Observing Extended Sources with the \Herschel SPIRE Fourier Transform Spectrometer
Ronin Wu, Edward T. Polehampton, Mireya Etxaluze, Gibion Makiwa, David A. Naylor, Carl Salji, Bruce M. Swinyard, Marc Ferlet, Matthijs H. D. van der Wiel, Antho… 展开作者
Ronin Wu, Edward T. Polehampton, Mireya Etxaluze, Gibion Makiwa, David A. Naylor, Carl Salji, Bruce M. Swinyard, Marc Ferlet, Matthijs H. D. van der Wiel, Anthony J. Smith, Trevor Fulton, Matt J. Griffin, Jean-Paul Baluteau, Dominique Benielli, Jason Glenn, Rosalind Hopwood, Peter Imhof, Tanya Lim, Nanyao Lu, Pasquale Panuzzo, Chris Pearson, Sunil Sidher, Ivan Valtchanov
The Spectral and Photometric Imaging Receiver (SPIRE) on the European Space Agency's Herschel Space Observatory utilizes a pioneering design for its imaging spectrometer in the form of a Fourier Transform Spectrometer (FTS). The standard FTS data reduction and calibration schemes are aimed at objects with either a spatial extent much larger than the beam size or a source that can be approximated as a point source within the beam. However, when sources are of intermediate spatial extent, neither of these calibrations schemes is appropriate and both the spatial response of the instrument and the source's light profile must be taken into account and the coupling between them explicitly derived. To that end, we derive the necessary corrections using an observed spectrum of a fully extended source with the beam profile and the source's light profile taken into account. We apply the derived correction to several observations of planets and compare the corrected spectra with their spectral models to study the beam coupling efficiency of the instrument in the case of partially extended sources. We find that we can apply these correction factors for sources with angular sizes up to θ_{D} ~ 17". We demonstrate how the angular size of an extended source can be estimated using the difference between the sub-spectra observed at the overlap bandwidth of the two frequency channels in the spectrometer, at 959<ν<989 GHz. Using this technique on an observation of Saturn, we estimate a size of 17.2", which is 3% larger than its true size on the day of observation. Finally, we show the results of the correction applied on observations of a nearby galaxy, M82, and the compact core of a Galactic molecular cloud, Sgr B2.
The SPIRE FTS Spectral Feature Finder (FF), developed within the Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) instrument team, is an automated spectral feature fitting routine that attempts to find significant features in SPIRE FTS spectra. The $^3$P$_1$ - $^3$P$_0$ and $^3$P$_2$ - $^3$P$_1$ neutral carbon fine structure lines are common features in carbon rich far-infrared astrophysical sources. These features can be difficult to detect using an automated feature detection routine due to their typically low amplitude and line blending. In thi…
We present the data processing pipeline to generate calibrated data products from the Spectral and Photometric Imaging Receiver (SPIRE) imaging Fourier Transform Spectrometer on the Herschel Space Observatory. The pipeline processes telemetry from SPIRE observations and produces calibrated spectra for all resolution modes. The spectrometer pipeline shares some elements with the SPIRE photometer pipeline, including the conversion of telemetry packets into data timelines and calculation of bolometer voltages. We present the following fundamental processing steps unique to the spectrometer: tempo…
The Herschel SPIRE FTS Spectral Feature Finder (FF) detects significant spectral features within SPIRE spectra and employs two routines, and external references, to estimate source radial velocity. The first routine is based on the identification of rotational CO emission, the second cross-correlates detected features with a line template containing most of the characteristic lines in typical far infra-red observations. In this paper, we outline and validate these routines, summarise the results as they pertain to the FF, and comment on how external references were incorporated.
