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Spire Global, Inc. operates a growing fleet of currently more than 100 CubeSats in different low Earth orbits for commercial Earth observation. These satellites are equipped with dual-frequency GPS receivers and an attitude determination and control system, allowing for precise orbit determination. For three different satellites and a time span of six months we analyze the performance and quality of the on-board collected GPS and attitude data and employ it for precise orbit determination using the Bernese GNSS Software and Napeos, two independent state-of-the-art GNSS processing software packages. We describe technical details crucial for POD and present and compare the in-flight calibrated phase center variation maps. Reduced-dynamic and kinematic orbits are then inter-compared between the two software packages as well as to the orbit solutions produced by Spire Global. We report pseudo-range and carrier phase residuals at the level of 3–4 m and 8–9 mm RMS and a good agreement between the reduced-dynamic and kinematic orbits of around 5 cm 3D RMS. The reduced-dynamic orbit positions and velocities produced with the two employed software packages agree in average on the level of 6–7 cm and 0.05–0.07 mm/s 3D RMS, while the comparison to the orbits produced by Spire Global is markedly worse with 27–30 cm and 0.32–0.36 mm/s 3D RMS. The presented results are an encouraging first step towards using GPS data from the Spire constellation for geodetic, geophysical and ionospheric applications. [ABSTRACT FROM AUTHOR]

The aerodynamic interaction between the wake flow structure behind a single spire with a smooth wall boundary layer at a long streamwise location was observed in a wind tunnel experiment. The application of a single spire is intended to generate a wake flow similar to the one generated behind a skyscraper. A quarter elliptic wedge spire was used and a long streamwise distance of up to 26 times the spire's height was adopted to ensure the development of the boundary layer and the wake recovery. To grasp how the smooth wall boundary layer interacts with the wake as well as how the wake recovers downstream, vertical and lateral velocity profiles were examined. Despite only one spire being utilized, it was found that the role of the spire as a vortex generator was confirmed the boundary layer height in the with-spire case increased compared to that of the without-spire case. Moreover, the velocity deficit recovery process was observed vertically and streamwise. However, within the boundary layer, the recovery rate in the streamwise direction was lower compared to the above it. This finding indicates that within the boundary, the turbulence generated can sustain the wake caused by the spire, reducing the recovery rate. Based on the current lateral velocity analysis, the final streamwise distance required by the wake to fully recover could not be predicted due to the large velocity deviation of 2.15% at the end of the streamwise distance. [ABSTRACT FROM AUTHOR]

The aerodynamic interaction between the wake flow structure behind a single spire with a smooth wall boundary layer at a long streamwise location was observed in a wind tunnel experiment. The application of a single spire is intended to generate a wake flow similar to the one generated behind a skyscraper. A quarter elliptic wedge spire was used and a long streamwise distance of up to 26 times the spire’s height was adopted to ensure the development of the boundary layer and the wake recovery. To grasp how the smooth wall boundary layer interacts with the wake as well as how the wake recovers downstream, vertical and lateral velocity profiles were examined. Despite only one spire being utilized, it was found that the role of the spire as a vortex generator was confirmed the boundary layer height in the with-spire case increased compared to that of the without-spire case. Moreover, the velocity deficit recovery process was observed vertically and streamwise. However, within the boundary layer, the recovery rate in the streamwise direction was lower compared to the above it. This finding indicates that within the boundary, the turbulence generated can sustain the wake caused by the spire, reducing the recovery rate. Based on the current lateral velocity analysis, the final streamwise distance required by the wake to fully recover could not be predicted due to the large velocity deviation of 2.15% at the end of the streamwise distance.

