The Spectral and Photometric Imaging REceiver (SPIRE), is the Herschel Space Observatory's submillimetre camera and spectrometer. It contains a three-band imaging photometer operating at 250, 350 and 500 μm, and an imaging Fourier-transform spectrometer (FTS) which covers simultaneously its whole operating range of 194-671 μm (447-1550 GHz). The SPIRE detectors are arrays of feedhorn-coupled bolometers cooled to 0.3 K. The photometer has a field of view of 4 × 8 , observed simultaneously in the three spectral bands. Its main operating mode is scan-mapping, whereby the field of view is scanned across the sky to achieve full spatial sampling and to cover large areas if desired. The spectrometer has an approximately circular field of view with a diameter of 2.6 . The spectral resolution can be adjusted between 1.2 and 25 GHz by changing the stroke length of the FTS scan mirror. Its main operating mode involves a fixed telescope pointing with multiple scans of the FTS mirror to acquire spectral data. For extended source measurements, multiple position offsets are implemented by means of an internal beam steering mirror to achieve the desired spatial sampling and by rastering of the telescope pointing to map areas larger than the field of view. The SPIRE instrument consists of a cold focal plane unit located inside the Herschel cryostat and warm electronics units, located on the spacecraft Service Module, for instrument control and data handling. Science data are transmitted to Earth with no on-board data compression, and processed by automatic pipelines to produce calibrated science products. The in-flight performance of the instrument matches or exceeds predictions based on pre-launch testing and modelling: the photometer sensitivity is comparable to or slightly better than estimated pre-launch, and the spectrometer sensitivity is also better by a factor of 1.5-2. Key words. instrumentation: photometers -instrumentation: spectrographs -space vehicles: instruments -submillimeter: generalHerschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Using the 3.5-m Herschel Space Observatory, imaging photometry of Cas A has been obtained in six bands between 70 and 500 μm with the PACS and SPIRE instruments, with angular resolutions ranging from 6 to 37 . In the outer regions of the remnant the 70-μm PACS image resembles the 24-μm image Spitzer image, with the emission attributed to the same warm dust component, located in the reverse shock region. At longer wavelengths, the three SPIRE bands are increasingly dominated by emission from cold interstellar dust knots and filaments, particularly across the central, western and southern parts of the remnant. Nonthermal emission from the northern part of the remnant becomes prominent at 500 μm. We have estimated and subtracted the contributions from the nonthermal, warm dust and cold interstellar dust components. We confirm and resolve for the first time a cool (∼35 K) dust component, emitting at 70−160 μm, that is located interior to the reverse shock region, with an estimated mass of 0.075 M .

The discovery with the Herschel Space Observatory of bright far infrared and submm emission from the ejecta of the core collapse supernova SN 1987A has been interpreted as indicating the presence of some 0.4-0.7 M of dust. We have constructed radiative transfer models of the ejecta to fit optical to far-infrared observations from the literature at epochs between 615 days and 24 years after the explosion, to determine when and where this unexpectedly large amount of dust formed.We find that the observations by day 1153 are consistent with the presence of 3×10 −3 M of dust. Although this is a larger amount than has previously been considered possible at this epoch, it is still very small compared to the amount present in the remnant after 24 years, and significantly higher dust masses at the earlier epochs are firmly ruled out by the observations, indicating that the majority of the dust must have formed at very late times. By 8515-9200 days after the explosion, 0.6-0.8 M of dust is present, and dust grains with radii greater than 2 µm are required to obtain a fit to the observed SED. This suggests that the dust mass increase at late times was caused by accretion onto and coagulation of the dust grains formed at earlier epochs.These findings provide further confirmation that core collapse supernovae can create large quantities of dust, and indicate that the reason for small dust masses being estimated in many cases is that the vast majority of the dust forms long after most supernovae have been detectable at mid-infrared wavelengths.

The VST Photometric Hα Survey of the Southern Galactic Plane and Bulge (VPHAS+) is surveying the southern Milky Way in u, g, r, i and Hα at ∼1 arcsec angular resolution. Its footprint spans the Galactic latitude range −5 o < b < +5 o at all longitudes south of the celestial equator. Extensions around the Galactic Centre to Galactic latitudes ±10 • bring in much of the Galactic Bulge. This ESO public survey, begun on 28th December 2011, reaches down to ∼20th magnitude (10σ) and will provide single-epoch digital optical photometry for ∼300 million stars. The observing strategy and data pipelining is described, and an appraisal of the segmented narrowband Hα filter in use is presented. Using model atmospheres and library spectra, we compute main-sequence (u − g), (g − r), (r − i) and (r − Hα) stellar colours in the Vega system. We report on a preliminary validation of the photometry using test data obtained from two pointings overlapping the Sloan Digital Sky Survey. An example of the (u − g, g − r) and (r − Hα, r − i) diagrams for a full VPHAS+ survey field is given. Attention is drawn to the opportunities for studies of compact nebulae and nebular morphologies that arise from the image quality being achieved. The value of the u band as the means to identify planetary-nebula central stars is demonstrated by the discovery of the central star of NGC 2899 in survey data. Thanks to its excellent imaging performance, the VST/OmegaCam combination used by this survey is a perfect vehicle for automated searches for reddened early-type stars, and will allow the discovery and analysis of compact binaries, white dwarfs and transient sources.

