.. _p3-variable-stars:

P03: Variable Stars
===================

Observing Goals:
^^^^^^^^^^^^^^^^

You will observe the light curve of a short period variable star over the course of a night
Useful Background and References:

Observation Planning:
^^^^^^^^^^^^^^^^^^^^^

    * Observation Time

        * You will be observing a HALF night. You will share your data
	  with another team observing the other half of the night.
	   * One group (Variable Star 1 and 3) will use the B and V filter images
	   * One group (Variable Star 2 and 4) will use the V and R filter images

    * Target Selection

        * Together with the other group, select a target that will reach its highest point in the sky at around 1:30am (half way between sunset and sunrise). A :download:`list of possible targets </files/p288176_4-16-2020_23-43-42.pdf>` with finder charts is attached.

    * Observations

        * You will observe the variable star in the B,V and R filters over the duration of the night
        * If possible, take standard star fields at the start and end of your observations to allow for calibration to the magnitude scale.

    * Tools

        * Read the "Automatic filter changer" under "Tools for observing".

Data Analysis:
^^^^^^^^^^^^^^^

    * Data Reduction Basic Steps

        *  Visit the page :ref:`data-reduction`

    * Further for this project

       	* You need to align all of your images -- but no not combine them
        * For each filter the you are assigned, you will do relative photometry (measuring brightness) over time to create a light curve
        * Identify other, non-variable, stars in the field to use as reference

    * Further Analysis for this project

        * Plot the corrected magnitude of the star as a function of time for each filter -- note that you should get the observation time from the header of the image, and account for the length of the exposure!
        * (You can also investigate if the colour between bands changes over time)

Results: 
^^^^^^^^^

Can you answer these questions with your work?

    * What is the shape of the variability? Is it sinusoidal or some other shape?
    * What is the period of the variability (the time between successive peaks or dips)?
    * What is the total amplitude of the variability? Does it change with band?
    * Does the star's colour change with time?
    * What kind of star is this?  Why do these sort of stars pulsate?

Presenting your results:
^^^^^^^^^^^^^^^^^^^^^^^^

   - :ref:`a1-poster`
   - :ref:`a2-talk`