Detection of h2o emission from galaxy ngc253

ABSTRACT THE 616–523 transition of water vapour at 22.235 GHz was observed for the first time in an external galaxy by Churchwell _et al._1 in M33 with the 100-m Effelsberg radio telescope

in late 1976, after some previous unsuccessful searches2,3. We report here the second detection of H2O emission from an external galaxy, NGC253, a large edge-on spiral galaxy situated at 3.4

Mpc (ref. 4), about five times farther away than M33. Previous observations of other molecules pointed NGC253 as a good candidate for H2O emission: OH was detected by Weliachew5 and

confirmed by other workers6,7; CO was detected by Rickard _et al._8 and by Soloman and Zafra9, and H2CO was detected by Gardner and Whiteoak10. The time schedule of the 13.7-m Itapetinga

radio telescope during 1977 May permitted a very long integration to be performed on this object, which is observable more than seven hours a day at elevation angles greater than 30°. The

observations were made with a double sideband balanced mixer receiver of about 1,000 K system temperature and a 46 channel, 100 kHz resolution filter bank. Beam switching at a frequency of

about 100 Hz was used, the main beam and then the 9′ reference beam being pointed at the nucleus of NGC253 for alternate intervals of 1 min. The sign of the recorded signal was changed every

minute by the data acquisition computer, so that possible zero-level offsets of the channels were eliminated. One-hour integrations were made with the filter bank centred alternatively at

three different frequencies in order to obtain greater velocity coverage, until a total on-source integration time of 21 h was completed at each frequency band. The data analysis program

corrected the antenna temperatures for atmospheric attenuation as a function of zenith angle exp (−_τ_ sec _z_) and then investigated the distribution of the results of the one-hour

observations for each channel, giving the standard error of the mean and rejecting data more than 3 _σ_ different from averaged values; the channels were subsequently averaged two by two,

simulating a 200 kHz resolution system. Access through your institution Buy or subscribe This is a preview of subscription content, access via your institution ACCESS OPTIONS Access through

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Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS H I 21-CENTIMETRE EMISSION FROM AN ENSEMBLE OF GALAXIES AT AN AVERAGE REDSHIFT OF ONE Article 14 October 2020

IONIZED GAS EXTENDS OVER 40 KPC IN AN ODD RADIO CIRCLE HOST GALAXY Article 08 January 2024 ASTROPHYSICAL CONSTRAINTS FROM THE SARAS 3 NON-DETECTION OF THE COSMIC DAWN SKY-AVERAGED 21-CM

SIGNAL Article 28 November 2022 REFERENCES * Churchwell, E. _et al._ _Astr. Astrophys._ 54, 969 (1977). ADS  CAS  Google Scholar  * Dickinson, D. F. & Chaisson, E. J. _Astrophys. J._

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AUTHORS AND AFFILIATIONS * CRA AM/ON/CNPq—Conselho Nacional de Desenvolvimento Científico e Tecnológico, Rua Ceará no. 290, 01243, São Paulo, SP, Brazil JACQUES R. D. LÉPINE & PAULO

MARQUES DOS SANTOS Authors * JACQUES R. D. LÉPINE View author publications You can also search for this author inPubMed Google Scholar * PAULO MARQUES DOS SANTOS View author publications You

can also search for this author inPubMed Google Scholar RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE LÉPINE, J., DOS SANTOS, P. Detection of H2O

emission from galaxy NGC253. _Nature_ 270, 501 (1977). https://doi.org/10.1038/270501a0 Download citation * Received: 31 May 1977 * Accepted: 13 October 1977 * Issue Date: 08 December 1977 *

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