4M Information, Specifications & Data

Contact email

Last Updated: 03/28/2016

- Instrument Capabilities
- Mayall Parameters
- Mayall Main Floor Crane Access
- Travel Requirements & Actuator Screw Length
- 4M Elevator Ball Nut Housing Modification

- The diameter of the hatch in the cass cage bottom is 48"
- The diameter of the cage opening, without the bottom is 106"
- The distance from the cage bottom to the bottom of the guider is 61"

Dimensions

- Instrument Weights & Rocket Weight Counts
- 2100-AD-013-0002
- The weight of the rotator is 1300 lbs
- The weight of the guider is 800 lbs
- The weight of the cass cage bottom is 1300 lbs
- The tube weights can make up for 400 lbs
- The regular cass cage bottom, with no weights, weighs 1300 lbs
- The weight of the prime focus corrector is 380 lbs

Weights

- The cable run from the cage to the console room is 150'
- The cable run from the cage to the computer room is 150'

Lengths

- The door opening to the coude room is 93" wide x 95" tall
- The RCS handling cart with RSC in it, is 69" x 72" x 84"
- The largest box that fits in the elevator is 58" x 37"

Misc Specs

Optics / Aperture Information

- The plate scale at F/8 is 6.624 arcsec/mm
- The plate scale at F/15 is 3.64 arcsec/mm
- The primary clear aperture is 3.797m
- The secondary clear aperture is 1.65m
- The F/8 focus clear aperture at Cass is 6.2"
- The focus travel of the prime focus pedestal is +/- 1.4" from center
- Pickoff mirror move times:
- From position 1 - 2 is 7 seconds
- From position 2 - 3 is 11 seconds
- From position 3 - 4 is 13 seconds

Guider Information

- The diameter of the opening in the guider is 20.25" +/-.003"
- The diameter of the recess in the guider is 31" +/-.003"
- The depth of the recess in the guider is .320" +/- .01"
- The instrument mounting bolt center diameter on the guider is 35"
- The size & depth of the mounting holes on the guider are 5/8-11 x 1.00
- The travel of the S guide probe for focus is +/- .312" from center
- The guider probe has approxomately 2000 motor steps
- The encoder readings for the guide probe are from 10-426, where 10 is all the way out
- The back focus from the guider to focal plane at F/8 is 6"
- The back focus from the guider to the focal plane for F/15 is 17
- There are 4 filters in the ILS side of the guider:
- A = Blue BG37 1mm thick
- B = Red OG 590 2mm thick
- C = Neutral Density (NG-3) ~2.5 mag (4500-6500l) 1mm thick
- D = Clear 1mm thick quartz plate