The Ultimate Light Curve of SN 1998bw/GRB 980425

TL;DR

This paper presents an extensive, multi-band light curve analysis of SN 1998bw associated with GRB 980425, extending previous observations and providing a unified, detailed dataset for understanding the supernova's evolution.

Contribution

It offers a comprehensive, calibrated, multi-band light curve dataset for SN 1998bw, extending observational coverage and standardizing data from multiple sources.

Findings

Extended U-band coverage by 30 days, capturing early tail slope.

Unified 300 observations across five bands, merged from various sources.

Constructed quasi-bolometric light curves with detailed spline fits.

Abstract

We present multicolor light curves of SN 1998bw which appeared in ESO184-G82 in close temporal and spacial association with GRB 980425. They are based on observations done at Cerro Tololo Inter-American Observatory and data from the literature. The CTIO photometry reaches ~86 days after the GRB in $U$ and ~160 days after the GRB in BV(RI)_C. The observations in U extend by about 30 days the previously known coverage, and determine the slope of the early exponential tail. We calibrate a large set of local standards in common with those of previous studies and use them to transform published observations of the SN to our realization of the standard photometric system. We show that the photometry from different sources merges smoothly and provide a unified set of 300 observations of the SN in five bands. Using the extensive set of spectra in public domain we compute extinction and K corrections, and build quasi-bolometric unreddened rest frame light curves. We provide low degree piecewise spline fits to these light curves with daily sampling. They reach ~86 rest frame days after the GRB with U band coverage, and ~498 rest frame days after the GRB without U.