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NASA NTRS1989

The NASA SETI sky survey: Recent developments

NASA's Search for Extraterrestrial Intelligence (SETI) project utilizes two complementary search strategies: a sky survey and a targeted search. The SETI team at the Jet Propulsion Laboratory (JPL) in Pasadena, California, has primary responsibility to develop and carry out the sky survey part. Described here is progress that has been made developing the major elements of the survey including a 2-million channel wideband spectrum analyzer system that is being designed and constructed by JPL for the Deep Space Network (DSN). The system will be a multiuser instrument; it will serve as a prototype for the SETI sky survey processor. This prototype system will be used to test the signal detection and observational strategies on DSN antennas in the near future.

Klein, M. J.↗
NASA NTRS1994

IRAS sky survey atlas: Explanatory supplement

This Explanatory Supplement accompanies the IRAS Sky Survey Atlas (ISSA) and the ISSA Reject Set. The first ISSA release in 1991 covers completely the high ecliptic latitude sky, absolute value of beta is greater than 50 deg, with some coverage down to the absolute value of beta approx. equal to 40 deg. The second ISSA release in 1992 covers ecliptic latitudes of 50 deg greater than the absolute value of beta greater than 20 deg, with some coverage down to the absolute value of beta approx. equal to 13 deg. The remaining fields covering latitudes within 20 deg of the ecliptic plane are of reduced quality compared to the rest of the ISSA fields and therefore are released as a separate IPAC product, the ISSA Reject Set. The reduced quality is due to contamination by zodiacal emission residuals. Special care should be taken when using the ISSA Reject images. In addition to information on the ISSA images, some information is provided in this Explanatory Supplement on the IRAS Zodiacal History File (ZOHF), Version 3.0, which was described in the December 1988 release memo. The data described in this Supplement are available at the National Space Science Data Center (NSSDC) at the Goddard Space Flight Center. The interested reader is referred to the NSSDC for access to the IRAS Sky Survey Atlas (ISSA).

Wheelock, S. L.↗
NASA NTRS1994

The Two Micron All Sky Survey

This paper describes the design, expectations, and prototyping of a new all sky survey, called 2MASS (Two Micron All Sky Survey) to be carried out with the new generation of infrared array detectors.

Kleinmann, S. G.↗
NASA NTRS1992

2MASS - The 2 Micron All Sky Survey

This paper describes a new sky survey to be carried out in three wavebands, J(1.25 m), H(1.65 m), and K(2.2 m). The limiting sensitivity of the survey, 10 sigma detection of point sources with K not greater than 14 mag, coupled with its all-sky coverage, were selected primarily to support studies of the large-scale structure of the Milky Way and the Local Universe. The survey requires construction of a pair of observing facilities, one each for the Northern and Southern Hemispheres. Operations are scheduled to begin in 1995. The data will begin becoming publicly available soon thereafter.

Kleinmann, S. G.↗
NASA NTRS1981

Preliminary results of the Air Force infrared sky survey

The paper presents a review of the Air Force Infrared Sky Survey with a discussion of the current status of the survey and an account of efforts to verify results contained in the AFCRL and AFGL catalogs. An overview of the AFGL catalog and subsets is given; 71% of the sources listed in the AFGL catalog are identified with sources in the Two Micron Sky Survey. Combining the data in the AFGL and TMSS catalogs yields information on the energy distributions of the brighter IR sources over four octaves. Attention is then given to studies of particular classes of objects found in the AFGL catalog, concentrating on objects not identified with stars in the TMSS or the Catalogue of Bright Stars. Finally, a summary is given of the relative populations of various classes of infrared sources found in the AFGL catalog, including a discussion of its extragalactic content.

Kleinmann, S. G.↗
NASA NTRS1985

Objectives and first results of the NASA SETI Sky Survey field tests at Goldstone, California

The objectives and preliminary results of the initial field tests of the prototype hardware and software for the NASA SETI program are reviewed with emphasis on the Sky Survey component of the NASA search strategy. In particular, attention is given to field test instrumentation, sky pixelation, sky survey field tests, baseline tests, antenna control tests, and radio frequency interference survey. The test results and observational experience will be used to finalize the design of the SETI Sky Survey processing system and to optimize the observational strategy and procedures in time to begin a full-scale Microwave Observing Program in 1990.

