Context. Over the last decade a series of results have lent support to the hypothesis of the existence of a long thin bar in the Milky Way with a half-length of 4.5 kpc and a position angle of around 45• . This is apparently a very different structure from the triaxial bulge of the Galaxy. Aims. In this paper, we analyse the stellar distribution in the inner 4 kpc of the Galaxy to see if there is clear evidence for two triaxial or barlike structures, or whether there is only one. Methods. By using the red-clump population as a tracer of the structure of the inner Galaxy we determine the apparent morphology of the inner Galaxy. Star counts from 2MASS are used to provide additional support for this analysis. Results. We show that there are two very different large-scale triaxial structures coexisting in the inner Galaxy: a long thin stellar bar constrained to the Galactic plane (|b| < 2• ) with a position angle of 43.• 0 ± 1.• 8, and a distinct triaxial bulge that extends to at least |b| ≤ 7.5• with a position angle of 12.• 6 ± 3.• 2. The scale height of the bar source distribution is around 100 pc, whereas for the bulge the value of this parameter is five times larger.

Long-duration γ-ray bursts (GRBs) at z < 1 are in most cases found to be accompanied by bright, broad-lined Type Ic supernovae (SNe Ic-BL). The highestenergy GRBs are mostly located at higher redshifts, where the associated SNe are hard to detect observationally. Here we present early and late observations of

We present colour transformations for the conversion of the Two Micron All Sky Survey (2MASS) photometric system to the Johnson–Cousins UBVRI system and further into the Sloan Digital Sky Survey (SDSS) ugriz system. We have taken SDSS gri magnitudes of stars measured with the 2.5‐m telescope from SDSS Data Release 5 (DR5), and BVRI and JHKs magnitudes from Stetson's catalogue and Cutri et al., respectively. We matched thousands of stars in the three photometric systems by their coordinates and obtained a homogeneous sample of 825 stars by the following constraints, which are not used in previous transformations: (1) the data are dereddened, (2) giants are omitted and (3) the sample stars selected are of the highest quality. We give metallicity, population type and transformations dependent on two colours. The transformations provide absolute magnitude and distance determinations which can be used in space density evaluations at short distances where some or all of the SDSS ugriz magnitudes are saturated. The combination of these densities with those evaluated at larger distances using SDSS ugriz photometry will supply accurate Galactic model parameters, particularly the local space densities for each population.

The dust ejecta of Main-Belt Comet P/2010 A2 (LINEAR) have been observed with several telescopes at the at the Observatorio del Roque de los Muchachos on La Palma, Spain. Application of an inverse dust tail Monte Carlo method to the images of the dust ejecta from the object indicates that a sustained, likely water-ice driven, activity over some eight months is the mechanism responsible for the formation of the observed tail. The total amount of dust released is estimated to be 5×10 7 kg, which represents about 0.3% of the nucleus mass. While the event could have been triggered by a collision, this cannot be decided from the currently available data.

Context. Asteroid (6478) Gault was discovered to exhibit a comet-like tail in observations from December 2018, becoming a new member of the so-called active asteroid population in the main asteroid belt. Aims. The aims are to investigate the grain properties of the dust ejected from asteroid (6478) Gault and to give insight into the activity mechanism(s). Methods. We use a Monte Carlo dust tail brightness code to retrieve the dates of dust ejection, the physical properties of the grains, and the total dust mass losses during each event. The code takes into account the brightness contribution of the asteroid itself. The model is applied to a large data set of images spanning the period from January 11, 2019 to March 13, 2019. In addition, both shortand long-term photometric measurements of the asteroid have been carried out. Results. It is shown that, to date, asteroid (6478) Gault has experienced two episodes of impulsive dust ejection, that took place around 2018 November 5 and 2019 January 2, releasing at least 1.4×10 7 kg and 1.6 ×10 6 kg of dust, respectively, at escape speeds. The size distribution, consisting of particles in the 1 µm to 1 cm radius range, follows a broken power-law with bending points near 15 µm and 870 µm. On the other hand, the photometric series indicate a nearly constant magnitude over several 5-7.3 h periods, a possible effect of the masking of a rotational lightcurve by the dust. Conclusions. The dust particles forming Gault's tails were released from the asteroid at escape speeds, but the specific ejection mechanism is unclear until photometry of the dust-free asteroid are conducted, in order to assess whether this was related to rotational disruption or to other possible causes.