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Ursa Astronomical Association

Half-sky auroras - 7.8.2022 at 23.00 - 8.8.2022 at 01.30 Plumas, Kanada Observation number 108203

Visibility IV / V

Observation began at 11:00 p.m. Central Daylight Time, with low diffuse aurora arc.  Many clouds made it difficult to see.  Breakup started about 12:18 and it danced for about 15 minutes.  Shortly after that approximately 12:40, there appeared to be an invisible SAR at the equator side of the main aurora in recovery phase.  At 1:06 a STEVE appeared visible in the SAR.  There was a hazy green band below the STEVE and I couldn't identify any pickets.  Green pulses from the main aurora bumped up against the STEVE and interacted with the green band below it.  By 1:16 the STEVE was extremely faint, and barely visible.  By 1:23 the STEVE seemed to have become invisible to the naked eye, and appeared to have a SAR colour.

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Additional information
  • Aurora brightness
    • Bright auroras
  • Observed aurora forms
    • STEVE-arc info

      STEVE (Strong Thermal Emission Velocity Enhancement), Pink, radial aurora-like arc  . The STEVE arc is seen clearly separated from the main aurora arc of the northern sky. It forms a long and narrow west-east aligned, usually dim form. It does not belong to traditional auroras as a phenomenon, but may appear same time with them. Occasionally there may also be a green, "toothed" band called ”picket fence” at the bottom of Steve.  

      Riku Talvio, STEVE
      Photo by: Riku Talvio

Comments: 3 pcs
Emma Bruus - 9.8.2022 at 09.52 Report this

Congratulations Donna! The recent day's images from Canada are simply amazing. I think this night will be discussed in many forums.

There aren't many known cases of STEVE/SAR merging. 

I know of four nights: Ian Griffin NZ, Alan Dyer CA, Pirjo Koski/Atacan Ergin FI and one short event witnessed by scientific instruments.

And then there is one night 2000, when Pekka Parviainen photoraphed an arc with STEVE/SAR -features in Turku, Finland.

Pirjo Koski - 9.8.2022 at 14.02 Report this

Congratulations Donna! Magnificent pics! 

Donna Lach - 9.8.2022 at 18.38 Report this

Thanks!  Since I am not a scientist, I can only describe what I saw.  When it is invisible to the naked eye and red in colour, I assume it is a SAR arc.  When it is visible to the naked eye and pink/mauve in colour it is a STEVE.  In photo 4, you can see the pink starting to appear in the red arc.  I really hope to learn more about this!

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