In this study, we investigate the performances of a commercial Global Navigation Satellite System (GNSS) Radio Occultation (RO) mission and a new-generation RO constellation, i.e., Spire and Constellation Observing System for Meteorology, Ionosphere, and Climate 2 (COSMIC-2), respectively. In the statistical comparison between Spire and COSMIC-2, the results indicate that although the average signal-to-noise ratio (SNR) of Spire is far weaker than that of COSMIC-2, the penetration of Spire is comparable to, and occasionally even better than, that of COSMIC-2. In our analysis, we find that the penetration depth is contingent upon various factors including SNR, GNSS, RO modes, topography, and latitude. With the reanalysis of the European Centre for Medium-Range Weather Forecasts and Radiosonde as the reference data, the identical error characteristics of Spire and COSMIC-2 reveal that overall, the accuracy of Spire's neutral-atmosphere data products was found to be comparable to that of COSMIC-2. [ABSTRACT FROM AUTHOR]

Global Navigation Satellite System (GNSS) Radio Occultation (RO) data play an essential role in improving numerical weather prediction (NWP) and monitoring climate change. The NOAA Commercial RO Purchase Program (CDP) purchased RO data provided by Spire Global Inc. To ensure the data quality from Spire Global Inc. is consistent with other RO missions, we need to quantify their accuracy and retrieval uncertainty carefully. In this work, Spire Wet Profile (wet temperature profile) data from 7 September 2021 to 31 October 2022, processed by the University Corporation for Atmospheric Research (UCAR), and COSMIC-2 (Constellation Observing System for Meteorology, Ionosphere, and Climate-2/Formosa Satellite Mission 7) data are evaluated through comparison with NOAA-20 Advanced Technology Microwave Sounder (ATMS) microwave sounder measurements and collocated RS41 radiosonde measurements. Through the Community Radiative Transfer Model (CRTM) simulation, we convert the Spire and COSMIC-2 RO retrievals to ATMS brightness temperature (BT) at sounding channels CH07 to CH14 (temperature channels), with weighting function peak heights from 8 km to 35 km, and CH19 to CH22 (water vapor channels), with weighting function peak heights ranging from 3.2 km to 6.7 km, and compare the simulations with the collocated NOAA-20 ATMS measurements over ocean. Using ATMS observations as references, Spire and COSMIC-2 BTs agree well with ATMS within 0.07 K for CH07-14 and 0.20 K for CH19-22. The trends between Spire and COSMIC-2 are consistent within 0.07 K/year over the oceans for ATMS CH07-CH13 and CH19-22, indicating that Spire/COSMIC-2 wet profiles are, in general, compatible with each other over oceans. The RO retrievals and RS41 radiosonde observation (RAOB) comparison shows that above 0.2 km altitude, RS41 RAOB matches Spire/COSMIC-2 temperature profiles well with a temperature difference of <0.13 K, and the trends between Spire and COSMIC-2 are consistent within 0.08 K/year over land, indicating that Spire/COSMIC-2 wet profiles are overall compatible with each other through RS41 RAOB measurements over land. In addition, the consistency of Spire and COSMIC-2 based on different latitude intervals, local times, and signal-to-noise ratios (SNRs) through ATMS was evaluated. The results show that the performance of Spire is comparable to COSMIC-2, even though COSMIC-2 has a higher SNR. The high quality of RO profiles from Spire is expected to improve short- and medium-range global numerical weather predictions and help construct consistent climate temperature records. [ABSTRACT FROM AUTHOR]

This paper investigates the use of solar thermal energy systems in SPIRE (sustainable process industry through resource and energy efficiency) and non-SPIRE industries and evaluates the use a novel solar Fresnel collector for generating temperatures of up to 400 °C. The investigation showed that solar thermal energy systems were mostly integrated into the non-SPIRE industries like food and beverages, paper and pulp and the textile industries with temperature requirements of up to 150 °C while few of them were used in the SPIRE industries like the non-metallic minerals, chemicals, basic metals and water industries with temperature requirements of up to 1500 °C. The limitation of those solar energy systems was seen in their application in higher irradiance regions due to the limited operation temperature of certain types of solar collectors, which particularly affected the SPIRE industry sector. To increase their use in high and low irradiance regions, a novel solar thermal system developed by the EU-ASTEP project that could achieve a temperature of up to 400 °C was introduced. The calculations of the theoretical and technical potential application of the ASTEP system in EU industrial processes showed an increase of 43%, of which 802.6 TWh totalled the theoretical potential and 96.3 TWh the technical potential. This resulted in a reduction of greenhouse gas (GHG) emissions by 24 thousand kt CO2 equivalent, which could help industries to achieve their 2050 targets for net-zero GHG emissions. [ABSTRACT FROM AUTHOR]

