ULTRACAM user manual

Vik Dhillon, version: 2 June 2021


  1. Introduction
  2. Powering up
  3. Powering down
  4. Afternoon activities
  5. Software startup
  6. Looking at data
  7. Logging of data
  8. Observing
  9. Archiving data
  10. Drift mode
  11. Changing filters
  12. Before you go to bed
  13. Troubleshooting
  14. Contacts


Introduction

This manual describes how to observe with ULTRACAM. Other useful information can be found in:

Powering up

A description of how ULTRACAM's cables and pipes are connected is outside the scope of this manual, and it will be assumed that this procedure has already been successfully accomplished. Since September 2019, ULTRACAM has been mounted on the NTT cube and users no longer need to mount/dismount the instrument at the start/end of each run. For details of how it used to be done on the NTT, please refer to Ed Daw's
ULTRACAM+NTT installation manual. For details of how to do this on the WHT, please refer to Liam Hardy's ULTRACAM+WHT installation manual. To then start ULTRACAM from cold, the following operations must be performed:
  1. In the control room, check that the ULTRACAM network switch housed in the blue NETGEAR box near the data reduction PC is powered on.
  2. Turn on the data reduction PC, housed in the aluminium case, by flicking the switch at the rear of the case and then pressing the round button on the front panel.
  3. In the dome, check that the green illuminated switch on the mains socket strip at the top of the rear of the electronics rack is lit - this means that the rack is connected to the mains. Note that it may be difficult to see the green light as it is usually covered in black tape to prevent light pollution in the dome.
  4. When the mains socket strip switch is turned on, the rack PC should start booting up automatically - you can tell this is happening due to the loud fans that start up. The rack PC is located in the bottom of the electronics rack and runs the ULTRACAM data acquisition system. If the rack PC doesn't start up automatically, it is likely that the remote power module (RPM) has been switched off. The RPM is the black box on the second shelf down in the electronics rack, to which the rack PC power is connected. To turn on the RPM, flick the red switch at its rear (which again may be covered with black tape), and the rack PC should then start booting up. The imedia PC, located just below the second shelf in the rack and which is used to monitor the peltier temperatures and control the focal-plane slide, should also boot up automatically. Note that it is very easy to dislodge the power cables going into the rear of the RPM when turning it on, so ensure that they are securely pushed in.
  5. If you want to see what is happening on the PC whilst it is booting, use the sliding LCD monitor and keyboard at the top of the rack; turn the silver knob clockwise to release the lid, slide out (it can be stiff!) and press the top-most button on the left-hand side of the monitor to power it on. To switch between the rack and imedia PCs, click the green button mounted on the front of the small grey box (D-Link KVM switch) on the shelf in the rack PC. Remember to turn the monitor off again when finished. To stow away, release the two catches at the front left and right-hand sides simultaneously and push in.
  6. Turn on the SDSU controller by flicking the switch "SDSU POWER SUPPLY" from 0 to 1. The switch can be found approximately half way up the rear of the rack near the centre of a white panel. If successful, two green LED's should illuminate on the SDSU controller and there should be no lit LEDs on the SDSU-PCI card in the rack PC. (Need to check this). If nothing happens, make sure the switch on the mains input connector to the Peltier/SDSU power supply unit is also switched from 0 to 1. If this doesn't work, check the fuses (see the Troubleshooting section for details).
  7. Don't flick any of the switches described below until you have read the whole of items 8 to 11. It is possible to damage both the peltiers (if there is no water flow) and the chips (if they are cooled too quickly) if the following procedure is not followed.
  8. Make sure that the power to the peltier temperature controllers is switched off. The peltier temperature controllers are located in the two aluminium-fronted units of the electronics rack. To turn off the power to peltier 3, flick the switch marked "PELTIER 3" at the rear of the rack from 1 to 0. To turn off the power to peltiers 1 and 2, locate the label "PELTIER 2" at the rear of the rack and then flick the switch to the right of this (next to where the mains cable plugs in) from 1 to 0.
  9. Ensure that the reservoir of the water chiller has been filled with bottled water to its maximum mark. Now turn on the water chiller by flicking the switch at the top of the rear of the unit and then pressing the right-hand button on the front panel with the "I/O" on it. The chiller will spring into life and you should immediately check both that the peltier temperature displays at the front of the rack remain unilluminated and that none of the pipe connections on the chiller, SDSU controller, flow sensor (attached to the underside of the mid-plate of ULTRACAM) are leaking. If you discover a leak, or if the peltier temperature displays illuminate, immediately power the water chiller off. If you have a leak, try disconnecting and reconnecting the pipe, and/or changing the bend of the pipe, and/or rotating the pipe until the leak stops. If this fails, check the o-rings for damage and, if necessary, replace the connector using the box of spares in the crates.
  10. The current temperature of the water is displayed on the front panel of the chiller and it will begin to drop as the chiller starts cooling the water down to the set temperature. The set temperature should be 10 degrees, unless this is within approximately 5 degrees of the dew point (in which case the water temperature should be increased). The dew point can be determined from the observatory's meteorological system. A useful check on this is to run your hand along the base of the SDSU controller - if it feels even slightly clammy to the touch, increase the set temperature. To change the set temperature, press the left-hand button with the penannular arrow on it and then alter the set temperature with the up and down arrow buttons. Press the button with the penannular arrow on it again to complete the setting process.
  11. After the chiller has been running for a short while, you may notice that the water level has dropped compared to when you turned the chiller on. This is most probably because of air pockets in the plumbing. It is important that you top up the reservoir in this case.
  12. Turn on the peltier temperature controllers, which are located in the top two units of the electronics rack. To turn on the power to peltier 3, flick the switch marked "PELTIER 3" at the rear of the rack from 0 to 1. To turn on the power to peltiers 1 and 2, locate the label "PELTIER 2" at the rear of the rack and then flick the switch to the right of this (next to where the mains cable plugs in) from 0 to 1. The peltier displays on the front of the rack will now illuminate. If nothing happens, make sure the switch on the mains input connector to the Peltier power supply units are also switched from 0 to 1. If you get an "Err" reported, which typically happens with the green peltier controller when using the 7.5m cable, try touching the connector at the rear of the controller with your hand.

