Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2019 Apr 9;10:1648. doi: 10.1038/s41467-019-09621-z

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© The Author(s) 2019

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

PMC Copyright notice

Fig. 7 — Radio images of different source types. Simulated images and related information of: a–e an ideal point source, corresponding to the point spread function (PSF) of the antenna array, f–j the effect of uncorrelated noise on the observations, and the effect of angular separation of two equal-power point sources in azimuth (k–o), and elevation (p–t). Each image shows the normalized intensity $(Ĩ)$ of a 0.7-μs exposure of sources at the location of NBE 2. Panels c and d show that the central lobe of the PSF has a standard deviation (SD) of 0.011 in both the cosα and cosβ directions, corresponding to SDs of 1.6° and 3.8° in azimuth and elevation, respectively. As seen in j, added noise has little effect on the size of the central lobe, remaining close to the PSF value of 0.011 (horizontal gray line) for signal-to-noise ratios down to 6. Binary sources have a much stronger effect, with the two sources being readily distinguishable for azimuthal separations of 2° or elevation separations of 5–6°. The fixed central lobe becomes noticeably deformed well before that (o and t)