The motivation of this waveform catalog is to allow for rigorous testing between Cauchy characteristic extraction (CCE) code in SpECTRE and the extrapolation code in scri. Asymptotic waveforms are provided for the gravitational-wave strain $h$ and the complete set of Weyl Scalars $(\Psi_4, \Psi_3, \Psi_2, \Psi_1, \Psi_0)$.

## Data Columns

Name Alt Name $M^{\text{ini,1}} / M^{\text{ini,2}}$ $\vec{\chi}^{\text{ini,1}}$ $\vec{\chi}^{\text{ini,2}}$ $N^{\text{orbits}}$ Files
SXS:BBH_ExtCCE:0001 q1_nospin 1.0 (0, 0, 0) (0, 0, 0) 20.78
SXS:BBH_ExtCCE:0002 q1_aligned_chi0_2 1.0 (0, 0, 0.2) (0, 0, 0.2) 18.99
SXS:BBH_ExtCCE:0003 q1_aligned_chi0_4 1.0 (0, 0, 0.4) (0, 0, 0.4) 19.26
SXS:BBH_ExtCCE:0004 q1_aligned_chi0_6 1.0 (0, 0, 0.6) (0, 0, 0.6) 19.35
SXS:BBH_ExtCCE:0005 q1_antialigned_chi0_2 1.0 (0, 0, 0.2) (0, 0, -0.2) 18.84
SXS:BBH_ExtCCE:0006 q1_antialigned_chi0_4 1.0 (0, 0, 0.4) (0, 0, -0.4) 18.84
SXS:BBH_ExtCCE:0007 q1_antialigned_chi0_6 1.0 (0, 0, 0.6) (0, 0, -0.6) 18.77
SXS:BBH_ExtCCE:0008 q1_precessing 1.0 (0.487, 0.125, -0.327) (-0.190, 0.051, -0.227) 20.47
SXS:BBH_ExtCCE:0009 q1_superkick 1.0 (0.6, 0, 0) (-0.6, 0, 0) 18.78
SXS:BBH_ExtCCE:0010 q4_nospin 4.0 (0, 0, 0) (0, 0, 0) 20.07
SXS:BBH_ExtCCE:0011 q4_aligned_chi0_4 4.0 (0, 0, 0.4) (0, 0, 0.4) 19.00
SXS:BBH_ExtCCE:0012 q4_antialigned_chi0_4 4.0 (0, 0, 0.4) (0, 0, -0.4) 18.76
SXS:BBH_ExtCCE:0013 q4_precessing 4.0 (0.487, 0.125, -0.327) (-0.190, 0.051, -0.227) 17.43

## Waveform Information

#### File Compression

The waveform files have been compressed using scri's RPXM compression format and can be opened with functions in that python module. See the scri documentation for more information.

#### Mass Scaling

The asymptotic waveforms and corresponding values of time have been made dimensionless by an appropriate factor of the system mass. The system mass is the combined Christodoulou mass of the two black holes measured at the reference time.

#### Center-of-Mass Correction

There is a known center-of-mass (CoM) drift during the numerical evolution in SpEC. We attempt to mitigate the resulting gauge effects in the waveforms by applying the correction described in Woodford+ (2019) [arXiv:1904.04842]. The space-translation and boost that have been applied can be found in the JSON file accompanying each waveform.

#### Memory Correction

The asymptotic strain waveforms produced by extrapolation are missing the contribution of displacement memory. This missing contribution has been added using the correction described in Mitman+ (2021) [arXiv:2011.01309].

#### CCE Waveforms

The characteristic evolution is performed by the CCE code in SpECTRE. See Moxon+ (2020) [arXiv:2007.01339] for details about this CCE scheme. The worldtube data is extracted at four different radii in the simulation, and there is a different set of asymptotic CCE waveforms for each worldtube radius. Due to the difficulty in choosing initial data, the asymptotic CCE strain waveforms exhibit spurious oscillations that are entirely gauge effects. The waveforms from the outermost worldtube radius have the least gauge effects. However, the waveforms from the second smallest worldtube radius satisfy the Bianchi identities best. For most purposes then, the waveforms from the second smallest worldtube radius are recommended.

#### Extrapolated Waveforms

Extrapolation is performed by the scri python module. See Iozzo+ (2021) [arXiv:2010.15200] for details about this extrapolation scheme. The extrapolation performed here is slightly different from the main SXS waveform database. The optimal extrapolation order $N$ for each data type in this Ext-CCE waveform database is:
• $h$: $N=5$
• $\Psi_4$: $N=7$
• $\Psi_3$: $N=7$
• $\Psi_2$: $N=5$
• $\Psi_1$: $N=4$ for merger/ringdown and $N=3$ for early inspiral
• $\Psi_0$: $N=2$
These orders were determined by considering the convergence of the extrapolation procedure and minimizing the violation of the Bondi gauge Bianchi identities. We include waveforms from two orders lower than the optimal order for convergence testing.