    There is one display for each CCD head. The upper figure on the display shows the current CCD temperature and the lower figure shows the set temperature. The temperature controllers will immediately begin cooling the chips to the set temperature by running the peltiers at their maximum power of -55%. However, it is possible to damage the peltiers by allowing them to cool by more than 5 degrees per minute, so it is essential to immediately increase the set point to 5 degrees below the current chip temperatures using the up and down arrow buttons to the right of the temperature displays. Once attained, drop the set temperatures by approximately 5 degrees per minute until the desired temperature of -40 degrees is reached. Once the chip temperatures have stabilised at -40 degrees, check the peltier power levels by pressing the left-hand turquoise buttons on the temperature displays once. The power level should be approximately -30% to -35%. If the value is close to or equal to the maximum value of -55% then the heads may have lost their vacuum and need to be pumped down. Alternatively, the water chiller might be running at too high a temperature. You can return to the temperature display by pressing the black button in the middle.

  13. Ensuring that the focal-plane slide is in the home position, slide the M4 mirror into the beam. If you've never done this before, please ask Vik Dhillon for instructions.

Powering down

During an observing run it is normal to leave the SDSU controller, water chiller and peltier coolers running continuously to prevent unecessary thermally and power cycling. It is no longer necessary to dismount ULTRACAM at the end of each observing run, as it is now permanently mounted on the NTT cube. Instead, the instrument should simply be powered down at the end of a run, in the following order (refer to the
Powering up section for the location of all relevant switches and devices).
  1. In the control room, prior to shutting down udriver on the data reduction PC for the last time, home the focal-plane slide. This is absolutely essential, as otherwise anyone sliding the M4 mirror out of the beam will collide it with the blade, likely destroying it and showering the ULTRACAM collimator with bits of metal!
  2. Still in the control room, ensure that the end_of_night_tasks has successfully completed on the data reduction PC.
  3. Now go up to the dome, and turn off the SDSU controller.
  4. Then turn off the water chiller. This will cut the water flow and hence will automatically turn the peltiers off (but check the peltier displays to make sure). With all cooling turned off, the chips will gradually warm up to ambient temperature at a safe rate.
  5. Turn off the peltier temperature controllers.
  6. If you've forgotten to home the slide, you've got one last chance - you can move it by logging into the imedia PC and following the instructions given in the Drift mode section.
  7. Shut down the rack PC by logging in as root and typing "init 0" in an xterminal connected to the PC or by using the sliding monitor and keyboard in the electronics rack (if doing the latter, make sure the KVM switch - the grey D-Link box on the rack shelf - is set to the rack pc login window rather than the imedia login window). This does not turn the PC power off, so when the LCD monitor says the system is halted you can press the power button on the front-panel of the rack PC.
  8. Shut down the imedia PC by pressing the toggle switch on the front of the unit - the unit will automatically power down after approximately 30 seconds.
  9. Turn off power to the entire ULTRACAM electronics rack by switching off the green illuminated switch on the mains socket strip at the top of the rear of the electronics rack.
  10. If instructed to do so by Paul Kerry or Vik Dhillon, shut down the data reduction PC in the control room by selecting the Log Out option from the Applications menu on the bottom bar, and then turn off the network switch, data reduction PC speakers and monitor. If Paul or Vik say nothing, please leave the DRPC and peripherals running, and just log out of the window manager.

Afternoon activities

Before you start observing in the evening, you should perform the following system checks:

