Rapid Response Multi-color Lightcurves with LCO and MuSCAT3

Near Earth Objects (NEOs) make up a rapidly moving and dynamic population that needs to be well understood to address both practical questions about potential impacts and scientific questions about Solar System formation. There are many surveys and programs dedicated to finding, tracking, and understanding the physical properties of NEOs. Las Cumbres Observatory (LCOGT) has been working on improving our contribution to rapid-response lightcurves for targets of interest. These lightcurves are typically made in conjunction with RADAR observations or other studies that necessitate short notice of observations and fast turnaround time for results.

As a global observatory with telescopes in both the northern and the southern hemispheres, LCO can request, observe, and analyse a target light curve within a few hours with results being automatically uploaded to our website, neoexchange.lco.global. The flexibility of LCO’s scheduling has allowed us to obtain lightcurves for targets very soon after confirmation, before RADAR observations to better help those facilities understand their results, and simultaneous to infra-red observations to help put those data in the context of the rotational phase of the target.

Most recently, LCO has added a new instrument, MuSCAT3. This instrument is a four channel simultaneous imager available on the LCO 2m telescope at Haleakala Observatory. MuSCAT3 is a clone of MuSCAT2 (Narita et al. 2018), currently installed at the 1.52m TCS. This new instrument will make truly simultaneous multi-color lightcurves possible for NEOs and other Solar System objects. Simultaneous colors offer substantial advantage over non-simultaneous observations such as those typically done by major surveys like PanSTARRS and LSST because the object’s rotation (and changing brightness) has no effect on the color calculation. Typical attempts to study the heterogeneity of an asteroid’s surface require either sparsely sampled photometry or observationally expensive alternating filter lightcurves that degrade the rotational resolution of the data. MuSCAT3 will allow 4-color griz photometry for every datapoint in a lightcurve without changing the total sampling. This will allow for a full phase of high fidelity color observations for rapidly rotating objects with substantially less observation time than was previously possible. Here we present results from the LCO lightcurve campaign and some first observations from the very recently commissioned MuSCAT3.