2101 transients classified by PESSTO so far
550 transients are being followed by PESSTO

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100 science papers from PESSTO and its successor surveys

PESSTO and its successor surveys have reached 100 published, refereed science papers. The latest 3 papers to bring us to 100 have just been published, on two long gamma ray burst and a plausible candidate for the first neutron star - white dwarf merger.

Owen McBrien, a PhD student at Queen’s University Belfast lead an ApJ Letter on the unusually fast declining transient SN2018kzr. It is the fastest declining transient that either PESSTO or ePESSTO has followed other than the kilonova AT2017gfo. It was also quite luminous, meaning a combination of low ejecta mass and a central powering source are required to explain the remarkably fast fade and its peak brightness. A plausible explanation is the formation of a magnetar during the merger of a white dwarf and a neutron star, although accretion induced collapse of a white dwarf is also possible. The ePESSTO spectra show a chemical composition compatible with the destruction of a white dwarf.

The other two papers are on long gamma ray bursts. Andy Melandri led the ePESSTO GRB science team with a paper on another identification of an emerging supernova in long GRB detected by Fermi at the rather large redshift of t z = 0.33. This is one of the few high redshift SNe for which spectroscopic identification of the type Ic supernova and a host galaxy analysis have been possible.

Finally, in a paper published in Nature the MAGIC collaboration detected the highest energy photons ever from a GRB, in the teraelectronvolt range (1012 eV). The remarkable emission from GRB190114C is associated with the afterglow and is explained by inverse Compton scattering of photons by high energy electrons. ePESSTO contributed to the multi-frequency campaign on GRB 190114C, which showed that such conditions for TeV emission may be typical for GRBs and that inverse Compton emission may be more commonly produced than previously thought.

The Start of ePESSTO+

PESSTO has now reached its second extension and another chapter with a new management (PI Cosimo Inserra) has started.

The “advanced” extended Public ESO Spectroscopic Survey of Transient Objects (ePESSTO+) was approved with an initial 1.5 year Large Programme by the ESO OPC starting in April 2019. From Period 103 we were approved to continue our spectroscopic survey as ePESSTO+. The operational mode of around 10N per month over 9 - 10 lunations during the year will continue and we will continue to provide immediate public classifications and classification spectra through the new Astronotes system, the IAU Transient Name Server and WiSeREP.

The scientific focus of ePESSTO+ leans towards exploring new exciting transient populations. We will expand the scientific focus to include gravitational wave sources, transients that evolve on the timescale of a few days and do not resemble any common class of extragalactic transient, as well as those with extreme energetics.
Superluminous supernovae are still a major focus along with unusual transients situated far (tens of kiloparsecs) from their host galaxies and transients in low-luminosity hosts. Gamma ray bursts and transients associated with fast radio bursts triggers will also be a major line of investigation.

Son of Xshooter (SOXS, PI Sergio Campana), the new instrument for the ESO NTT, which will replace SOFI, is due for installation in 2021 and we foresee that ePESSTO+ will, at least, bridge the gap from now until SOXS is delivered to ESO in 2021.

a few of the most recent PESSTO papers ...

GRB 171010A/SN 2017htp: a GRB-SN at z = 0.33  Melandri, A.; Malesani, D. B.; Izzo, L. et al.
SN 2017gmr: An Energetic Type II-P Supernova with Asymmetries  Andrews, Jennifer E.; Sand, D. J.; Valenti, S. et al.