Measuring star tick: 50BN
Measuring star tick: 50BN
50BN partners
50BN Parameter
major goals
minor goals

50cm Binocular Network (50BN) project:

50 centimeter Binocular Network

50BN project is a Chinese initiative to do stellar variability studies, which is planned as a sub system of SONG. The global site plan is exactly the same as SONG (northernhamisphere): Canari islands (Observatorio del Teide), West-China (PMO at Delingha), US continent (APO) and Hawaii islands (Mauna Lua). Other additional sites, such as the 50cm telescope at Virgin island after upgrading its instruments, can also join the network to ensure better coverage. Large field time domain studies of stars pioneered by MACHO and OGLE show that nearly all stars oscillate at various frequencies and amplitudes. Red giants usually show complicated oscillating properties as shown by very extended observations of stars in Galactic bulge. Previous observations in time series for open clusters discovered many different types of variable objects such as intrinsic oscillators, outbursts and transiting types, and this kind of discoveries are usually limited by observation windows therefore can hardly lead to meaningful statistics. With traditional single site sampling, detailed analysis of oscillation property of pulsators (usually in multiple modes), detection of transiting and outburst phenomena of various eclipsing periods or frequency, and many interesting variabilities are always not reaching a good enough completeness level to allow good statistics in star clusters. Stars in clusters, having nearly a single set of physical parameters, can provide much more information for both individual stars and statistical study than field objects. Going for long time baseline, high duty cycle and fine cadence photometry in dense open clusters can accommodate a wide range of stellar research interests. Being a part of SONG, 50BN will have great potential in time domain astronomy thanks to SONG's infrastructure platform. Apart from targeting a number of well selected open clusters, 50BN will also be used to do many ToO type and other special studies that require such a network.

Fundamental Requirements for hardware:

  1. To realize long time base line and high duty cycle, a 50BN telescope should be attached to each SONG node, at least in SONG-North;
  2. To realize our science goals, (simultaneous) 2 color (UBVRI or SDSS filters) photometry system is needed;
  3. To cover large enough cluster and vicinity area of Galactic open clusters, especially the well studied old populations of clusters, such as M67, NGC188, NGC7789 etc., a minimum of 20'x20' FOV is needed;
  4. Limited by budget,  an aperture of 50cm to optimize our science goals has been adopted;
  5. To get an ideal sampling, 2kx2k CCD(s) is needed;