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We analyze and report in detail new near-infrared (1.45-2.45 mu m) observations of the Dusty S-cluster Object (DSO/G2) during its approach to the black hole at the center of the Galaxy that were carried out with the ESO Very Large Telescope/SINFONI between 2014 February and September. Before 2014 May we detect spatially compact Br gamma and Pa alpha line emission from the DSO at about 40 mas east of Sgr A*. The velocity of the source, measured from the redshifted emission, is 2700 +/- 60 km s(-1). No blueshifted emission above the noise level is detected at the position of Sgr A* or upstream of the presumed orbit. After May we find spatially compact Br. blueshifted line emission from the DSO at about 30 mas west of Sgr A* at a velocity of -3320 +/- 60 km s-1 and no indication for significant redshifted emission. We do not detect any significant extension of the velocity gradient across the source. We find a Br gamma line FWHM of 50 +/- 10 angstrom before and 15 +/- 10 A after the peribothron transit, i.e., no significant line broadening with respect to last year is observed. Br. line maps show that the bulk of the line emission originates from a region of less than 20 mas diameter. This is consistent with a very compact source on an elliptical orbit with a peribothron time passage in 2014.39 +/- 0.14. For the moment, the flaring activity of the black hole in the near-infrared regime has not shown any statistically significant increment. Increased accretion activity of Sgr A* may still be upcoming. We discuss details of a source model according to which the DSO is a young accreting star rather than a coreless gas and dust cloud.

We analyze and report in detail new near-infrared (1.45-2.45 mu m) observations of the Dusty S-cluster Object (DSO/G2) during its approach to the black hole at the center of the Galaxy that were carried out with the ESO Very Large Telescope/SINFONI between 2014 February and September. Before 2014 May we detect spatially compact Br gamma and Pa alpha line emission from the DSO at about 40 mas east of Sgr A*. The velocity of the source, measured from the redshifted emission, is 2700 +/- 60 km s(-1). No blueshifted emission above the noise level is detected at the position of Sgr A* or upstream of the presumed orbit. After May we find spatially compact Br. blueshifted line emission from the DSO at about 30 mas west of Sgr A* at a velocity of -3320 +/- 60 km s-1 and no indication for significant redshifted emission. We do not detect any significant extension of the velocity gradient across the source. We find a Br gamma line FWHM of 50 +/- 10 angstrom before and 15 +/- 10 A after the peribothron transit, i.e., no significant line broadening with respect to last year is observed. Br. line maps show that the bulk of the line emission originates from a region of less than 20 mas diameter. This is consistent with a very compact source on an elliptical orbit with a peribothron time passage in 2014.39 +/- 0.14. For the moment, the flaring activity of the black hole in the near-infrared regime has not shown any statistically significant increment. Increased accretion activity of Sgr A* may still be upcoming. We discuss details of a source model according to which the DSO is a young accreting star rather than a coreless gas and dust cloud.

We analyze and report in detail new near-infrared (1.45-2.45 mu m) observations of the Dusty S-cluster Object (DSO/G2) during its approach to the black hole at the center of the Galaxy that were carried out with the ESO Very Large Telescope/SINFONI between 2014 February and September. Before 2014 May we detect spatially compact Br gamma and Pa alpha line emission from the DSO at about 40 mas east of Sgr A*. The velocity of the source, measured from the redshifted emission, is 2700 +/- 60 km s(-1). No blueshifted emission above the noise level is detected at the position of Sgr A* or upstream of the presumed orbit. After May we find spatially compact Br. blueshifted line emission from the DSO at about 30 mas west of Sgr A* at a velocity of -3320 +/- 60 km s-1 and no indication for significant redshifted emission. We do not detect any significant extension of the velocity gradient across the source. We find a Br gamma line FWHM of 50 +/- 10 angstrom before and 15 +/- 10 A after the peribothron transit, i.e., no significant line broadening with respect to last year is observed. Br. line maps show that the bulk of the line emission originates from a region of less than 20 mas diameter. This is consistent with a very compact source on an elliptical orbit with a peribothron time passage in 2014.39 +/- 0.14. For the moment, the flaring activity of the black hole in the near-infrared regime has not shown any statistically significant increment. Increased accretion activity of Sgr A* may still be upcoming. We discuss details of a source model according to which the DSO is a young accreting star rather than a coreless gas and dust cloud.

We analyze and report in detail new near-infrared (1.45-2.45 mu m) observations of the Dusty S-cluster Object (DSO/G2) during its approach to the black hole at the center of the Galaxy that were carried out with the ESO Very Large Telescope/SINFONI between 2014 February and September. Before 2014 May we detect spatially compact Br gamma and Pa alpha line emission from the DSO at about 40 mas east of Sgr A*. The velocity of the source, measured from the redshifted emission, is 2700 +/- 60 km s(-1). No blueshifted emission above the noise level is detected at the position of Sgr A* or upstream of the presumed orbit. After May we find spatially compact Br. blueshifted line emission from the DSO at about 30 mas west of Sgr A* at a velocity of -3320 +/- 60 km s-1 and no indication for significant redshifted emission. We do not detect any significant extension of the velocity gradient across the source. We find a Br gamma line FWHM of 50 +/- 10 angstrom before and 15 +/- 10 A after the peribothron transit, i.e., no significant line broadening with respect to last year is observed. Br. line maps show that the bulk of the line emission originates from a region of less than 20 mas diameter. This is consistent with a very compact source on an elliptical orbit with a peribothron time passage in 2014.39 +/- 0.14. For the moment, the flaring activity of the black hole in the near-infrared regime has not shown any statistically significant increment. Increased accretion activity of Sgr A* may still be upcoming. We discuss details of a source model according to which the DSO is a young accreting star rather than a coreless gas and dust cloud.

We present a comprehensive data description for K-s-band measurements of Sgr A*. We characterize the statistical properties of the variability of Sgr A* in the near-infrared, which we find to be consistent with a single-state process forming a power-law distribution of the flux density. We discover a linear rms-flux relation for the flux density range up to 12 mJy on a timescale of 24 minutes. This and the power-law flux density distribution implies a phenomenological, formally nonlinear statistical variability model with which we can simulate the observed variability and extrapolate its behavior to higher flux levels and longer timescales. We present reasons why data with our cadence cannot be used to decide on the question whether the power spectral density of the underlying random process shows more structure at timescales between 25 minutes and 100 minutes compared to what is expected from a red-noise random process.

We present a comprehensive data description for K-s-band measurements of Sgr A*. We characterize the statistical properties of the variability of Sgr A* in the near-infrared, which we find to be consistent with a single-state process forming a power-law distribution of the flux density. We discover a linear rms-flux relation for the flux density range up to 12 mJy on a timescale of 24 minutes. This and the power-law flux density distribution implies a phenomenological, formally nonlinear statistical variability model with which we can simulate the observed variability and extrapolate its behavior to higher flux levels and longer timescales. We present reasons why data with our cadence cannot be used to decide on the question whether the power spectral density of the underlying random process shows more structure at timescales between 25 minutes and 100 minutes compared to what is expected from a red-noise random process.