Early ComeOn+ adaptive optics observation of GQ Lupi and its substellar companion

We present an analysis of adaptive optics K-band imaging data of GQ Lup acquired in 1994 by the first generation adaptive optics system ComeOn+ at the ESO 3.6 m optical telescope in La Silla. The data reveal a likely candidate for the low-mass companion recently reported in the literature. An a posteriori detection in the 11-year old data would provide a useful astrometric data point for the very long-period (similar to 1000 yr) orbit of the GQ Lup system. However, the data is severely contaminated by speckle noise at the given projected separation, which decreases the confidence of the detection. Still, from the data we can conclude that GQ Lup B is not an unrelated background source, but instead a physical companion to GQ Lup A. We present here the reduction and analysis of the ComeOn+ images, as well as the results. We also discuss the nature of the companion based on data and models available in the scientific literature and examine claims made regarding the classification of the object as a planet.