2MASS近红外巡天点源表数据库的建立和使用

简要介绍2MASS近红外巡天计划．利用PHP动态网页编程语言及MySQL关系数据库查询语言建立2MASS点源数据库及其网络查询系统．并根据2MASS近红外巡天计划的科研成果，提出了一些利用该数据库可能开展的一些研究领域和研究方向．     

多波段巡天和LAMOST观测目标

综述了国际上多波段巡天工作的进展。其中，x射线波段列举了至今主要的x射线卫星，特别介绍了ROSAT、ASCA、Chandra和XMM—Newton的情况；光学波段主要介绍了SDSS、DEEP以及2df的星系和类星体巡天；红外波段主要介绍了2MASS和SWIRE巡天；射电波段主要介绍了NVSS和FIRST巡天。根据光谱能力和观测模式，提出了LAMOST的选题目标，分析讨论了LAMOST可以开展的交叉证认工作。     

“心事浩茫连广宇”——功勋卓著的大天区巡天

在天文学飞速发展的20世纪里,天文学家在每一个可能的电磁波段都进行了多次巡天。这些巡天引领了无数个激动人心的伟大发现,并为许多研究课题,例如描绘银河系结构乃至宇宙大尺度结构以及搜寻极端天体等等方面,提供了海量的基础性数据。本文是对各种巡天的综合“巡视”,对近年来比较著名的大天区巡天——2MASS、SDSS、2dfGRS、UKIDSS等进行了简单介绍,列举了它们作出的部分重要科学发现,并对未来的巡天工作进行了展望,希望能有助于大家更深入地认识巡天。     

宇宙画廊

今年6月底,研究人员有了关于脉冲星新发现：移动最快的脉冲星!他们动用三个不同的望远镜拍摄,利用多个波段观测来合成影像,使得这幅图片色彩非常丰富：绿色标示的部分来自钱德拉X射线望远镜的结果,紫色展示的是XMM-牛顿望远镜的结果,这里还联合使用了2MASS项目的数据以及数字巡天的光学数据,光学部分包含红、绿、蓝三色,综合看来在图中呈现为白色。     

“英澳望远镜”获得大奖

当我们提到研究级的天文望远镜时,脑海中首先冒出的就是哈勃空间望远镜、凯克望远镜、欧洲南方天文台的甚大望远镜VLT等等新一代巨无霸以及斯隆数字巡天、2MASS巡天等做出过重大发现的巡天项目。的确,这些威力巨大的观天巨眼在科学上的产出也是最多的。那么,接下来呢？就要数英澳望远镜了。     

基于JDBC的通用数据库访问和星表录人工具

LAMOST（Large Sky Area Multi-Object Fiber Spectroscopy Telescope）的巡天战略系统的主要功能是安排观测计划,而规划巡天星表是开展所有工作的初始步骤。天文研究人员或者巡天观测人员需要从各种类型的数据库进行选星、提取和录入。使用JDBC（Java Database Connectivity）数据库访问技术,利用面向对象的编程思想,实现了一个能访问多种类型数据库、获取星表数据、数据格式转换和星表录入的工具,支持大数据量处理,为天文研究人员以及巡天观测管理人员提供帮助。     

基于JDBC的通用数据库访问和星表录入工具

LAMOST(Large Sky Area Multi-Object Fiber Spectroscopy Telescope)的巡天战略系统的主要功能是安排观测计划,而规划巡天星表是开展所有工作的初始步骤。天文研究人员或者巡天观测人员需要从各种类型的数据库进行选星、提取和录入。使用JDBC(JavaDatabase Connectivity)数据库访问技术,利用面向对象的编程思想,实现了一个能访问多种类型数据库、获取星表数据、数据格式转换和星表录入的工具,支持大数据量处理,为天文研究人员以及巡天观测管理人员提供帮助。     

基于分布式执行框架的低频射电干涉阵列成像管线优化

平方公里阵列(Square Kilometre Array,SKA)项目是建设全球最大射电望远镜的国际合作项目,其灵敏度和测量速度将比当前所有的射电望远镜都要高出一个数量级.连续谱巡天是SKA的主要观测模式之一,基于连续谱成像建立巡天区域的标准星图,将能为后续天文科学研究奠定重要基础.银河系与河外星系全天默奇森宽场阵列拓展巡天(GaLactic and Extragalactic All-sky Murchison Widefield Array survey eXtended,GLEAM-X)是2018—2020年利用SKA先导望远镜默奇森宽场阵列(Murchison Wide-field Array,MWA)二期拓展阵列开展的新的射电连续谱巡天项目,观测期间积累了大量的低频巡天观测数据.海量观测数据的自动化、大批量处理是SKA望远镜项目所面临的的最大挑战和难题之一,基于分布式执行框架的成像管线优化经验将有助于解决海量数据处理问题.详细介绍了GLEAM-X成像管线并对其进行整合和改进,在中国SKA区域中心原型机(China SKA Regional Centre Prototype,...     

