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The Near-Infrared Spectrograph (NIRSpec) is one of the four focal plane instruments on the James Webb Space Telescope. In this paper, we summarize the in-orbit performance of NIRSpec, as derived from data collected during its commissioning campaign and the first few months of nominal science operations. More specifically, we discuss the performance of some critical hardware components such as the two NIRSpec Hawaii-2RG detectors, wheel mechanisms, and the microshutter array. We also summarize the accuracy of the two target acquisition procedures used to accurately place science targets into the slit apertures, discuss the current status of the spectrophotometric and wavelength calibration of NIRSpec spectra, and provide the “as measured” sensitivity in all NIRSpec science modes. Finally, we point out a few important considerations for the preparation of NIRSpec science programs.

We have used the new extended A configuration of the IRAM Plateau de Bure interferometer to study the dense molecular gas in the nucleus of the nearby spiral galaxy NGC 6946 at unprecedented spatial resolution in the HCN(1–0) and 12CO(2–1) lines. The gas distribution in the central 50 pc has been resolved and is consistent with a gas ring or spiral driven by the inner 400 pc long stellar bar. For the first time, it is possible to directly compare the location of (dense) giant molecular clouds with that of (optically) visible HII regions in space-based images. We use the 3 mm continuum and the HCN emission to estimate in the central 50 pc the star formation rates in young clusters that are still embedded in their parent clouds and hence are missed in optical and near-IR surveys of star formation. The amount of embedded star formation is about 1.6 times as high as that measured from HII regions alone, and appears roughly evenly split between ongoing dust-obscured star formation and very young giant molecular cloud cores that are just beginning to form stars. The build-up of central mass seems to have continued over the past ≥10 Myr, to have occurred in an extended (albeit small) volume around the nucleus, and to be closely related to the presence of an inner bar.

Context. The morphology of massive star formation in the central regions of galaxies is an important tracer of the dynamical processes that govern the evolution of disk, bulge, and nuclear activity. Aims. We present optical imaging of the central regions of a sample of 73 spiral galaxies in the Hαline and in optical broad bands, and derive information on the morphology of massive star formation. Methods. We obtained images with the William Herschel Telescope, mostly at a spatial resolution of below one second of arc. For most galaxies, no Hαimaging is available in the literature. We outline the observing and data reduction procedures, list basic properties, and present the I-band and continuum-subtracted Hαimages. We classify the morphology of the nuclear and circumnuclear Hαemission and explore trends with host galaxy parameters. Results. We confirm that late-type galaxies have a patchy circumnuclear appearance in Hα, and that nuclear rings occur primarily in spiral types Sa-Sbc. We identify a number of previously unknown nuclear rings, and confirm that nuclear rings are predominantly hosted by barred galaxies. Conclusions. Other than in stimulating nuclear rings, bars do not influence the relative strength of the nuclear Hαpeak, nor the circumnuclear Hαmorphology. Even considering that our selection criteria led to an over-abundance of galaxies with close massive companions, we do not find anysignificant influence of the presence or absence of a close companion on the relative strength of the nuclear Hαpeak, nor on the Hαmorphology around the nucleus.

Using the IRAM $30\>{\rm m}$telescope, we have surveyed an unbiased sample of 47 nearby spiral galaxies of very late (Scd-Sm) Hubble-type for emission in the $\rm ^{12}CO(1{-}0)$and $(2{-}1)$lines. The sensitivity of our data (a few mK) allows detection of about 60% of our sample in at least one of the CO lines. The median detected $\rm H_2$mass is $1.4\times 10^7\>{M_{\odot}}$within the central few kpc, assuming a standard conversion factor. We use the measured line intensities to complement existing studies of the molecular gas content of spiral galaxies as a function of Hubble-type and to significantly improve the statistical significance of such studies at the late end of the spiral sequence. We find that the latest-type spirals closely follow the correlation between molecular gas content and galaxy luminosity established for earlier Hubble types. The molecular gas in late-type galaxies seems to be less centrally concentrated than in earlier types. We use Hubble Space Telescopeoptical images to correlate the molecular gas mass to the properties of the central galaxy disk and the compact star cluster that occupies the nucleus of most late-type spirals. There is no clear correlation between the luminosity of the nuclear star cluster and the molecular gas mass, although the CO detection rate is highest for the brightest clusters. It appears that the central surface brightness of the stellar disk is an important parameter for the amount of molecular gas at the galaxy center. Whether stellar bars play a critical role for the gas dynamics remains unclear, in part because of uncertainties in the morphological classifications of our sample.