In the dome

  1. If there is heavy rain, it is likely that water will leak through the roof of the NTT Nasmyth room. To protect ULTRACAM from drips, there is a roll-away plastic cover above the rotator (see photo) which normally covers EFOSC. This has two carabiners attached to it, which must be clipped to the triangle-shaped fastenings on the far wall (see photo) in order to hold the screen in place over ULTRACAM. If necessary, you should ask ESO for an additional piece of plastic (usually stored on top of the green cupboard in the Nasmyth room - see photo) to cover any bits of the instrument that may stick out.
  2. Check water temperature on the chiller display is set to 10 degrees unless this is within approximately 5 degrees of the dew point (in which case the water temperature should be increased). The dew point can be determined from the observatory's meteorological system. A useful check on this is to run your hand along the base of the SDSU controller. If it feels even slightly clammy to the touch, increase the water temperature slightly.
  3. Check the temperature of the air in the Nasmyth room. The water in the chiller reservoir will freeze if the ambient temperature approaches 0 degrees. This is because the fan in the chiller blows air past the reservoir on its way to the heat exchanger. Hence the water in the reservoir can freeze even though the water circulating through the chiller and ULTRACAM remains at the set temperature. Ice forming in the reservoir can damage the chiller, so we have installed a temperature sensor to measure the temperature of the water in the reservoir. The temperature is reported by AutoLogger and can also be accessed by pointing a web browser running on the data reduction or rack PC at the following url: http://192.168.1.5. If the temperature of the water in the reservoir is close to 0 degrees, try to surround the chiller with some of the large black foam panels in the crates, so that some of the warm air produced by the chiller recirculates through it.
  4. Check CCD temperatures on the rack-mounted temperature controllers are stable at -40 degrees.
  5. Check peltier power usage on the rack-mounted temperature controllers. These should typically be in the range -30% to -40%. If the value is close to or equal to the maximum value of -55% then there is either a problem with the vacuum in the head or the CCD temperatures have been set too low (or the water temperature too high).
  6. Check for water leaks by running your fingers along the pipe connectors on the water chiller, the SDSU controller, the flow sensor (attached to the underside of the mid-plate of ULTRACAM) and the individual CCD heads. There are twelve connectors to check.
  7. If the humidity in the Nasmyth room is over 75%, the ESO nitrogen gas supply will automatically turn on, flushing the CCD windows with dry gas to prevent condensation. Every once in a while, it is worth checking that the blue pipework and syringe needles on ULTRACAM are connected, and that the small brass valves on ULTRACAM are fully open.
  8. Ensure that the pipes and cables leading to the instrument via the twister arrangement are not overly taut, are neatly arranged, show no signs of damage and are in no danger of snagging on anything.
  9. Check that the SDSU controller is powered on by removing one of the black velcro strips covering the status window and looking for lit green LEDs. If none are present, power on the SDSU (see Powering up).
  10. Check to see if you need to make a filter change for the start of the night. If you do, refer to Changing filters.
  11. Ensure all lights are turned off in the dome.

In the control room

  1. Check that the end_of_night_tasks data-archiving script (see Archiving data for details) successfully completed without error.
  2. Once you are happy that the previous night's data is safely archived, delete all the /data/run* files on the rack PC. This ensures that the first run of the coming night will be run001 (strongly recommended) and also ensures that there will be sufficient disk capacity for the entire night's observing.
  3. Start the observing system (see Software startup), take some full frame bias frames in both slow and fast readout and check the readout noise and bias level using the python quality control script: /home/observer/qc/ultracam/qc.py. This script writes the results to a local database so that you can compare your results with those obtained previously. Note that this script now uses the HiPERCAM pipeline, but still numbers the ULTRACAM CCDs in the traditional manner: 1=Red, 2=Green, 3=Blue (i.e. RGB).
  4. Take bias frames for all of the setups on the previous night. You can use the ULTRACAM pipeline reduction routine unique to help you with this, and the routine missbias at the end of a run to ensure you've got bias frames for every setup used.

Software startup

ULTRACAM can be controlled from any unix system connected to the ULTRACAM internal network (see the
Troubleshooting section for details), although it is usual to use the aluminium data reduction PC in the control room:

  1. Login as observer to the ultracam data reduction PC (known as ultracam; IP address 192.168.1.1). If you don't know the password, please contact one of the ULTRACAM team members.

  2. Open an xterm on ultracam and login as observer to the rack PC (either ucam4 or ucam5 - see the ULTRACAM logistics page for which is currently in use). You can do this in a number of ways:
    1. By clicking on the desktop icon labelled rack.
    2. By typing rack in the xterm.
    3. By typing ssh 192.168.1.2 in the xterm.
    You shouldn't need a password to do this. If you need to know the password, please contact one of the ULTRACAM team members.

  3. Ensuring that the SDSU controller is switched on, type the following in the xterm on the rack PC:

    start_ucam

    The following windows should then appear: The "Camera" window provides information on the commands used to control the CCD, which are sent to the SDSU controller. The "Filesave" window provides information on the commands used to define the quantity of data to be expected, which are sent to the SDSU-PCI card in the rack PC. The java-based GUI (known as udriver) sends the xml documents containing the camera and filesave parameters to the SDSU controller and PCI card via the http protocol. Note that if you have to shut the system down for some reason, you should try to remember to kill udriver first so that the current settings are saved.

  4. Perform a software power-on of the CCD controller by clicking on the "Initialise" button on the left-hand side of the GUI. The filesave window should then report the creation of a new run file in the /data directory. You are now ready to take data.

  5. Finally, open another xterm on ultracam and type talert. This runs a modified version of Tom's talert python script, which checks each frame as it is taken for problems with GPS timestamps. The results are monitored by AutoLogger, which outputs visual and audible alarms if any timestamp errors occur. [Note by VSD on 2019/03/07: I suspect this problem has been fixed (by repairing the GPS trigger cable), so it is probably not necessary to run talert any more.]


Looking at data

You can use the c-based ULTRACAM pipeline reduction software to look at data either in real-time or off-line - see the
manual for details. The latest version of the software is version 9.16 and can be initialised by typing the following command on the data reduction PC:

ultracam9.16

You can then type any of the pipeline reduction commands, e.g. rtplot. In order to run the system whilst observing, it is necessary to access the data on the rack PC over the server. To do this, open an xterminal on the rack PC and type:

FileServer

As of February 2019, you can also use the python-based HiPERCAM pipeline reduction software. This is now the recommended method of looking at ULTRACAM data. It requires the same FileServer to be running, but no initialisation command is required to start the pipeline. Please ensure that the real-time data reduction performed on each night is stored in a directory of the form /home/observer/reduce/yyyy_mm_dd on the DRPC. Please also ensure that all output files from the pipeline are named according to the run number being reduced. So the standard reduction sequence using the HiPERCAM pipeline would be: Please tidy up the /home/observer/reduce/yyyy_mm_dd directory at the end of each night, as it is now archived along with the raw data by the end_of_night_tasks data-archiving script (see Archiving data for details). Note that when looking at ULTRACAM data with the HiPERCAM pipeline, the CCDs are still numbered in the same order as with the ULTRACAM pipeline: 1=Red, 2=Green, 3=Blue (i.e. RGB).

