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
   output of the ``hw_monitor`` script on the DRPC (see :ref:`Pumping
   and cooling down <pumping>` for how to start this script 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
   :ref:`Pumping and cooling down <pumping>`, 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 :ref:`Pumping and cooling down
     <pumping>`.

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 :ref:`Changing filters <filters>`.
   
4. Check that the ``end_of_night_tasks_hipercam`` data-archiving
   script (see :ref:`Archiving data <archiving>`) 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   that they have either been archived elsewhere, or that they are not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 :ref:`Software startup
   <software>`). 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.
     
7. 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 ``python3 /home/observer/reduce/qc/hicam_qc.py`` on
   the DRPC. This script 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. Ensure
   all lights are turned off in the dome and the focal-plane mask is
   placed in the beam.