Spitzer + VLTI-GRAVITY Measure the Lens Mass of a Nearby Microlensing Event

We report the lens mass and distance measurements of the nearby microlensing event TCP J05074264+2447555. We measure the microlens parallax vector ${\pi}_{\rm E}$ using Spitzer and ground-based light curves with constraints on the direction of lens-source relative proper motion derived from Very Large Telescope Interferometer (VLTI) GRAVITY observations. Combining this ${\pi}_{\rm E}$ determination with the angular Einstein radius $\theta_{\rm E}$ measured by VLTI GRAVITY observations, we find that the lens is a star with mass $M_{\rm L} = 0.495 \pm 0.063~M_{\odot}$ at a distance $D_{\rm L} = 429 \pm 21~{\rm pc}$. We find that the blended light basically all comes from the lens. The lens-source proper motion is $\mu_{\rm rel,hel} = 26.55 \pm 0.36~{\rm mas\,yr^{-1}}$, so with currently available adaptive-optics (AO) instruments, the lens and source can be resolved in 2021. This is the first microlensing event whose lens mass is unambiguously measured by interferometry + satellite parallax observations, which opens a new window for mass measurements of isolated objects such as stellar-mass black holes.Comment: 3 Figures and 6 Tables Submitted to AAS Journa

MACAO-VLTI first light: adaptive optics at the service of interferometry

International audienceThe AO department of ESO has completed the design of an adaptive AO system for the VLT Interferometer. Ordering of components, manufacturing and integration took place in 2001 and 2002. The system is built in four copies, one for each VLT. It is installed at the Coudé room and the Coudé train is used as a 'science path'. Only one of the mirrors (M8, pupil conjugated) is replaced by the corrective optics. The 60 elements system should allow a Strehl ratio of ~0.6 on bright sources. Commissioning activities started in April 2003 and the delivery of the 4th system is planned for late 2004. At the time of this writing the first commissioning of the first MACAO has been completed and results are encouraging. The integration and test phase of the 2nd system is in full swing

MACAO-VLTI first light: adaptive optics at the service of interferometry

International audienceThe AO department of ESO has completed the design of an adaptive AO system for the VLT Interferometer. Ordering of components, manufacturing and integration took place in 2001 and 2002. The system is built in four copies, one for each VLT. It is installed at the Coudé room and the Coudé train is used as a 'science path'. Only one of the mirrors (M8, pupil conjugated) is replaced by the corrective optics. The 60 elements system should allow a Strehl ratio of ~0.6 on bright sources. Commissioning activities started in April 2003 and the delivery of the 4th system is planned for late 2004. At the time of this writing the first commissioning of the first MACAO has been completed and results are encouraging. The integration and test phase of the 2nd system is in full swing

MACAO-VLTI first light: Adaptive optics at the service of interferometry

The AO department of ESO has completed the design of an adaptive AO system for the VLT Interferometer. Ordering of components, manufacturing and integration took place in 2001 and 2002. The system is built in four copies, one for each VLT. It is installed at the Coudé room and the Coudé train is used as a "science path". Only one of the mirrors (M8, pupil conjugated) is replaced by the corrective optics. The 60 elements system should allow a Strehl ratio of ~0.6 on bright sources. Commissioning activities started in April 2003 and the delivery of the 4th system is planned for late 2004. At the time of this writing the first commissioning of the first MACAO has been completed and results are encouraging. The integration and test phase of the 2nd system is in full swing