Transient Effects in ISOPHOT Data: Status of Modelling and Correction Procedures

The calibration of ISOPHOT observations is hampered in many cases by the transient response of the detectors. Here we outline thebehaviour observed in flight for the different ISOPHOT detectors. We also present some of the procedures which are currently used to correct transienteffects and their implementation in the ISOPHOT Interactive Analysis.     

ISOPHOT S Observations of 3 M Dwarfs

The M dwarfs GL 832 (spectral type M2), GL 887 (M1), and GL 1 (M2) have been observed with the ISOPHOT spectrophotometers in the range 2.5-12μm at high signal-to-noise ratios. Since optical and ground based near-infrared data are also available, more than 95 % of the total flux is now covered for these objects. It is seen that between 2.5 μm and about 9 μm the fluxes fall off faster than a Rayleigh-Jeans tail of a black body distribution and that for longer wavelengths the decline is smaller. This indicates that the ISO data are probing the region around the temperature minimum and that our stars have some kind of chromosphere although Hα emission is not observed. Comparison with a model indicates that the features are considerably weaker than predicted. This revised version was published online in August 2006 with corrections to the Cover Date.     

ISOPHOT Observations of Vega and Vega-like Stars

Detailed ISOPHOT observations of the far infrared excess of α Lyrae (Vega) are presented. The data comprise photometry in the range 25μm to 200μm and high resolution 60μm scan data to compare with 60μm and 90μm oversampled maps. The dust disk around Vega is clearly resolved. In addition similar maps of HD98800, SAO226057, SAO186777 and α Piscis Austrinus (HR8728) are evaluated, resolving the disks of two Vega-like stars/candidates and providing upper limits for the size of the other two. This revised version was published online in August 2006 with corrections to the Cover Date.     

ISOPHOT observations of narrow-line Seyfert 1 galaxies

Broad infrared spectra (7–200 μm) of four NLS1 galaxies, obtained with the imaging photo-polarimeter (ISOPHOT) on board the Infrared Space Observatory (ISO), are presented. The infrared luminosities and temperatures, opacities and sizes of the emitting dust components are derived. A comparison between the observed infrared spectra and the optical emission line fluxes of a sample of 16 NLS1 galaxies suggests that these objects suffer different degrees of dust absorption according to the inclination of the line of sight with respect to the dust distribution.     

GEO空间碎片光度测量标定方法的研究

基于GEO卫星、太阳和观测站的空间几何关系,建立了消除太阳赤纬角对地球同步轨道( Geostationary Orbit,GEO)卫星光学特性的影响的方法.以三轴稳定GEO盒状卫星缩比模型为研究样本,在不同太阳赤纬角下进行仿真实验光度测量,研究太阳赤纬角和相位角的空间几何关系,得出消除太阳赤纬角对其辐亮度值以及以相位角...     

Deglitching methods by the ISOPHOT Interactive Analysis (PIA)

The ISOPHOT detectors were continuously exposed to high energy cosmic particles hits, resulting in an average hit rate frequency of an event per every 7 s. The net effect is a disturbance of the readout voltages, which decreases the signal-to-noise ratio and hence the photometric accuracy level. Thanks to the highly redundant readout method of ISOPHOT it is relatively easy to identify cosmic particle hits which have enough energy to produce a noticeable deviation in the readouts. The most energetic particles can cause a short term change in the detector response. Different algorithms are implemented into PIA to cope with this problem. PIA provides handy interfaces to perform individual treatment of the data and optimize the parameters of the deglitching algorithms.     

Calibration of the Classical Cepheid Period-Luminosity Relation from Hipparcos Data

The calibration of the classical Cepheid Period-Luminosity (PL) relation is a fundamental step for the determination of the cosmic distance scale. In this paper a calibration obtained from Hipparcos data is presented and used to estimate the LMC distance modulus. A value of 18.35^m ± 0.13 is obtained. This revised version was published online in July 2006 with corrections to the Cover Date.     

Coronal-Temperature-Diagnostic Capability of the Hinode/X-Ray Telescope Based on Self-consistent Calibration. II. Calibration with On-Orbit Data

The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray imager that observes the solar corona with the capability of diagnosing coronal temperatures from less than 1 MK to more than 10 MK. To make full use of this capability, Narukage et al. (Solar Phys. 269, 169, 2011) determined the thickness of each of the X-ray focal-plane analysis filters based on calibration measurements from the ground-based end-to-end test. However, in their paper, the calibration of the thicker filters for observations of active regions and flares, namely the med-Be, med-Al, thick-Al and thick-Be filters, was insufficient due to the insufficient X-ray flux used in the measurements. In this work, we recalibrate those thicker filters using quiescent active region data taken with multiple filters of XRT. On the basis of our updated calibration results, we present the revised coronal-temperature-diagnostic capability of XRT.     