MIRI (the Mid-Infrared Instrument for the James Webb Space Telescope[JWST]) operates from 5 to 28.5 ?m and combines over this range: (1) unprecedented sensitivity levels; (2) subarcsecond angular resolution; (3) freedom from atmospheric interference; (4) the inherent stability of observing in space; and (5) a suite of versatile capabilities including imaging, low- and medium-resolution spectroscopy (with an integral field unit), and coronagraphy. We illustrate the potential uses of this unique combination of capabilities with various science examples: (1) imaging exoplanets; (2) transit and eclipse spectroscopy of exoplanets; (3) probing the first stages of star and planet formation, including identifying bioactive molecules; (4) determining star formation rates and mass growth as galaxies are assembled; and (5) characterizing the youngest massive galaxies.

We summarize the results of a monitoring program which was executed following the cryogen exhaustion of the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on board the Hubble Space Telescope. During the subsequent warm-up, detector parameters such as detective quantum efficiency, dark current, bias offsets, and saturation levels have been measured over the temperature range 62 K to about 100 K. The measurements provide a unique database of the characteristics of PACE-I HgCdTe detector arrays in the space environment. A surprising result of the analysis is the fact that all three NICMOS detectors showed an enhanced dark current in the temperature range between 77 and 85 K. However, a subsequent laboratory experiment designed to replicate the on-orbit warm-up did not reproduce the anomaly, despite the fact that it employed a flight-spare detector of the same pedigree. The mechanism behind the on-orbit dark current anomaly is therefore believed to be unique to the space environment. We discuss possible explanations for these unexpected observational results, as well as their implications for future NICMOS operations.

Abstract: Purpose: To evaluate the long-term outcome (>6 years) of retinal reattachment by pneumatic retinopexy. Methods: Seventy-eight eyes were examined retrospectively after treatment of a retinal detachment with pneumatic retinopexy. The average follow-up period was 6.35 years. The fundus was examined and visual acuity was documented and compared to that of the fellow eye. Any reoperations were evaluated. Results: In 98.7% of cases permanent reattachment of the retina was achieved. In 85.9% the primary intervention had been successful. However, the retina redetached in 19.4% of these during the first 3 months and in a further 4.5% later during the observation period, requiring reoperation. The average number of operations necessary to obtain permanent reattachment of the retina in the 77 eyes was 1.39. One eye was lost due to phthisis bulbi and had to be enucleated. Six years after the first intervention visual acuity of the eyes without reoperation was 0.57 (±0.25 SD) with initially detached macula [fellow eye 0.67 (±0.27)] and 0.7 (±0.27) with attached macula [fellow eye 0.7 (±0.25)]. Visual acuity of the eyes with reoperation was 0.36 (±0.3) [fellow eye 0.51 (±0.29)] with initially detached macula and 0.64 (±0.26) [fellow eye 0.63 (±0.35)] with attached macula. Conclusion: Six years after initial pneumatic retinopexy the retina was found to be attached in 98.7% of eyes. In 65.4% this result had been achieved by minimally invasive primary surgery alone. The need for reoperation was evident during the first 3 months in 89% of the cases. The final visual outcome was satisfactory overall.

• Background: Retinal pigment epithelium cells and activated phagocytes are believed to be involved in the pathogenesis of proliferative vitreoretinopathy (PVR). Both cell types are capable of producing oxygen free radicals and other molecules with a high oxidative potential which can lead to a propagation of oxidative damage. It was the aim of this study to investigate whether products of oxidative reactions are detectable in the vitreous body of patients suffering from PVR. • Methods: In vitreous aspirates of patients vitrectomized because of PVR (n = 27), macular pucker (n = 9), or other reasons (controls, n = 31), the following parameters were determined: lipid peroxides (LPO), determined as malondialdehyde-like substances (MDA) and as thiobarbituric acid-reactive substances (TBARS), and myeloperoxidase activity (MPO). • Results: Compared with the controls, both LPO levels and MPO activities were significantly elevated in the vitreous of patients suffering from PVR. Vitreous of patients with macular pucker did not reveal any significant differences from controls in the parameters analyzed. • Conclusion: Our results suggest that both oxygen free radicals and inflammation-related reactions participate in the process of PVR. Oxidative tissue damage is obviously not involved in the pathogenesis of macular pucker.

