Quiet, Please! Second Science Run Now Underway!

 
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In mid-February LIGO began S2, the Second Science Run of its interferometers. To date, progress has been smooth and steady--and occasionally exceptional.

At Hanford, both interferometers have had a cumulative science mode duty cycle since the S2 start of between 60 and 65 percent, although this figure has diminished at times due to sustained high and gusting winds at the Washington site. Sensemon NS-NS averaged inspiral ranges--or the distance out to which the interferometer can detect a Neutron Star/Neutron Star Binary--were typically between 300 and 350kpc for H1, and between 150-300kpc for H2. This monitor is a key indicator of interferometer performance and we are quite pleased by the numbers.

Opening run calibrations and in-run astrophysical injections were performed, impacting the duty cycle slightly. Still, lock duration records were broken in the first week on both interferometers: 35 hours for H1, and 30 hours for H2--with 21 hours of continuous overlap. Most recently, H1 achieved an impressive locked stretch of 66 hours.

Meanwhile, at LIGO Livingston the interferometer is operating at just around 40 percent duty cycle. We are able to maintain lock in science mode for several hours during the day. This is a significant improvement relative to prior daytime operating experience. The Y-end controller failed at one point but was repaired and reinstalled the same night. One of the real highlights has been the NS-NS range for L1, which has reached as high as 1.2 mpc, or 1200 kpc. This gives it the range to see as far as the Andromeda galaxy, the nearest large spiral galaxy!