# Data Challenge 1: Open Data Sets

The open part of IPTA Data Challenge 1 consists of three data sets with different parameters. These “open” data sets are not part of the formal data challenge and may be used to test your algorithms prior to attempting the closed part of the data challenge.

The parameters used to generate these data sets were as follows:

### Dataset 1: Uniformly sampled data with a stochastic GW background and white noise

• White Noise: 100 nano-seconds for each pulsar
• GW Background: Characteristic strain spectrum is a power law with index -2/3. The amplitude of the strain spectrum at a frequency of  $(\textrm{year})^{-1}$ is $5\times 10^{-14}$
• Cadence: Once every two weeks
• Total Time Span: Five Years

### Dataset 2: Non-uniformly sampled data with a stochastic GW background and white noise

• White Noise: Different for all pulsars, consistent with measured values of residuals for IPTA pulsars. Click here to get the list of the white noise RMS for each pulsar.
• GW Background: Characteristic strain spectrum is a power law with index -2/3. The amplitude of the strain spectrum at a frequency of $(\textrm{year})^{-1}$ is $5\times 10^{-14}$
• Cadence: Randomly sampled. Average interval of two weeks, ±5 days. Same time base for all pulsars
• Total Time Span: Five Years

### Dataset 3: Non-uniformly sampled data with a stochastic GW background together with white and red noise

• White Noise: Same as in dataset 2
• Red Noise: Same power spectrum for all pulsars, different realization

Red Noise Power Spectrum is of the form: $P(f)=A f^{-\alpha}$ where f is in Hz, A = 5.77*10^-22 seconds^1.3 and  α= 1.7.

• GW Background: Characteristic strain spectrum is a power law with index -2/3. The amplitude of the strain spectrum at a frequency of $(\textrm{year})^{-1}$ is $10^{-14}$
• Cadence: Randomly sampled. Average interval of two weeks, ±5 days. Same time base for all pulsars
• Total Time Span: Five years