Looking back at two decades of research on SPIRE actin nucleator proteins, the first decade was clearly dominated by the discovery of SPIRE proteins as founding members of the novel WH2-domainbased actin nucleators, which initiate actin filament assembly through multiple WH2 actin-binding domains. Through complex formation with formins and class 5 myosins, SPIRE proteins coordinate actin filament assembly and myosin motor-dependent force generation. The discovery of SPIRE-regulated cytoplasmic actin filament meshworks in oocytes initiated the next phase of SPIRE research, which has found that SPIRE proteins are integrated in a diverse range of cell biological processes. In addition to regulating vesicle-based actin filament meshworks, SPIRE proteins function in the organisation of actin structures driving the inward movement of pronuclei of the mouse zygote. Localisation at cortical ring structures and the results of knockdown experiments indicate that SPIRE proteins function in the formation of meiotic cleavage sites in mammalian oocytes and the externalisation of von Willebrand factor from endothelial cells. Alternative splicing targets mammalian SPIRE1 towards mitochondria, where it has a role in fission. In this Review, we summarise the past two decades of SPIRE research by addressing the biochemical and cell biological functions of SPIRE proteins in mammalian reproduction, skin pigmentation and wound healing, as well as in mitochondrial dynamics and host-pathogen interactions. [ABSTRACT FROM AUTHOR]

To investigate the pollutant dispersion of a nuclear power plant, a field tracing experiment was carried out in neutral stratification weather with the main wind direction SSW. On this basis, a wind speed profile and turbulence intensity profile consistent with the site were created in the wind tunnel. Meanwhile, how to generate a wind field of neutral stratification in a wind tunnel was studied in detail. Finally, a 1:1000 nuclear power area model was made to conduct tracing experiments in the wind tunnel. The results show that when the horizontal and vertical distances of the spire are 300 mm and 500 mm, and the horizontal and vertical distances of the rough element are 250 mm and 500 mm. A wind speed profile with a wind profile index of 0.321 was generated in the wind tunnel (0.334 in the field test), and the wind tunnel tracer experiment had the same diffusion trend as the field, which verified the accuracy of the flow field. [ABSTRACT FROM AUTHOR]

In this study, we investigate the performances of a commercial Global Navigation Satellite System (GNSS) Radio Occultation (RO) mission and a new-generation RO constellation, i.e., Spire and Constellation Observing System for Meteorology, Ionosphere, and Climate 2 (COSMIC-2), respectively. In the statistical comparison between Spire and COSMIC-2, the results indicate that although the average signal-to-noise ratio (SNR) of Spire is far weaker than that of COSMIC-2, the penetration of Spire is comparable to, and occasionally even better than, that of COSMIC-2. In our analysis, we find that the penetration depth is contingent upon various factors including SNR, GNSS, RO modes, topography, and latitude. With the reanalysis of the European Centre for Medium-Range Weather Forecasts and Radiosonde as the reference data, the identical error characteristics of Spire and COSMIC-2 reveal that overall, the accuracy of Spire’s neutral-atmosphere data products was found to be comparable to that of COSMIC-2.

Global Navigation Satellite System (GNSS) Radio Occultation (RO) data play an essential role in improving numerical weather prediction (NWP) and monitoring climate change. The NOAA Commercial RO Purchase Program (CDP) purchased RO data provided by Spire Global Inc. To ensure the data quality from Spire Global Inc. is consistent with other RO missions, we need to quantify their accuracy and retrieval uncertainty carefully. In this work, Spire Wet Profile (wet temperature profile) data from 7 September 2021 to 31 October 2022, processed by the University Corporation for Atmospheric Research (UCAR), and COSMIC-2 (Constellation Observing System for Meteorology, Ionosphere, and Climate-2/Formosa Satellite Mission 7) data are evaluated through comparison with NOAA-20 Advanced Technology Microwave Sounder (ATMS) microwave sounder measurements and collocated RS41 radiosonde measurements. Through the Community Radiative Transfer Model (CRTM) simulation, we convert the Spire and COSMIC-2 RO retrievals to ATMS brightness temperature (BT) at sounding channels CH07 to CH14 (temperature channels), with weighting function peak heights from 8 km to 35 km, and CH19 to CH22 (water vapor channels), with weighting function peak heights ranging from 3.2 km to 6.7 km, and compare the simulations with the collocated NOAA-20 ATMS measurements over ocean. Using ATMS observations as references, Spire and COSMIC-2 BTs agree well with ATMS within 0.07 K for CH07-14 and 0.20 K for CH19-22. The trends between Spire and COSMIC-2 are consistent within 0.07 K/year over the oceans for ATMS CH07-CH13 and CH19-22, indicating that Spire/COSMIC-2 wet profiles are, in general, compatible with each other over oceans. The RO retrievals and RS41 radiosonde observation (RAOB) comparison shows that above 0.2 km altitude, RS41 RAOB matches Spire/COSMIC-2 temperature profiles well with a temperature difference of

