2.4m Mirror Washing ProcedureLast Updated: 06/06/07 Steven Magee

Prerequisites

This procedure is used when washing the mirror on the 2.4m telescope. Instrument rotator needs to face North. Equipment Needed

● Allen wrenches.● Cable ties.● Side cutters.● Natural sea sponges – 3.● Distilled water – 15 gallons.● Orbis SLS soap.● Lint free cloths.● Vinegar.● Trash can.● Plastic sheeting.● Spray bottles – 3.● Lint free wipes.● Gloves – powder free.● Duct tape.● Trash bags.● Torque wrench.

Washing Procedure

Soak the sea sponges in vinegar for a few days to remove any calcium. Afterwards wash them in distilled water.

Open mirror covers. Raise the platform and move the telescope over in Right Ascencion to remove the baffle by releasing the three clips.

Using the “T” wrench, undo the three screws that secure the baffle base and remove it.

Remove the mirror temperature sensor.

Close the mirror covers.

Stand the telescope vertical and remove the mirror air conditioner North hose.

Install the telescope Declination stay bar and Right Ascension pin.

Remove the instrument and MIS unit.

In the computer room, type “cl” on the airbag computer to deflate the airbags. After they deflate type “qq” to exit the program. Turn off the computer.

In the control room, turn off the guider computer.

In the dome, turn off the airbag compressor in the electrical box at the rear wall.

Install the two hydraulic RA axis jacks and tension up.

Remove cables off the rotator ring.

Remove the four bolts from the central baffle and remove it.

Remove the four segments of the instrument rotator.

Install the three mirror hard point jacks. Wind up the jacks by hand and then tighten by a quarter of a turn on each folled by another quarter turn each using the spanner. Half a turn in total.

Install the three mirror cell supports on the hydralic platform and bolt them down.

Jack telescope RA axis to 2000 lbs.

Remove platform railing. Raise platform & adjust lift speed to slow.

Disconnect mirror cell power connector.

Disconnect rotator encoder buffer box.

Disconnect rotator encoder power.

Disconnect air line.

Disconnect temperature connector.

Disconnect rotator motor connection.

Using duct tape, tape a trash bag onto the primary mirror hole and cut a hole in the bottom of it to allow the water to drain out.

Raise the platform and move it out by 2”. Raise it until one of the jacks touches. Adjust the jacks so that they all touch the mirror cell.

Unbolt the mirror cell from three sides using three people

Slowly lower the mirror cell with one person North and one person South guiding the cables out of the cell.

Lower the platform all the way to floor level.

Remove the four earthquake restraints.

Dust off the mirror cell.

Tape plastic sheeting around the edge of the mirror cell using duct tape.

Mix up solution of soap using one tablespoon of soap to two and a half gallons of distilled water.

Install the trash can under the hole in the mirror to collect the water.

Spray distilled water onto the mirror surface, working from the outside inwards. Go around twice.

Spray soap onto the mirror and use the sea sponge in a figure of eight motion to clean the mirror. Only use the weight of the sponge, do not press down.

Use the sprayer to push the dirt down the center of the hole in the mirror. It is important to keep the mirror constantly wet & keep rinsing the sponges in clean distilled water to remove particles and contaminants from them. After going around the mirror twice with the sponges, rinse the soap off using the distilled water spray.

Spray with soap again and wash the mirror with the sponges. Only use pressure to remove stubborn dirt.

Rinse with the distilled water spray.

Final rinse with distilled water poured from a jug.

Using lint free wipes, blot up the water from the mirror.

Blot up the water from the sides of the mirror and the plastic sheeting.

Remove the plastic sheeting from the edge of the mirror.

Dry off the mirror cell.

Dry off the hydraulic platform.

Install the North & South alignment pins into the mirror cell. The pins are kept in the “Special Tools” drawer in the workshop.

Install the four earthquake restraints using feeler gauges to a height of 1/32” – 1/16” from the mirror surface. The flat should be to the outside.

Raise the mirror cell and feed the cables through. There should be five cables to the North and two to the South.

Continue to raise the platform and makes sure that all four earthquake restraints clear the mirror cell.

Continue to raise the platform and make sure that the North & South alignment pins align. Raise the cell up completely.

Start installing the mirror cell bolts and remove the two alignment pins.

Torque all of the mirror cell bolts to 120 lbs.

Lower the hydraulic platform.

Reconnect the five cables and hoses in the North mirror cell box.

Reconnect the two cables in the South mirror cell box.

Remove the trash bag from the center of the telescope and dry the area.

Remove the three mirror cell supports from the hydraulic platform.

Remove the two Right Ascension Jacks.

Install the safety rail.

Insert the baffle into the rotator and tighten the four bolts, making sure that it is aligned with the fudicial marks.

Back off each mirror jack by quarter of a turn, followed by another quarter of a turn. Keep doing this until the mirror jacks are free.

Remove the mirror jacks and store in their box.

Put the air supply back onto the airbag system.

Check that the gauge reads 23 PSI.

Reinstall the four segments of the instrument rotator.

Reconnect cables onto the instrument rotator.

Install the MIS if needed & the instrument.

Remove the Declination stay bar and the Right Ascension pin.

Move the telescope over in Right Ascension and install the center baffle section using the “T” wrench.

Install the final baffle using the three clips.

Install the temperature gauge onto the mirror using aluminum tape.

• Turn on the mirror support system. • Check the telescope balance. • Check that all systems work on the telescope. • Tidy up.