COSMOGRAIL XVII: Time delays for the quadruply imaged quasar PG 1115+080

Understand

We present time-delay estimates for the quadruply imaged quasar PG 1115+080.

• Our resuls are based on almost daily observations for seven months at the ESO MPIA 2.2m telescope at La Silla Observatory, reaching a signal-to-noise ratio of about 1000 per quasar image.
• In addition, we re-analyse existing light curves from the literature that we complete with an additional three seasons of monitoring with the Mercator telescope at La Palma Observatory.
• When exploring the possible source of bias we consider the so-called microlensing time delay, a potential source of systematic error so far never directly accounted for in previous time-delay publications.