To investigate the pollutant dispersion of a nuclear power plant, a field tracing experiment was carried out in neutral stratification weather with the main wind direction SSW. On this basis, a wind speed profile and turbulence intensity profile consistent with the site were created in the wind tunnel. Meanwhile, how to generate a wind field of neutral stratification in a wind tunnel was studied in detail. Finally, a 1:1000 nuclear power area model was made to conduct tracing experiments in the wind tunnel. The results show that when the horizontal and vertical distances of the spire are 300 mm and 500 mm, and the horizontal and vertical distances of the rough element are 250 mm and 500 mm. A wind speed profile with a wind profile index of 0.321 was generated in the wind tunnel (0.334 in the field test), and the wind tunnel tracer experiment had the same diffusion trend as the field, which verified the accuracy of the flow field.

Multiple radio occultation (RO) missions are currently providing observations that are assimilated by the world’s leading numerical weather prediction centers. These RO missions use the same signals originating from the Global Navigation Satellite Systems (GNSS), but they have different satellite designs and sizes with different antennas and receivers. This results in different noise levels for different missions. Although the amplitude data are characterized by the Signal-to-Noise Ratio (SNR), the noise, to which they are normalized, is not the real Noise Floor (NF) of the RO observations. We study the statistical distributions of the SNR and NF for RO missions including COSMIC, COSMIC2, METOP-A, METOP-B, METOP-C, and Spire. We demonstrate that different missions have different NF values and different NF and SNR distributions, sometimes multimodal. We propose to use the most probable NF value as an SNR normalization constant in order to compare the SNR values from different RO missions.

The residents of Dublin, Ireland have developed a robust commemorative infrastructure throughout the city since the early eighteenth century. A prominent site in this landscape is at the centre of O'Connell Street (Sackville Street from the late 1700s to 1924). Today, the Spire of Dublin (2003) is located at this site. But it projects an ambiguous connection to both the city's and the country's factious history. Two other statues previously stood on the site, both commemorating British imperial military figures: the Blakeney Monument (1759) and Nelson's Pillar (1808). Both works were intentionally destroyed in acts of urban iconoclasm. An analysis of the changes in the monumental public art on this site over the centuries demonstrates that iconoclasm has been a factor in shifting Irish attitudes toward the British and themselves, Irish associations with power and memory, and a potent symbol in Dublin's urban landscape. This is established by using an expanded conceptualisation of iconoclasm that incorporates a series of post-fall responses to a monument and its site's physical state and context over time, the site's continued symbolic meanings, and the site becoming home to new monumental or other symbolic expressions. The result illustrates that this site has been significantly inscribed into British imperial and Irish national iconography regardless of the monument or public sculpture it has held. [ABSTRACT FROM AUTHOR]