The SPIRE Fourier Transform Spectrometer on board the Herschel Space Observatory had two standard spectral resolution modes for science observations: high resolution (HR) and low resolution (LR), which could also be performed in sequence (H+LR). A comparison of the HR and LR resolution spectra taken in this sequential mode, revealed a systematic discrepancy in the continuum level. Analysing the data at different stages during standard pipeline processing, demonstrates the telescope and instrument emission affect HR and H+LR observations in a systematically different way. The origin of this dif…
We describe an update to the Herschel-SPIRE Fourier-Transform Spectrometer (FTS) calibration for extended sources, which incorporates a correction for the frequency-dependent far-field feedhorn efficiency, $η_\mathrm{FF}$. This significant correction affects all FTS extended-source calibrated spectra in sparse or mapping mode, regardless of the spectral resolution. Line fluxes and continuum levels are underestimated by factors of 1.3-2 in the Spectrometer Long-Wavelength band (SLW, 447-1018 GHz; 671-294 $μ$m) and 1.4-1.5 in the Spectrometer Short-Wavelength band (SSW, 944-1568 GHz; 318-191 $μ$…
Calibration of the Herschel SPIRE Fourier Transform Spectrometer
Herschel SPIRE仪器由成像光度照相机和成像傅里叶变换光谱仪（FTS）组成，两者都在450-1550 GHz的频率范围内工作。在本文中，我们简要地回顾了FTS的设计，操作和数据处理，并详细描述了相对校准（去除仪器签名）和绝对校准对标准天文源的方法。校准方案假设一个空间扩展的源，并使用赫歇尔望远镜作为主要的校准器。从扩展到点源校准的转换是使用天王星的观测进行的。望远镜发射的模型被证明是精确到6%以内，可重复性好于0.06%，与火星和海王星的模型相比，天王星模型被证明是精确到3%以内。对多个点源的多次观测表明，在校正卫星绝对指向误差（APE）的影响后，定标的重复性优于1%。卫星APE导致导出的通量减少，在任务的第一部分中，在SPIRE范围的高频端，其可以高达~10%（1 sigma），并且在Herschel操作第1011天之后为~4%。由于较大的波束尺寸，SPIRE频带的较低频率范围不受此指向误差的影响。总体而言，对于指向良好的点状源，绝对通量校准优于6%，对于需要映射的扩展源，绝对通量校准优于7%。
The SPIRE Photometer Interactive Analysis Package SPIA
Herschel Common Science System（HCSS）（Ott et al. 2006）（Ott & Science Ground Segment Consortium 2010）是一个重要的Java软件包，伴随着Herschel Mission（Pilbratt et al. 2010）的开发，支持其所有阶段。特别是从科学仪器的数据减少仪器检验，校准和天文分析是其主要应用之一。数据简化软件被分成多个模块，称为“任务”。任务的顺序形成流水线，提供定义良好的标准产品，存储在网络可访问的赫歇尔科学档案（HSA）中（Leon等人，2009年）。然而，随着天文学家和仪器科学家继续描述仪器效应，天文学家已经需要发表科学结果，可能没有时间对系统进行足够深入的了解以应用必要的修复。需要提供比刚性管道更大灵活性的中间级分析工具。HCSS中的任务框架和高度通用的Herschel交互式处理环境（HIPE），以及丰富的库集，为Herschel仪器开发基于GUI的交互式分析软件包提供了必要的工具。SPIRE光度计交互式分析（SPIA）包，在本次会议上展示，证明了SPIRE仪器概念的有效性（Griffin等人，2010年），将流水线简化分解为逻辑组件，使所有相关的处理参数在GUI中可用，并提供了一个更可控和用户友好的访问系统的复杂性。
The ESA Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to extract all prominent spectral features from all publicly available SPIRE FTS observations. In this work, we demonstrate the use of the FF information extracted from three observations of the edge-on spiral galaxy NGC 891 to measure the rotation of NII and CI gas at Far-infrared frequencies in complement to radio observations of the HI 21cm line and the CO(1-0) …
The ESA Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to extract all prominent spectral features from all publicly available SPIRE FTS observations. We present the extension of the FF to include the off-axis detectors of the FTS in sparsely sampled single-pointing observations, the results of which have been ingested into the catalogue. We also present the results from an automated routine for identifications of the a…
We provide a detailed description of the Herschel-SPIRE Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF). The FF is an automated process designed to extract significant spectral features from SPIRE FTS data products. Optimising the number of features found in SPIRE-FTS spectra is challenging. The wide SPIRE-FTS frequency range (447-1568 GHz) leads to many molecular species and atomic fine structure lines falling within the observed bands. As the best spectral resolution of the SPIRE-FTS is ~1.2 GHz, there can be significant line blending, depending on the source type. In order…
We compare the absolute gain photometric calibration of the Planck/HFI and Herschel/SPIRE instruments on diffuse emission. The absolute calibration of HFI and SPIRE each relies on planet flux measurements and comparison with theoretical far-infrared emission models of planetary atmospheres. We measure the photometric cross calibration between the instruments at two overlapping bands, 545 GHz / 500 $μ$m and 857 GHz / 350 $μ$m. The SPIRE maps used have been processed in the Herschel Interactive Processing Environment (Version 12) and the HFI data are from the 2015 Public Data Release 2. For our …
Estimating hyperparameters and instrument parameters in regularized inversion. Illustration for SPIRE/Herschel map making
Institut d’Astrophysique de Paris（巴黎天体物理研究所）；Laboratoire des Signaux et Systèmes（信号与系统实验室）；Univ. Bordeaux, IMS, UMR 5218（波尔多大学，IMS，UMR 5218）；Institut d’Astrophysique Spatiale（空间天体物理研究所）
