Utilize the input text as a context reference, choose the right relationship between Sirtex and Sydney from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Broker Watch: Rio Tinto, Horizon Oil, Greencross, SEEK Broker Watch: CSR, Aristocrat Leisure, Northern Star Broker Watch: Iron ore majors, Aurelia Metals, Alcoa, Gryphon Minerals Broker Watch: Gold stocks, insurance sector, Incitec Pivot Broker Watch: Crown Resorts, Aurelia Metals, Orica, Amcor Broker Watch: Asciano, BlueScope Steel, James Hardie, Cue Energy Broker Watch: Energy sector picks, REA, PacBrands, Treasury Wine Broker Watch: James Hardie, Brambles, Recall Holdings, GPT Group Broker Watch: Air New Zealand, Scentre, Aurizon, Transurban Group Broker Watch: Wesfarmers, Myer, Sandfire Resources, Sydney Airport Broker Watch: Brambles, Arrium, Tabcorp, Monadelphous Group Broker Watch: Origin Energy, Flight Centre, iSelect, Dexus Property Group Broker Watch: Fletcher Building, IAG, BT Investment Management, CSR Broker Watch: Woolworths, CSL Ltd, Metcash, Scentre Group Broker Watch: Sydney Airport, Resmed, Challenger Financial, Arrium Broker Watch: TFS Corporation, Western Areas, NAB, Spark Infrastructure Group Broker Watch: Primary Health Care, Metcash, Ten Network, Sonic Healthcare Broker Watch: Cover-More, SCA Property Group, Telstra, Boral Broker Watch: Federation Centres, Rio Tinto, CBA, Alexium International Broker Watch: Goodman Group, QBE, Adelaide Brighton, Seven Group Holdings Broker Watch: Eclipx, Independence, Alumina, ANZ Banking Broker Watch: ERA, Mirvac, Qube, DUET Broker Watch: QBE, Goodman, Seven, TPG Broker Watch: Greencross, Qantas, South32, Woolworths Broker Watch: Mesoblast, APA Group, Recall, Iluka Broker Watch: AGL, AWE, Qube, Nine Broker Watch: Metcash, Fleetwood, Otto Energy, McPherson's Broker Watch: BHP, Newcrest, Yowie, REA Broker Watch: Virtus Health, CSL, Spotless, Crown Broker Watch: Slater & Gordon, UGL, Flight Centre, Sirtex Broker Watch: Ardent, BWP Trust, Domino's, DUET Broker Watch: AGL, ALS, Ramsay, DuluxGroup Broker Watch: Woodside, Adelaide Brighton, Programmed, Brambles Broker Watch: BHP Billiton, WorleyParsons, Telstra, St Barbara Broker Watch: Ramsay Health Care, WOW, Dulux, Spark ​

Answer: headquarters_location