ROSAT选射电源的性质：Ⅰ.样本

ＲＯＳＡＴ卫星的全天巡天观测到了一大批射电星系和各种活动星核,为我们研究这些活动性剧烈的河外天体的辐射机制、多波段辐射相关性以及各类星系核之间的演化联系提供了重要数据。通过将ＲＯＳＡＴ全天巡天观测与ＰＭＮ射电（５ＧＨｚ）巡天观测进行交叉证认,我们得到了６４２颗天射电源。对这些对应体随后进行的光学证认构建了一个星系和活动星系核的大样本。其中３１１个对应体（占５２％）被过去的光学观测证实为河外天体（包     

VO_IMPAT:中国虚拟天文台图像处理分析工具

中国虚拟天文台图像处理分析工具（VO_IMPAT），是由国家天文台虚拟天文台项目组开发的一项服务，它提供了对数字巡天图像数据（Digital Sky Survey，DSS）、天文星表以及其他数据库的交互访问。VO_IMPAT的设计目的是实现多波段天文数据的融合。可以将不同波段的星表叠加到DSS底图上，如光学波段的USNO星表、近红外波段的2MASS星表、射电波段的NVSS星表和X射线波段的RASS星表。同时VO_IMPAT还可以对图像进行放大、缩小、伪彩色、等高线、直方图、尖锐化、平滑化、旋转等处理，不同的星表数据可以采用不同的颜色和图标显示。     

Cross-correlation between WMAP and 2MASS: non-Gaussianity induced by the SZ effect

We study the non-Gaussianity induced by the Sunyaev–Zel'dovich (SZ) effect in cosmic microwave background (CMB) fluctuation maps. If a CMB map is contaminated by the SZ effect of galaxies or galaxy clusters, the CMB maps should have similar non-Gaussian features to the galaxy and cluster fields. Using the WMAP data and 2MASS galaxy catalogue, we show that the non-Gaussianity of the 2MASS galaxies is imprinted on WMAP maps. The signature of non-Gaussianity can be seen with the fourth-order cross-correlation between the wavelet variables of the WMAP maps and 2MASS clusters. The intensity of the fourth-order non-Gaussian features is found to be consistent with the contamination of the SZ effect of 2MASS galaxies. We also show that this non-Gaussianity can not be seen by the high-order autocorrelation of the WMAP . This is because the SZ signals in the autocorrelations of the WMAP data generally are weaker than the WMAP –2MASS cross-correlations by a factor f ², which is the ratio between the powers of the SZ-effect map and the CMB fluctuations on the scale considered. Therefore, the ratio of high-order autocorrelations of CMB maps to cross-correlations of the CMB maps and galaxy field would be effective to constrain the powers of the SZ effect on various scales.     

Searching for an intrinsic stellar population in compact high-velocity clouds

We are investigating the hypothesis that Compact High-Velocity Clouds (CHVCs) are the left-over building blocks of Local Group galaxies. To this end, we are searching for their embedded stellar populations using FORS at the VLT. The search is done with single-star photometry in V and I bands, which is sensitive to both, young and old, stellar populations. Five CHVCs of our sample have been observed so far down to I=24. We pointed the VLT towards the highest HI column density regions, as determined in Effelsberg radio data. In an alternate approach, we searched 2MASS public data towards those 5 CHVCs down to K=16. While the VLT data probe the central regions out to distance moduli of about 27, the 2MASS data are sensitive to a population of red giant stars to distance moduli of about 20. The 2MASS data, on the other hand, cover a much wider field of view than the VLT data (radius of 1 degree versus FORS field of 6.8 arcmin). We did not find a stellar population intrinsic to the CHVCs in either data. In this paper, we illustrate our search methods. This revised version was published online in August 2006 with corrections to the Cover Date.     

Photometric analysis of the eclipsing binary 2MASS 19090585+4911585

We report on observations of the eclipsing binary 2MASS 19090585+4911585 with the 25 cm auxiliary telescope of the University Observatory Jena. We show that a nearby brighter star (2MASS 19090783+4912085) was previously misclassified as the eclipsing binary and find 2MASS 19090585+4911585 to be the true source of variation. We present photometric analysis of VRI light curves. The system is an overcontact binary of W UMa type with an orbital period of (0.288374 ± 0.000010) d (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The XPM Catalogue: absolute proper motions of 280 million stars

We combined data from the Two-Micron All Sky Survey (2MASS) and USNO-A2.0 catalogues in order to derive the absolute proper motions of about 280 million stars distributed all over the sky excluding a small region near the Galactic Centre, in the magnitude range  12 < B < 19 mag  . The proper motions were derived from the 2MASS Point Sources and USNO-A2.0 catalogue positions with a mean epoch difference of about 45 years for the Northern hemisphere and about 17 years for the Southern one. The zero-point of the absolute proper motion frame (the 'absolute calibration') was specified with the use of about 1.45 million galaxies from 2MASS. Most of the systematic zonal errors inherent in the USNO-A2.0 catalogue were eliminated before the calculation of proper motions. The mean formal error of absolute calibration is less than 1 mas yr⁻¹. The XPM Catalogue will be available via CDS in Strasbourg during 2010. The generated catalogue contains the International Celestial Reference System positions of stars for the J2000 epoch, original absolute proper motions, as well as   B , R , J , H   and K magnitudes. A comparison of the proper motions obtained in this work with the data of other recent catalogues of quasars was fulfilled.     

