Reduced data from programme 60.A-9392(B) - GW follow-up

NaCo imaging observations were carried out under ESO program 60.A-9392(A), PI A. Kaufer, to constrain the spectral energy distribution at 3.80 micron of the source identified by the LIGO-VIRGO GW 170817 and the gamma-ray burst GRB 170817A alerts. The data were acquired in eleven different nights, from late-Aug –to early-Sep 2017, mostly under good conditions. The NaCo imaging was carried out with the L’ filter and the L27 camera, with a pixel scale of 0.027 arcsec/pixel . The FWHM of the photometric standard star observed together with the science data indicates a seeing of about 0.11 arcsec. The images from individual nights were co-added us- ing the offset parameters from the headers. The extended nearby galaxy NGC 4993 falls inside the NaCo field of view, and it was detected on some of the the combined frames, but no unresolved sources were detected in the field. This release includes only processed images form the nights when NGC 4993 was detected, because a standard was observed only on one night, and the galaxy was used to perform a consistent photometric calibration across the data from different nights. Detection limits were derived for single night observations, and for image products obtained from multiple nights combined together