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Title: SIGGMA: A SURVEY OF IONIZED GAS IN THE GALAXY, MADE WITH THE ARECIBO TELESCOPE

A Survey of Ionized Gas in the Galaxy, made with the Arecibo telescope (SIGGMA), uses the Arecibo L-band Feed Array (ALFA) to fully sample the Galactic plane (30 Degree-Sign {<=} l {<=} 75 Degree-Sign and -2 Degree-Sign {<=} b {<=} 2 Degree-Sign ; 175 Degree-Sign {<=} l {<=} 207 Degree-Sign and -2 Degree-Sign {<=} b {<=} 1 Degree-Sign ) observable with the telescope in radio recombination lines (RRLs). Processed data sets are being produced in the form of data cubes of 2 Degree-Sign (along l) Multiplication-Sign 4 Degree-Sign (along b) Multiplication-Sign 151 (number of channels), archived and made public. The 151 channels cover a velocity range of 600 km s{sup -1} and the velocity resolution of the survey changes from 4.2 km s{sup -1} to 5.1 km s{sup -1} from the lowest frequency channel to the highest frequency channel. RRL maps with 3.'4 resolution and a line flux density sensitivity of {approx}0.5 mJy will enable us to identify new H II regions, measure their electron temperatures, study the physics of photodissociation regions with carbon RRLs, and investigate the origin of the extended low-density medium. Twelve Hn{alpha} lines fall within the 300 MHz bandpass of ALFA; they are resampled to amore » common velocity resolution to improve the signal-to-noise ratio (S/N) by a factor of three or more and preserve the line width. SIGGMA will produce the most sensitive fully sampled RRL survey to date. Here, we discuss the observing and data reduction techniques in detail. A test observation toward the H II region complex S255/S257 has detected Hn{alpha} and Cn{alpha} lines with S/N > 10.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8]
  1. National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
  2. University of New Mexico, Albuquerque, NM 87131 (United States)
  3. Cornell University, Ithaca, NY 14853 (United States)
  4. Arecibo Observatory, HC03 Box 53995, Arecibo 00612, PR (United States)
  5. West Virginia University, Morgantown, WV 26506 (United States)
  6. University of Wisconsin-Madison, Madison, WI 53706 (United States)
  7. University of Puerto Rico, P.O. Box 23323, 00931-3323, San Juan (Puerto Rico)
  8. National Radio Astronomy Observatory, Green Bank and Charlottesville, VA 22903 (United States)
Publication Date:
OSTI Identifier:
22136523
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 146; Journal Issue: 4; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON; DISSOCIATION; ELECTRON TEMPERATURE; FLUX DENSITY; GALAXIES; LINE WIDTHS; PHOTOLYSIS; RECOMBINATION; SENSITIVITY; SIGNAL-TO-NOISE RATIO; TELESCOPES; VELOCITY