Logging of data

AutoLogger is a c-shell script which produces a log of ULTRACAM observations on a web browser. AutoLogger also provides status information on the current run, outputting an audible and visual alarm if the CCD temperatures rise above -40 degrees, if the GPS stops working and if the file size goes over a user-defined limit. Please refer to the Troubleshooting section for advice on how to deal with the problems reported by AutoLogger.

The AutoLogger script runs in real time on the rack PC. The script works by polling the directory containing the data (usually /data) and extracting information from all the xml files it finds. For each ULTRACAM data file, it also determines the start/end times, file size, number of frames and exposure time. Comments on each run are input using an optional comments file, which must reside in the same directory in which AutoLogger is run. An example of the optional comments file can be found here - it is essential that you do not change the format of the file, i.e. the two header lines and the order of the columns. Any keyboard character can be used in this file except < and >.

To run AutoLogger whilst observing on 2010_04_24, for example, open an xterm on the rack pc, logged in as observer (see Software startup for how to do this). Then type:

cd AutoLogger
emacs 2010_04_24_log.dat &  -   and enter the run number and comments for any runs already taken
AutoLogger
  >   /data (the directory on the rack PC to which data is written)
  >   2010_04_24_log (the name of the log file - omit the .dat)
  >   6000 (the file size at which you wish a maximum filesize alarm to go off)
  >   y (to test the speaker volume level)
(AutoLogger   /data   2010_04_24_log   6000   y   typed on the command line will also work).

The script will run indefinitely, polling the data directory a few times every minute and looking for changes in either the data files or the comments file. If it finds a change, it will update the log displayed on the web browser. To exit AutoLogger, just type crtl-c, but only do this when AutoLogger says that it is safe to do so. The final log is written to a file in html format - in the example above the resulting file would be called 2010_04_24_log.html.

To view the logs from previous nights, open a web browser on the rack PC, avoiding the use of the konqueror browser, which would clash with AutoLogger if running. Then load the html log file, all of which are stored in /home/observer/AutoLogger.


Observing

Tom Marsh has written an excellent observing check list which is well worth running through each night to ensure you've not forgotten anything. It is also full of useful tips to get the best quality data as efficiently as possible. Some additional useful notes are given below.

Target acquisition: If you are going to repeatedly revisit a target, it is usually desirable to be able to reacquire it onto the same ULTRACAM pixel with no time-consuming tweaking of telescope position. This can be done on the WHT, but not the NTT. (Need to check this.) To do this, it is imperative that you note down the following information once you've acquired a target for the first time:

When you wish to reacquire a target, give the above information to the TO. He/she should then slew the telescope to the given RA, declination and rotator angle. Once there, he/she should apply the offsets. Then, he/she should move the autoguider probe (i.e. the x-y or radial-azimuthal stage that the autoguider CCD is mounted on) to the given position. The guide star should then appear on the autoguider CCD. The TO should then position the guide star onto the desired pixel position on the autoguider CCD by moving the telescope (not the guide probes, which is what the TO would normally do). The above operation can place a target back on the same pixel of the ULTRACAM CCDs from one night to the next with no additional tweaking.

Twilight flats: When taking twilight-sky flat fields, try to observe a blank field near the zenith and also dither the telescope in a spiral pattern. Scripts are available at the WHT and NTT to do this automatically. On the NTT, make sure that you ask the telescope operator to use the spiral parameters 50, 6, 10, which corresponds to the number of steps, the time in seconds between steps, and the size of a step in arcseconds, respectively.

Catalogue files: To save time and minimise errors during acquisition at the NTT, it is useful to send the catalogue file of target positions created by Tom's phase II web pages directly to the telescope operator. To do this, navigate to the directory on the DRPC that the catalogue is saved in. Assuming the catalogue name is ultracam.cat, enter the following commands on the DRPC:

At the TO's end, they follow the same steps but use get ultracam.cat instead of put ultracam.cat. Then, on the TO's PC, they should move the catalogue file to /diska/vltdata/pointing/catalogs, and select it using the telescope control system.

Telescope rotator: Since September 2019 when ULTRACAM was mounted on the cube, a Sky PA of 0 on the TCS places N up and E left on the ULTRACAM CCDs. So no rotator offsets are required. For the record, when the cube is not in use, the sequence of events for dealing with Sky PA when acquiring a new target is as follows:

Autoguiding: When using the autoguider, it is important to be aware of the "Zone of Avoidance" for the autoguider probe. If it enters this, you will vignette the ULTRACAM beam. The original email I sent around about this on the google group in 2011 can be found here: https://groups.google.com/forum/#!searchin/vikcam/executive$20summary/vikcam/FO3k2uN9hR8/lRb28xi3K_gJ
There is a printout showing the zone of avoidance in the blue ULTRACAM folder in the control room.

Active optics calibration: You should ask the TO to calibrate the active optics in twilight at the start of each night, which takes ~10 mins. However, don't bother doing it again later in the night. Even with the active optics calibrated, you will often need to refocus after each slew to a new target. It is imperative that you do this with reduce, looking at all three chips simultaneously and ensuring that you're plotting the target aperture FWHM (not the comparison). Doing this you should always be able to find a telescope focus that approximately minimises the target FWHM on all three chips, although this telescope focus would be different depending on whether your target is in the centre or the edge of the field (as we have a curved focal plane).


