I couldn't find the pixel dimension for the service desk logo (not the portal logo). You have the option to chose a logo under Settings - Portal Settings
Screen Shot 2015-02-24 at 10.50.57.png
In the popup window only hints for the file type but not the size are give:
Screen Shot 2015-02-24 at 10.51.06.png
It looks like the logo shows up as 64x64 when visiting the Portal as a Customer (ie: http://localhost:8080/servicedesk/customer/portal/2). When at the Global Portal landing page, (ie: http://localhost:8080/servicedesk/customer/portals) the logo is scaled down to 32x32.
Hello Atlassian Community! I'm Teresa, the Product Marketing Manager for Jira Service Desk Server at Atlassian. I'm excited to announce two exciting releases for Jira Service De...
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