This week we look back at another ‘old(ish) friend’ of this feature, and one of the HOYS auxiliary targets: The Gaia alert source Gaia19fct. Located quite far south (DEC=-10.5deg), it is tricky to observe for most of our observers. The object was flagged up as erupting by Gaia in 2019. A detailed look at it’s light curve shows it has had other eruptions of short duration before, which were not recognised. Based on these eruptions it can most likely be classified as an EX-Ori object.
We did observe the source as part of HOYS since it’s original alert and have followed the eruption in multiple filters until the source became too faint to observe last year. Recently, one of the teachers participating in our training program with the Las Cumbres Observatory (LCO), observed this target and we realised that it has become brighter again. The Gaia data shows that this latest eruption has started sometime between early June and early September this year. Indeed the brightness has risen almost four magnitudes from it’s faint state. This is still about 1.5 to 2.0mag shy of the peak in the previous eruption.
In our long term light curve, shown above, one can see that we have picked the source up again round about its current peak brightness. Indeed it has already started to fade again by about 10% in the last few days. We will continue to keep an eye on the object to see how it evolves. Follow-up spectra have already been taken by collaborators and we hope to start working on contributing to a publication about the object soon.
This is a good example to show that also our additional, auxiliary fields for the Gaia alert sources harbour interesting objects. Even if their main eruption of dipping event is over, we need to keep an eye on their long-term behaviour. Good other examples are Gaia17bpi and ASAS-SN13db. So please keep looking at those other fields as well. Thank you!