We present high resolution MERLIN radio images of multiple relativistic ejections from GRS 1915+105 in 1997 October / November. The observations were made at a time of complex radio behaviour, corresponding to multiple optically-thin outbursts and several days of rapid radio flux oscillations. The radio imaging resolved four major ejection events from the system. As previously reported from earlier VLA observations of the source, we observe apparent superluminal motions resulting from intrinsically relativistic motions of the ejecta. However, our measured proper motions are significantly greater than those observed on larger angular scales with the VLA. Under the assumption of an intrinsically symmetric ejection, we can place an upper limit on the distance to GRS 1915+105 of 11.2 +/- 0.8 kpc. Solutions for the velocities unambiguously require a higher intrinsic speed by about 0.1c than that derived from the earlier VLA observations, whilst the angle to the line-of-sight is not found to be significantly different. At a distance of 11 kpc, we obtain solutions of v = 0.98 (-0.05,+0.02)c and theta = 66 +/- 2 degrees. The jet also appears to be curved on a scale which corresponds to a period of around 7 days. We observe significant evolution of the linear polarisation of the approaching component, with large rotations in position angle and a general decrease in fractional polarisation. The power input into the formation of the jet is very large, >10^38 erg/s at 11 kpc for a pair plasma. If the plasma contains a cold proton for each electron, then the mass outflow rate, >10^18 g/sec is comparable to inflow rates previously derived from X-ray spectral fits.Comment: 14 pages, 7 figures. Accepted for publication in MNRA

Abstract. Here we discuss two consecutive MERLIN observations of the X-ray binary LS I +61• 303. The first observation shows a double-sided jet extending up to about 200 AU on both sides of a central source. The jet shows a bent S-shaped structure similar to the one displayed by the well-known precessing jet of SS 433. The precession suggested in the first MERLIN image becomes evident in the second one, showing a one-sided bent jet significantly rotated with respect to the jet of the day before. We conclude that the derived precession of the relativistic (β = 0.6) jet explains puzzling previous VLBI results. Moreover, the fact that the precession is fast could be the explanation of the never understood short term (days) variability of the associated gamma-ray source 2CG 135+01/3EG J0241+6103.

We have studied the 1999 soft X‐ray transient outburst of XTE J1859+226 at radio and X‐ray wavelengths. The event was characterized by strong variability in the disc, corona and jet – in particular, a number of radio flares (ejections) took place and seemed well‐correlated with hard X‐ray events. Apparently unusual for the canonical‘soft’ X‐ray transient, there was an initial period of low/hard state behaviour during the rise from quiescence but prior to the peak of the main outburst – we show that not only could this initial low/hard state be a ubiquitous feature of soft X‐ray transient outbursts, but also it could be extremely important in our study of outburst mechanisms.

The CORNISH project is the highest resolution radio continuum survey of the Galactic plane to date. It is the 5 GHz radio continuum part of a series of multi-wavelength surveys that focus on the northern GLIMPSE region (10 • < l < 65 • ), observed by the Spitzer satellite in the mid-infrared. Observations with the Karl G. Jansky Very Large Array (VLA) in B and BnA configurations have yielded a 1.5 ′′ resolution Stokes I map with a root-mean-squared noise level better than 0.4 mJy beam −1 . Here we describe the data-processing methods and data characteristics, and present a new, uniform catalogue of compact radioemission. This includes an implementation of automatic deconvolution that provides much more reliable imaging than standard CLEANing. A rigorous investigation of the noise characteristics and reliability of source detection has been carried out. We show that the survey is optimised to detect emission on size scales up to 14 ′′ and for unresolved sources the catalogue is more than 90 percent complete at a flux density of 3.9 mJy. We have detected 3,062 sources above a 7σ detection limit and present their ensemble properties. The catalogue is highly reliable away from regions containing poorly-sampled extended emission, which comprise less than two percent of the survey area. Imaging problems have been mitigated by downweighting the shortest spacings and potential artefacts flagged via a rigorous manual inspection with reference to the Spitzer infrared data. We present images of the most common source types found: H II regions, planetary nebulae and radio-galaxies. The CORNISH data and catalogue are available online at http://cornish.leeds.ac.uk.Note.-The properties of the data differ in the combination of antenna types included in the array, the configuration of the array, the weather experienced and the declination range observed. Unless otherwise noted the weather during the observations was reasonable.

