Using the simulator to generate data

While this simulation is designed to be used to sequencially generate a site at a time, it can also be used to produce multiple observations at once, so that data may be generated for multiple sites for each timestep without having to iterate over each site of interest.

For this purpose, code can be left mostly unchanged, and the only modifications are in the form of custom configuration files.

Specifying variables of interest

The only requirements to change the variables included in the simulation is to specify them by name in the survey_configuration file. Modifying the field variables will set the contents of the simulation.

For example;

variables: ["airmass", 'alt', 'ha']

See the survey configuration documention for further details.

Specifying observation sites

To set which sites are included, they can either be set in the observator program configuration, or manually changing them in the step function of the survey program.

Using The Configuration File

If you wish to calculate variables for the same Right Ascension/Declination pairs throughout the course of the survey, these sites can be given in the observator confuguration file.

There are two formats - n_sites or ra/ delc pairs. n_sites evenly distributes them across the sky, and ra / decl supports specific location assignement.

The format of this follows:

location : {'n_sites': 10}

for uniformally distributed locations, and

location : {
    'ra': [0, 10, 20, 30],
    'decl': [0, 0, 0, 0]
    }

for site specifiications. Note that these must be given in pairs. See the survey configuration documention for further details.

Using the step function

If using different observation sites for each timestep, the pairs of ra/decl must be given in the step function.

In this case, this is done during code execution using the format:

for timestep in all_timesteps:
    next_location = {
        "ra": [0, 10, 20, 30],
        "decl":[0, 0, 0, 0]
    }
    next_action = {
        "time": [timestep],
        "location": next_location
    }

    new_observation, reward, stop, log = Survey.step(next_action)

Specifying observation times

Using stop

To set the survey to run until a certain condition is met, within the survey configuration step -

stopping:
    - "timestep": 400,
    - "airmass":
        - "value": 2
        - "lesser": False
start_time: 59946

For example - This configuration block sets a survey to run for 400 timesteps, or until airmass is greater than 2. The start time is also specified to be January 1, 2023.

Using step

Using step provides more fine-control. The format follows:

for timestep in timesteps_in_mjd:
    next_action = {
        "time": [timestep],
    }
    new_observation, reward, stop, log = Survey.step(next_action)

Specifying observation filters

Different filters are only avalible through use of the step function. The specifics of the wavelength each filter is given in the observator configuration file, a as a pair of filter name and associated wavelength.

For example: .. code-block:: yaml

wavelengths: {‘u’: 380.0, ‘g’: 475.0}

This allows filters ‘u’ and ‘g’ to be used in the step function to change the filter. Then the step function can be used as follows.

for timestep in timesteps_in_mjd:
    next_action = {
        "time": [timestep],
        "filter":"g"
    }
    new_observation, reward, stop, log = Survey.step(next_action)

Running the simulation

To run the simulation, simply run results = Survey(survey_config, observer_config)().

Manual control is still done with the step function.

Accessing and saving the output

Use the IO module to order to save the results of the survey and the configuration files. View See the io module documention for further details.