A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to ∼15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from 2014 September to late November, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C 138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at ∼350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy.

We report the results from recent observations of Sgr A* at short-/submillimeter wavelengths made with the partially finished Sub-Millimeter Array (SMA) on Mauna Kea. A total of 25 epochs of observations were carried out over the past 15 months in 2001 March to 2002 May. Noticeable variations in flux density at 1.3 mm were observed showing three "flares". The SMA observations suggest that Sgr A* highly increases towards submillimeter wavelengths during a flare suggesting the presence of a break wavelength in spectral index around 3 mm. A cross-correlation of the SMA data at 1 mm with the VLA data at 1 cm show a global delay of t delay > 3d, suggesting that sub-millimeter wavelengths tend to peak first. Only marginal day-to-day variations in flux density (2-3σ) have been detected at 1.3 mm. No significant flares on a short time scale (∼ 1 hr) have been observed at 1.3 mm. We also failed to detect significant periodic signals at a level of 5% (3σ) from Sgr A* in a periodic searching window ranging from 10 min to 2.5 hr. The flares observed at the wavelengths between short-centimeter and sub-millimeter might be a result of collective mass ejections associated with X-ray flares that originate from the inner region of the accretion disk near the supermassive black hole.

We have performed the monitoring observations of flux density of Sagittarius A * at short millimeter wavelengths (100 and 140 GHz bands) on seven years in the period from 1996 to 2003 using the Nobeyama Millimeter Array (NMA). We found intra-day variation of Sgr A * in March 2000 flare. The flux density at the peak of the flares increases 100-200% at 100 GHz and 200-400% at 140 GHz (∆S/S), respectively. The two-fold increase timescale of the flare is estimated to be about 1.5 hours at 140 GHz. The intra-day variation at mm-wavelengths has similar increase timescale as those in the X-ray and infrared flares but has smaller amplitude. This short timescale variability suggests that the physical size of the emitting region is smaller than 12 AU (≈ 150 R s ). The decay timescale of the flare was at most 24 hours. Such a light curve with rapid increase and slow decay is similar to that often observed in outburst phenomena with ejections.

We present the first image of the thermal Sunyaev–Zel'dovich effect (SZE) obtained by the Atacama Large Millimeter/submillimeter Array (ALMA). Combining 7-m and 12-m arrays in Band 3, we create an SZE map toward a galaxy cluster RX J1347.5−1145 with 5″ resolution (corresponding to a physical size of 20 h−1 kpc), the highest angular and physical spatial resolutions achieved to-date for imaging the SZE, while retaining extended signals out to 40″. The 1 σ statistical sensitivity of the image is 0.017 mJy beam−1 or 0.12 mKCMB at the 5″ full width at half maximum. The SZE image shows a good agreement with an electron pressure map reconstructed independently from the X-ray data and offers a new probe of the small-scale structure of the intracluster medium. Our results demonstrate that ALMA is a powerful instrument for imaging the SZE in compact galaxy clusters with unprecedented angular resolution and sensitivity. As the first report on the detection of the SZE by ALMA, we present detailed analysis procedures including corrections for the missing flux, to provide guiding methods for analyzing and interpreting future SZE images obtained by ALMA.

Tactile sensors for slip detection are essential for implementing human-like gripping in a robot hand. In previous studies, we proposed flexible, thin and lightweight slip detection sensors utilizing the characteristics of pressuresensitive conductive rubber. This was achieved by using the high-frequency vibration component generated in the process of slipping of the gripped object in order to distinguish between slipping of the object and changes in the normal force. In this paper, we design a slip detection sensor for a multi-fingered robot hand and examine the influence of noise caused by the operation of such a hand. Finally, we describe an experiment focusing on the adjustment of the gripping force of a multifingered robot hand equipped with the developed sensors.