Wednesday, March 28, 2012

Photos for a change!

What with all the serious science going on at SALT, there haven't been too many photos on the blog lately...  Apologies to those disgruntled followers out there ;)

Here's a shot showing the RSS readout after a successful Multi Object Spectroscopy (MOS) observation.  MOS is the latest mode on RSS to be successfully commissioned, another exciting milestone in SALT's progress :)  Each row across the screen is a spectrum from an individual slit in a custom-cut mask that gets inserted at the focal plane.  3 of these spectra were from extremely bright objects (the white stripes), the one just below the centre belongs to a fainter source while most of the rest were dominated by emission features from the night sky (the bright vertical lines towards the right of the frame).

Today Jono & I climbed down under the tracker bridge to take a look at the liquid light guides that feed light from the arc and flat-field lamps in the payload to the calibration screen that's mounted just below the SAC.  There we are in the bottom few segments of the primary :)

Here's the bay in the payload that houses the calibration lamps: copper-argon, mercury-argon and argon for the blue & xenon, neon and thorium-argon for the red.  The red and blue channels also each have a quartz-tungsten-halogen flat-field lamp, as well as a set of colour filters.  A graduated neutral density filter can slide into the beam if grey attenuation is needed. 

Plano-convex lenses are used to focus light from the lamps onto the entrance faces of the red and blue liquid light guides.  These "light pipes" then snake down to the cal screen below and inject the light into the SAC.  The pic below shows the argon lamp shining down through the 2 lenses, onto the tip of the blue light guide (centre, bottom).

The cal screen (carbon fibre contraption on the right) rotates in below the hole in M3 (left) and shines light up through the SAC to the instruments whenever calibration frames need to be taken.  One of the liquid light guides (the one optimised for blue light) is visble to the lower right.

Having disconnected the blue light guide, we could see its exit face - glowing here with light from the copper-argon arc lamp up inside the payload.

More than a year & a half since the SAC went back up, it's really cool to get to see M2 again!  Also visible in this shot is the little baffle affectionately known as Blackbeard's Patch, & even the stubborn little piece of yellow duct tape that we couldn't quite reach after M5 was put back in after its wash!

Back down in the kitchen, my new compact camera (that had performed so well during its maiden tracker voyage) was subjected to untold horrors when Keith got hold of it...

Fortunately, there are considerably cuter furry creatures around on site to take photos of!  This is Mongo, a baby grey mongoose that seemed to have been abandoned on Verlatekloof Pass.  Dreading that he/she would get run over if left out there, it was relocated to a safer spot up on the plateau.

On a clear autumn afternoon, it's really not that bad a place to call home!

1 comment:

  1. Excellent shots of the instrumentation and the MOS shot.