We report on the bright burst detected by four Interplanetary network ( IPN ) spacecraft on 2015 April 12 .
The IPN localization of the source is consistent with the position of the recently discovered soft gamma-repeater SGR 1935+2154 .
From the Konus- Wind ( KW ) observation , we derive temporal and spectral parameters of the emission , and the burst energetics .
The rather long duration of the burst ( \sim 1.7 s ) and the large measured energy fluence ( \sim 2.5 \times 10 ^ { -5 } erg cm ^ { -2 } ) put it in the class of rare ‘ ‘ intermediate ’ ’ SGR flares , and this is the first one observed from SGR 1935+2154 .
A search for quasi-periodic oscillations in the KW light curve yields no statistically significant signal .
Of four spectral models tested , optically thin thermal bremsstrahlung and a single blackbody ( BB ) function can be rejected on statistical grounds ; two more complex models , a cutoff power law ( CPL ) and a sum of two BB functions ( 2BB ) , fit the burst spectra well and neither of them may be ruled out by the KW observation .
The CPL and 2BB model parameters we report for this bright flare are typical of SGRs ; they are also consistent with those obtained from observations of much weaker and shorter SGR 1935+2154 bursts with other instruments .
From the distribution of double blackbody spectral fit parameters we estimate the SGR 1935+2154 distance to be < 10.0 kpc , in agreement with that of the Galactic supernova remnant G57.2+0.8 at 9.1 kpc .