We present deep optical spectra of 23 galactic planetary nebulae, which are analysed in conjunction with archival infrared and ultraviolet spectra. We derive nebular electron temperatures based on standard collisionally excited line (CEL) diagnostics as well as the hydrogen Balmer jump and find that, as expected, the Balmer jump almost always yields a lower temperature than the [O III] nebular-to-auroral line ratio. We also make use of the weak temperature dependence of helium and O II recombination line ratios to further investigate the temperature structure of the sample nebulae. We find that, in almost every case, the derived temperatures follow the relation T e (CEL)T e (BJ) T e (He I) T e (O II), which is the relation predicted by two-component nebular models in which one component is cold and hydrogen-deficient. T e (O II) may be as low as a few hundred Kelvin, in line with the low temperatures found for the hydrogen-deficient knots of Abell 30 by Wesson, Liu and Barlow.Elemental abundances are derived for the sample nebulae from both CELs and optical recombination lines (ORLs). ORL abundances are higher than CEL abundances in every case, by factors ranging from 1.5 to 12. Five objects with O 2+ abundance discrepancy factors greater than 5 are found. DdDm 1 and Vy 2-2 are both found to have a very large abundance discrepancy factor of 11.8.We consider the possible explanations for the observed discrepancies. From the observed differences between T e (O III) and T e (BJ), we find that temperature fluctuations cannot resolve the abundance discrepancies in 22 of the 23 sample nebulae, implying some additional mechanism for enhancing ORL emission. In the one ambiguous case, the good agreement between abundances derived from temperature-insensitive infrared lines and temperature-sensitive optical lines also points away from temperature fluctuations being present. The observed recombination line temperatures, the large abundance discrepancies and the generally good agreement between infrared and optical CEL abundances all suggest instead the existence of a cold hydrogen-deficient component within the 'normal' nebular gas. The origin of this component is as yet unknown.

We have analysed optical spectra of two of the hydrogen-deficient knots (J1 & J3) in the born-again planetary nebula Abell 30, together with UV spectra of knots J3 & J4. We determine electron temperatures in the knots based on several diagnostics. The [O III] nebular-to-auroral transition ratio yields temperatures of the order of 17 000 K. The weak temperature dependence of the ratios of helium lines at 4471, 5876 and 6678 Angstroms is used to derive a temperature of 8850 K for knot J3 and 4600 K for knot J1. Ratios of O II recombination lines, which directly measure the temperature in the coldest regions of the knots, are used to derive temperatures of 2500 K for knot J3, and just 500 K for knot J1. We calculate abundances both from collisionally excited lines and from the well-observed recombination spectra of C, N, O and Ne ions. The forbidden line abundances agree well with previous determinations, but the recombination line abundances are several hundred times higher. These results confirm the scenario proposed by Harrington and Feibelman (1984) in which the knots contain a cold core highly enriched in heavy elements. Forbidden lines are almost entirely emitted by the hot outer part of the knot, while recombination lines are emitted predominantly from the cold core. The C/O ratios we derive imply that the knots are oxygen-rich, contrary to theoretical predictions for born-again nebulae (Iben et al 1983).Comment: 11 pages, no figure

Theoretical models predict that core-collapse supernovae (CCSNe) can be efficient dust producers (0.1-1.0 M ), potentially accounting for most of the dust production in the early Universe. Observational evidence for this dust production efficiency is however currently limited to only a few CCSN remnants (e.g., SN 1987A, Crab Nebula). In this paper, we revisit the dust mass produced in Cassiopeia A (Cas A), a ∼330-year old Orich Galactic supernova remnant (SNR) embedded in a dense interstellar foreground and background. We present the first spatially resolved analysis of Cas A based on Spitzer and Herschel infrared and submillimetre data at a common resolution of ∼0.6 for this 5 diameter remnant following a careful removal of contaminating line emission and synchrotron radiation. We fit the dust continuum from 17 to 500 µm with a fourcomponent interstellar medium (ISM) and supernova (SN) dust model. We find a concentration of cold dust in the unshocked ejecta of Cas A and derive a mass of 0.3-0.5 M of silicate grains freshly produced in the SNR, with a lower limit of ≥0.1-0.2 M . For a mixture of 50% of silicate-type grains and 50% of carbonaceous grains, we derive a total SN dust mass between 0.4 M and 0.6 M . These dust mass estimates are higher than from most previous studies of Cas A and support the scenario of supernova dominated dust production at high redshifts. We furthermore derive an interstellar extinction map for the field around Cas A which towards Cas A gives average values of A V = 6-8 mag, up to a maximum of A V = 15 mag.

We present new Herschel photometric and spectroscopic observations of Supernova 1987A, carried out in 2012. Our dedicated photometric measurements provide new 70 µm data and improved imaging quality at 100 and 160 µm compared to previous observations in 2010. Our Herschel spectra show only weak CO line emission, and provide an upper limit for the 63 µm [O i] line flux, eliminating the possibility that line contaminations distort the previously estimated dust mass. The far-infrared spectral energy distribution (SED) is well fitted by thermal emission from cold dust. The newly measured 70 µm flux constrains the dust temperature, limiting it to nearly a single temperature. The far-infrared emission can be fitted by 0.5±0.1 M of amorphous carbon, about a factor of two larger than the current nucleosynthetic mass prediction for carbon. The observation of SiO molecules at early and late phases suggests that silicates may also have formed and we could fit the SED with a combination of 0.3 M of amorphous carbon and 0.5 M of silicates, totalling 0.8 M of dust. Our analysis thus supports the presence of a large dust reservoir in the ejecta of SN 1987A. The inferred dust mass suggests that supernovae can be an important source of dust in the interstellar medium, from local to high-redshift galaxies.