Abstract. We present deep, wide-field European VLBI Network (EVN) 1.6 GHz observations of the Hubble Deep Field (HDF) region with a resolution of 0.025 arcseconds. Above the 210 µJy/beam (5σ) detection level, the EVN clearly detects two radio sources in a field that encompasses the HDF and part of the Hubble Flanking Fields (HFF). The sources detected are: VLA J123644+621133 (a z=1.013, low-luminosity FR-I radio source located within the HDF itself) and VLA J123642+621331 (a dust enshrouded, optically faint, z=4.424 starburst system). A third radio source, J123646+621404, is detected at the 4σ level. The VLBI detections of all three sources suggest that most of the radio emission of these particular sources (including the dusty starburst) is generated by an embedded AGN.

We have obtained Hubble Space T elescope (HST ) Space Telescope Imaging Spectrometer highresolution spectra of the Orion proplyd LV 2 in the C III doublet at 1906.68 and 1908.73 New images A . at the 6 cm wavelength with MERLIN complement earlier HST images at a similar spatial resolution. This object is one of the closest proplyds to h1 Ori C, the source of the photoionizing and photoevaporating radiation. Combining the spectra with the HST images and detailed theoretical models has allowed a determination of the mass-loss rate as 8.2 ] 10~7yr~1^10%. This rate of mass loss is M _ used to address the conundrum of the continued existence of proplyds. Even though they should be photoevaporated in only about 105 yr, there is no evidence for their destruction. It is concluded that the only explanation is that the age of h1 Ori C is less than 105 yr. These spectra and previously unpublished ground-based spectra in [O III] also show the presence of a monopolar microjet, redshifted by about 100 km s~1 with respect to the systemic velocity. This jet is more visible in the 6 cm MERLIN images than in HST images, and this image together with the spectra are used to determine the Ñow parameters for the jet. Our spectra also include the stand-o † shock that lies between LV 2 and h1 Ori C. This is the result of the high-velocity wind coming from the hot star h1 Ori C with the low-velocity wind coming from the proplyd. As expected, this shock is at rest with respect to the two objects.

A B S T R A C TObservations of the starburst galaxy, M82, have been made with a 20-station global very long-baseline interferometry (VLBI) array at l 18 cm. Maps are presented of the brightest young supernova remnants (SNR) in M82 and the wide-field mapping techniques used in making images over a field of view of ,1 arcmin with 3-milliarcsecond resolution are discussed. A limit has been placed on the power-law deceleration of the young supernova remnant (SNR) 43.311592 with an index greater than 0X73^0X11 from observations with the European VLBI Network. Using the global array we have resolved compact knots of radio emission in the source which, with future global observations, will enable better constraints to be placed on the expansion parameters of this SNR.The latest global observations have also provided high-resolution images of the most compact radio source in M82, 41.951575. We determine an upper limit to the radial expansion rate along the major axis of 2000 km s 21 . However, the new images also show structure resembling that of collimated ejection which brings into question the previous explanation of the source as being a result of the confinement of a supernova by a highdensity circumstellar medium.It is apparent that we are now able to image the brightest supernova remnants in M82 with a linear scale which allows direct comparison with galactic SNR such as Cassiopeia A.

In this paper, we investigate the radio‐mid‐infrared (MIR) correlation at very low flux densities using extremely deep 1.4‐GHz subarcsec angular resolution Multi‐Element Radio‐Linked Interferometer + Very Large Array observations of a field centred upon the Hubble Deep Field‐North, in conjunction with Spitzer 24‐μm data. From these results, the MIR‐radio correlation is extended to the very faint (∼μJy) radio source population. Tentatively, we detect a small deviation from the correlation at the faintest infrared flux densities. We suggest that this small observed change in the gradient of the correlation is the result of a suppression of the MIR emission in faint star‐forming galaxies. This deviation potentially has significant implications for using either the MIR or non‐thermal radio emission as a star formation tracer of very low luminosity galaxies.