In case you want to search for all the issues updated after 9am previous day until today at 9AM, please try: updated >= startOfDay(-15h) and updated <= startOfDay(9h)
. (explanation: 9AM - 24h/day = -15h)
You can also use updated >= startOfDay(-900m)
. where 900m = 15h*60m
Reference: https://confluence.atlassian.com/display/JIRA/Advanced+Searching