Gulkis, S.↗
NASA NTRS1998

Dwarfs Cooler Than M: The Definition of Spectral Type L Using Discoveries from the 2-Micron All-Sky Survey (2MASS)

Before the 2-Micron All-Sky Survey (2MASS) began, only six objects were known with spectral types later than M9.5 V. In the first 371 sq. deg. of actual 2MASS survey data, we have identified another twenty such objects spectroscopically confirmed using the Low Resolution Imaging Spectrograph (LRIS) at the W.M. Keck Observatory.

class T low mass brown dwarf stellar atmosphere 2-↗
NASA NTRS2001

Galactic SNR Candidates in the ROSAT All-Sky Survey

Identified radio supernova remnants (SNRS) in the Galaxy comprise an incomplete sample of the SNR population due to various selection effects. ROSAT performed the first all-sky survey with an imaging X-ray telescope, and thus provides another window for finding SNRS and compact objects that may reside within them. Performing a search for extended X-ray sources in the ROSAT all-sky survey database about 350 objects were identified as SNR candidates in recent years. Continuing this systematic search, we have reanalyzed the ROSAT all-sky survey (BASS) data of these candidates and correlated the results with radio surveys like NVSS, ATNF, Molonglo, and Effelsberg. A further correlation with SIMBAD and NED were used for subsequent identification purpose. About 50 of the 350 candidates turned out to be likely galaxies or clusters of galaxies. We found 14 RASS sources which are very promising SNR candidates and are currently subject of further follow-up studies. We will provide the details of the identification campaign and present first results.

Schaudel, Daniel↗
NASA NTRS1992

Observation of the Coma cluster of galaxies with ROSAT during the all-sky survey

The Coma cluster of galaxies was observed with the position sensitive proportional counter (PSPC) during the ROSAT all sky survey. We find evidence for substructure in this cluster. Diffuse X-ray emission is detected from the regions of the NGC 4839 and 4911 subgroups at 6 percent and 1 percent of the total cluster emission respectively. There may be emission associated with the NGC 4874 and 4889 subgroups as well. The NGC 4839 group appears to be in the process of merging with the cluster. These X-ray data show that at least some of the groups previously found in projection are in fact physical objects possessing potential wells deep enough to trap their own X-ray gas. Because of the unlimited field of view of the all sky survey and the low background of the PSPC, we were able to measure the azimuthally averaged surface brightness of Coma out to approximately 100 arcmin, twice as far as was previously possible. Given the validity of our mass models, these new X-ray data imply that within 5/h(50) Mpc the binding mass of the Coma cluster is 1.8 +/- 0.6 x 10 exp 15/h(50) solar mass, and the fraction of cluster mass contained in hot gas is 0.30 +/- 0.14h(50) exp -3/2. Furthermore, the binding mass is more centrally concentrated than is the X-ray gas.

Briel, U. G.↗
NASA NTRS1980

A very long baseline interferometry sky survey

A systematic very long baseline interferometry (VLBI) sky survey, undertaken to find a suitable set of compact celestial radio sources from which a more complete VLBI reference frame can be constructed, discussed. The survey was conducted by searching known celestial radio sources for compact components by means of VLBI observations. Baseline lengths were about 7 x 10 to the 7th power RF wavelengths (lambda = 13.1 cm), so the spatial wavelengths being sampled by the interferometer were generally on the order of a few milliarcseconds. Hence, the radio sources detected have a measurable portion of their total flux density contained in components that are no more than a few milliarcseconds in angular extent. Existing information of radio sources were used as clues to source size.

Preston, R. A.↗
NASA NTRS1985

SETI - The microwave search problem and the NASA sky survey approach

NASA's microwave observing program for SETI is presented. This strategy is composed of a high sensitivity, narrow frequency coverage, Target Search and a low sensitivity, broad frequency coverage, Sky Survey. The complementary nature of this dual mode search strategy is discussed. An overview is given of ongoing work in the development of the search strategy for the Sky Survey.

Klein, M. J.↗
NASA NTRS1985

A signal detection strategy for the SETI All Sky Survey

A source detection strategy for the SETI All Sky Survey is described. The method is designed to detect continuous wave (or very narrowband) sources transitting an antenna beam. The short-time spectra of the received signal are accumulated, and candidate extraterrestrial sources are recognized by the recognized by the presence of narrowband power exceeding a threshold function. The threshold function is derived using a Neyman-pearson hypothesis test.

