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

Ursa Astronomical Association

Quiet aurora arc - 18.9.2021 at 00.13 - 18.9.2021 at 00.22 Elva, Viro Observation number 101324

Visibility II / V


For a long time, a decent northern lights were visible in southern Estonia. The fires began to appear shortly before midnight as the clouds gradually began to dissipate. The arc gradually brightened, and was at its brightest about 15 min after midnight. The fires reached above Otava at best. Fairly bright rays were visible for less than ten minutes. For a long time, a few green spots clearly above the arc of northern lights were visible.

In the west, there was a possible SAR arc. It was not visible to the naked eye, but the images show a faint reddish arch to the west.

Pictures taken with the phone.

#sarg



More similar observations
Additional information
  • Observed aurora forms
    • Stable Auroral Red (SAR) arc info

      The Stable Auroral Red arcs (SAR arcs)  are usually clearly distanced to the south from the aurora oval and is a very opaque and normally red ribbon. In most cases SAR arcs are only visible in the photo or on the liveview screen of the SLR camera. Using a camera with very high sensitivity is the best method for capturing these faint arcs. The arch usually settles between east and west.

      A stable red arc of aurora is a rare phenomenon. In some rare occasions, several SAR arcs may be simultaneously visible.

      The first SAR arcs of the Skywarden were observed on nights between November 3-4. and 4-5. days in 2015 in the latitudes of central Finland.   

      SAR
      SAR arc photographed by Lasse Nurminen 2018. Observation of the Skywarden 79113.

    • 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

    • Band info

      Bands are usually narrower, more twisty at the bottom, brighter, and more active than arches. Bands usually develop from arches.

      Bands can form J and U shapes, sometimes even full spirals. The corona can also arise from bands. Bands are a fairly common form of aurora.

      Aurora band. Photo by Merja Ruotsalainen.

      Aurora band. Photo by Matias Takala.

      Aurora band. Photo by Lea Rahtu-Korpela.

      Aurora bands. Photo by Lauri Koivuluoma.

      Aurora band. Photo by Matias Takala.

  • Aurora brightness
    • Dim auroras
  • 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.

Comments: 1 pcs
Emma Bruus - 19.9.2021 at 12.28 Report this

Kiitos tästä havainnosta! Kyllähän se SAR-kaarelle vahvasti vaikuttaa. Hieman samankaltainen näkymä on toisessa havainnossa Porista. Karhunvartijoiden kamerakaan ei valota ihan riittävän pitkään tuodakseen SAR:ia esiin kunnolla, mutta kyllä sen taustalta erottaa.

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