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.

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A B S T R A C TWe have obtained deep optical spectra of the planetary nebula NGC 6153, both along its minor axis and by uniformly scanning a long slit across the whole nebula. The scanned spectra, when combined with the nebular total Hb flux, yield integrated fluxes for all the lines (,400) in our spectra, which are rich in strong recombination lines from C, N, O and Ne ions. A weak O vi l 3811 emission line from the central star has been detected, suggesting that the nucleus of NGC 6153 has a hydrogen-deficient surface. The optical data, together with the ISO LWS 43±197 mm spectrum and the archival IUE and IRAS LRS spectra, are used to study the thermal and density structure and to derive the heavy-element abundances from lines produced by different excitation mechanisms. In all cases, the C 21 aH 1 Y N 21 /H 1 , O 21 /H 1 and Ne 21 /H 1 abundances derived from multiple optical recombination lines (ORLs) are consistently higher, by about a factor of 10, than the corresponding values deduced from optical, UV or infrared (IR) collisionally excited lines (CELs), regardless of the excitation energies or critical densities of the latter. The agreement between the temperature-sensitive optical forbidden lines and the temperature-insensitive IR fine-structure lines rules out temperature fluctuations as the cause of the large difference between the ORL and CEL abundances.We present the results of a new calculation of recombination coefficients for [O ii] which lead to good agreement between the observed and predicted [O ii] ll7320, 7330 forbidden line intensities if these lines are solely excited by recombination at the Balmer jump temperature. Recombination excitation is also found to be important in exciting the [N ii] l 5754 line, which, if unaccounted for, would lead to an overestimated [N ii] temperature from the observed (l65481l 6584)/l 5754 ratio. Analysis of a number of C ii lines arising from levels as high as 7g in the recombination ladder reveals excellent agreement between their reddening-corrected relative intensities and those predicted by recombination theory. Spatial analysis of the long-slit spectra taken along the nebular minor axis yields a varying [O iii] temperature, whereas the hydrogen Balmer jump temperature of 6000 K is approximately constant across the nebula, and is 2000±3000 K lower than the [O iii] temperature. The observed high-n Balmer line decrement indicates that the hydrogen lines arise from material having an electron density of 2000 12000 21000 cm 23 , consistent with the optical and IR forbidden-line density diagnostics, which yield average line-of-sight electron densities along the minor axis varying between 2000 and 4000 cm 23 .While the He/H ratio mapped by He i and He ii recombination lines is constant within 5 per cent across the nebula, the C 21 /H 1 and O 21 /H 1 recombination-line abundances decrease by a factor of 2±3 over a radius of 15 arcsec from the centre, pointing to the presence of abundance gradients. We consider a variety of hypotheses to account for the observed b...

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The Isaac Newton Telescope (INT) Photometric Hα Survey of the Northern Galactic Plane (IPHAS) is a 1800‐deg2 CCD survey of the northern Milky Way spanning the latitude range −5° < b < + 5° and reaching down to r′≃ 20 (10σ). Representative observations and an assessment of point‐source data from IPHAS, now underway, are presented. The data obtained are Wide Field Camera images in the Hα narrow‐band, and Sloan r′ and i′ broad‐band filters. We simulate IPHAS (r′−Hα, r′−i′) point‐source colours using a spectrophotometric library of stellar spectra and available filter transmission profiles: this defines the expected colour properties of (i) solar metallicity stars, without Hα emission, and (ii) emission‐line stars. Comparisons with observations of fields in Aquila show that the simulations of normal star colours reproduce the observations well for all spectral types earlier than M. A further comparison between colours synthesized from long‐slit flux‐calibrated spectra and IPHAS photometry for six objects in a Taurus field confirms the reliability of the pipeline calibration. Spectroscopic follow‐up of a field in Cepheus shows that sources lying above the main stellar locus in the (r′− Hα, r′−i′) plane are confirmed to be emission‐line objects with very few failures. In this same field, examples of Hα deficit objects (a white dwarf and a carbon star) are shown to be readily distinguished by their IPHAS colours. The role IPHAS can play in studies of spatially resolved northern Galactic nebulae is discussed briefly and illustrated by a continuum‐subtracted mosaic image of Shajn 147 (a supernova remnant, 3° in diameter). The final catalogue of IPHAS point sources will contain photometry on about 80 million objects. Used on its own, or in combination with near‐infrared photometric catalogues, IPHAS is a major resource for the study of stellar populations making up the disc of the Milky Way. The eventual yield of new northern emission‐line objects from IPHAS is likely to be an order of magnitude increase on the number already known.

