WatchThis is a program to put ten traffic lights on an X-Window display to monitor radioastronomy observing at Haystack Observatory. WatchThis allows students and others, in effect, to watch over the shoulders of investigators who are doing radio astronomy at Haystack and who will also be watching WatchThis on their own X displays.
In each traffic light, red means something is wrong or broken, yellow means (temporarily)
not usable or not normal state, and all dark (gray) means not in use or no information available. Pnt
will be yellow, for example, while slewing to a new source, and Cor will be all dark while doing
continuum instead of spectroscopy. With Tmpr and Weda, this is a judgement call; you may
disagree. Green means working fineCas far as WatchThis can tell.
Click on each of these traffic lights, regardless of its color, to see a text display with details
of the status of the corresponding device or program. These text displays update periodically at
intervals appropriate for the speed of the corresponding information. Right click on a text display
to make it go away. (If you tell your window manager to kill it, then it might come back from the
dead.)
Following is a brief description of the function of each traffic light from left to right:
Cpd
The Cpdio program controls a bank of digital inputs and outputs connected to the beamswitcher, 13-mm calibration noise sources, and certain other switches. WatchThis checks for proper operation of these devices and compares their status with Umbrella’s last commands.
Thrm
A separate computer controls a set of thermoelectric heaters and coolers on the splice plate, which is a thick aluminum ring that joins the outer and inner panels of the surface of the antenna. Temperatures of the four sectors of the splice plate are offset from the adjacent panels by amounts calculated as a function of elevation to partially compensate for gravitational distortions of the antenna surface. When changing to a source at a different elevation, there can be a delay up to several minutes before the splice plate’s temperatures reach their prescribed values. The splice plate’s computer reports many details of this operation in a status display on its console and in a status file. WatchThis monitors the status of these splice-plate temperatures, and the associated text display is a copy of this status file.
Cor
Our spectrometer is a digital autocorrelator. WatchThis monitors its status, and the corresponding text display shows what the spectrometer is doing. Umbr Umbrella’s shared-memory segment contains most of the setup and state parameters for radio-astronomy observing. This traffic light tries to show whether sensible observations are in progress. The associated text display starts with a quick tabulation of important parameters (some folks leave this on the screen all the time) followed by a long listing of nearly all these parameters.
Pnt
WatchThis checks for correct pointing, which needs to have Upoint running, the antenna available to be moved, a proper source to be observed, and the antenna actually pointing toward this source. The associated text display normally shows the sidereal time, right ascension, declination, hour angle, azimuth, elevation, and any servo pointing offsets in azimuth and elevation.
Subr A
separate computer controls our deformable subreflector, which moves in three directions, tilts around two axes, and deforms in astigmatism and two rings as a function of elevation and temperature. When changing to a source at a different elevation, there can be a delay up to many seconds before subreflector parameters reach their prescribed values. The details of this operation are not available to WatchThis, but this traffic light shows whether the subreflector has accepted commands and has finished moving.
Tmpr
The temperature of the air inside the radome is heated to the temperature, about 12 C, at which the antenna was rigged. Temperatures of various parts of the antenna structure and the air inside the radome are monitored by WatchThis. We have no way to refrigerate the radome, and, in summer, these temperatures are often too high by an amount that produces distortions in the antenna that are significant at short wavelengths.
CDP
The continuum data processor is a separate computer that does synchronous detection and other processing of continuum data before passing them to Umbrella. The associated text display shows recent results such as system temperatures.
LORF
The local-oscillator reference frequency, to which a local oscillator is phase locked, is set by Dop (Doppler velocity calculations) and monitored with a frequency counter as shown by this traffic light. Dop also controls and monitors the new HP LO system. Monitoring is suspended (all gray) while the CDP is in use.
Weda
This weather information is for locations around Haystack as reported by the National Weather Service.