The dust complex G159.6–18.5 in the Perseus region has previously been observed with the COSMOSOMAS experiment on angular scales of ≈1°, and was found to exhibit anomalous microwave emission. We present the first high angular resolution observations of this dust complex, performed with the Very Small Array (VSA) at 33 GHz, to help increase the understanding of the nature of this anomalous emission. On the angular scales observed with the VSA (≈10–40 arcmin), G159.6–18.5 consists of five distinct components, all of which are found to exhibit an excess of emission at 33 GHz that is highly correlated with far‐infrared emission. Within the region, we find a range of physical conditions: one of the features, which is associated with the reflection nebula IC 348, has a dust emissivity comparable to that of H ii regions, while the other four features have values in agreement with previous observations of intermediate Galactic latitudes. We provide evidence that all of these compact components have anomalous emission that is consistent with electric dipole emission from very small, rapidly rotating dust grains. We find that these five components contribute ≈10 per cent to the flux density of the diffuse extended emission detected by COSMOSOMAS, implying that the bulk of the anomalous emission in Perseus is diffuse and not concentrated in these compact components.

We present resolved-star V I photometry of the Local Group dwarf irregular galaxy IC1613 reaching I ∼ 23.5, obtained with the wide-field camera at the 2.5 m Isaac Newton Telescope. A fit to the stellar density distribution shows an exponential profile of scale length 2. ′ 9 ± 0.1 and gives a central surface brightness µ V,0 = 22.7 ± 0.6. The significant number of red giant branch (RGB) stars present in the outer part of our images (r > 16. ′ 5) indicates that the galaxy is actually more extended than previously estimated. A comparison of the color-magnitude diagrams (CMDs) as a function of galactocentric distance shows a clear gradient in the age of its population, the scale length increasing with age, while we find no evidence of a metallicity gradient from the width of the RGB. We present quantitative results of the recent star formation history from a synthetic CMD analysis using IAC-STAR. We find a mean star formation rate of (1.6 ± 0.8) × 10 −3 M ⊙ yr −1 kpc −2 in the central r 2. ′ 5 for the last 300 Myr.

Context. The evolution of galaxies through cosmic time is studied observationally by means of extragalactic surveys. The usefulness of these surveys is greatly improved by increasing the cosmological volume, in either depth or area, and by observing the same targets in different wavelength ranges. A multi-wavelength approach using different observational techniques can compensate for observational biases. Aims. The OTELO survey aims to provide the deepest narrow-band survey to date in terms of minimum detectable flux and emission line equivalent width in order to detect the faintest extragalactic emission line systems. In this way, OTELO data will complements other broad-band, narrow-band, and spectroscopic surveys. Methods. The red tunable filter of the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC) is used to scan a spectral window centred at 9175 Å, which is free from strong sky emission lines, with a sampling interval of 6 Å and a bandwidth of 12 Å in the most deeply explored EGS region. Careful data reduction using improved techniques for sky ring subtraction, accurate astrometry, photometric calibration, and source extraction enables us to compile the OTELO catalogue. This catalogue is complemented with ancillary data ranging from deep X-ray to far-infrared, including high resolution HST images, which allow us to segregate the different types of targets, derive precise photometric redshifts, and obtain the morphological classification of the extragalactic objects detected. Results. The OTELO multi-wavelength catalogue contains 11 237 entries and is 50% complete at AB magnitude 26.38. Of these sources, 6600 have photometric redshifts with an uncertainty δ zphot better than 0.2 (1+zphot). A total of 4336 of these sources correspond to preliminary emission line candidates, which are complemented by 81 candidate stars and 483 sources that qualify as absorption line systems. The OTELO survey results will be released to the public on the second half of 2019.

Context. The OSIRIS Tunable Filter Emission Line Object (OTELO) survey is a very deep, blind exploration of a selected region of the Extended Groth Strip and is designed for finding emission-line sources (ELSs). The survey design, observations, data reduction, astrometry, and photometry, as well as the correlation with ancillary data used to obtain a final catalogue, including photo-z estimates and a preliminary selection of ELS, were described in a previous contribution. Aims. Here, we aim to determine the main properties and luminosity function (LF) of the [O III] ELS sample of OTELO as a scientific demonstration of its capabilities, advantages, and complementarity with respect to other surveys. Methods. The selection and analysis procedures of ELS candidates obtained using tunable filter pseudo-spectra are described. We performed simulations in the parameter space of the survey to obtain emission-line detection probabilities. Relevant characteristics of [O III] emitters and the LF ([O III]), including the main selection biases and uncertainties, are presented. Results. From 541 preliminary emission-line source candidates selected around z = 0.8, a total of 184 sources were confirmed as [O III] emitters. Consistent with simulations, the minimum detectable line flux and equivalent width in this ELS sample are ∼5 × 10−19 erg s−1 cm2 and ∼6 Å, respectively. We are able to constrain the faint-end slope (α = −1.03 ± 0.08) of the observed LF ([O III]) at a mean redshift of z = 0.83. This LF reaches values that are approximately ten times lower than those from other surveys. The vast majority (84%) of the morphologically classified [O III] ELSs are disc-like sources, and 87% of this sample is comprised of galaxies with stellar masses of M⋆ <  1010 M⊙.

We present follow-up observations of 97 point sources from the Wilkinson Microwave Anisotropy Probe (WMAP) 3-yr data, contained within the New Extragalactic WMAP Point Source catalogue between −4 • ≤ δ ≤ 60 • ; the sources form a flux-density-limited sample complete to 1.1 Jy (≈5σ ) at 33 GHz. Our observations were made at 16 GHz using the Arcminute Microkelvin Imager and at 33 GHz with the Very Small Array (VSA).94 of the sources have reliable, simultaneous -typically a few minutes apart -observations with both telescopes. The spectra between 13.9 and 33.75 GHz are very different from those of bright sources at low frequency: 44 per cent have rising spectra (α 33.75 13.9 < 0.0), where S ∝ ν −α , and 93 per cent have spectra with α 33.75 13.9 < 0.5; the median spectral index is 0.04. For the brighter sources, the agreement between VSA and WMAP 33-GHz flux densities averaged over sources is very good. However, for the fainter sources, the VSA tends to measure lower values for the flux densities than WMAP. We suggest that the main cause of this effect is the Eddington bias arising from variability.