Changes to the APT

In reverse chronological order:

• 07-Apr-1996 / MCBA--Software changes:
  • The ``exp'' command no longer exists. It has been replaced by ``expose'', which doesn't clear the CCD before beginning an exposure (which is a useful feature for doing multiple exposures on the same image). To get the same effect as the old ``exp'' command, use ``clear expose''.
  • The ``fftime'' command has been replaced by the more flexible ``scale peak'' and ``scale average'' commands.
  • The ``wait'' command now takes an argument, and can wait for the telescope to stop slewing (``wait tel'') or for an exposure to end (``wait exp'').
  • The ``move'' and ``centre'' commands now work from pixel coordinates as displayed with SAOimage, not absolute coordinates on the CCD.
  • The PC can now be run from a floppy disk if necessary.
  • The software on the DECstation has been considerably improved:
    • ``aptstart'' has been renamed ``apt_start'', and you can now easily start the components using various ``apt_start_*'' commands.
    • The ``APT PC screen'' window shows you what is on the PC screen.
    • The last image number is now stored in a file, so that it is always correctly updated.
    • The ``apt'' command can be executed from any directory (it used to by only from /morejunk/data).
    • The data directories have been renamed /data0 through /data4.
    • The software automatically moves to the next data directory when one fills up.
    • The Xterminal now boots up in a more friendly configuration, and ``apt_start'' works with it.
• 04-Feb-1995 / MCBA--Software changes:
  • The CCD readout code has been entirely overhauled to improve reliability and increase speed. As a result, the entire chip can be read out in high-speed mode in 6 seconds (used to be 10) and in low-speed mode in 34 seconds (used to be 38).
  • Exposures now start immediately after executing the "exp" command--they used to wait about 3 seconds, and were synchronised to the PC seconds-clock.
  • Exposure timing has been improved, eliminating one cause of the program crashing.
  • The focus stepper motor speed has been reduced, to avoid the problem of missing steps which has occurred recently. A new command, ``focus delay xxx'' has been added so that users can change the speed--the number xxx is the delay in microseconds between steps.
  • A new command, ``move peak x y'' will move the telescope so that the brightest single pixel in the most recent image processed with ``stats'' or ``readstats'' is moved to coordinate x y on the CCD. This command is expected to be very useful for automatically calibrating the telescope, and in assisting the registration of images.
  • A better algorithm has been incorporated for detecting the completion of a telescope slew. This is not easy, due to the unreliability of the information returned by the Apple II. The slew wait can now be interrupted more easily by hitting a key on the keyboard.
  • The statistics area on the CCD can now be set to a subset of the image readout area, which means that it is possible to use the ``readstats'' command with negligible time overhead if only a small area is being used for statistics (as is the case for estimating flat-field exposures).
  • Communication between the PC and the workstation has been improved. The link will now be re-established more rapidly if it goes down.

  The focus motor controller has had low-pass filtering installed on the inputs from the PC; this has fixed the problem whereby the controller would spontaneously reset or issue pulses when a power spike occurred on the mains.

  An Uninterruptible Power Supply (UPS) has been brought up from Sydney, as has a revised version of a servo amplifier. Neither has been tested, so please don't use them yet.

• 20-Dec-1995 / MCBA--Mostly repairs following lightning damage:
  • VT131 configured as DECstation console due to failure of graphics card.
  • Ethernet damage isolated, and repair begun.
  • Half-a-dozen ICs replaced in the servo controller and Apple servo interface.
  • Spare IEEE488 interface board made to work.
  • Problems with ``auslast'' command fixed.
• 29-Aug-1995 / MCBA, PM, Bruce Grossan--Various things:
  • Apple software and servo coefficients updated for the new RA motor and encoder.
  • RA knife-edge calibration fixed.
  • New Wright Instruments CCD control board installed--this fixes the old 32767 bug.
  • Fans installed to prevent dewing of the lens.
  • Various electrical and cable faults fixed (DEC incremental encoder, RA servo board).
  • New commands added to MCCD: lrc, writeapple, runapple, abort.
  • New networking software installed on the PC--seems to have fixed some communication bugs.
  • Mistral's e-mail and name server fixed.
  • APT lens cleaned.
• 14-Aug-1995 / CSB, JBWC--New RA motor and incremental encoder installed. New RA limit switch stops.
• 17-May-1995 / MCBA--Some modifications were made to the MCCD program:
  • At last, the FITS headers stored with APT images have some useful information in them!
  • New commands added to assist with adding information to the FITS headers: ``object observer imagetyp object filter epoch equinox''. The ``status'' command was upgraded to show this new information.
  • ``slewnowait'' and ``wait'' added so that the CCD can be read out while the telescope is slewing to the next object.
  • Software added so that it is possible to see on the workstation a copy of what is on the PC screen.
• 15-May-1995 / MCBA--The workstation CPU was upgraded to a DECstation 5000/200, with 86 Mbytes of memory. This gives about a factor of 3 improvement in performance, allowing real-time processing of data.
• 15-May-1995 / MCBA--The workstation software was upgraded from ULTRIX 4.2 to 4.4. One new 600 Mbyte disk was added, and several of the existing disks were reorganised to provide more space for data.
• 1-May-1995 / CSB--Added the wiring for the zero hour angle microswitch to disable the roof movement. Installed new bookcase in the APT building.
• 20-Apr-1995 / MCBA--The PC was upgraded from Windows 3.1 to Windows for Workgroups 3.11, and the C compiler was upgraded from Microsoft Visual C++ V1.0 to V1.51. The Beame & Whiteside FTP program was upgraded to version 3.0.
• 20-Apr-1995 / MCBA--Some modifications were made to the MCCD program:
  • The PC can now determine when the telescope has reached the desired coordinate and has resumed tracking after a slew.
  • ``caldec'' now simply calibrates the Dec axis (it used to do both). A new command, ``calaxes'' does both axes simultaneously.
  • ``fftime'' added, allowing the optimal choice of exposure times for flat fields (and other exposures).
  • Scripts written (``TWI1.APT'' and ``TWI2.APT'') for the automatic acquisition of twilight flat fields.
  • ``stats'' and ``readstats'' added, so that you can find out the minimum, maximum, and average pixel value, as well as the locations of the minimum and maximum (a future command will automatically move the telescope to put the brightest object at a given location on the CCD).
  • Lots of small bug fixes and enhancements to the user interface (e.g., the input buffers are now checked for overflow).
  • Alarms added. This allows you to schedule observations at particular times.
  • Much of the source code is now identical to the program that controls the IRPS at the South Pole.

• 20-Apr-1995 / MCBA--The power supply for the servo controller was changed from a low-power ex-Apple supply which was not capable of providing the peak current, to a switch-mode supply with ten times the capacity. This should improve the reliability of the servo controller.
• 21-Mar-1995 / MCBA--The ``APT Link'' window now gives you a display of the number of bytes received, the data-rate in kbytes/sec (should be about 30 during a slow readout), and the time taken to readout an image.
• 20-Mar-1995 / MCBA--A ``new'' Apple-IIe installed as the control computer (bought for $5 from a Canberra-based recycling centre).
• 20-Mar-1995 / MCBA--A second ethernet interface added to the workstation so that the traffic from the PC to the workstation is isolated from the mountain network.
• 20-Mar-1995 / MCBA--The workstation software has been made much easier to use with the advent of the ``APT Link'' and ``APT Console'' windows, and the ``aptstart'' command.
• 20-Mar-1995 / MCBA--The PC software has been made easier to use with a new batch file that sets things up automatically.