Archiving data

At the end of the night, ensure that AutoLogger has been correctly shut down and that data taking has completely finished. Run the script end_of_night_tasks from the data reduction PC. This archives the original data, which is stored in /data on the rack PC, to two large-capacity USB disk drives in the control room. The script also makes a copy of the data on the archiving disk /data1 in the rack PC, and a subdirectory of /data. The script also now makes a copy of the /home/observer/reduce/yyyy_mm_dd directory on the DRPC containing the pipeline-reduced data obtained that night. The script is self-explanatory to run, and is described in more detail in /home/star/archiving.


Drift mode

To obtain the highest frame rates it is necessary to use drift mode, where CCD windows are stacked up in the masked region of the frame transfer chip. A full description of the algorithm is given in the
ULTRACAM MNRAS paper. Generally speaking, it is best to use drift mode when you require approximately 10 Hz frame rates or higher, as otherwise the dead-time due to frame transfer across the 1024 rows in the masked region (which takes approximately 24 milliseconds) becomes a significant fraction of the exposure time.

To take data in drift mode, it is recommended that the observing system is started (see Software startup) with the "-q" (for "quiet") option as follows:

start_ucam -q

The above command suppresses the frame number from being written to the filesave window, reducing the demand on the data reduction PC. It is recommended that you do not overload the rack PC, data reduction PC and ULTRACAM internal network with non-essential tasks when running in drift mode at the highest frame rates in order to minimise the chances of crashes.

If the sky is bright, you might notice that the top part of a window has a different background level compared to the bottom half. This occurs when it is impossible to fit an integer number of windows in the image area and hence part of each window exists on the chip (and hence accumulates sky) for slightly longer than the other part. To negate this effect, put the focal plane mask in the beam. The focal plane mask can also be used to prevent bright stars lying on the same column as your target star but on a higher row from corrupting your image. The slide is also useful if you want to minimise the light falling on the chips when taking bias frames and darks.

The focal plane mask is most easily moved from udriver by pressing the Focal Plane Mask button on the observing tab. The slide can also be moved by logging into the imedia PC. You can do this from the data reduction PC in a number of ways:

  1. By clicking on the desktop icon labelled imedia1.
  2. By typing ssh root@imedia1 in the xterm.
  3. By typing ssh root@192.168.1.3 in the xterm.
If you don't know the password, please contact one of the ULTRACAM team members.

Once logged in to the imedia PC, type the commands:

cd /home/httpd/slide ./slide

This will list the various options available to you on the command line.


Changing filters

There are many different filters available for use in ULTRACAM - please refer to the
ULTRACAM filter database. The filters not being used are stored in a small, blue briefcase. If you want to change a filter in ULTRACAM, you should first check that the required filter is mounted in an aluminium cartridge, which you can also find in the blue briefcase. Make sure that the filter is not slopping around in the cartridge. If it is, use one of the square plastic spacers in the blue briefcase. If you need to make more of these, you will find an envelope full of shims in one of the packing crates and a scalpel and metal ruler for cutting them to shape in the tool box.

Since September 2019, ULTRACAM has been mounted on the cube. Changing filters is probably best done with the instrument horizontal. You can either ask the TO to rotate it to this position from the TCS in the control room, or you can do it manually yourself in the dome. To do this, press the red emergency stop button on the end of the cable twister. This prevents anyone moving the rotator whilst you are changing filters. Press the hand-held rotator brake button, which will make a hissing sound as the brake releases. Keeping this button pressed, carefully rotator the rotator into the required position and release the button to engage the brake again. After you have changed the filter, remember to release the emergency stop button by twisting it either left or right, after which it will pop out.

The red and green filters are relatively straightforward to change: simply unfasten the two velcro strips holding the top edge of the foam baffle down, remove the foam piece and replace the filter. The blue filters are more tricky. Carefully slide out the cartridge containing the filter you wish to remove. Using the 15cm metal ruler found in the ULTRACAM tool box to prevent the blue foam ring from slipping, slowly slide the new filter cartridge into the filter slot (you may feel the ball-bearing retainer click into position when complete). Slide the metal ruler out, remembering to check that the two syringe needles for the dry-nitrogen flushing system are still attached to the blue foam ring. Don't worry if the blue foam ring is not centrally located over the CCD window - it would have to be seriously out of position to vignette the field. Make sure you keep the metal ruler parallel to the filter, CCD head and re-imaging camera at all times to ensure that you don't inadvertently scratch the outer surface of the re-imaging lens, CCD window or filter with it.

Always use the optics handling equipment (e.g. latex gloves, lens tissues, air spray) when changing filters - you can find these either in the blue briefcase or in the "optics handling equipment" box in one of the ULTRACAM packing crates. When blowing air across the filter, be sure to hold the can steady and upright, otherwise propellant may fall on the filter. It is also wise to make a few test blows into the air before spraying the filter. A head torch to assist with the filter change can be found in the tool box.


Before you go to bed

  1. Make sure that you have written the night report on the ULTRACAM google site.
  2. Make sure that the AutoLogger logs are up-to-date and complete for the night.
  3. Shut down the observing system by closing udriver using "File" on the top bar, and then typing ctrl-c in the filesave and camera windows (preferably in that order).
  4. Archive all data obtained during the night (see Archiving data). If this is the last night of the run and you need to dismount the instrument in the morning, please wait for the archiving script to finish, check all is ok, and then delete the night's runs from /data. This prevents the next person who has to install ULTRACAM from worrying about whether or not the last night of data from the previous run have been successfully archived.
  5. If you suspect that the dew point might rise to within approximately 5 degrees of the water chiller set temperature whilst you are asleep, raise the set point accordingly.
  6. If this is your last night, make sure you home the focal-plane slide to prevent damage in case someone tries to move M4.
  7. Go to bed.