The study of eukaryotic extremophiles is relatively novel, and, therefore, documentation of the structure and function of micro-organisms in continental hydrothermal systems globally is limited. In this study, we investigate fossil diatoms in siliceous hydrothermal deposits of the Upper Geyser and Yellowstone Lake hydrothermal basins in Yellowstone National Park, and utilize preserved diatom assemblages to infer local environmental conditions. Siliceous sinter from both the Upper Geyser Basin and Yellowstone Lake contains evidence of in-situ diatom growth within these environments. At Upper Geyser Basin, the assemblage consisted of species that could grow on moist siliceous sinter and was dominated by Rhopalodia gibberula. Diatom valves were found in various preservation states, ranging from nearly pristine to highly diagenetically altered. Diatoms collected from siliceous spires in Yellowstone Lake consisted largely of tychoplanktonic and benthic species that were almost certainly growing on the outside of the structure, with an assemblage indicative of relatively shallow, alkaline waters. What remains unclear without access to material for high-resolution dating is whether diatoms colonized the spires during hydrothermal activity or after activity ceased. Our results indicate that diatom frustules can, to some extent, survive alteration in low-temperature (<76°C) hydrothermal environments. [ABSTRACT FROM AUTHOR]

GPS-Radio Occultation (GPS-RO), and generally, Global Navigation Satellite System Radio Occultation (GNSS-RO), is a technique that measures the refractivity of the Earth's atmosphere as a Low Earth Orbit (LEO) satellite listens to the radio signal of a GNSS satellite. As the signal between the two satellites travels through the different levels of the Earth's atmosphere, temperature and water vapor content can be derived at each occultation point, allowing for a new weather dataset to be available to meteorologists. In this article we describe the benefits of large-scale GNSS-Radio Occultation (GNSS-RO) as a method of gathering large amounts of extremely accurate atmospheric data that exceptionally contributes to the performance of advanced numerical weather prediction (NWP) models.

GPS-Radio Occultation (GPS-RO), and generally, Global Navigation Satellite System Radio Occultation (GNSS-RO), is a technique that measures the refractivity of the Earth's atmosphere as a Low Earth Orbit (LEO) satellite listens to the radio signal of a GNSS satellite. As the signal between the two satellites travels through the different levels of the Earth's atmosphere, temperature and water vapor content can be derived at each occultation point, allowing for a new weather dataset to be available to meteorologists. In this article we describe the benefits of large-scale GNSS-Radio Occultation (GNSS-RO) as a method of gathering large amounts of extremely accurate atmospheric data that exceptionally contributes to the performance of advanced numerical weather prediction (NWP) models. [ABSTRACT FROM AUTHOR]

We can imagine many of our emotions in our family pet: hunger, fear, anger, lust, and even the bonding that we call love. But not the appreciation of a sunset, sonnet, musical passage, or good joke. Mechner takes on the gamut of such aesthetic appreciations, removed from the urgency of the primal ones, and gives us the first thorough attempt at a behavioral explication. Because he has been so thorough and apt, my commentary can add little value to his thesis, only subtract from it. Therefore, rather than critique, I exemplify, and then simplify. By reducing his voluminous report to two lines: a theorem and an equation, I thereby encapsulate aesthetics in a sweet pill of spire. Aesthetic appreciation of this note may require a willing suspension of disbelief. [ABSTRACT FROM AUTHOR]

There is growing evidence for a coupling of actin assembly and myosin motor activity in cells. However, mechanisms for recruitment of actin nucleators and motors on specific membrane compartments remain unclear. Here we report how Spir actin nucleators and myosin V motors coordinate their specific membrane recruitment. The myosin V globular tail domain (MyoV-GTD) interacts directly with an evolutionarily conserved Spir sequence motif. We determined crystal structures of MyoVa-GTD bound either to the Spir-2 motif or to Rab11 and show that a Spir-2:MyoVa:Rab11 complex can form. The ternary complex architecture explains how Rab11 vesicles support coordinated F-actin nucleation and myosin force generation for vesicle transport and tethering. New insights are also provided into how myosin activation can be coupled with the generation of actin tracks. Since MyoV binds several Rab GTPases, synchronized nucleator and motor targeting could provide a common mechanism to control force generation and motility in different cellular processes.

