O365 CSOM (javascript) 'SiteOwners' managed property in Search results

Question

The requirement is to pull SiteOwners [secondary site collection admins] for each site on Office 365 tenancy, using CSOM (JavaScript).
The following is the code
var keywordQuery = new Microsoft.SharePoint.Client.Search.Query.KeywordQuery(context);
keywordQuery.set_queryText('contentclass:"STS_Site" contentclass:"STS_Web"');
keywordQuery.set_trimDuplicates(false); //returns sub-sites
var Managedproperties = ['Title', 'Path', 'SiteDescription', 'ParentLink', 'Rank', 'SiteLogo', 'SiteName', 'Author', 'SiteID', 'WebId', 'SiteOwners', 'AuthorOWSUSER', 'WebTemplate'] //'People','SiteMembers'
var kwqProperties = keywordQuery.get_selectProperties();
for (var i = 0; i < Managedproperties.length; i++)
kwqProperties.add(Managedproperties[i]);
var searchExecutor = new Microsoft.SharePoint.Client.Search.Query.SearchExecutor(context);
searchresults = searchExecutor.executeQuery(keywordQuery);
context.executeQueryAsync(onQuerySuccess, onQueryFail)
Though "SiteOwners" [secondary site collectin admins] are defined for each site, the value for "SiteOwners" is always empty ("").
Though calls can be made to individual sites to pull the siteowners, want to avoid multiple calls by making use of Indexed search data.
Any suggestion/help please.
Sai

Answer 1

The SiteOwners managed property has no crawled property mapped to it. There does not appear to be a specific site owners crawled property. I would suggest using the Author managed property. It appears to be the same as the site owner. Some side loaded
or installed third party apps will have System Account as the author, this would be correct since a timer job deploys the app.
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