Time Series for FQ Circinus

American Association of Variable Star Observers (AAVSO)
Fri, 08/05/2022 - 02:40

Hi All

I was fortunate to discover what appears to be a strange nova on June 25th which has been designated FQ Circinus.  The CVnet-outburst announcement and Atel #15743 provides some early details.  The suspect was also picked up by Gaia a few days after my discovery (AT 2022nyt).  The brighness peaked at just about 11th magnitude.  Rob McNaught captured the eruption in full on the night before (June 24th).  Incredibly his images showed the outburst occurred over only a 2 1/2 hour interval!  The Gaia team confirmed that the progenitor appears to be a mag 13.7 blue star which is very unusual for a nova to have only about a 3 magnitude outburst amplitude as well as being an odd progenitor for a nova.  The nova suspect faded rapidly as can be seen from the AAVSO light curve.

Dr Elias Aydi from Michigan State University has taken a number of spectra of FQ Cir.  As has Tom Love from New Zealand.  Tom notes that the event initially had the spectrum of a reddened classical nova and it faded rapidly and developed distinctive twin peaked Balmer lines.  Approximately two weeks after the eruption his spectrum was that of a hot blue star.  

Elias is still unsure as to what we have here.  From a photometry perspective, he recommended to obtain time series to potentially determine the orbital period of the system (if there is one).

Therefore if anyone is able to perform time series V photometry, I would encourage them to do so.  FQ Cir is still relatively well placed int he southern evening sky.