Mounting
The section describes how to mount HiPERCAM and its collar on the GTC. It does not yet include a description of how to install the cable twister and cables.
Attach the lifting eye stored in the HiPERCAM collar’s wooden storage box to the collar and carefully lift the collar up onto the rotator.
Align the rotator so that the white stickers on the GTC rotator flange and HiPERCAM collar rim line up with each other. Ensure that there are two brass locator pins bolted into the rotator (as they are removable), one located next to the white sticker and one 180 degrees opposite to this.
If the usual lifting-eye hole on the collar is used, the rotator should be positioned at an orientation of 270 degrees to align the stickers. Tighten the collar mounting bolts, which can be found in the HiPERCAM bolts box, using a torque wrench setting of 200Nm, but do not insert the four bolts on each side of the collar used to mount the vacuum pump and counterweight plates - these locations can be identified by the position of the slot in the collar for the focal-plane mask. Once the bolts have been tightened, rotate the collar by 180 degrees and try tightening the bolts again.
Now mount the two plates with the vacuum pump and counterweights on opposite sides of the collar from each other, with the counterweight plate located on the same segment as the focal-plane slide. These plates weigh approximately 20kg each so two people will need to hold them up whilst a third tightens the four bolts onto the rotator. There are 8 extra-long bolts in the HiPERCAM bolts box which you must use for this. Do not attempt to dismantle the pump and weights from their plates prior to mounting - it is much easier to install the plates fully assembled.
Now mount the HiPERCAM electronics cabinet. This process is performed entirely by GTC staff and no further details will be given here.
Wheel the instrument in its handling trolley onto the dome floor directly underneath the crane, and then lock the trolley wheels.
Rotate HiPERCAM to the horizontal position. To do this, 4 people are required - one holding each axle locking pin and one at each end of the instrument. As soon as the locking pins are removed, the instrument will want to tip, i.e, the top plate/collimator will want to drop down and the CCD controller will want to rise. The instrument is quite out of balance on the axles, so the 2 people holding the ends will have to be prepared to take the weight when the locking pins are removed and then allow the instrument to slowly drop into a horizontal position. Once there, the other 2 people should re-insert the locking pins.
Locate the 4 swivel eyelets, which are stored in their own grey plastic box in the HiPERCAM crates. Attach the swivel eyelets to the top and bottom plates of HiPERCAM. These can be seen in the right-hand photo above.
Attach one purple sling to each eyelet using a shackle bolt and attach the other end of the slings to the scales, which is itself attached to the hook on the main dome crane. Sometimes, the GTC use two longer purple slings instead of four short ones, one end of each long sling attached to a top-plate eyelet and the other end to a bottom-plate eyelet. In this case, it is important to adjust the position of the two slings on the crane hook so that the instrument remains horizontal as it is lifted away from the trolley.
Raise the crane until the weight indicated on the scales is just below the weight of HiPERCAM. The weight of HiPERCAM is given by a sticker on the top plate. This procedure ensures that HiPERCAM does not tip when the locking pins are removed. If the trolley starts to lift off the floor as the crane is lifted, lower the crane slighty, as otherwise it will be difficult and dangerous to remove the locking pins and axle locking clamps on the trolley.
Now remove the two locking pins and undo the bolts holding down the two axle locking clamps. The instrument should hover on the crane, maintaining its position.
Slowly raise the crane, with one person holding each end of the instrument and checking for anything snagging on the trolley as the instrument rises. When HiPERCAM has cleared the trolley, unclamp the trolley wheels and move it out of the way. Never work on the instrument or walk under it when it is suspended on the crane - this is against Spanish law!
Rotate the rotator until the white alignment stickers on the mounting collar and the top plate of HiPERCAM line up, as shown in the photo below. Insert the G10 insulation bushes from the telescope side of the collar flange. Then insert the bolts and washers as shown in the photo below and tighten the nuts. Once the nuts and bolts have been tightened, rotate the instrument by 180 degrees and try tightening them again. Note that some of the bushes and washers have cut-outs to allow them to be inserting without fouling on the collar vanes or HiPERCAM hemispheres. The bushes, bolts, washers and nuts can all be found in the HiPERCAM bolts box.
Once HiPERCAM has been safely attached to the collar, remove the two axles from the middle plate of HiPERCAM. These weigh approximately 20kg each, so it is a two-person job. You will not be able to remove one of the bolts and bushes on the CCD2 side due to fouling with the head - this is not a problem - they cannot fall out and can be left in position, although you can attach a nut if you do not want the bolt and bush to rattle around.
Do not attempt to carry the axles down the stairs. Instead, place them in the red metal basket used to crane equipment down from the elevation platform. Once on the dome floor, re-attach the axles to the HiPERCAM trolley and move the trolley to its storage location on the dome floor, locking the wheels.
Attach the focal-plane slide, which is stored in its own cardboard box in the HiPERCAM crates. Then attach the focal-plane blade. Ensure that the micrometer is adjusted so that the GTC stickers on its scale line up - this ensures that the blade will be in focus on the CCDs. The blade will have to be aligned for tilt once the instrument has been powered up and the CCDs are cold.
Use the scissor lift to lift the cable ends stored underneath the elevation platform onto the platform and begin cabling up of the instrument.
