A radio burst lasting up to 72 hr at a high Galactic latitude was detected by interferometric drift-scanning observation using an eight-element, 20 m diameter fixed spherical dish array at the Waseda Nasu Pulsar Observatory in Japan.
In order to search for radio bursts in radio transient objects, we have developed an automatic radio burst search system. The system is being used at Nasu Pulsar Observatory of Waseda University in Jiyu-Gakuen Nasu Farm, 160 km north of Tokyo. The drift-scan fringe data from four different declinations are simultaneously obtained with an eight-element interferometer. Using the automatic radio burst search system, some radio transients were detected. Here we discuss its fringe-finding algorithms and the application in burst search observations. The application is similar to that of the blink comparator in optical telescopes to search for novae.
Radio transient surveys at high Galactic latitudes have not been conducted until now, as they require long periods of observation. We have constructed a full-time survey facility, the eight-element Nasu Spherical Dish Array, for radio transients and pulsars. The observing frequency is 1.4 GHz, and the bandwidth is 20 MHz. We started the radio transient survey project in 2004 and have detected some radio transients. In this paper, we report the first radio transient detected in this project. During 11 days of drift-scan observations in 2004, an outburst of approximately 1.6 Jy, which we are calling WJN J1737ϩ3808, was detected on May 20, 15:59 UT, at a p 17 h 37 m 02 s ע 05 s , d p 38Њ08Ј ע 0.4Њ (J2000.0), (l p 63Њ12Ј, b p 30Њ19Ј). We have not yet identified the object as a known celestial object.
We have developed a new technique, called quick-look data analysis, for radio transient searches at the Nasu Interferometer. Quick-look data, a color map according to the radio source signal-to-noise ratio (S/N), were generated spatially and temporally from drift-scanning data. A steady source appears at the same right ascension with the same color every day. In contrast, transient objects such as radio bursts appear irregularly in the sky, and the resulting map will have sporadic patches. Radio transient WJN J1443ϩ3439 has already been detected using this technique. The quick-look data were created using processes that we call the fringe-detecting method and color image creation, which we describe here, and we show actual color images of Cyg A, 3C 48, Mrk 501, and the transient radio source WJN J1443ϩ3439 found in 2005.
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