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Fermi-LAT Gamma-ray Observations of Nova Lupus 2016 (ASASSN-16kt)

ATel #9594; C. C. Cheung (NRL), P. Jean (IRAP, Toulouse), on behalf of the Fermi Large Area Telescope Collaboration, S. N. Shore (U. Pisa and INFN)
on 4 Oct 2016; 21:25 UT
Credential Certification: Teddy Cheung (ccheung@milkyway.gsfc.nasa.gov)

Subjects: Gamma Ray, >GeV, Nova, Transient

Referred to by ATel #: 9644, 10722, 10749

The Fermi Gamma-ray Space Telescope performed a ~6-day Target of Opportunity (ToO) observation of Nova Lupus 2016 (ATel #9538, #9539, CBET #4322) that commenced on September 28. Considering earlier all-sky survey Large Area Telescope (LAT) observations as well, preliminary analysis indicates gamma-ray emission at ~2 sigma was detected around 1 to 2 days after the optical peak on September 25th (pre-validated AAVSO visual lightcurve; ATel #9550, CBET #4322) when the optical spectra show opaque ejecta, similar to previous gamma-ray detected novae (Fermi-LAT collaboration, 2014 Science 345, 554; Cheung et al. 2016 ApJ 826, 142). Combining about 3.2 days of LAT exposure beginning on September 26, a source at the nova optical position was present at 4.4 sigma with an average flux, F(E>100 MeV) ~ (1.8 +/- 0.6) x 10^-7 ph cm^-2 s^-1 (assuming a single power-law with photon index = 2.2 fixed in the fit; statistical errors only). During the subsequent ~4.8 days of exposure through the end of the ToO, the source was not significantly detected with a 95% confidence flux upper limit of < 0.6 x 10^-7 ph cm^-2 s^-1.

We encourage multiwavelength observations. Fermi is currently performing a ToO observation of the Crab nebula for at least 4 days (ATel #9588) with minimal exposure toward the nova; its all-sky survey profile will resume thereafter. For this source the Fermi LAT contact persons are: C.C. Cheung (Teddy.Cheung at nrl.navy.mil) and P. Jean (pjean at irap.omp.eu).

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.