Troubleshooting

Rack PC or DRPC fails

The correct response to such a problem depends on whether the hard disk has failed or some other piece of hardware, e.g. the PC motherboard, has failed. In the former case, it is possible to recover quite easily using the clone disks. In the latter case, it will probably be necessary to install the spare rack PC or spare DRPC from the ULTRACAM crates. For full details on how to respond to each such problem, please refer to Paul Kerry's user guide - don't try anything before you've read that document!

start_ucam does not bring up filesave window

This problem usually occurs when the SDSU controller is not powered on or has failed in some way. The SDSU controller can be turned on and off remotely using the remote power module. To do this, point a web browser on the data reduction machine to http://rpm/, enter the username (admin) and password (12345678) and then click the off button, followed by apply, and then the on button, followed by apply. The moment you power the SDSU off like this, the blue peltier will also be turned off. You must therefore immediately power the SDSU on again, otherwise the blue CCD will warm up and when the peltier is turned on again it will try to cool the chip all the way down to -40 degrees in one go, possibly damaging the peltier and/or CCD. If the SDSU seems ok, try rebooting the rack PC by typing init 6.

Unable to connect to the rack PC

Unless you can spot a broken or disconnected network cable, this usually happens because the rack PC has crashed. Go into the dome, turn on the LCD monitor in the rack and hit return on the keyboard. If the normal login prompt does not appear, then the rack PC has probably crashed. If you are unable to bring it back up, switch to the spare rack PC, which is located in one of the black crates, and contact one of the ULTRACAM team.

Data reduction PC hangs whilst exposing

If the data reduction PC hangs or crashes whilst exposing, it is possible to safely stop the exposure by opening an xwindow on the rack PC from another computer connected to the internal network and then typing udriver. When the GUI appears, go into expert mode by checking the expert button on the Settings menu. Then click on the observing tab and click the STOP button. With the data safe, you can then try to reboot the data reduction PC. This will kill the camera and filesave windows, of course, so you might also have to reboot the rack PC.

There has been one occasion when the data reduction keyboard stopped responding, probably due to an illegal combination of keystrokes. This was fixed by killing the windows one by one until the offending window had been killed and the keyboard started responding again.

If you are unable to get the data reduction PC working again, you can switch to the spare data reduction PC ULTRACAM2, or the ULTRACAM laptop magnetar, which are both stored in the black crates. Please refer to Paul Kerry's user guide for details on how to do this.

Inexplicable crash whilst taking data

This hasn't happened with the new data acquisition system installed in early 2010. If it does recur, one reason could be because you have filled the /data disk. Another reason could be that you are pushing the system to its limits either in terms of data rate or frame rate. The former occurs, for example, when using drift mode at high-frame rates with the fast readout speed. If you experience a crash, try running the same application with the slow readout speed, in quiet mode, which should be more stable.

GPS problems

You can check whether the GPS is working by typing mbgstatus on the rack PC. The output of this command is also displayed in the GPS window in AutoLogger. We have not yet experienced any problems with the new Meinberg GPS system installed in early 2010. If you do experience problems, possible causes might include: has water entered the antenna, perhaps due to a spell of very bad weather? Has the GPS cable running outside the dome been damaged in some way? Has there been a lightning strike nearby? If the GPS does not work, there is a complete spare GPS system in one of the black packing crates.

Chips suddenly output nothing but 32768 counts

This is a problem with the power control board in the SDSU controller, which has now hopefully been fixed. If it does recur, try stopping and restarting the exposure. If this fails, power cycle the SDSU. If this fails, power cycle the rack PC, ensuring the power really is removed by taking out the power cables at the rear of the PC (as this ensures the SDSU-PCI card is power cycled). If this fails then you might have to use the spare SDSU controller in one of the black packing crates, but please first contact a member of the ULTRACAM team.

Pickup noise

This is evident as a series of horizontal, vertical, diagonal, or chevron-like lines in a bias frame. Removing it is a black art. The first step is to verify that the pattern is not simply an artifact of the image display device you are using - try zooming in to see if the pattern persists. If it does, estimate how serious a problem it is by determining the standard deviation - image display devices can make a very insignificant level of pickup noise (say, 0.1 counts) appear as if there is a serious problem with the CCD.

If you are determined to try to remove it, first try power cycling the SDSU controller and then allow it to settle down by taking some images for a while before measuring the readout noise again. If the pickup noise persists, try rearranging the cables. Experience has shown that by far the most important factor seems to be the arrangement of the data cables running between the SDSU controller and the CCD heads. Without disconnecting them, try altering the position and angle of these cables with respect to each other using cable ties to hold the data cables in place. If this fails, adjust the position of the other cables on the instrument so that none of them passes close to the data cables and their connectors. The aim here is to try to separate any power-carrying cables from cables carrying data, although I'm not convinced how much this helps. It might also be worth avoiding tying cables together in loops, but again I'm not sure this makes much difference.

If the above fails, ensure that the chiller is not too close to the electronics rack, as I've noticed pickup from this before on the NTT.

