Afternoon activities

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

  1. Check the CCD head pressures and temperatures by inspecting the graphs on the Grafana server http://pulsar.shef.ac.uk:3000 (see Pumping and cooling down for how to start this up if it is not already running). If any of the head pressures are in the high e-3 mbar range or greater, it is likely that the CCD temperatures will be struggling to maintain their set points and hence you will need to pump down the heads to avoid high dark current in the coming night. The pumping procedure, which is described in Pumping and cooling down, is very quick when the CCDs are cold - it should take no longer than about 30 minutes of pumping before all 5 CCD heads are down in the low e-5 mbar pressure range. For CCDs 1,3,4,5 this should only need to be done approximately once per week. For CCD2, however, this needs to be done every ~2 days.

  2. Whilst you are up on the elevation platform for the pumping, give the instrument a thorough check:

    • Ensure that the cables running from HiPERCAM to the cable twister are neatly arranged, show no signs of damage and are not under any stress.

    • Check for any water leaks or condensation by inspecting the pipes and connectors of the HiPERCAM cooling circuit. Also check the observing floor directly beneath HiPERCAM for drips.

    • Visually inspect the focal-plane mask and the brushes it runs through.

    • Verify that the nitrogen-gas supply is gently flowing across the CCD head windows, as described in Pumping and cooling down.

  3. Check to see if you need to make a filter change or insert the diffuser for the start of the night. In the unlikely event that you do, refer to Changing filters.

  4. Check that the end_of_night_tasks_hipercam data-archiving script (see Archiving data) successfully completed without error on the DRPC.

  5. Check that there are no run files in the /data directory on the rack PC, which should have been moved by the end_of_night_tasks_hipercam script. If there are any, make sure that they have either been archived elsewhere, or that they are not required, and then delete them. This ensures that the first run of the coming night will be run0001.fits.

  6. Start the observing system (see Software startup). It is very important that you do this each afternoon, as this resets the first run number to run0001.fits, assuming that the /data directory is empty of run files on startup.

  1. Use the COMPO control widget in the hfinder GUI to ensure that the COMPO arms are parked and out of the light path to the CCD. If the COMPO control widget is not displayed, click the COMPO button in the right-hand-side of the hfinder GUI. Click Home to initialise the COMPO arms. Once the arms are successfully homed, select the P radio button in the COMPO control widget and click Move.

  2. Take some full frame, unbinned bias frames in slow readout speed and check the readout noise and bias level by running the quality control script. To do this, change to the /home/observer/reduce/qc directory on the DRPC. Then grab some frames from the one of the biases you have taken. Then run the quality control script python3 hcam_qc.py, which will prompt you for the bias frame you wish to analyse. The bias frame for each CCD will be plotted - check each image carefully for pickup noise (chevron-line patterns) and inspect the readout noise values for the four quadrants - they should all lie in the range 3.8-4.2 counts. The quality control script also writes the results to a database so that you can compare your results with those obtained previously. Take bias frames for all of the setups observed on the previous night. When doing so, ensure that all lights are turned off in the dome and the focal-plane mask is placed in the beam.

  3. Start hlogger to produce an html log of HiPERCAM observations displayed in a web browser (see Logging of data).