Sunday, February 4, 2018

PFS Upgrade Series, Day 11: Moving The Instrument (and things inside of it), Again

This is part of a series of posts about upgrading an instrument at Las Campanas Observatory. If you want to start at the beginning, it's here.

I started off the day as I usually do, with a walk out to the du Pont Telescope, but since I slept in a bit I was taking this walk later than I normally do. I was lucky enough to see some guanacos! 

Okay, but to the business of the day -- moving PFS from the clean room. 
PFS, ready to get buttoned up and moved!

First we had to put the side panel back on. Here is Emilio helping to take off the straps after we aligned the side panel and put all the screws in around the outside of the panel.

This time I took a time lapse of the process of loading the instrument onto the truck. I mostly stayed out of the way but you can see me come in towards the end to help raise the instrument to turn the wheels, then lower it again. 

And after another harrowing walk, this time up the hill, we made it safe and sound. Again, super big props to the LCO staff. They are making our science possible! 

Putting the instrument on the telescope is in itself not trivial, let alone moving it up the hill first! We lift the instrument up to the dome platform from the ground level using an elevator, on which we have to take off most of the side railings to accommodate the instrument. Once the elevator is aligned with the nasmyth platform, it is rolled off onto the platform, where we plug in the electronics, glycol feed, and ethernet cables. We also install our custom telescope guider cover plate that narrows the light beam right into our instrument, and in that path we put a baffle and a filter that cuts off some  of the red light that, for our purposes, we aren't that interested in. Then we gently maneuver the instrument so it is lined up exactly with three spherolinder mount plates, in which we place spherolinder blocks. The blocks align with holes in the bottom of the instrument cart, and we lower the instrument so that its weight is mostly supported by these blocks, rather than the wheels of the cart. That is a slightly simplified version of the procedure, which is detailed here, and the whole thing takes about an hour if all goes well. 

Above: You can see the three spherolinder blocks in their mounts, two in the foreground and one in the background. Below: Close-up of pre-slit assembly, with guider camera and glycol feed plugged in at the top. Here to the right is our guider cover plate (big round thing with handles), and the baffle and filter in between the two (little round connectors).

After we got the instrument installed, we spent the rest of the afternoon making sure the GUI was working, calibrating the slit positions, and examining images to convince ourselves we were good with all the settings/positions of the CCD and grating. 

Our first frame of real data at the telescope! See, it says "GUANACO WORKSTATION".

However, upon this examination, Steve decided he did not like how we had positioned the blaze on the detector, and he wanted to move the grating by a little bit. So, after dinner, with the instrument on the platform, we took off the side panel closest to the grating -- eeps! -- and took off the back end of the grating can to tilt it a bit more in one direction. This also meant we had to break the vacuum inside the grating can, so we'll have to pump that down later, meaning we'll have to move the instrument a bit on the platform to be able to fit the vacuum pump close to the grating valve. Phew! But we made Steve happy, that's what counts. 

Above: Side panel of instrument floating in the air in the dome. Don't worry, we put it on the ground, we did not leave it hanging in mid-air. Below: Grating adjusted to get the blaze in the Steve-approved position, see right monitor, plot with a bell-shaped curve. 

Before we replace the side panel (we've been using a black piece of cardboard to keep it relatively dark), we want to take a stellar spectrum to verify the positioning of the light in the spectral direction. That is, do we get our coveted Ca II H&K lines in the blue and the Halpha line in the red? If so, which I suspect is the case, then we are good to go!

I'll report back tomorrow, but for now I'll leave you with some glamour which I mean in black and white. 

Steve examining the electronics box as we wait for the transport truck.

Jeff and his instrument, waiting on the truck for some straps to hold it down.

Christoph, me, Steve, and Jeff, after PFS was closed up and we were waiting to move it up to the telescope.

UPDATE: 20:37 local time WE JUST GOT OUR FIRST STELLAR SPECTRUM with the new instrument! You can see vignetting at the bottom because we took out the filter as an experiment, but those photons are from a star.

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