SDSS Engineering

2.5m PSS Access Hatches

Sloan Digital Sky Survey Telescope Technical Note 20011010_02

Russell Owen

The location and "contents" of the outer ring of access hatches on the back of the SDSS 2.5m primary mirror support structure (PSS) are as follows:

Angles (°)		Hatch 1	Hatch 2
2	182	Astig 1 Mitutoyo A	Astig 7
-22	158	Astig 2	Astig 8
-42	138	no astig	no astig Mitutoyo B
-65	115	Astig 3	Astig 9
-85	95	Astig 4	Astig 10
-107	73	Astig 5 Mitutoyo C	Astig 11
-128	52	no astig	no astig A/C outlet
-152	28	Astig 6	Astig 12 Mitutoyo F Wires to M1 & M2 MIGs

Where:

• Angles gives two instrument rotator angles 180° apart that will expose the hatches.
• Hatch1 and Hatch2 are two hatches 180 degrees apart.
• Astig means an astigmatism actuator.
• Mitutoyo means a Mitutoyo electronic linear gauge.