Alpy spectrum of Nova Cas 2021 near maximum

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Hugh Allen

Amazingly there was a hole in the weather here in Somerset last night. The nova was incredibly bright! I had to drop the camera exposure from 300 to 90sec to avoid over exposing the H alpha emission. It is now putting on a complex display of emission lines with beautiful P Cygni profiles. The H Balmer series is still prominent whilst helium emission lines have now disappeared to be replaced by a forest of singly ionised iron emission lines some of which I’ve marked. Also very striking is the pair of singly ionised calcium emission lines down in the violet, their associated blue-shifted absorption reminiscent of the solar spectrum. A wonderful spectrum!