We report far-infrared and submillimeter observations of supernova 1987A, the star whose explosion was observed on 23 February 1987 in the Large Magellanic Cloud, a galaxy located 160,000 light years away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of about 17 to 23 kelvin at a rate of about 220 times the luminosity of the Sun. The intensity and spectral energy distribution of the emission suggest a dust mass of about 0.4 to 0.7 times the mass of the Sun. The radiation must originate from the supernova ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high redshifts.

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A B S T R A C TWe present deep, high-resolution optical spectra of two Galactic bulge planetary nebulae (PN), M 1-42 and M 2-36. The spectra show very prominent and rich optical recombination lines (ORLs) from C, N, O and Ne ions. Infrared spectra from 2:4-197 mm were also obtained using the Short and Long Wavelength Spectrometer (SWS and LWS) on board ISO. The optical and infrared spectra, together with archival IUE spectra, are used to study their density and thermal characteristics and to determine elemental abundances.We determine the optical and UV extinction curve towards these two bulge PN using observed H I and He II recombination line fluxes and the radio free -free continuum flux density. In the optical, the reddening curve is found to be consistent with the standard Galactic extinction law, with a total to selective extinction ratio R ; AðVÞ/ EðB 2 VÞ ¼ 3:1. However, the extinction in the UV is found to be much steeper, consistent with the earlier finding of Walton, Barlow & Clegg.The rich ORL spectra from C, N, O and Ne ions detected from the two nebulae have been used to determine the abundances of these elements relative to hydrogen. In all cases, the resultant ORL abundances are found to be significantly higher than the corresponding values deduced from collisionally excited lines (CELs). In M 2-36, the discrepancies are about a factor of 5 for all four elements studied. In M 1-42, the discrepancies reach a factor of about 20, the largest ever observed in a PN. M 1-42 also has the lowest Balmer jump temperature ever determined for a PN, T e ðBJÞ ¼ 3560 K, 5660 K lower than its [O III] forbidden line temperature.We compare the observed intensities of the strongest O II ORLs from different electronic configurations, including l4649 from 3s-3p, l4072 from 3p-3d, l4089 from 3d-4f, and l4590 and l4190 from the doubly excited 3s 0 -3p 0 and 3p 0 -3d 0 configurations, respectively. In all cases, in spite of the fact that the ratios of the ORL to CEL ionic abundances span a wide range from ,5-20, the intensity ratios of l4649, l4072, l4590 and l4190 relative to l4089 are found to be nearly constant, apart from some small monotonic increase of these ratios as a function of electron temperature. Over a range of Balmer jump temperature from 3500-8100 K, the variations amount to about 20 per cent for the 3s-3p and 3p-3d transitions and a factor of 2 for the primed transitions, and are consistent with the predictions of the current recombination theory. Our results do not support the claim by Dinerstein, Lafon & Garnett that the relative intensities of O II ORLs vary from nebula to nebula and that the scatter is largest in objects where the discrepancies between ORL and CEL abundances are also the largest.We find that the ORL to CEL abundance ratio is highly correlated with the difference between the temperatures yielded by the [O III] forbidden line ratio and by the H I Balmer jump, providing the strongest evidence so far that the two phenomena, i.e. the disparity between ORL and CEL temperature and abundance ...