NDLI: A radio telescope for the calibration of radio sources at 32 GHz

Content Provider	IEEE Xplore Digital Library
Author	Gatti, M.S. Stewart, S.R. Bowen, J.G. Paulsen, E.B.
Copyright Year	1995
Description	Author affiliation: Jet Propulsion Lab., California Inst. of Technol., Pasadena, CA, USA (Gatti, M.S.; Stewart, S.R.; Bowen, J.G.; Paulsen, E.B.)
Abstract	Knowledge of the flux of celestial sources is important to radio astronomers and telecommunications engineers who wish to accurately calibrate their large aperture antennas. At 32 GHz the flux of celestial objects is given by extrapolations using the spectral indices obtained from measurements at lower frequencies; there have been no direct calibrations. We have therefore developed a program whereby a 5-meter diameter radio telescope at the Owens Valley Radio Observatory (OVRO) operating at 32 GHz will observe a list of radio sources. By accurately calibrating the 5-meter antenna we will be able to have direct measures of celestial radio source fluxes. Accurate calibration of the 5-meter radio telescope must be done in-situ at OVRO; therefore, we have built a radio telescope intended to be a standard gain tool to be used to perform the accurate 5-meter calibration. This telescope uses a highly efficient 1.5-meter offset feed Cassegrainian optics configuration whose aperture efficiency is nearly 80%. The telescope uses a radiometer with a high electron mobility transistor (HEMT) low noise amplifier (LNA), and a pair of feeds to operate in a beam switching mode. When tracking a celestial source, one of the two beams is pointed to the source and the other is pointed to an empty part of the sky. Coherent detection of the difference signal of this rapidly switched signal provides a measure of the signal due to the source. The technical challenge for this standard gain telescope is that it must provide accurate tracking of the celestial source with minimum pointing errors; it must contribute a minimum noise temperature; each beam on the sky has to be nearly equal in performance; and a stable radiometer that can detect signals in millikelvins is required. Such a system is summarized.
Starting Page	1750
Ending Page	1753
File Size	231750
Page Count	4
File Format	PDF
ISBN	0780327195
DOI	10.1109/APS.1995.530922
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	1995-06-18
Publisher Place	USA
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Radio astronomy Calibration Extraterrestrial measurements Telescopes Apertures Antenna measurements Performance gain Feeds Optical noise Radiometry
Content Type	Text
Resource Type	Article

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

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