If you still have no luck, you could try the various earthing cables in the cables box in the black crates. Connect the plug to a mains socket and then try earthing the instrument and/or electronics rack to this same point. Try to see if there are alternative routes to earth from the instrument, e.g. I once noticed the metal pipes carrying helium to the WHT Cassegrain focus were touching the top of the (isolated) electronics rack. If you have no luck with this, and you've noticed that the pickup noise is particularly bad on one of the chips, you might be able to isolate the problem by swapping the peltier power supplies around by exchanging the cables going into the power supplies at the rear of the electronics rack (and power cycling them in the process). If you have no luck with this, check the dome environment to see if anyone has turned on equipment which might be interfering with ULTRACAM and, if possible, ask them to turn it off.

Can't remember how to plot setup windows in rtplot

A really useful trick when trying to determine the optimum window parameters to use is to take full-frame acquisition images of the field and then overlay the windows defined on udriver on the images using rtplot. You can then see the windows move and change size/shape as you adjust their parameters on udriver. I always forget how to do this, so here is a reminder:

rtplot...
SETUP - do you want to plot setup windows? [no]: y
SETWIN - name of setup windows file [setwin]: http://192.168.1.2

SDSU won't turn on

This has happened on a number of occasions and has always been due to a blown fuse. There are three different fuses to check. The first is in the plug in the power cable from the back of the SDSU/peltier rack unit to the socket strip at the top of the electronics enclosure. The second is in a small tray which slides out from beneath the socket at the back of the SDSU/peltier rack unit. The third is inside the SDSU/peltier unit itself, at the back of the SDSU power supply. To get at this, you will have to slide the rack out of the electronics enclosure and open the lid. There are spare fuses in the ULTRACAM tool box (usually found in either the control room or the packing crates), as well as a whole spare SDSU controller.

Low/high red-channel bias

This is a rare, intermittent fault which occurs when a new run is started. The bias level on the red CCD suddenly jumps to a very high or low level, sometimes with a loss of sensitivity and an increase in the readout noise. Note that Tom Marsh has implemented a check in rtplot which issues a warning if it detects an abnormal bias level. It can usually be fixed by simply stopping the run and restarting it. If this does not work, try it again. If the problem persists, try a system reset by clicking on the System reset button when in expert mode on udriver, followed by an Initialise.

If this fails, try switching the SDSU controller on and off, which can be done remotely using the remote power module (see above).

CCD temperature problems

On some occasions the peltiers have powered themselves off, as indicated by the blank temperature displays at the front of the electronics rack and/or AutoLogger reporting a CCD temperature error of N/A. If the latter, ensure that the CCD temperatures reported by AutoLogger really are in error by opening a web browser on the data reduction PC and going to http://imedia1. Click on the Temperature monitor link and check the CCD temperatures and if they are being updated. There are at least five reasons why the peltiers might power themselves off:
  1. The water chiller has failed. There is a spare in the packing crates.
  2. The water flow might have stopped. If the chiller is still running, this is almost certainly because one of the water pipe connectors on the CCD heads, SDSU controller, flow sensor (attached to the underside of the mid-plate of ULTRACAM) or water chiller have become disconnected. The connectors are self-sealing, so if you have inadvertently pressed the quick-release catch on the connector (perhaps when changing filters), the pipe will pop out by a few millimetres, close its seal, and cut off the water supply to the flow sensor (even though the chiller is still running), thereby cutting power to the peltiers. To determine if this has occurred, go round the instrument ensuring each pipe is securely connected to its socket. If you cannot find a loose fitting, try disconnecting and reconnecting each water pipe in turn, as it has been known for an apparently securely-connected pipe to block the flow due to tension on the connector. Remember that the moment you rectify the problem, the peltiers will power up. Therefore, it is essential that you immediately raise the set temperatures on the peltiers so that it is within 5 degrees of current chip temperature, and then slowly reduce the temperature as described in Powering up.
  3. The flow sensor has failed. This is a small black box located on the underside of the central plate of ULTRACAM through which the water flows. When the sensor in this box detects a disruption of flow, or if the sensor fails, the peltiers will cut out. There is a complete spare flow sensor, complete with the water pipe connectors at each end, in the cardboard box marked "ULTRACAM ELECTRONICS TEST EQUIPMENT" in the packing crates, so try replacing this first. Remember that the moment you rectify the problem, the peltiers will power up. Therefore, it is essential that you immediately raise the set temperatures on the peltiers so that it is within 5 degrees of current chip temperature, and then slowly reduce the temperature as described in Powering up.
  4. If this still does not work, perform a sanity check by removing the little black plastic cube surrounding the flow sensor. Stop the chiller, shine a torch on the clear tube that is exposed and, whilst watching the propeller in the tube, turn the chiller on. If it starts spinning, then you have flow and should proceed to the next item below. If it doesn't spin, either you have a problem with one of the pipe connectors, or the chiller has failed.
  5. The grey plastic box on the top shelf of the electronics rack marked "ULTRACAM PELTIER POWER SUPPLY CONTROL BOARD" might not be functioning. On one occasion, a chip in the box failed. There is a spare box in the ULTRACAM crates, although this is black plastic, not grey. Replacing it is awkward, due to its location on the top shelf of the rack, so you will need to use the largest red step ladder in the dome. Remember that the moment you rectify the problem, the peltiers will power up. Therefore, it is essential that you immediately raise the set temperatures on the peltiers so that it is within 5 degrees of the current chip temperature, and then slowly reduce the temperature as described in Powering up.
  6. It is possible that a fuse has blown in one of the peltier power supplies. If all of the peltiers displays are off, it is unlikely to be this, but if just one of the units fails to come on, then check the fuses. There are three different fuses to check. The first is in the plug in the power cable from the back of the peltier rack unit to the socket strip at the top of the electronics enclosure. The second is in a small tray which slides out from beneath the socket at the back of the peltier rack unit. The third is inside the peltier rack unit itself, at the back of the temperature controller. To get at this, you will have to slide the rack out of the electronics enclosure and open the lid. There are spare fuses in the ULTRACAM tool box (usually found in either the control room or the packing crates). There is also a spare peltier unit in the packing crates.
  7. As an absolute last resort, and ensuring that you have verified that water is actually flowing by following the sanity check outlined in item 4 above, then it may be necessary to bypass the flow sensor. To do this, you have to bypass the grey box on the top shelf of the electronics rack marked "ULTRACAM PELTIER POWER SUPPLY CONTROL BOARD". Remove the three co-axial cables from the rear of the grey box and attach all of them to the small metal box marked "FLOW CONTROL BYPASS" which you can find in the cardboard box marked "ULTRACAM ELECTRONICS TEST EQUIPMENT" in the packing crates. Remember that the moment you rectify the problem, the peltiers will power up. Therefore, it is essential that you immediately raise the set temperatures on the peltiers so that it is within 5 degrees of the current chip temperature, and then slowly reduce the temperature as described in Powering up. Remember also that the ULTRACAM CCDs are not now protected if there is a real disruption in the flow, e.g. if the water chiller fails, in which case the chips would overheat and be damaged. It is imperative that you fix the problem as soon as possible and in the meantime carefully monitor the water flow by placing your hand on the SDSU controller at frequent intervals: if it is cold, then the water is flowing. Alternatively, you can check if the propeller in the flow sensor is spinning, as described in item 4 above.

