Using Python Classes

The ParentSample class

To tell timewise which data you want to download, you have to create a subclass of ParentSampleBase. The subclass has to define two key attributes:

• ParentSample.df: A pandas.DataFrame consisting of minimum three columns: two columns holding the sky positions of each object in the form of right ascension and declination and one row with a unique identifier.

• ParentSample.default_keymap: a dictionary, mapping the column in ParentSample.df to ‘ra’, ‘dec’ and ‘id’

Further, ParentSampleBase requires a base_name determining the location of any data in the timewise data directory.

from timewise import ParentSampleBase
import pandas as pd


class MyParentSample(ParentSampleBase):

    default_keymap = {
        'ra': 'RA',
        'dec': 'DEC',
        'id': 'Name'
    }

    def __init__(self):
        self.df = pd.DataFrame(
            {'RA': [1, 2, 3], 'DEC':[-5, 0, 5], 'Name':['Wolf359', 'Vulcan', 'Kamino']}       
        )
        base_name = 'weird_sources'
        super().__init__(base_name=base_name)

The WISEData class

This is the class that implements all core functionality:

• match your catalogue to WISE sources

• download photometric data

• bin the photometric data

Any WISEData class must be derived from timewise.WISEDataBase and implement the methods bin_lightcurves() and _calculate_metadata()

When initialising an instance of the class you need following arguments:

• parent_sample_class: your class of parent sample (Attention: yes tha class and not an instance!)

• min_sep_arcsec: the separation from your parent sample source where you want to look for WISE data

• n_chunks: number of chunks into which your parent sample data will be split

• base_name: same as for the parent sample

Currently there are two usable classes:

• timewise.WiseDataByVisit: bins the photometric data by the “visit” of WISE to each sky position. These are periods when the sky position is observed by WISE and consists typically of few tens of observations each six months. The metadata that is calculated gives some basic measures on the variability.

• timewise.WISEDataDESYCluster: derived from timewise.WiseDataByVisit, uses the DESY cluster in Zeuthen to do the binning

Continuing from the example above let’s use that parent sample to download the corresponding data:

from timewise import ParentSampleBase, WiseDataByVisit
import pandas as pd


base_name = 'weird_sources'


class MyParentSample(ParentSampleBase):

    default_keymap = {
        'ra': 'RA',
        'dec': 'DEC',
        'id': 'Name'
    }

    def __init__(self):
        self.df = pd.DataFrame(
            {'RA': [1, 2, 3], 'DEC':[-5, 0, 5], 'Name':['Wolf359', 'Vulcan', 'Kamino']}       
        )
        super().__init__(base_name=base_name)

wd = WiseDataByVisit(
    base_name=base_name,
    min_sep_arcsec=8,
    parent_sample_class=MyParentSample,
    n_chunks=1
)

# matches the parent sample to sources in the AllWISE source catalog
wd.match_all_chunks(table_name="AllWISE Source Catalog")

# load photometric data 
wd.get_photometric_data(
    tables=None,            # query the default tables 'AllWISE Multiepoch Photometry Table' and 'NEOWISE-R Single Exposure (L1b) Source Table'
    perc=1,                 # get 100% of the data
    wait=0,                 # wait 0 hours bewteen queries
    service=None,           # use the dafault service, options are 'gator' (recommended for <300 sourecs) and 'tap'
    chunks=None,            # default is to download all chunks
    overwrite=True,         # overwrite any data that was previously downloaded
    query_type='positional' # get photometry by position or by AllWISE ID ('by_allwise_id'), the latter needs the AllWISE ID in the parent sample
                            # You can get that by executing wd.match_all_chunks(table_name="AllWISE Source Catalog")
)

# plot some results
wd.plot_lc(
    parent_sample_idx=0,        # the index in the parent sample
    service='gator',            # use data downloaded with this service
    plot_unbinned=False,        # plot unbinned data as well
    plot_binned=True,           # plot the binned data
    interactive=False,          # if True, assumes you're in a Jupyter Notebook and return the Figure and axes
    fn='0_flux_density.pdf',    # filename for saving, if None will save in the data directory
    ax=None,                    # any pre-existing axes you want to plot in
    save=True,                  # if True saves the figure
    lum_key='flux_density'      # can also be 'mag'
                                # and **kwargs will be passed to plt.subplots()
)

Util function for point sources

If you only want data for a point source there is a util function for this, yay!

from timewise.point_source_utils import get_point_source_wise_data

wd = get_point_source_wise_data(
    base_name="my_point_source",
    ra=2,
    dec=0
)