• Purpose: This investigation was carried out to ascertain whether oxygen free radicals can influence the growth behaviour and consecutive lipid peroxidation of retinal pigment epithelium (RPE) cells in vitro and whether scavengers can counteract these effects.

Lipid peroxide (LPO) levels, as determined by high-performance liquid chromatography (HPLC) and by the thiobarbituric acid (TBA) method, and myeloperoxidase (MPO) activity in vitreous of patients vitrectomized because of proliferative diabetic retinopathy were compared with LPO levels and MPO activity in vitreous of patients with no vitreoretinal proliferation. Both LPO levels and MPO activity were significantly elevated in the vitreous of patients with fibrovascular vitreoretinal proliferations secondary to diabetes. The TBA method produced higher values for LPO levels than did the HPLC method. The correlation between the two methods was 0.94. Our results suggest that both oxygen-free radicals and inflammation-related reactions can participate in the pathogenesis of diabetic retinopathy.

• Purpose: An intravitreal injection of Fluosol-DA leads to a higher alteration of the macrophage system of the retina than perfluorooctane and perfluorodecalin administered by the same route. The difference may be due to different kinds of oxidative damage caused by the three chemicals. To test the validity of this assumption, the degree of cell alteration, expressed as reduction of cytoplasmic motility, caused by these three perfluorochemicals was examined. • Methods: Using the hepatic macrophage system of the rat, cell alteration was examined by magnetometry after intravenous application of various perfluorochemicals [emulsified perfluorodecalin (C10F18), perfluorooctane (C8F17Br) and Fluosol-DA (corresponding to a 20% emulsion of 70% perfluorodecalin and 30% perfluorotripropylamine, C9F21N)]. • Results: After administration of high doses, all perfluorochemicals led to cytoskeleton alteration. This alteration, expressed as retardation of the relaxation period of ferromagnetic iron oxide particles, was most pronounced after administration of Fluosol-DA. • Conclusion: The compromising effect of perfluoro-chemicals is dose dependent and differs among the three compounds tested, with Fluosol-DA showing the greatest decrease in cytoplasmic motility.

• Purpose: To clarify whether the prolonged presence of perfluorochemicals (PFC) in the vitreous cavity causes oxidative tissue damage and inflammatory response of the retina and, if so, what the process is. • Methods: After three different perfluorochemicals [perfluorodecalin (C10F18), perfluorooctane (C8F18) and Fluosol-DA (corresponding to a 20% emulsion of 70% PFD and 30% perfluorotripropylamine, C9F21N)] had been in the vitreous cavity of rabbits for 2 weeks, lipid peroxide concentration and myeloperoxidase activity in the retina were determined. • Results: Whereas only Fluosol-DA showed significant oxidative damage, the inflammatory activity was significantly increased in all groups. • Conclusion: The increased myeloperoxidase activity and the observed oxidative damage of the retina seem to be the effect of both perfluorochemical-loaded macrophages and inflammatory-induced lipid peroxidation.

We have studied the molecular gas in the vicinity of low-luminosity active galactic nuclei (AGNs) in three bulge-less spiral galaxies: NGC 1042, NGC 4178, and NGC 4395. The (1−0) and (2−1) transitions of gaseous carbon monoxide (CO) are clearly detected within the central kpc of all three galaxies. In the case of NGC 4395, this constitutes the first reported detection of CO. In general, the CO emission is faint, as may be expected from their less-than-spectacular star formation activity. Interestingly, however, both face-on galaxies in our sample (which allow an unimpeded view of their nucleus) show an elevated intensity ratio CO(2−1)/CO(1−0) when compared to similar late-type spirals without an AGN. We discuss that this is unlikely due to a very compact CO source. Instead, we speculate that even energetically weak AGN can impact the physical state of the surrounding gas. We do not detect any tracers of dense molecular gas such as HCN or HCO+, but the sensitivity of our observations allows us to establish upper limits that lie at the low end of the range observed in more energetic AGN. The derived gas density is less than nH2≈ 2 × 103cm-3which is significantly lower than in most other nearby galaxies. The scarcity of dense gas suggests that the conditions for star formation are poor in these nuclei.