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.

No abstract

We report the detection of two radio transients in the Nasu 1.4 GHz wide-field survey. In the survey, we use four pairs of the two-element interferometer aligned east-west to monitor the wide-field sky and simultaneously survey the region at þ32 < < þ42 in drift scanning. In 27 days of continuous observation at a declination between +41 and +42 , we have detected two radio transients of 1 Jy intensity. Since they appeared on only a single day during the 27 days, we consider these detections to be 1 Jy class bursts that brightened and faded within 2 days and have constant emission smaller than 200 mJy, the detection limit of the 27 days of integrated data. While one transient was in low Galactic latitudes, the other transient was detected in high Galactic latitudes and has counterparts only in -ray databases. Therefore, the high Galactic latitude transient might be one of the active galactic nuclei that are normally very faint in X-ray and quiet in radio wavelengths.

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.

The Nasu Radio Interferometer, consisting of eight equally spaced, 20-m diameter fixed spherical antennas, was developed for the purpose of surveying unknown variable radio sources at 1.4 GHz. An asymmetrical Gregorian sub-reflector was designed and installed on each antenna for the purpose of correcting aberrations caused by the spherical reflector. The total collecting area is 2512 m 2 and the field-of-view of each antenna is 0. • 6 × 0. • 6. In survey observations a spatial-fast Fourier-transform (FFT)-type multi-beam system will be used. We report on the design of spherical reflectors and a digital back-end system, the basic principle of spatial-FFT image forming, and a result of interferometric observations with an FPGA-based digital correlator.