Careful selection of dominant T cell epitope peptides of major allergens that display degeneracy for binding to a wide array of MHC class II molecules allows induction of clinical and immunological tolerance to allergen in a refined treatment strategy. From the original concept of peptide-induced T cell anergy arising from in vitro studies, proof-of-concept murine models and flourishing human trials followed. Current randomized, double-blind, placebo-controlled clinical trials of mixtures of T cell-reactive short allergen peptides or long contiguous overlapping peptides are encouraging with intradermal administration into non-inflamed skin a preferred delivery. Definitive immunological mechanisms are yet to be resolved but specific anergy, Th2 cell deletion, immune deviation, and Treg induction seem implicated. Significant efficacy, particularly with short treatment courses, in a range of aeroallergen therapies (cat, house dust mite, grass pollen) with inconsequential non-systemic adverse events likely heralds a new class of therapeutic for allergy, Synthetic Peptide Immuno-Regulatory Epitopes (SPIRE). [ABSTRACT FROM AUTHOR]

Background: The actin cytoskeleton is a hallmark of eukaryotic cells. Its regulation as well as its interaction with other proteins is carefully orchestrated by actin interaction domains. One of the key players is the WH2 motif, which enables binding to actin monomers and filaments and is involved in the regulation of actin nucleation. Contrasting conserved domains, the identification of this motif in protein sequences is challenging, as it is short and poorly conserved. Findings: To identify divergent members, we combined Hidden-Markov-Model (HMM) to HMM alignments with orthology predictions. Thereby, we identified nearly 500 proteins containing so far not annotated WH2 motifs. This included shootin-1, an actin binding protein involved in neuron polarization. Among others, WH2 motifs of 'proximal to raf' (ptr)-orthologs, which are described in the literature, but not annotated in genome databases, were identified. Conclusion: In summary, we increased the number of WH2 motif containing proteins substantially. This identification of candidate regions for actin interaction could steer their experimental characterization. Furthermore, the approach outlined here can easily be adapted to the identification of divergent members of further domain families. [ABSTRACT FROM AUTHOR]

Background The actin cytoskeleton is a hallmark of eukaryotic cells. Its regulation as well as its interaction with other proteins is carefully orchestrated by actin interaction domains. One of the key players is the WH2 motif, which enables binding to actin monomers and filaments and is involved in the regulation of actin nucleation. Contrasting conserved domains, the identification of this motif in protein sequences is challenging, as it is short and poorly conserved. Findings To identify divergent members, we combined Hidden-Markov-Model (HMM) to HMM alignments with orthology predictions. Thereby, we identified nearly 500 proteins containing so far not annotated WH2 motifs. This included shootin-1, an actin binding protein involved in neuron polarization. Among others, WH2 motifs of 'proximal to raf' (ptr)-orthologs, which are described in the literature, but not annotated in genome databases, were identified. Conclusion In summary, we increased the number of WH2 motif containing proteins substantially. This identification of candidate regions for actin interaction could steer their experimental characterization. Furthermore, the approach outlined here can easily be adapted to the identification of divergent members of further domain families. [ABSTRACT FROM AUTHOR]

William Golding is known for his Lord of the Flies (1954), however his other novels are also equally worthy of critical attention. The Spire (1964) is a remarkable novel with the underlying contention that there is no innocent work however sacred and religious it may be. This paper is an attempt to explore the novel as a scathing critique of both, religion and reason. The protagonist Dean Jocelin represents faith and master builder Roger Mason stands for reason. Jocelin's unconsummated sexual craving for his daughter-in-God Goody Pangall who is married to the impotent Mr. Pangall is sublimated in the form of the phallic symbol of the spire. But Roger has an illicit relation with Goody but ends as an unsatisfied drunkard. Mr. Pangall is killed by the workers in frenzy and Jocelin sacrifices Goody for his vision of building a 404 feet spire which he ascribes to God. In spite of insufficient foundations the spire stands as a miracle conceived by faith and accomplished by reason with a great doubt. Jocelin comes to know that his deanship which he owes to Lady Alison is result of her illegitimate relationship with the king. Thus the myth that religion leads to salvation is busted. Neither reason nor religion makes man happy. [ABSTRACT FROM AUTHOR]

