Police were called following the incident, which happened sometime between midnight and 6.40am ton Saturday (November 21) on a footpath which goes between Middle Park Way and Charlton Crescent.
Officers are in the area making enquiries, and you will continue to see a presence throughout the day.
The woman is being supported by specialist officers.
Detective Inspector Emma Crute said: “This has understandably been a very distressing incident for the woman involved and we are keen to hear from anyone who can assist our investigation.
“If you were out walking your dog between 5am and 6.40am in the area of Middle Park Way and Charlton Crescent, were driving through the area or have CCTV outside your home, please cast your mind back or check your footage.
“However small you believe a piece of information to be, it could be vitally important to our investigation, and we want to hear from you.
“If you heard anything, or saw anything that looked suspicious or out of the ordinary, please get in touch.
“Anyone with information should call 101, quoting the reference 44200450570.
“If you have any concerns, or want to share any information that can assist us, please do not hesitate to approach any of the officers in the area today.”