The Benefit of Simultaneous Seven-filter Imaging: 10 Years of GROND Observations

Abstract

A variety of scientific results have been achieved over the last 10 years with the GROND simultaneous 7-channel imager at the 2.2m telescope of the Max-Planck Society at ESO/La Silla. While designed primarily for rapid observations of gamma-ray burst afterglows, the combination of simultaneous imaging in the Sloan g r i z and near-infrared JHK s bands at a medium-sized (2.2 m) telescope and the very flexible scheduling possibility has resulted in an extensive use for many other astrophysical research topics, from exoplanets and accreting binaries to galaxies and quasars.

GRB 160410A: the first Chemical Study of the Interstellar Medium of a Short GRB

“…We obtained multi-band photometric observations with the Gamma-Ray burst Optical and Near-infrared Detector (GROND) (Greiner et al 2008;Greiner 2019) mounted on the 2.2 m MPG telescope at ESO La Silla observatory (originally published in Yates et al 2016) in the 𝑔 𝑟 𝑖 𝑧 𝐽𝐻𝐾 bands. GROND observations began about half an hour after the GRB, at very high airmass (2.7).…”

Key Space and Ground Facilities in GRB Science

“…Since a typical GRB afterglow rapidly fades by about 2-3 mag within 5-10 min after its onset and by another 3 mag in the following 50 min [151], quick GRB follow-ups are extremely important. The low latency and cost and high reliability and efficiency of the observations with robotic telescopes are provided by computer-controlled low-level behavior, ensuring the absence of manual control by humans.…”

“…Installed at the 2.2 m f /8 Ritchey-Chretien telescope on an equatorial fork mount in La Silla (Chile), the Gamma-Ray Burst Optical Near-IR Detector (GROND) performs imaging in the Sloan g r i z filters and NIR JHK bands with a 0.4 intrinsic image quality in a 5.4 × 5.4 FoV in each visual band and a 10 × 10 FoV in the NIR (2048 × 2048 CCD with the 0.158 /pixel plate scale) using a focal reducer (1024 × 1024 array with a plate scale of 0.60 /pixel) with a 0.6 FWHM, allowing the linear increase of sensitivity with additional exposure up to 3-4 h [151,247].…”

“…The primary goal of GROND is a rapid follow-up of GRB afterglows and estimation of their redshifts. The main scientific highlights include the start of systematic GRB afterglow follow-up in the near-infrared (JHKs) band, enabling the discovery of high-redshift GRBs, studying the abundance of dust along the GRB line-of-sight, i.e., assessment of the "dark burst" incidence, measurements of GRB afterglow SEDs, studies of the GRB-SNe connection, observations of the black widow binaries, and blazar redshift estimates [151].…”

Half-a-century of gamma-ray astrophysics at the Max-Planck Institute for Extraterrestrial Physics

“…Other scientific highlights include (iii) studies of Fermi-detected GRBs [112] (including the redshift estimate of GRB 080916C), (iv) measurements of the SEDs of non-canonical light curve variability such as flares or intensity jumps, (v) the discovery and detailed study of a large fraction of all GRB-SNe, most prominently the SN 2011kl related to the ultra-long GRB 111209A [62], (vi) tests of the simplest fireball scenario based on the evolution of afterglow SEDs, (vii) the investigation of the jet structure and/or off-axis viewing geometry based on achromatic afterglow light curves, and (viii) the characterisation of about half of all optically detected short GRB afterglows [117]. An overview on non-GRB science with GROND is given in Greiner [53]. Over the years, 26 PhD and Master theses were written using GROND data.…”