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We have developed back-end electronics (BEE) for Hyper Suprime-Cam (HSC), the next generation of wide-field cameras to be mounted on the 8.2-meter diameter Subaru Telescope in Hawaii. HSC employs 116 pieces of 2 k\,\times\,4 k charge coupled devices to cover a 1.5-degree-diameter field of view. The BEE is the digital part of the readout electronics that bridges the analog front end and the data acquisition computers. The BEE is required to read out 2.3-GB imaging data within 10 s without being a major source of readout noise; to fit within the three blocks of the 7-slot 3U Euro-card system; and to have a power consumption too low to affect the light path. Our BEE was designed to achieve all of these requirements, and measurements of its performance showed that all of these requirements were satisfied. Hence we concluded that the BEE we designed is sufficient for HSC. [ABSTRACT FROM AUTHOR]

We report the result of our near-infrared observations ( JHKs) for type II Cepheids (including possible RV Tau stars) in galactic globular clusters. We detected variations of 46 variables in 26 clusters (10 new discoveries in seven clusters) and present their light curves. Their periods range from 1.2 d to over 80 d. They show a well-defined period–luminosity relation at each wavelength. Two type II Cepheids in NGC 6441 also obey the relation if we assume the horizontal branch stars in NGC 6441 are as bright as those in metal-poor globular clusters in spite of the high metallicity of the cluster. This result supports the high luminosity which has been suggested for the RR Lyr variables in this cluster. The period–luminosity relation can be reproduced using the pulsation equation assuming that all the stars have the same mass. Cluster RR Lyr variables were found to lie on an extrapolation of the period–luminosity relation. These results provide important constraints on the parameters of the variable stars. Using Two Micron All-Sky Survey (2MASS) data, we show that the type II Cepheids in the Large Magellanic Cloud (LMC) fit our period–luminosity relation within the expected scatter at the shorter periods. However, at long periods ( d, i.e. in the RV Tau star range) the LMC field variables are brighter by about one magnitude than those of similar periods in galactic globular clusters. The long-period cluster stars also differ from both these LMC stars and galactic field RV Tau stars in a colour–colour diagram. The reasons for these differences are discussed. [ABSTRACT FROM AUTHOR]

The data of 8852 and 2927 variable stars detected by the OGLE survey in the Large and Small Magellanic Clouds are presented. They are cross-identified with the SIRIUSJHKsurvey data, and their infrared properties are discussed. Variable red giants are well separated on the period–plane, suggesting that it could be a good tool to distinguish their pulsation mode and type. [ABSTRACT FROM AUTHOR]

We have performed a cross-identification between Optical Gravitational Lensing Experiment II (OGLE-II) data and single-epoch Simultaneous three-colour Infrared Imager for Unbiased Surveys (SIRIUS) near-infrared (NIR) JHK survey data in the Large and Small Magellanic Clouds (LMC and SMC, respectively). After eliminating obvious spurious variables, variables with too few good data and variables that seem to have periods longer than the available baseline of the OGLE-II data, we determined the pulsation periods for 8852 and 2927 variables in the LMC and SMC, respectively. Based on these homogeneous data, we studied the pulsation properties and metallicity effects on period– K magnitude ( PK) relations by comparing the variable stars in the LMC and SMC. The sample analysed here is much larger than the previous studies, and we found the following new features in the PK diagram. (1) Variable red giants in the SMC form parallel sequences on the PK plane, just like those found by Wood in the LMC. (2) Both sequences A and B of Wood have discontinuities, and they occur at the K-band luminosity of the tip of the red giant branch. (3) The sequence B of Wood separates into three independent sequences B± and C′. (4) A comparison between the theoretical pulsation models and observational data suggests that the variable red giants on sequences C and newly discovered C′ are pulsating in the fundamental and first overtone modes, respectively. (5) The theory cannot explain the pulsation mode of sequences A± and B±, and they are unlikely to be the sequences for the first and second overtone pulsators, as was previously suggested. (6) The zero-points of PK relations of Cepheids in the metal deficient SMC are fainter than those of the LMC by ≈0.1 mag but those of SMC Miras are brighter than those of the LMC by ≈0.13 mag (adopting the distance modulus offset between the LMC and SMC to be 0.49 mag and assuming the slopes of the PK relations are the same in the two galaxies), which are probably due to metallicity effects. [ABSTRACT FROM AUTHOR]

Cites a study published in the journal 'Mon. Not. R. Astron. Soc.,' which focuses on an optical and near infrared search for brown dwarfs in pleiades cluster. Difficulties in detection of L-type brown dwarfs at optical wavelengths; Factors for selection of pleiades brown dwarf candidate stars.

“Time-Delay Integration (TDI)” readout technique has been adopted to a mosaic CCD camera equipped with four fully-depleted CCDs. Optical distortion and image deformation due to the TDI operation are discussed. The manner and advantages of the TDI method in survey observations of geosynchronous orbit objects are summarized. We propose a new TDI application method of getting short-term light curves of artificial space objects. This method of detecting a short-term variability can be applied for a variety of objects, ranging from satellites to stars. It can also be used for the light-curve observations of transient objects which might show short-term variability and of which the precise time information is needed. [ABSTRACT FROM AUTHOR]

The first results of our ongoing near-infrared (NIR) survey of the variable red giants in the Large Magellanic Cloud, using the Infrared Survey Facility (IRSF) and the SIRIUS infrared camera, are presented. Many very red stars were detected and we found that most of them are variables. In the observed colour-magnitude diagram (J - K, K) and the stellar K magnitude distribution, the tip of the first giant branch (TRGB), where helium burning in the core starts, is clearly seen. Apart from the genuine AGB variables, we found many variable stars at luminosities around the TRGB. From this result, we infer that a substantial fraction of them are RGB variables. [ABSTRACT FROM AUTHOR]