Chiller water temperature monitor not working or its alarm goes off on AutoLogger

The chiller water temperature monitor is designed to notify the user, via a status display and alarm in the AutoLogger window, of the water temperature in the chiller reservoir falling close to freezing. If ice forms, it can destroy the chiller, and this can occur if the ambient temperature falls to within a few degrees above zero. It has happened once before on the NTT. If the alarm goes off on AutoLogger, go up to the Nasmyth room and open the chiller water reservoir cap and check for ice. If any ice is present, turn the chiller off immediately and allow it to melt (you may have to move it to a warm room to do this). To carry on observing, you will have to use the spare chiller located in one of the ULTRACAM crates. If no ice is present, which should be the case as the alarm goes off well above the temperature where this should happen, you can keep the chiller running, but you should try to insulate the area around the chiller with foam, without blocking the air flow around it completely. This should allow the chiller's internally generated heat to warm the water reservoir.

If the chiller water temperature monitor is not working, it is likely that it needs to be power cycled. The easiest way to do this is to use the RPM, to which there is a link bookmarked on the web browser running on the ULTRACAM data reduction PC. Just select the chiller water temperature monitor and turn it off and then on again. If this still doesn't work, check that the chiller water-temperature probe is immersed in the water in the chiller reservoir by passing it through the black filler cap, and that its connector (a headphone jack and socket) is fully pushed together - it is easy to leave this connector only partially connected. Check also that the other end of the cable is connected to the control box in the shelf in the rack.

rtplot or reduce inexplicably fails

If rtplot or reduce have been working nicely all night and then suddenly fails with the following error:

Traceback (most recent call last):
  File "/usr/local/bin/rtplot", line 8, in 
    sys.exit(rtplot())
  File "/usr/local/lib/python3.7/dist-packages/hipercam/scripts/rtplot.py", line 583, in rtplot
    with spooler.data_source(source, resource, first, full=False) as spool:
  File "/usr/local/lib/python3.7/dist-packages/hipercam/spooler.py", line 405, in data_source
    return HcamServSpool(resource, first)
  File "/usr/local/lib/python3.7/dist-packages/hipercam/spooler.py", line 319, in __init__
    self._iter = hcam.Rdata(run, first, True)
  File "/usr/local/lib/python3.7/dist-packages/hipercam/hcam.py", line 796, in __init__
    Rhead.__init__(self, fname, server, full)
  File "/usr/local/lib/python3.7/dist-packages/hipercam/hcam.py", line 214, in __init__
    self._ws = websocket.create_connection(URL + fname)
  File "/usr/local/lib/python3.7/dist-packages/websocket/_core.py", line 592, in create_connection
    websock.connect(url, **options)
  File "/usr/local/lib/python3.7/dist-packages/websocket/_core.py", line 252, in connect
    self.handshake_response = handshake(self.sock, *addrs, **options)
  File "/usr/local/lib/python3.7/dist-packages/websocket/_handshake.py", line 79, in handshake
    status, resp = _get_resp_headers(sock)
  File "/usr/local/lib/python3.7/dist-packages/websocket/_handshake.py", line 164, in _get_resp_headers
    raise WebSocketBadStatusException("Handshake status %d %s", status, status_message, resp_headers)
websocket._exceptions.WebSocketBadStatusException: Handshake status 200 OK
This is probably because you've inadvertently overwritten the defaults file, e.g. with a badly timed ctrl-c, and it is using the ULTRACAM server, say, rather than the HiPERCAM one. The fix is simple - run rtplot or reduce again with the prompt parameter on the command line, and check the value of the source parameter.

Networking and computing problems

Please refer to Paul Kerry's user guide.


Contacts

If you experience problems with ULTRACAM that you are unable to solve, please contact one of the following project personnel: