Alert Notice 742: V1405 Cas = N Cas 2021 brightening

Note: This nova continues to behave very unusually. Please continue to observe!  -  Elizabeth O. Waagen, July 6, 2021

V1405 Cas faded from its brightening and is now plateauing again around 7.8V. Please continue to observe this interesting nova!  -  Elizabeth O. Waagen, May 28, 2021

May 10, 2021

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Further to AAVSO Alert Notice 735, V1405 Cas (Nova Cas 2021), discovered on March 18 UT at unfiltered CCD magnitude 9.6, is undergoing a sudden increase in brightness. Observations submitted to the AAVSO International Database (approximately 6,000 to date) show it had brightened in 24 hours after discovery to ~7.8 V, declined slightly, and then slowly brightened to ~7.1 V by May 5. It then began brightening more rapidly, and as of May 10.194 UT it was 5.45 V +/-0.023 (P. Lindner, Hoyerswerda, Germany).

An AAVSO light curve of the slow nova V1405 Cas, including the table of contributing observers, may be created via the AAVSO Light Curve Generator.

Spectroscopic observations of V1405 Cas submitted to the AAVSO may be downloaded from the AAVSO Spectroscopy Database.

Please observe V1405 Cas as it continues to evolve, with observations of all types (visual, CCD, DSLR, PEP, spectroscopy) and multiple bands as instrumentation permits. Frequency of observation depends on the rate of change, but should be at least one observation per night per band. For spectroscopy, Dr. Fred Walter (Stony Brook University) recommends spectra in blue to observe He II 4686, H-beta, and the Bowen blend (4640A), in addition to H-alpha. Cadence for spectra depends on how fast the nova evolves.

Coordinates (2000.0): R.A. 23 24 47.73  Decl. +61 11 14.8  (from VSX page for V1405 Cas)

Charts: Charts with comparison stars for V1405 Cas may be created using the AAVSO Variable Star Plotter (VSP).

Submit observations: Please submit observations using the name V1405 CAS.
 - Submit optical observations to the AAVSO International Database using WebObs (see below).
 - Submit spectra to the AAVSO Spectroscopy Database (AVSpec).

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.


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