The Herschel SPIRE Fourier transform spectrometer (FTS) performs spectral imaging in the 447-1546 GHz band. It can observe in three spatial sampling modes: sparse mode, with a single pointing on sky, or intermediate or full modes with 1 and 1/2 beam spacing, respectively. In this paper, we investigate the uncertainty and repeatability for fully sampled FTS mapping observations. The repeatability is characterised using nine observations of the Orion Bar. Metrics are derived based on the ratio of the measured intensity in each observation compared to that in the combined spectral cube from all observations. The mean relative deviation is determined to be within 2 %, and the pixel-by-pixel scatter is ∼ 7 %. The scatter increases towards the edges of the maps. The uncertainty in the frequency scale is also studied, and the spread in the line centre velocity across the maps is found to be ∼ 15 km s . Other causes of uncertainty are also discussed including the effect of pointing and the additive uncertainty in the continuum. [ABSTRACT FROM AUTHOR]

Out-of-field stray-light spots of the Herschel telescope optics relative to the PACS and SPIRE instrument apertures were modeled by ray tracing simulations with the Advanced Systems Analysis Program (ASAP, by Breault Research Organization) prior to launch. The predicted stray-light behaviour was verified by dedicated stray-light calibration observations in-flight. This resulted in a special feature of the Herschel Science Mission Planning Software, marking the sky positions of stray-light spots by the very bright infrared planetary sources Venus, Mars, Jupiter, and Saturn, as well as the Moon, thus avoiding contamination of scientific photometric observations by out-of-field stray-light of these sources. [ABSTRACT FROM AUTHOR]

We present a method to derive the relative pointing offsets for SPIRE Fourier-Transform Spectrometer (FTS) solar system object (SSO) calibration targets, which were observed regularly throughout the Herschel mission. We construct ratios R( ν) of the spectra for all observations of a given source with respect to a reference. The reference observation is selected iteratively to be the one with the highest observed continuum. Assuming that any pointing offset leads to an overall shift of the continuum level, then these R( ν) represent the relative flux loss due to mispointing. The mispointing effects are more pronounced for a smaller beam, so we consider only the FTS short wavelength array (SSW, 958-1546 GHz) to derive a pointing correction. We obtain the relative pointing offset by comparing R( ν) to a grid of expected losses for a model source at different distances from the centre of the beam, under the assumption that the SSW FTS beam can be well approximated by a Gaussian. In order to avoid dependency on the point source flux conversion, which uses a particular observation of Uranus, we use extended source flux calibrated spectra to construct R( ν) for the SSOs. In order to account for continuum variability, due to the changing distance from the Herschel telescope, the SSO ratios are normalised by the expected model ratios for the corresponding observing epoch. We confirm the accuracy of the derived pointing offset by comparing the results with a number of control observations, where the actual pointing of Herschel is known with good precision. Using the method we derived pointing offsets for repeated observations of Uranus (including observations centred on off-axis detectors), Neptune, Ceres and NGC 7027. The results are used to validate and improve the point-source flux calibration of the FTS. [ABSTRACT FROM AUTHOR]

Celestial standards play a major role in observational astrophysics. They are needed to characterise the performance of instruments and are paramount for photometric calibration. During the Herschel Calibration Asteroid Preparatory Programme approximately 50 asteroids have been established as far-IR/sub-mm/mm calibrators for Herschel. The selected asteroids fill the flux gap between the sub-mm/mm calibrators Mars, Uranus and Neptune, and the mid-IR bright calibration stars. All three Herschel instruments observed asteroids for various calibration purposes, including pointing tests, absolute flux calibration, relative spectral response function, observing mode validation, and cross-calibration aspects. Here we present newly established models for the four large and well characterized main-belt asteroids (1) Ceres, (2) Pallas, (4) Vesta, and (21) Lutetia which can be considered as new prime flux calibrators. The relevant object-specific properties (size, shape, spin-properties, albedo, thermal properties) are well established. The seasonal (distance to Sun, distance to observer, phase angle, aspect angle) and daily variations (rotation) are included in a new thermophysical model setup for these targets. The thermophysical model predictions agree within 5 % with the available (and independently calibrated) Herschel measurements. The four objects cover the flux regime from just below 1,000 Jy (Ceres at mid-IR N-/Q-band) down to fluxes below 0.1 Jy (Lutetia at the longest wavelengths). Based on the comparison with PACS, SPIRE and HIFI measurements and pre-Herschel experience, the validity of these new prime calibrators ranges from mid-infrared to about 700 μm, connecting nicely the absolute stellar reference system in the mid-IR with the planet-based calibration at sub-mm/mm wavelengths. [ABSTRACT FROM AUTHOR]

