WAITING FOR THE SHADOW

     ASTROPHOTOGRAPHY by Joseph Cali

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Aurora (?) no airglow, on 30/31 October 2021
The Sun has been very active lately.  I've been keeping my eye on the two orbiting LASCO coronagraphs. Following the a large coronal mass ejection on 28 October, I sent out a heads up to the Yass Valley Astronomical Society members to be on the lookout for an Aurora Australis display on the night of Saturday 30 October around and after midnight. Based on the solar wind predictions, it was predicted to arrive at the Earth's atmosphere at 11pm last night at Kp=5 and strengthen to 6 during the night. the Kp scale is a scale used to describe the strength of geomagnetic storms.  At Kp=4,  and at my latitude 34 south, the aurora is detectable photographically in short exposures looking south. At Kp 5 it is easier and at Kp 6, it can cover the entire sky as occurred last night. I might have been looking for an aurora, what I got was a major airglow event and no aurora. Airglow is chemiluminescence. Cosmic rays and solar radiation break the molecular bonds of  oxygen, O2  and nitrogen, N2 into their consituent atoms.  The energy required to break these strong bonds is released when these atoms recombine into molecules again. This is seen as a glow that occurs at around 90km above the Earth's surface.




Storm growing in intensity at 13:05UT 12:05 am local time.
Pentax K1   ISO 12800   20s  Samyang 14mm f2.8
The little streak near the pointers might be some starlink satellites.
Several appeared one after the other on the same orbital track.






Above:  Pentax K1   ISO 12800  30s  Samyang 14mm f2.8  This photo was taken at 13:14 UT about
10 mins after the first photo I posted (top) and when the event had strengthened.  In this image
you can see Orion  on the far left, Sirius and Canis Major left of centre with Canopus and the Magell
anic Clouds on the right.  This photo spans the horizon north east through east to south.



  Above:  Pentax K1   ISO 12800  30s  Samyang 14mm f2.8  This photo was taken at 13:46 UT about
an hour after the first photo I posted (top) and when the event had strengthened.  In this image
you can see Orion and Taurus above the north and north east horizon.





A multipanel panorama showing about 1.3 of the sky.  13:40UT   Pentax K1   ISO 12800  30s  Samyang 14mm f2.8


Above: This photo was taken at 13:57 UT about an hour after the
  first photo I posted (top) and when the event had strengthened.
In this image, you can see the Magellanic Clouds (top) Pointers(lower left)
Jupiter (lower right) above the southern horizon.
Pentax K1   ISO  25600   30s  Samyang 14mm f2.8








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