ACCESS: Above Top Secret
- Jan 21, 2015
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New nova in Cassiopeia brightens rapidly
There’s a ‘new star’ – a classical nova – on show among the stars of the far-northern constellation of Cassiopeia. Nova Cas 2021 was discovered on 18 March shining at around magnitude +9.6, but it appears to have brightened rapidly to around magnitude +7.5 on 19 March.
Nova Cas 2021 was discovered by Yuji Nakamura of Japan on 18 March at about 10h UT, when it shone at around magnitude +9.6. He shot four 15-second frames with a 135mm, f/4 lens coupled to a CCD camera (a set-up which provided a limiting magnitude of +12) and further reported that no object was seen at the transient object’s position on frames shot with the same equipment on 14 March.
Just hours later, professional astronomers from the National Astronomical Observatory of Japan swung into action, obtaining a spectrum of the object with the 3.8-m Seimei Telescope at Okayama Observatory and photometry through a 0.4-m telescope at Kyoto University. The spectrum revealed the tell tale features of a classical nova, with emission lines of the Balmer series, N-III 4640 and He-II 4686, and He-I emission lines with P-Cyg profiles. They further found and identified lines N-II 5679, C-III 5695 and Paschen emission lines. The position of Nova Cas 2021 precisely coincides with that of the W UMa-type eclipsing variable star CzeV3217, which lies at a distance of about 5,500 light years.