We present the COPS-DIGIT-FOOSH (CDF) Herschel spectroscopy data product archive, and related ancillary data products, along with data fidelity assessments, and a user-created archive in collaboration with the Herschel-PACS and SPIRE ICC groups. Our products include datacubes, contour maps, automated line fitting results, and best 1-D spectra products for all protostellar and disk sources observed with PACS in RangeScan mode for two observing programs: the DIGIT Open Time Key Program (KPOT_nevans_1 and SDP_nevans_1; PI: N. Evans), and the FOOSH Open Time Program (OT1_jgreen02_2; PI: J. Green).…
We created the Herschel Footprint Database and web services for the Herschel Space Observatory imaging data. For this database we set up a unified data model for the PACS and SPIRE Herschel instruments, from the pointing and header information of each observation, generated and stored sky coverages (footprints) of the observations in their exact geometric form. With this tool we extend the capabilities of the Herschel Science Archive by providing an effective search tool that is able to find observations for selected sky locations (objects), or even in larger areas in the sky.
Dust grains play a key role in the physics of star-forming regions, even though they constitute only $\sim$1 % of the mass of the interstellar medium. The derivation of accurate dust parameters such as temperature ($T_{dust}$), emissivity spectral index ($β$) and column density requires broadband continuum observations at far-infrared wavelengths. We present Herschel-SPIRE Fourier Transform Spectrometer (FTS) measurements of three starless cores: L1521E, L1521F and L1689B, covering wavelengths between 194 and 671 $μ$m. This paper is the first to use our recently updated SPIRE-FTS intensity cal…
This research focuses on identifying high redshift galaxies from LABOCA(LArge APEX BOlometer CAmera) and SPIRE(The Spectral and Photometric Imaging Receiver) maps towards proto-cluster candidates initially selected from the SPT (South pole telescope) survey. Based on the Multi-Gaussian fitting algorithm, we cross-match all significant LABOCA sources at SPIRE wavelengths based on their coordinates and signal to noise ratio to derive their photometry at 250, 350, 500 and 870 $μm$. We use this information to calculate a photometric redshift for SPT sources towards cluster fields. The code was dev…
The Spectral and Photometric Imaging Receiver (SPIRE) was launched as one of the scientific instruments on board of the space observatory Herschel. The SPIRE photometer opened up an entirely new window in the Submillimeter domain for large scale mapping, that up to then was very difficult to observe. There are already several catalogs that were produced by individual Herschel science projects. Yet, we estimate that the objects of only a fraction of these maps will ever be systematically extracted and published by the science teams that originally proposed the observations. The SPIRE instrument…
Future far-infrared space missions require highly-sensitive spectroscopy as a primary diagnostics tool. However, these systems are sensitive to straylight, due to the ultra-sensitive few-mode detectors used, which affects the measurement and calibration of the spectrum, as revealed by the Herschel mission. To ensure that the science goals of future missions are met, the complex modal behaviour has to be understood, and appropriate verification and calibration strategies must be developed. We propose a modal framework to addresses these issues, using Herschel-SPIRE as a case study, and demonstr…
We present the largest submillimeter images that have been made of the extragalactic sky. The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) is a survey of 660 deg$^2$ with the PACS and SPIRE cameras in five photometric bands: 100, 160, 250, 350, and 500μm. In this paper we present the images from our two largest fields which account for ~75% of the survey. The first field is 180.1 deg$^2$ in size centered on the North Galactic Pole (NGP) and the second field is 317.6 deg$^2$ in size centered on the South Galactic Pole. The NGP field serendipitously contains the Coma cluster. Ove…
We present the first major data release of the largest single key-project in area carried out in open time with the Herschel Space Observatory. The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) is a survey of 600 deg^2 in five photometric bands - 100, 160, 250, 350 and 500 um - with the PACS and SPIRE cameras. In this paper and a companion paper (Bourne et al. 2016) we present the survey of three fields on the celestial equator, covering a total area of 161.6 deg^2 and previously observed in the Galaxy and Mass Assembly (GAMA) spectroscopic survey. This paper describes the Hersc…
