Abbott, B.Abbott, R.Adhikari, R.Agresti, J.Ajith, P.Allen, B.Amin, R.Anderson, S.Anderson, W.Arain, M.Araya, M.Armandula, H.Ashley, M.Aston, S.Aufmuth, P.Aulbert, C.Babak, S.Ballmer, S.Bantilan, H.Barish, B.et al.2008-07-022008-07-022007Physical Review D: Particles, Fields, Gravitation and Cosmology, 2007; 76(8):082003-1-082003-111550-79981550-2368http://hdl.handle.net/2440/46005We searched for an anisotropic background of gravitational waves using data from the LIGO S4 science run and a method that is optimized for point sources. This is appropriate if, for example, the gravitational wave background is dominated by a small number of distinct astrophysical sources. No signal was seen. Upper limit maps were produced assuming two different power laws for the source strain power spectrum. For an f^-3 power law and using the 50 Hz to 1.8 kHz band the upper limits on the source strain power spectrum vary between 1.2e-48 Hz^-1 (100 Hz/f)^3 and 1.2e-47 Hz^-1 (100 Hz /f)^3, depending on the position in the sky. Similarly, in the case of constant strain power spectrum, the upper limits vary between 8.5e-49 Hz^-1 and 6.1e-48 Hz^-1. As a side product a limit on an isotropic background of gravitational waves was also obtained. All limits are at the 90% confidence level. Finally, as an application, we focused on the direction of Sco-X1, the closest low-mass X-ray binary. We compare the upper limit on strain amplitude obtained by this method to expectations based on the X-ray luminosity of Sco-X1.en©2007 American Physical SocietyJournal article002007404010.1103/PhysRevD.76.0820030002506214000082-s2.0-3564901089246612Ottaway, D. [0000-0001-6794-1591]Veitch, P. [0000-0002-2597-435X]