[vsnet-alert 26174] 1RXS J041924.8+653006 outburst

[Denis Denisenko d.v.denisenko@gmail.com via vsnet-alert]

This unusual variable in Camelopardalis is in outburst according to ZTF
(Masci et al., 2019) and ATLAS (Tonry et al., 2018) data:

1RXS J041924.8+653006
  20210810.4502  19.75g  ZTF
  20210810.4716  18.70r  ZTF
  20210813.4467  16.61g  ZTF
  20210813.4758  16.01r  ZTF
  20210814.5668  15.37o  ATLAS
  20210814.5747  15.39o  ATLAS
  20210814.5811  15.37o  ATLAS
  20210814.5935  15.34o  ATLAS
  20210816.4513  15.17r  ZTF
  20210816.4508  15.22r  ZTF
  20210816.4766  15.78g  ZTF
  20210816.4831  15.73g  ZTF
  20210820.3922  14.78r  ZTF
  20210820.4094  14.85r  ZTF
  20210820.4632  15.44g  ZTF
  20210820.4813  15.38g ZTF

ZTF Lasair data and snapshots: https://lasair.roe.ac.uk/object/ZTF18aabfgws/
ATLAS light curve for the last 4 years:
http://scan.sai.msu.ru/~denis/J0419+6530-ATLAS-LC.gif

Position: 04 19 23.60 +65 30 04.2

Variability was found by me in December 2006. Spectrum taken with RTT150
was showing unusual shapes of H_beta and He II 4686 AA lines. See
[vsnet-alert 16729] posted in December 2013 when MASTER detected another
outburst. I have marked this variable as even more unusual two years ago
based on its ZTF light curve, because it reminds that of dwarf nova V392
Per before its classical Nova eruption in 2018. Same triangular saw-tooth
shape, long duration, nearly the same cycle and even the amplitude. Another
telltale feature in common to both stars is their nearly non-detection in
UV by GALEX.

Moreover, it is considered by S. Hoffmann and N. Vogt as a possible
counterpart (2nd of 5) of the Far Eastern Guest Star 369 CE! See
arXiv:2007.01013 and/or 2020MNRAS.497.1419H for details.

Orbital period near 0.522 days was determined by John Thorstensen (personal
message of 2018 Nov. 20). On the contrary, V392 Per has P=3.22 days.
Time-resolved spectroscopy is strongly encouraged while J0419+6530 is near
the peak brightness.

Denis Denisenko