There are several Elixir systems which process and display data in
real-time during observations. This page summarizes the relevant
process, the machines where they are located, and support information.
| elixir.fork || select analysis for image || director (endgo) || session host |
| getseeing || measure image quality || elixir.fork || wekiu |
| getfocus || generate focus plot || elixir.fork || wekiu |
| mkjpeg || create binned greyscale image || elixir.fork || wekiu |
| Xvnc (summit) || X server || wekiu |
| Xvnc (waimea) || X server || naio |
| ert || waimea elixir realtime jobs || naio |
| srt || skyprobe plot generation || wekiu |
| skyprobed || skyprobe image acquisition || wekiu |
| apache || Elixir web server || ulu |
Waimea Realtime Jobs (from ert)
| elixir imstats || basic image statistics || naio (distributed) |
| elixir sextract || detailed image analysis || naio (distributed) |
| gettemps || extract probe data || naio |
| el_plots || generate elixir plots || naio |
| elixir.link || gather new images || naio |
Synchronous Processes for Images
Every image which is obtained by the relevant cameras (CFH12K) are
passed to an elixir module which in turn runs one of several analysis
jobs on the image. These jobs are synchronous in the sense that they
are triggered by the acquisition of the image and run immediately. In
addition, this set of jobs run completely at the summit with as few
interactions with the Waimea computers as possible.
NEO calls the elixir.fork command at the end of every exposure. This
command is passed the relevant filename for the current exposure,
which is in the form /complete/path/filename.fits for MEF images, and
/complete/path/filename (a directory) in the case of SPLIT images.
Based on the image type, elixir.fork calls several different possible
commands, launching them remotely on specific machines. The available
commands, with the appropriate image type in parenthesis, are:
getseeing (OBJECT), getfocus (FOCUS) and mkjpeg (OBJECT). The
elixir.grab function has been deprecated.
this process calculates the image quality and the sky level for chip
03, and sends the results to the elixir display tool 'edisp' by
writing the seeing value in a specific file read by edisp. It also
sends the result to the QSO database.
this process analyses a focus image and creates a plot of the focus vs
image quality for four specified chip (01, 04, 07, 10). The plot is
made available to edisp for display. getfocus depends on a
functioning Xvnc display server at the summit (XHOST.SUMMIT = wekiu).
this process generates a greyscale image of the current frame, and
makes it available to edisp. mkjpeg depends on a functioning Xvnc
display server at the summit (XHOST.SUMMIT = wekiu).
skyprobed is daemon based on the elixir 'nightd' daemon and controls
the skyprobe camera. Like all 'nightd' daemons, it has functions
defined for the start of the night, for the end of the night, and
repeated functions for the middle of the night. At the start of the
night, is issues a command which cools the camera to a specified
temperature. During the night, once every minute, it takes an image
which is saved in a file with a name based on the time and date; the
file is then passed to the elixir processing system. At the end of
the night, it sends a command to let the camera warm up.
Waimea to Summit
The Elixir system receives images from CFH12K, CFHT-IR (and eventually
other cameras) via the archive system. The archive system copies the
images to data partitions in Waimea, ensures that the image is written
to tape, and distributes the image to a variety of systems, including
Elixir. For Elixir, a link to the image is placed in a specific
directory. Elixir is responsible for identifying new links, creating
a reference of its own, and removing the link.
The bulk of the Elixir analysis and data quality control occurs on the
cluster in Waimea. During a camera run, there are a variety of
processes which happen in semi-real time. In order for these systems
the Elixir RealTime daemon, ert is based on the 'nightd' daemon and
runs a variety of systems on a regular basis. There is a sequence of
programs executed at the beginning of each night. These programs
define the camera and runid for the current night and initialize the
various directories and files if needed. During the night, ert runs
certain functions on a regular basis to update the elixir plots, or to
sequence of events:
At the beginning of the night, ert runs a process (el_plots init)
which initializes the elixir plotting system. In practice this simply
checks if the Xvnc is running and writes an error to the logfile if
not. In addition, ert runs a process (elixir.reload) which tells the
imstats and sextract elixir systems to reload their configuration
files. If these processes are not running, the command starts up
these elixirs. During the night, ert runs three main functions once
every 6 minutes. First, it runs the 'gettemps' function which
extracts specific probes from the data logger for the current night.
Second, it runs the elixir plotter system which generates several
plots based on the current night's image statistics. Third, it runs
the elixir.link system, which searches the archive link directory and
identifies new images for the Elixir system. At the end of the night,
ert launches the mkdetrend auto run system to generate the latest
detrend report. It also launches the end-of-night routine for the
plotting system, which currently does nothing, but could copy the
plots to an archive, for example.
the Skyprobe RealTime daemon, src is based on the 'nightd' daemon and
generates the plots for skyprobe during the night. At the start of
the night, it tests the Xvnc. Every 300 seconds during the night, it
generates the standard skyprobe plot of the night and past few hours
of data. At the end of the night, it saves the plot in the archive
there are Xvnc daemons running on a machine at the summit (wekiu) and
in Waimea (koa) which provide a guaranteed 16bit X server to
processes which need an X server. The vnc is running as user
'cfh12k'. Test that a particular Xvnc is running with the command
xdpyinfo -display wekiu:1
[lots of stuff ending with:]
visual id: 0x22
depth: 16 planes
available colormap entries: 64 per subfield
red, green, blue masks: 0xf800, 0x7e0, 0x1f
significant bits in color specification: 8 bits
If a vnc crashes, log into the relevant machine as user
cfh12k, and issue the command 'vncstart'. This will kill off the
existing vnc, if it is hung, remove the lock files, and start a new
random: rsh -l cfh12k wekiu
Killing Xvnc process ID 548
Couldn't start Xvnc; trying default font path.
Please set correct fontPath in the vncserver script.
New 'X' desktop is wekiu.cfht.hawaii.edu:1
Starting applications specified in /h/cfh12k/.vnc/xstartup
Log file is /h/cfh12k/.vnc/wekiu.cfht.hawaii.edu:1.log
Note that the fontPath error is not a problem.
the apache web server is used as a interface to the elixir detrend &
fringe creation systems. The server runs on koa.