Two hundred and fifty-one ^12^C_2_D_2_ transitions have been measured in the 0.2-1.6THz region of its nu_5_-nu_4_ difference band and 202 of them were observed for the first time. The accuracy of these measurements is estimated to be ranging from 50kHz to 100kHz. The ^12^C_2_D_2_ molecules were generated under room temperature by passing 120-150mTorr D_2_O vapor through calcium carbide (CaC_2_) powder. A multistate analysis was carried out for the bending vibrational modes nu_4_ and nu_5_ of ^12^C_2_D_2_, which includes the lines observed in this work and prior microwave, far-infrared and infrared data on the pure bending levels. Significantly improved molecular parameters were obtained for ^12^C_2_D_2_ by adding the new measurements to the old data set, which had only 10 lines with microwave measurement precision. New frequency and intensity predictions have been made based on the obtained molecular parameters. The more precise measurements and new predictions reported here will support the analyses of astronomical observations by the future high-resolution spectroscopy telescopes such as Herschel, SOFIA, and ALMA, which will work in the terahertz spectral region.
Following tentative detection of cyclopropene (C_3_H_4_) in Sgr B2 through its transition 3_22_-2_21_, several attempts to confirm the presence of cyclopropene in astronomical objects (including Sgr B2 itself) have been made. We suggest that cyclopropene may be observed in astronomical objects through its transition 2_20_-2_21_ at 3.67218GHz, in absorption, even against the cosmic 2.7K background, in a region having low density and low kinetic temperature.
Cyclopropenylidene C_3_H_2_ and ethylene oxide C_2_H_4_O molecules are of astronomical importance as their observed lines, distributed throughout the observable microwave region, have a number of pairs having nearly equal frequencies, but different excitation energies and/or belonging to two different species of the molecule. Hence, these molecules may play important role in detecting physical conditions in cosmic objects. Therefore, in order to calculate intensities of the lines, we have investigated transfer of radiation through a cosmic object containing the molecule at a kinetic temperature of 10K. Our results show that some lines of the molecule may be found in absorption against the cosmic 2.7K background.
Einstein A-coefficients for vib-rotational transitions in CS isotopomers, for vibrational quantum number v up to 20, rotational quantum number J up to 140, and {DELTA}v up to 4, are calculated. The change in J is governed by the selection rules {DELTA}J=+/-1. These coefficients play an important role in astronomy, as CS has been observed in a number of astronomical object.
Einstein A-coefficients for the electric dipole transitions in Silicon Dicarbide molecule and its isotopomers between rotational levels of the ground vibrational state up to 51cm^-1^ are calculated. These coefficients are used for computing radiative life times of the levels. The A-coefficients are one of the important input parameters for the radiative transfer calculations.
This database table consists of a preliminary source list for the Einstein Observatory's High Resolution Imager (HRI). The source list, obtained from EINLINE, the Einstein On-line Service at the Smithsonian Astrophysical Observatory (SAO), contains basic information about the sources detected with the HRI. This is a service provided by NASA HEASARC .
This database table contains primary HRI source parameters for the 202 HRI sources found in the Einstein Deep Survey. The Einstein Deep Survey (EDS) program consisted of very deep X-ray exposures in selected regions of the sky at high galactic latitude. The main purposes of the survey are to investigate the nature of the extragalactic X-ray background through direct source counts at very low flux levels and to study the nature of the very faint X-ray sources which comprise a significant fraction, if not all, of the soft X-ray background. This is a service provided by NASA HEASARC .
The Einstein High Resolution Imager (HRI) consisted of a micro-channel plate. This database table has been generated at the EXOSAT observatory by automatically processing all the HRI images. Both the images and detected sources are available. This catalog has not been cleaned or checked. Users should beware of two possible problems: (1) spurious detections caused by extended sources have not been checked, and (2) there may be a one-pixel offset in some positions. For HRI images, one pixel is one arcsecond. (The images are rebinned from the original 0.5 arcseconds.) This is a service provided by NASA HEASARC .
IPCDEEP is created from a table containing basic source parameters for each of the 178 IPC sources detected by the Einstein Deep Survey. The Einstein Deep Survey program (EDS) consists of very deep X-ray exposures in selected regions of the sky at high galactic latitude. The main purposes of the survey are to investigate the nature of the extragalactic X-ray background through direct source counts at very low flux levels and to study the nature of the very faint X-ray sources which comprise a significant fraction, if not all, of the soft X-ray background. This is a service provided by NASA HEASARC .
This database table contains information from the Einstein Extended Medium Sensitivity Survey (EMSS) which consists of 835 serendipitous X-ray sources detected at or above 4 times the rms level in 1435 IPC fields with their centers located away from the galactic plane. Their limiting sensitivities range from ~5*10E-14 to ~3*10-12 ergs cm-3 s-1 in the 0.3-3.5keV band. A total area of 778 square degrees of the high galactic latitude sky (|b|>20) has been covered. The analysis has been performed using data from the Rev 1 processing system at the CfA. The resulting EMSS catalog is a flux-limited and homogeneous sample of astronomical objects that can be used for statistical studies. Additional information is available from the HEASARC. This is a service provided by NASA HEASARC .