Gosh, what rotten luck. So sorry to hear about your ticket. The good news is that it sounds as though this may be a "Camera Ticket". If so, that is good because even though the fine is steep for a school zone (and by law can not be mitigated) the consequences are nil for your insurance because camera tickets are not reported on your DOL record.
You may have some defenses based upon the way the citation is charged and the report is written. When responding to a camera ticket it is important to carefully review all the information on the back of the citation to know your rights and responsibilities. You may also want to review the infraction rules (specifically those relating to service of the citation). Best wishes with this.