Research of the 21 CM radiation at Agassiz Station.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Research of the 21 CM radiation at Agassiz Station. Bok, Bart J. ; Ewen, Harold I. Abstract The present paper by A. E. Lilley and D. S. Heeschen reports on the progress made to date on the Radio Astronomy Project at Agassiz Station. A 24-foot parabolic antenna operating in conjunction with a comparison radiometer has been used to record the profiles of the 21 cm line of neutral hydrogen. The electronic equipment is essentially a double conversion superheterodyne microwave receiver. The comparison radiometer feature is accomplished by separately detecting two portions of the received spectrum after separation by a double band pass filter network. By continuously comparing these two rectified noise powers in a balanced recorder, the inherent gain fluctuations of the overall equipment are minimized to a level well below the detectable difference produced by the presence of a hydrogen signal in one. To date, the Agassiz Station Project has concentrated its efforts upon analyses of regional surveys of 21 cm profiles along the Milky Way. Two projects have already been completed, the first that of Lilley, who has been primarily concerned with the study of interstellar hydrogen associated with cosmic dust in the dark nebulae complex in Taurus, and the second that of Heeschen, who has studied certain astrophysical problems related to the line profiles for the section of the galactic center. The total number of centers for these two projects combined is about two hundred; for each center a minimum of four scans was considered necessary. Several programs are now under way at Agassiz Station. Thomas A. Matthews is studying the sections of the Milky Way near 1 = 800 and 1 = 1150, with several connecting strips and extensions at galactic latitudes b = - 150, 00 and + ISo, and with, for each section, one strip running from b = - 600 to +600. This section was selected because of the interesting feature that the separation between the two principal spiral arms is very marked in the profiles. Three other sections of the Milky Way are under investigation. David S. Heeschen has already obtained profiles for a number of centers in Cygnus and will complete this program in collaboration with Campbell M. Wade. Wade is investigating the variation in the line profiles at b = +150 for the connection between the Ophiuchus and Cygnus centers. Finally, T. K. Menon is concentrating on the section from Gemini, thr~ugh Orion and Monoceros to Canis Major, with special emphasis on the region of the Orion Nebula. The Agassiz Station Project has been supported by a gift from a friend of the Station and through two grants from the National Science Foundation. John A. Campbell is the electronic engineer on the project. Harvard College Observatory, Cambridge, Mass. Publication: The Astronomical Journal Pub Date: August 1954 DOI: 10.1086/107070 Bibcode: 1954AJ.....59Q.318B full text sources ADS |