(Well a couple of days late but I could not resist the alliteration).

I normally don’t bother going after faint supernovae during the summer but I had been following the unusual supernova SN 2024igg in NGC 5876 so I  decided to try for another spectrum with the ALPY 200 faint object spectrograph. With a full moon and the sun only 11 deg below the horizon the sky background was much brighter than the mag 16.4 supernova but after sky subtraction the spectrum was clear if rather noisy.

SN 2024igg is a somewhat unusual supernova. It was discovered on 2024-05-07 by ZTF and initially classified as a type II by a student team at Stockholm University based on an apparent H alpha absorption line. It was then reclassified by the OxQUB team as an overluminous type Ia, with the usual Si II 6355A line, characteristic of type Ia emerging and the original line being attributed to C II at 6580A from a dense carbon rich circumstellar envelope.  My series of spectra recorded 20240517, 20240530, 20240623 show the C II line fading, the Si II line strengthening and the spectrum then evolving towards the nebular phase with multiple forbidden Fe lines emerging. All spectra in the BAA spectroscopy database