Making Software MDCs for Supernova Searches

Minke is currently capable of producing software injections for mock data challenges for a large number of waveforms, including all of the waveforms supported by LALSimulation, and also numerical waveforms, such as supernova waveforms.

In this tutorial we will produce a set of supernova injections using a set of pre-rotated waveforms.

We’ll start by importing minke::
>>> from minke import mdctools, distribution, sources

Then we can create the MDC Set. To do that we need to tell Minke which interferometers took part in the run. For O1 this was LIGO Livingston, and LIGO Hanford (4km).:

>>> mdcset = mdctools.MDCSet(['L1', 'H1'])

Next, we need to set up the distribution which we’ll use to select the injection times. For the O1 injection set we inject signals at a fixed cadence throughout the run, but each injection point can have a small amount of “jitter”, so the signals could be injected slightly off the fixed locations. This is simply a random offset up to 20 seconds either side of the fixed location, in the case that jitter = 20. Note that the start and end times are the gps times which bounded the observing run.

>>> times = distribution.even_time(start = 1126620016, stop = 1136995216, rate = 630720, jitter = 20)

We could also have injected them at random times drawn from a uniform distribution, for example, if we wanted to make 1000 injections over the O1 period.:

>>> times = distribution.uniform_time(start =  1126620016, stop = 1136995216, number = 1000)

We also need a distribution of theta and phi values for the orientation of the supernova. Since we’re using pre-computed rotations we need to use the supernova_angle distribution, which by default assumes that there are 100 evenly spaced combinations.

>>> angles = distribution.supernova_angle(len(times))

Making a single injection is simple. All of the injection waveforms are located in Minke’s source module. We can create an Ott+13 waveform, for example, with the line

>>> sn = sources.Ott2013(theta = 0 , phi = 0, time=1126620016,
...                      filepath="/home/daniel.williams/repositories/snsearch/RawWaveforms/",
...                      family="R1E1CA")
We can add this injection to our MDC set using standard python syntax.::
>>> mdcset + wnb

Of course, we need injections for the entire run, so we can set this up in a Python loop.:

>>> for time, (theta, phi) in zip(times, angles):
...    sn = sources.Ott2013(theta = 0 , phi = 0, time=1126620016,
...                         filepath="/home/daniel.williams/repositories/snsearch/RawWaveforms/",
...                         family="R1E1CA")
...    mdcset + sn

Now that we have the MDC set (and it might take a while, especially for white noise burst sets), we can produce the various data products that we need for MDC analyses.

The XML file which defines the injection set can be produced using the save_xml method of the mdcset.:

>>> mdcset.save_xml('ott13.xml.gz')