1. Hexabundles meet OzPoz Hexabundle science workshop University of Sydney 24 th November 2008 Andrew McGrath, AAO

2. OzPoz – the FLAMES positioner

3. Buttons Existing OzPoz has single-fibre buttons and mini-IFUs with 20 fibres each Mini-IFUs view 2x3 arcsec FoV FACBs (acquisition bundles) with 19 fibres Common button package

4. Bundles Single-fibre buttons fed with sleeved fibre 19- and 20-fibre bundles also carried in slightly larger diameter sleeve

5. Buttons

6. Retractor Take up slack in fibre Keep mild tension in fibre to button (~1 N) Diameter of bundle Bend radius ~24 mm Flexibility

7. Retractor Take up slack in fibre Keep mild tension in fibre to button (~0.1N)

8. Magnetic attachment Buttons secured magnetically to field plate Strong enough – Static friction must hold button stable to ~1 N retractor tension, in arbitrary orientation wrt gravity Not too strong – Robot gripper limits to ~4 N Clamping force ~2.5 N

9. Bundle handling experience Works well for existing design No evidence of effects of ‘tangling’ of fibres against each other within 19- and 20-fibre sleeved bundles 2dF retractors carry unsleeved bundles of fibres for guide bundles

10. FLAMEing Hexabundles? Can we use the existing arrangement to fit one or more 61-core hexabundle fibre bundles to OzPoz? Notionally, assemble a FACB or mini-IFU button with a hexabundle feed –Seems OK

11. FLAMEing Hexabundles? Can the existing OzPoz retractor accommodate a bundle of 61 fibres? Currently handles 20 Diameter of bundle will increase Stiffness of sleeved bundle will increase

12. FLAMEing Hexabundles? Need to identify a suitable sleeve Could increase retractor spring force to accommodate increased stiffness Flow-on effects to magnetic force and robot force capacity could render unfeasible

13. FLAMEing Hexabundles? Could subdivide the bundle to manageable subsets Multiple adjacent retractors per button Minor additional placement limitations Probable requirement for increased magnetic force to provide static friction Robot flow-on effects may render unfeasible

14. FLAMEing Hexabundles? Unsleeved bundle likely much more flexible Similar arrangement to 2dF, fibres in a loose plait Tangling issues and fibre breakage are important concerns

15. FLAMEing Hexabundles? Or… consider FLAMEing Hexabundles as a one-off type of test Don’t run the fibre bundle through a retractor at all Manually place the button on the field plate Use the robot for metrology only Tweak the button(s) into place by tapping with a finger