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The progenitor system(s) as well as the explosion mechanism(s) of thermonuclear (Type Ia) supernovae are long-standing issues in astrophysics. Here we present ejecta masses and other physical parameters for 28 recent Type Ia supernovae inferred from multiband photometric and optical spectroscopic data. Our results confirm that the majority of SNe Ia show observableejecta masses below the Chandrasekhar-limit (having a mean Mej≈ 1.1 ± 0.3 M⊙), consistent with the predictions of recent sub-MChexplosion models. They are compatible with models assuming either single- or double-degenerate progenitor configurations. We also recover a sub-sample of supernovae within 1.2 M⊙< Mej< 1.5 M⊙that are consistent with near-Chandrasekhar explosions. Taking into account the uncertainties of the inferred ejecta masses, about half of our SNe are compatible with both explosion models. We compare our results with those in previous studies, and discuss the caveats and concerns regarding the applied methodology.

We present a robust and fast algorithm for performing astrometry and source cross-identification on lists of two-dimensional points, such as between a catalog and an astronomical image, or between two images. The method is based on minimal assumptions: the lists can be rotated, magnified, and inverted with respect to each other in an arbitrary way. The algorithm is tailored to work efficiently on wide fields with a large number of sources and significant nonlinear distortions, as long as the distortions can be approximated with linear transformations locally over the scale length of the average distance between the points. The procedure is based on symmetric point matching in a newly defined continuous triangle space that consists of triangles generated by extended Delaunay triangulation. Our software implementation performed at the 99.995% success rate on ?260,000 frames taken by the HATNet project.

The determination of the secular variations of the orbital elements of objects in N-body systems is based on the literal development of the perturbing function. The development makes use of the Laplace coefficients and their derivatives. In this paper a new method is described for the analytical computation of the derivatives of the Laplace coefficients. It is an explicit formula in the sense that it only contains the Laplace coefficients and the parameter α on which the Laplace coefficients depend. The advantage of this method is that it is unnecessary to calculate all the derivatives up to the desired order. It is enough to calculate the Laplace coefficients. Easy coding is a further benefit of the method and it provides more accurate numerical results. The paper describes in detail the application of the method through an example and gives comparison with former methods.

The Transiting Exoplanet Survey Satellite (TESS) is a NASA Explorer-class mission designed for finding exoplanets around nearby stars. TESS image data can also serve as a valuable resource for asteroid and comet detection, including near-Earth objects (NEOs). In order to exploit the TESS image data for moving object detection and potential object discovery, our team has developed an image processing pipeline as part of the Lincoln Near-Earth Asteroid Research (LINEAR) program, sponsored by the NASA NEO Observations Program. The LINEAR-TESS pipeline is currently in operation and reporting asteroid observations to the Minor Planet Center. In this paper we discuss the algorithms and methodology utilized to push the limits of the astrometric accuracy and photometric sensitivity of the TESS instrument for asteroid detection without a priori information on the ephemerides of the objects, and report on observation statistics from the first two years of TESS mission data.

The Transiting Exoplanet Survey Satellite(TESS), launched successfully on 2018 April 18 will observe nearly the full sky, and will provide timeseries imaging data in ?27-day-long campaigns. TESSis equipped with four cameras, each of which has a field of view of 24 × 24°. During the first two years of the primary mission, one of these cameras, Camera #1, is going to observe fields centered at an ecliptic latitude of 18°. While the ecliptic plane itself is not covered during the primary mission, the characteristic scale height of the main asteroid belt and Kuiper Belt implies that a significant amount of small solar system bodies will cross this camera's field of view. Based on the comparison of the expected amount of information of TESSand Kepler/K2, we can compute the cumulative étendues of the two optical setups. This comparison results in roughly comparable optical étendues; however, the net étendue is significantly larger in the case of TESSbecause all of the imaging data provided by the 30-minute cadence frames are downlinked rather than the pre-selected stamps of Kepler/K2. In addition, many principles of the data acquisition and optical setup are clearly different, including the level of confusing background sources; full-frame integration and cadence; the field-of-view centroid with respect to the apparent position of the Sun; as well as the differences in the duration of the campaigns. As one would expect, TESSwill yield timeseries photometry, and hence rotational properties for only brighter objects, but in terms of spatial and phase space coverage, this sample will be more homogeneous and more complete. Here, we review the main analogs and differences between the Kepler/K2 mission and the TESSmission, focusing on scientific implications and possible yields related to our solar system.

In this paper, we describe a hexapod-based telescope mount system intended to provide sidereal tracking for the Fly's Eye Camera project-an upcoming moderate, 21? pixel?1resolution all-sky survey. By exploiting such a kind of meter-sized telescope mount, we get a device that is both capable of compensating for the apparent rotation of the celestial sphere and the same design can be used independently from the actual geographical location. Our construction is the sole currently operating hexapod telescope mount performing dedicated optical imaging survey with a sub-arcsecond tracking precision.