We report results of the measurement of the trigonometric parallax of an H2O maser source in IRAS 22555+6213 with the VLBI Exploration of Radio Astrometry (VERA). The annual parallax was determined to be 0.2780.019 mas, corresponding to a distance of 3.66+0:30 -0:26 kpc. Our results conrm that IRAS 22555+6213 is located in the Perseus arm. We computed the peculiar motion of IRAS 22555+6213 to be (Usrc; Vsrc;Wsrc) = (0 ± 1,-32 ± 1, 9 ± 1) km s􀀀1, where Usrc, Vsrc, and Wsrc are directed toward the Galactic center, in the direction of Galactic rotation and toward the Galactic north pole, respectively. IRAS 22555+6213, NGC7538 and Cepheus A lie along the same line of sight, and are within 2 on the sky. Their parallax distances, with which we derived their absolute position in the Milky Way, show that IRAS 22555+6213 and NGC7538 are associated with the Perseus arm, while Cepheus A is located in the Local arm. We compared the kinematic distances of IRAS 22555+6213 derived with at and non- at rota- tion curve with its parallax distance and found the kinematic distance derived from the non- at rotation assumption (—32 km s-1 lag) to be consistent with the parallax distance.

WFIRST microlensing observations will return high-precision parallaxes, σ(π) . 0.3 μas, for the roughly 1 million stars with H < 14 in its 2.8 deg2 field toward the Galactic bulge. Combined with its 40,000 epochs of high precision photometry (∼ 0.7 mmag at Hvega = 14 and ∼ 0.1 mmag at H = 8), this will yield a wealth of asteroseismic data of giant stars, primarily in the Galactic bulge but including a substantial fraction of disk stars at all Galactocentric radii interior to the Sun. For brighter stars, the astrometric data will yield an external check on the radii derived from the two asteroseismic parameters, the large-frequency separation h
νnli and the frequency of maximum oscillation power νmax, while for the fainter ones, it will enable a mass measurement from the single measurable asteroseismic parameter νmax. Simulations based on Kepler data indicate that WFIRST will be capable of detecting oscillations in stars from slightly less luminous than the red clump to the tip of the red giant branch, yielding roughly 1 million detections.

I show that the WFIRST microlensing survey will enable detection and precision orbit determination of Kuiper Belt Objects (KBOs) down to Hvega = 28.2 over an effective area of ∼ 17 deg2. Typical fractional period errors will be ∼ 1.5% × 100.4(H−28.2) with similar errors in other parameters for roughly 5000 KBOs. Binary companions to detected KBOs can be detected to even fainter limits, Hvega = 29, corresponding to R ∼ 30.5 and effective diameters D ∼ 7 km. For KBOs H ∼ 23, binary companions can be found with separations down to 10 mas. This will provide an unprecedented probe of orbital resonance and KBO mass measurements. More than a thousand stellar occultations by KBOs can be combined to determine the mean size as a function of KBO magnitude down to H ∼ 25. Current ground-based microlensing surveys can make a significant start on finding and characterizing KBOs using existing and soon-to-be-acquired data.