroras can be picked from six of the seven nights, when the iCCD camera has been in operation. Quite nice start for the aurora season! Couple of nights were cloudy, but still the green emission of the Northern Lights illuminated trough the clouds to the imager. So far the best show of the season was the night of Sunday-Monday. Check the video!

The Northern Lights season starts in Lapland

The approaching autumn means also start of the season of the Northern Lights in Lapland and Finland. Past week, during a moderate geomagnetic storm (Kp max ~ 5 ), first aurora observations were reported from Central and Southern Finland in the Taivaanvahti observation system of the URSA (the Astronomical Association of Finland).

The all-sky imagers at SGO were switched on earlier this week. The first observation night, 25 August 2014, was clear and some minor auroras were visible in the northern horizon of the sky. The dark time is still short, but every night is about nine minutes longer than previous one. The all-sky camera starts operation, when the Sun is six degrees below horizon and the latest image is updated once per minute, when camera is in operation.

The starting season is 15th winter with present imager. Of course, some parts of the camera has been replaced, like the intensifier and data storing computer. The iCCD imager has three filters for  auroral spectral lines: 428.8 nm (blue), 557.7nm (green) and 630.0nm (red). The video is composition of the image sequence every minute. Note, the time is running fast making auroras more active than they are in reality. More movies about active northern light display (ie. 25 March 2014) can be browsed from SGO data server.

Sodankylä Geophysical Observatory has long tradition of automatic aurora imaging. Digital era of all-sky cameras started in 2000, when all-sky camera with photo tube intensifier and iCCD unit was bought. Before that film camera with spherical mirror were used for all sky imaging. SGO camera is part of the MIRACLE network. More details about the imagers can be found from MIRACLE website.

SGO has also EMCCD spectral imager, which operates in Abisko, Sweden to get better overlapping with the similar imager of FMI in Kilpisjärvi.

SGO hosts also All Sky Colour Imager of  APL, University College of London, UK. The main purpose of the imager is support for the Fabry-Perot Interferometer, which has been in operation since 2002.

According to FMI forecast coming nights seems to be cloudy. Waiting for clear skies...