Emission from the Herschel telescope is the dominant source of radiation for the majority of SPIRE Fourier transform spectrometer (FTS) observations, despite the exceptionally low emissivity of the primary and secondary mirrors. Accurate modelling and removal of the telescope contribution is, therefore, an important and challenging aspect of FTS calibration and data reduction pipeline. A dust-contaminated telescope model with time invariant mirror emissivity was adopted before the Herschel launch. However, measured FTS spectra show a clear evolution of the telescope contribution over the mission and strong need for a correction to the standard telescope model in order to reduce residual background (of up to 7 Jy) in the final data products. Systematic changes in observations of dark sky, taken over the course of the mission, provide a measure of the evolution between observed telescope emission and the telescope model. These dark sky observations have been used to derive a time dependent correction to the telescope emissivity that reduces the systematic error in the continuum of the final FTS spectra to ∼0.35 Jy. [ABSTRACT FROM AUTHOR]

The different algorithms appropriate for point source photometry on data from the SPIRE instrument on-board the Herschel Space Observatory, within the Herschel Interactive Processing Environment (HIPE) are compared. Point source photometry of a large ensemble of standard calibration stars and dark sky observations is carried out using the 4 major methods within HIPE: SUSSEXtractor, DAOphot, the SPIRE Timeline Fitter and simple Aperture Photometry. Colour corrections and effective beam areas as a function of the assumed source spectral index are also included to produce a large number of photometric measurements per individual target, in each of the 3 SPIRE bands (250, 350, 500 μm), to examine both the accuracy and repeatability of each of the 4 algorithms. It is concluded that for flux densities down to the level of 30mJy that the SPIRE Timeline Fitter is the method of choice. However, at least in the 250 and 350 μm bands, all 4 methods provide photometric repeatability better than a few percent down to at approximately 100mJy. The DAOphot method appears in many cases to have a systematic offset of ∼8 % in all SPIRE bands which may be indicative of a sub-optimal aperture correction. In general, aperture photometry is the least reliable method, i.e. largest scatter between observations, especially in the longest wavelength band. At the faintest fluxes, <30mJy, SUSSEXtractor or DAOphot provide a better alternative to the Timeline Fitter. [ABSTRACT FROM AUTHOR]

A He sorption cooler produced the operational temperature of 285 mK for the bolometer arrays of the Photodetector Array Camera and Spectrometer (PACS) instrument of the Herschel Space Observatory. This cooler provided a stable hold time between 60 and 73 h, depending on the operational conditions of the instrument. The respective hold time could be determined by a simple functional relation established early on in the mission and reliably applied by the scientific mission planning for the entire mission. After exhaustion of the liquid He due to the heat input by the detector arrays, the cooler was recycled for the next operational period following a well established automatic procedure. We give an overview of the cooler operations and performance over the entire mission and distinguishing in-betweenthe start conditions for the cooler recycling and the two main modes of PACS photometer operations. As a spin-off, the cooler recycling temperature effects on the Herschel cryostat He bath were utilized as an alternative method to dedicated Direct Liquid Helium Content Measurements in determining the lifetime of the liquid Helium coolant. [ABSTRACT FROM AUTHOR]

Herschel/SPIRE Fourier transform spectrometer (FTS) observations contain emission from both the Herschel Telescope and the SPIRE Instrument itself, both of which are typically orders of magnitude greater than the emission from the astronomical source, and must be removed in order to recover the source spectrum. The effects of the Herschel Telescope and the SPIRE Instrument are removed during data reduction using relative spectral response calibration curves and emission models. We present the evolution of the methods used to derive the relative spectral response calibration curves for the SPIRE FTS. The relationship between the calibration curves and the ultimate sensitivity of calibrated SPIRE FTS data is discussed and the results from the derivation methods are compared. These comparisons show that the latest derivation methods result in calibration curves that impart a factor of between 2 and 100 less noise to the overall error budget, which results in calibrated spectra for individual observations whose noise is reduced by a factor of 2-3, with a gain in the overall spectral sensitivity of 23 % and 21 % for the two detector bands, respectively. [ABSTRACT FROM AUTHOR]