面向单脉冲信号分类的集成特征选择与评价

受大量射频干扰信号影响,快速从海量观测数据中准确识别出单脉冲信号已成为天文数据处理的一项重要任务,而设计和提取有效数据特征,是利用机器学习进行单脉冲信号高效识别的决定因素.针对如何选择最优特征,进而提升单脉冲信号的分类精度这一关键问题,设计了面向单脉冲信号分类的集成特征选择方法.方法首先混合单脉冲信号的参数特征、统计特征和抽象特征,然后分别利用5种单一特征选择方法选出各自的最优特征集,最后利用贪心策略对5种单一方法获取的最优特征集进行集成筛选,获取最优集成特征集.实验表明,最优特征集合既包含统计特征也包含抽象特征.在相同特征数量下,利用集成特征选择比单一特征选择能获得更高的模型精度,可使F1值最高提升1.8%.在海量数据背景下,集成特征选择对减少特征数量、提升分类性能和加快数据处理速度具有重要作用.     

基于Python的全息测量数据校准软件

微波全息测量是检测抛物面面形分布的重要手段之一,数据校准软件是全息处理软件中关键的一部分。以新疆天文台南山25 m天线改造计划为背景,在分析全息测量中引起误差的几个因素的基础上,开发了全息测量数据校准软件。该软件以Linux为开发平台,使用Python语言进行编程,其优点是:具有误差评估功能,方便用户筛选由于误差过大造成的数据不合理;标准化接口更易嵌入天线控制软件中;可视化界面既能方便用户操作,又可以直观显示运行结果。软件调试结果显示该软件运行时间在2 min以内,效果良好,具有一定的实用价值,不仅对于25 m的改造至关重要,也为未来110 m射电望远镜的技术预研创造了条件。     

Absolute Calibration of the Clementine UVVIS Data: Comparison with Ground-Based Observation of the Moon

Calibrated Clementine images of the Moon and data from Pieters's absolutized spectrophotometric catalog are compared. The scales of these two photometric systems are shown to differ greatly: the albedo of the lunar surface at a phase angle of 6° determined from the Clementine data turns out to be a factor of 2.5 higher than that inferred from ground-based photometry. The fact that the lunar-soil samples from the Apollo 16 landing site used for absolute calibration of the Clementine data are not representative may be responsible for the differences between the scales. Maps are constructed (for wavelengths of 0.42, 0.75, and 0.95 m), which reproduce the distribution of the ratio of the brightnesses determined from telescopic images of the visible lunar hemisphere and from the corresponding Clementine mosaics. The comparison shows fairly good agreement in the details. On the average, the differences are about 10%. The streakiness of the Clementine mosaics are clearly seen in the maps, which is attributable to a low quality of the photometric joining of the data from two one-month imaging series.     

绕月探测工程CCD立体相机的实验室辐射定标

探月光学有效载荷系统含CCD立体相机与干涉成像光谱仪两台光学遥感器,CCD立体相机完成的科学目标主要是与激光高度计配合获取月球表面三维立体图像。文章主要叙述了三线阵立体相机的工作原理,定标内容、目的以及CCD裸片像元检测和整机的相对定标和绝对定标过程。     

绕月探测工程卫星数据的存储与管理

从数据的类型和产品格式说明开始,对绕月探测工程中的科学探测数据的管理方法进行了研究.通过数据存储架构和软件结构的分析,指出数据存储的软硬件环境;通过数据存储和备份策略的分析,指出数据存储的可靠性.这些存储与管理方法将为更好地管理数据并向外界提供检索和获取服务提供保障.     

Data Calibration and Analysis for He I 1083 nm Imaging Spectroscopy

Solar Physics - Imaging spectroscopy in the He?i 1083&;nbsp;nm lines is a powerful tool for probing the top of the chromosphere and bottom of the transition region, but simple techniques...     

The initial conditions of isolated star formation – V. ISOPHOT imaging and the temperature and energy balance of pre-stellar cores

ISO data taken with the long-wavelength imaging photo-polarimeter ISOPHOT are presented of 18 pre-stellar cores at three far-infrared wavelengths, 90, 170 and 200 μm. Most of the cores are detected clearly at 170 and 200 μm, but only one is detected strongly at 90 μm, indicating that mostly they are very cold, with typical temperatures of only ∼     . Colour temperature images are constructed for each of the cores. Most of the cores are seen either to be isothermal, or to have associated temperature gradients from the core centres to their edges, with all except one being cooler at the centre. We compare the data with previous ISOCAM absorption data, and calculate the energy balance for those cores in common between the two samples. We find that the energy radiated by each core in the far-infrared is similar to that absorbed at shorter wavelengths. Hence there is no evidence for a central heating source in any of the cores – even those for which previous evidence for core contraction exists. This is all consistent with external heating of the cores by the local interstellar radiation field, confirming their pre-stellar nature.     

空间碎片观测精度分析

文章分别用内符合精度和外符合精度两种精度指标对云南天文台SBG望远镜的观测数据进行判定，确定了其观测精度。得到高轨空间碎片的观测精度约为2″，和低轨空间碎片的观测精度约为7″，并对观测误差的来源作了一些初步的分析。