Context. AKARI is the first Japanese astronomical satellite dedicated to infrared astronomy. One of the main purposes of AKARI is the all-sky survey performed with six infrared bands between 9 μm and 200 μm during the period from 2006 May 6 to 2007 August 28. In this paper, we present the mid-infrared part (9 μm and 18 μm bands) of the survey carried out with one of the on-board instruments, the infrared camera (IRC). Aims. We present unprecedented observational results of the 9 μm and 18 μm AKARI all-sky survey and detail the operation and data processing leading to the point source detection and measurements. Methods. The raw data are processed to produce small images for every scan, and the point sources candidates are derived above the 5σ noise level per single scan. The celestial coordinates and fluxes of the events are determined statistically and the reliability of their detections is secured through multiple detections of the same source within milli-seconds, hours, and months from each other. Results. The sky coverage is more than 90% for both bands. A total of 877 091 sources (851 189 for 9 μm, 195 893 for 18 μm) are confirmed and included in the current release of the point source catalog. The detection limit for point sources is 50 mJy and 90 mJy for the 9 μm and 18 μm bands, respectively. The position accuracy is estimated to be better than 2 . Uncertainties in the in-flight absolute flux calibration are estimated to be 3% for the 9 μm band and 4% for the 18 μm band. The coordinates and fluxes of detected sources in this survey are also compared with those of the IRAS survey and are found to be statistically consistent.

Aims. We compare the observed and theoretical parameters for the quiescent and outburst phases of the recurring nova T Pyx. Methods. IUE data were used to derive the disk luminosity and the mass accretion rate, and to exclude the presence of quasi-steady burning at the WD surface. XMM-NEWTON data were used to verify this conclusion.. These values were about twice as high in the pre-1966-outburst epoch. This allowed the first direct estimate of the total mass accreted before outburst, M accr =Ṁ pre−OB ·Δt, and its comparison with the critical ignition mass M ign . We found M accr and M ign to be in perfect agreement (with a value close to 5 × 10 −7 M ) for M 1 ∼ 1.37 M , which provides a confirmation of the thermonuclear runaway theory. The comparison of the observed parameters of the eruption phase, with the corresponding values in the grid of models by Yaron and collaborators, provides satisfactory agreement for values of M 1 close to 1.35 M and logṀ between −8.0 and −7.0, but the observed value of the decay time t 3 is higher than expected. The long duration of the optically thick phase during the recorded outbursts of T Pyx, a spectroscopic behavior typical of classical novae, and the persistence of P Cyg profiles, constrains the ejected mass M ign to within 10 −5 −10 −4 M . Therefore, T Pyx ejects far more material than it has accreted, and the mass of the white dwarf will not increase to the Chandrasekhar limit as generally believed in recurrent novae. A detailed study based on the UV data excludes the possibility that T Pyx belongs to the class of the supersoft X-ray sources, as has been postulated. XMM-NEWTON observations have revealed a weak, hard source and confirmed this interpretation.

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Abstract. In the framework of a phenomenological study of the ultraviolet properties of classical novae in outburst, we have selected 12 objects among the best monitored at low resolution with the IUE satellite, and studied the temporal evolution of the ultraviolet continuum and of the O i 1300Å line flux during the early post-outburst phase. We confirm that the UV flux maximum takes place systematically after the visual maximum and that its time delay is a linear function of t3. A linear dependence on t3 is also found for the duration of the UV outburst and for the time the O i line flux reaches a maximum. This latter time marks the start of the transition phase to nebular conditions. Within the uncertainties imposed by the sample of objects used and by the observational errors, these results suggest a quite homogeneous behaviour of classical novae in the ultraviolet range.

We present a unified model of infrared (IR), optical, ultraviolet (UV ), and X-ray light curves for the 1983 outburst of GQ Muscae (Nova Muscae 1983) and estimate its white dwarf (WD) mass. Based on an optically thick wind model of nova outbursts, we model the optical and IR light curves with free-free emission, and the UV 1455 8 and supersoft X-ray light curves with blackbody emission. The best-fit model that simultaneously reproduces the IR, optical, UV 1455 8, and supersoft X-ray observations is a 0:7 AE 0:05 M WD with an assumed chemical composition of the envelope of X ¼ 0:35Y0:55, X CNO ¼ 0:2Y0:35, and Z ¼ 0:02 by mass weight. The mass lost by the wind is estimated to be ÁM wind $ 2 ; 10 À5 M . We provide a new determination of the reddening, E(B À V ) ¼ 0:55 AE 0:05, and of the distance, $5 kpc. Finally, we discuss the strong UV flash that took place on JD 2,445,499 (151 days after the outburst).

The presence of narrow high-temperature emission lines from nitrogen-rich gas close to SN 1987A has been a principal observational constraint on the evolutionary status of the supernova's progenitor. A new analysis of the complete five-year set of low and high resolution IUE ultraviolet spectra of SN 1987A (1987SN 1987A ( .2-19923) provide fluxes for the N V λ1240, N IV] λ1486, He II λ1640, O III] λ1665, N III] λ1751, and C III] λ1908 lines with significantly reduced random and systematic errors and reveals significant short-term fluctuations in the light curves. The N V , N IV] , and N III] lines turn on sequentially over 15 to 20 days and show a progression from high to low ionization potential, implying an ionization gradient in the emitting region. The line emission turns on suddenly at 83 ± 4 days after the explosion, as defined by N IV] . The N III] line reaches peak luminosity at 399 ± 15 days. A ring radius of (6.24 ± 0.20) × 10 17 cm and inclination of 41. • 0 ± 3. • 9 is derived from these times, assuming a circular ring. The probable role of resonant scattering in the N V light curve introduces -2systematic errors that leads us to exclude this line from the timing analysis. A new nebular analysis yields improved CNO abundance ratios of N/C= 6.1 ± 1.1 and N/O= 1.7 ± 0.5, confirming the nitrogen enrichment found in our previous paper. From the late-time behavior of the light curves we find that the emission originates from progressively lower density gas and that the emitting region has a multi-component density structure. We estimate the emitting mass near maximum (∼ 400 days) to be ∼ 4.7 × 10 −2 M ⊙ , assuming a filling factor of unity and an electron density of 2.6 × 10 4 cm −3 . These results are discussed in the context of current models for the emission and hydrodynamics of the ring.