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Skywarden,
Ursa Astronomical Association
Kopernikuksentie 1
00130 Helsinki
taivaanvahti(at)ursa.fi

Ursa Astronomical Association

Aurora rays - 15.7.2000 at 23.50 - 16.7.2000 at 02.00 Porvoo, Sondby Observation number 116329

Visibility III / V

Jorma Koski, Ursa (Helsinki)

My observation site is 20 km south of Poroo, a really dark (in winter) place by the sea. I spend my holidays and weekends there wondering the wonders of heaven; especially deep sky targets with a reasonable scope and camera arsenal.

Three weeks after Midsummer, SpaceWeather started to warn of mass solar eruptions, of which on July 14, 2000 sunspot group 9077 caused an X5-level dash straight towards Earth.

Tähdet ja võis magazine had talked about night clouds illuminating digital camera pictures, so I had already spent several nights shooting them with the Olympus Camedia C-3030ZOOM. They were dim and barely stood out in the pictures.

I sat in my ragged observation chair, which had missed the Leonids many times, and watched the summer triangle play hide and seek with cloud rafts. The full moon laughed every now and then behind my back, polluting the rest of the light summer sky.

Around one o'clock a red color started to appear. From the eastern horizon I observed a very dim reddish area rising from the horizon to 30 degrees; at times it was very unbelievable and only with a distant eye did you get some kind of idea of it. But a familiar phenomenon caught me off guard and my head was spinning like crazy for the next half hour.

At 01:10, weak green rays began to appear around Vega, which was near the zenith, and after a while they reached the western horizon - the red flag in the east had already dimmed.

The fiddling with the digital camera started and after a couple of flashes of the flash, the adjustments started to be more on point. 01:16 I got the first of four pictures.

01:20 The corona had already formed and I snapped the rest of the pictures here and there, I got the SLR camera, the western sky was already a zebra. I got a whopping two slides exposed when the repos turned off and clouds started to appear.

I sat still staring until two o'clock. The sun's glare was already getting on my nerves. There was not a single strip of repos added. The night clouds were on their way. The wind started to pick up and the toes were freezing.

After a couple of hours, I downloaded the pictures to my laptop and they were - considering the circumstances - unavoidable. I sent one to SpaceWeather's Tony Phillips, who put it on their homepage. The storm was a G5 level - wish it had been dark...

See also Tähdet ja Avaruus magazine 2000/5 page 55.


Additional information
  • Aurora brightness
    • Bright auroras
  • Observed aurora forms
    • Corona info

      CoronaA corona is a hand fan shaped structure, it usually forms south of the observer's zenith, most commonly consisting of rays or bands. The corona is usually the most beautiful part of the aurora show. It is bright and active, but on the other hand also short-lived.

      Aurora corona. Photo by Anna-Liisa Sarajärvi.

      Aurora corona. Photo by Merja Ruotsalainen.

      Corona formed from bands. Photo by Markku Ruonala.

      Aurora corona. Photo by Tapio Koski.

    • Rays info

      The raysare parallel to the lines of force of the magnetic field, i.e. quite vertical, usually less than one degree thick light streaks. The rays can occur alone or in connection with other shapes, mainly with arcs and bands. Short rays are usually brightest at the bottom but dim quickly. The longest rays, even extending almost from the horizon to the zenith, are usually uniformly bright and quite calm, and unlike the shorter rays, most often occur in groups of a few rays or alone. Rays, like bands, are a very typical form of aurora.

      Artificial light pillars, which are a halo phenomenon visible in ice mist, can sometimes be very similar to the rays of aurora. Confusion is possible especially when the lamps that cause the artificial light pillars are far away and not visible behind buildings or the forest. The nature of the phenomenon is clear at least from the photographs.

      Rays. Picture of Tom Eklund.

      Rays. Photo by Mika Puurula.

      Two beams rise from the aurora veil. Photo by Anssi Mäntylä.

      Two radial bands. Show Jani Lauanne.

      Radial band and veil. Photo by Jussi Alanenpää.

      Two rays. Photo by Aki Taavitsainen.

      It may be possible to confuse such rays with artificial light columns. Compare the image below. Picture of Tom Eklund.

      There is no aurora in this image, but all the light poles - including the wide and diffuse bar seen at the top left - are artificial light pillars born of ice mist. Photo by Sami Jumppanen.

      Aurora and artificial light pillars. All the radial shapes in the picture above are probably artificial light pillars that coincide appropriately with the aurora band. In the image below, the aurora band has shifted and does not overlap with the pillars produced by the orange bulbs. There is no orange in auroras. Photo by Katariina Roiha

  • Colors with unaided eye and other features
    • Green auroras info

      Green, seen with the naked eye, is one the most common colors of the aurora. The green color is derived from atomic oxygen.

      Green auroras. Lea Rahtu-Korpela.

      Green auroras. Photo by Juha Ojanperä.

    • Fully red auroras info

      Completely dark red aurora is a very rare and strikingly handsome revelation. This phenomenon is also due to the discharge of an excitation state of an atomic oxygen.

      Throughout red aurora. Photo by Tobias Billings.

Technical information

Four images: Olympus Camedia C-3030ZOOM settings were 400 ASA, HQ JPEG, zoom 32mm, exposure time one second, F/2

Two images: Canon EOS-1V and 20mm F/2.8 lens
Film: ISO400ASA Fujichrome Sensia II slide
Exposures: one second with aperture 2.8
Resolution: in these images it is about 20% of the Olympus ES-10 scanner's maximum, which is 1770dpi.

Sunspot image Meade LX-200 10" F/6.3 + 2Xbarlow + 26mm Plößl + Baader Astro-Solar filter and the same camera.

Comments: 3 pcs
Matti Helin - 26.5.2023 at 08.04 Report this

Hieno havainto. Yhtä lailla hienoa on lukea, millaista digikameralla kuvaaminen oli kyseisen tekniikan alkuaskeleiden aikaan. On kehitystä tapahtunut. Nykyään homma on melkein liiankin helppoa :D

Pirjo Koski - 26.5.2023 at 09.13 Report this

Komea havis ja kuvat! 

Tapio Lahtinen - 26.5.2023 at 17.50 Report this

Komeasti ollut pilkuja silloinkin.

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