Lawton, W.↗
NASA NTRS1992

Rosat X-ray All-Sky Survey observations of hybrid stars

Data from the Rosat All-Sky Survey for nine hybrid stars, objects showing spectroscopic evidence for cool massive winds and 500,000-K material, are presented. Two of the nine stars were detected above a limiting flux threshold of 2 x 10 exp -13 ergs/sq cm s. The K3 III star Delta And was detected just at this threshold. The K4 III star Alpha TrA was measured at 8 x 10 exp -13 ergs/sq cm s. Since these detections were made in both low- and high-energy bands of the Rosat 0.1-2.4-keV passband, it is suggested that the emissions originate in coronae of about 10 exp 7 K.

Haisch, Bernhard↗
NASA NTRS1993

The ROSAT All-Sky Survey of active binary coronae. I - Quiescent fluxes for the RS Canum Venaticorum systems

One hundred and thirty-six RS CV(n) active binary systems were observed with the ROSAT Position Sensitive Proportional Counter (PSPC) during the All-Sky Survey component of the mission. The entire sky was surveyed, which represents the largest sample of RS CV(n) systems observed to date at any wavelength, including X-rays. X-ray surface fluxes for the RS CV(n) systems are found to lie in the range 10 exp 4 to 10 exp 8 ergs/sq cm seconds. Surface flux as a function of (B - V) color is reported. A decrease in surface flux with increasing rotation period for the entire sample is observed. The rotation period provides the best stellar or orbital parameter to predict the X-ray surface flux level. The absence of correlation of F(x) or L(x) with Gamma is noted due to the fact that the coronal heating mechanism for these active stars must be magnetic in character, and the magnetic field depends on the interaction between convection and differential rotation inside the star. X-ray properties of the RS CV(n) systems with 6 cm radio and C IV UV emission systems is compared.

Dempsey, Robert C.↗
NASA NTRS1996

The ROSAT All-Sky Survey view of the Large Magellanic Cloud (LMC)

During the Rosat all sky survey, centered on the Large Magellanic Cloud (LMC), 516 X-ray sources were detected. The field was covered from July 1990 to January 1991. The X-ray parameters of the sources, involving position, count rates, hardness ratios, extent, and time variability during the observations, are discussed. Identifications with objects from optical, radio and infrared wavelength allow the LMC candidates to be separated from the foreground stars and the background objects.

Pietsch, W.↗
NASA NTRS1996

Distribution to the Astronomy Community of the Compressed Digitized Sky Survey

The Space Telescope Science Institute has compressed an all-sky collection of ground-based images and has printed the data on a two volume, 102 CD-ROM disc set. The first part of the survey (containing images of the southern sky) was published in May 1994. The second volume (containing images of the northern sky) was published in January 1995. Software which manages the image retrieval is included with each volume. The Astronomical Society of the Pacific (ASP) is handling the distribution of the lOx compressed data and has sold 310 sets as of October 1996. ASP is also handling the distribution of the recently published 100x version of the northern sky survey which is publicly available at a low cost. The target markets for the 100x compressed data set are the amateur astronomy community, educational institutions, and the general public. During the next year, we plan to publish the first version of a photometric calibration database which will allow users of the compressed sky survey to determine the brightness of stars in the images.

Postman, Marc↗
NASA NTRS1987

A catalog of galaxies in Hercules from the Palomar Sky Survey and the Minnesota Automated Plate Scanner

The development of galaxies catalogs from the Palomar Sky Survey using the Minnesota Automated Plate Scanner (APS) is examined. The design and operation of APS are described. The algorithm used to distinguish stars from galaxies is discussed, and the completeness and confusion of the algorithm as a function of magnitude are estimated. The quality of the photometric calibration for galaxy magnitudes and surface-brightness thresholds is evaluated. The relation between the distribution of colors and morphological types is studied. The luminosity functions for Hercules galaxies are calculated and presented. The catalog generated using the APS is 80 percent complete; photometry good to 0.23 mag rms is possible; and J-F colors are good to 0.17 mag rms.

Dickey, John M.↗