The past photometric history of the FU Ori-type young eruptive star 2MASS J06593158-0405277 = V960 Mon

The known FU Ori-type young eruptive stars are exceedingly rare (a dozen or so confirmed objects) and 2MASS J06593158-0405277, with its 2014 outburst, is likely the latest addition to the family. All members have displayed just one such eruption in their recorded history, an event lasting for decades. To test the FU Ori nature of 2MASS J06593158-0405277, we have reconstructed its photometric history by measuring its brightness on Harvard photographic plates spanning the time interval 1899–1989. No previous large amplitude eruption similar to that initiated in 2014 has been found, as in bona fide FU Ori-type objects. The median value of the brightness in quiescence of 2MASS J06593158-0405277 is B = 15.5, with the time interval 1935–1950 characterized by a large variability ( ∼ 1 mag amplitude) that contrasts with the remarkable photometric stability displayed at later epochs. The variability during 1935–1950 can either be ascribed to some T Tau like activity of 2MASS J06593158-0405277 itself or to the also young and fainter star 2MASS J06593168-0405224 that lies 5 arcsec to the North and forms an unresolved pair at the astrometric scale of Harvard photographic plates.     

Astrometric observations of the Uranian satellites with the Faulkes Telescope North in 2007 September

The results of astrometric observations of the main Uranian satellites taken with the Faulkes Telescope North are presented. A median filter algorithm was applied to subtract a scattered-light halo caused by Uranus. The Two-Micron All-Sky Survey (2MASS) and USNO-B1.0 were used as reference catalogues. The mean value of the differences between the equatorial coordinates of the satellites determined with 2MASS and USNO-B1.0 is close to 200 mas. A comparison of the observed equatorial coordinates of the satellites and their relative positions with ephemerides based on different combinations of theories of motion of Uranus and its satellites (DE405+GUST86, DE405+GUST06, INPOP+GUST86, INPOP+GUST06) was performed. The satellites' positions obtained with respect to 2MASS are in better agreement with theories. The values of (O−C) of the equatorial coordinates determined with the 2MASS are mainly less than 100 mas. The majority of (O−C) of relative positions are within ±50 mas. The mean values of the standard errors of (O−C) are within 20 to 60 mas.     

Infrared study of the extreme carbon stars based on IRAS, 2MASS and ISO data

We collected 55 galactic extreme carbon stars from the published literature in this paper. Observational data from IRAS, 2MASS and ISO were analyzed. The results show that the infrared properties of extreme carbon stars are quite different to those for ordinary visual carbon stars. It is shown from IRAS and 2MASS photometric data that extreme carbon stars have much redder infrared colors not only in the far infrared, but also in the near infrared, hence they have much thicker ciucumstellar envelopes and mass loss. It is also indicated from IRAS Low-Resolution Spectra (LRS) and ISO Short Wavelength Spectra (SWS) that they have much redder infrared spectra from 2 μm to 45 μm. The above results are believed to be the signature of undergoing the last stages of AGB evolution for extreme carbon stars.     

Five supernova survey galaxies in the southern hemisphere. I. Optical and near-infrared database

The determination of the supernova (SN) rate is based not only on the number of detected events, but also on the properties of the parent galaxy population. This is the first paper of a series aimed at obtaining new, refined, SN rates from a set of five SN surveys, by making use of a joint analysis of near-infrared (NIR) data. We describe the properties of the 3838 galaxies that were monitored for SNe events, including newly determined morphologies and their DENIS, and POSS-II/UKST I, 2MASS and DENIS J and K_s and 2MASS H magnitudes. We have compared 2MASS, DENIS and POSS-II/UKST IJK magnitudes in order to find possible systematic photometric shifts in the measurements. The DENIS and POSS-II/UKST I band magnitudes show large discrepancies (mean absolute difference of 0.4 mag.), mostly due to different spectral responses of the two instruments, with an important contribution (0.33 mag rms) from the large uncertainties in the photometric calibration of the POSS-II and UKST photographic plates. In the other wavebands, the limiting near infrared magnitude, morphology, and inclination of the galaxies are the most influential factors which affect the determination of photometry of the galaxies. Nevertheless, no significant systematic differences have been found between any pair of NIR magnitude measurements, except for a few percent of galaxies showing large discrepancies. This allows us to combine DENIS and 2MASS data for the J and K_s filters. Published in Astrofizika, Vol. 52, No. 1, pp. 47–62 (Februay 2009).     

Cross-identification between the HIPPARCOS and 2MASS catalogs: The second 2MASS data release (162 million stars)

A cross-identification between the HIPPARCOS and 2MASS (the second data release, 162 million stars) catalogs has been made. This cross-identification has been used to produce a reference infrared catalog of 41143 stars.