Geographic and seasonal influences on optical followup of gravitational wave events

TL;DR

This study examines how observatory location and seasonal timing influence the likelihood of detecting optical/infrared counterparts to gravitational wave events, highlighting latitude and seasonal effects on discovery chances.

Contribution

It provides an analysis of geographic and seasonal factors affecting optical followup success for gravitational wave sources, with implications for observatory planning.

Findings

Latitude affects detection probability, with some dependence.

Seasonal timing influences discovery chances, favoring northern observatories in winter.

Three-detector network observations in 2017 favored southern observatories.

Abstract

We investigate the effects of observatory locations on the probability of discovering optical/infrared counterparts of gravitational wave sources. We show that for the LIGO--Virgo network, the odds of discovering optical/infrared (OIR) counterparts show some latitude dependence, but weak or no longitudinal dependence. A stronger effect is seen to arise from the timing of LIGO/Virgo observing runs, with northern OIR observatories having better chances of finding the counterparts in northern winters. Assuming identical technical capabilities, the tentative mid-2017 three-detector network observing favors southern OIR observatories for discovery of EM counterparts.