The MaLTPyNT (Matteo’s Libraries and Tools in Python for NuSTAR Timing) suite is designed for the quick-look timing analysis of NuSTAR data. It treats properly orbital gaps (e.g., occultation, SAA passages) and performs the standard aperiodic timing analysis (power density spectrum, lags, etc.), plus the cospectrum, a proxy for the power density spectrum that uses the signals from two detectors instead of a single one (for an explanation of why this is important in NuSTAR, look at Bachetti et al., ApJ, 800, 109 -arXiv:1409.3248). The output of the analysis, be it a cospectrum, a power density spectrum, or a lag spectrum, can be fitted with Xspec, Isis or any other spectral fitting program.
Despite its main focus on NuSTAR, the software can be used to make standard spectral analysis on X-ray data from, in principle, any other satellite (for sure XMM-Newton and RXTE). Input files can be any event lists in FITS format, provided that they meet certain minimum standard. Also, light curves in FITS format or text format can be used. See the documentation of MPlcurve for more information.
MaLTPyNT vs FTOOLS (and together with FTOOLS)¶
MaLTPyNT does a better job than POWSPEC from several points of view:
- Good time intervals (GTIs) are completely avoided in the computation. No gaps dirtying up the power spectrum! (This is particularly important for NuSTAR, as orbital gaps are always present in typical observation timescales)
- The number of bins used in the power spectrum (or the cospectrum) need not be a power of two! No padding needed.
Clarification about dead time treatment¶
MaLTPyNT does not supersede
If one is only interested in frequencies below ~0.5 Hz, nulccorr treats
robustly various dead time components and its use is recommended. Light
curves produced by nulccorr can be converted to MaLTPyNT format using
MPlcurve --fits-input <lcname>.fits, and used for the subsequent
steps of the timing analysis.
Improved livetime correction in progress!
In the next release MaLTPyNT 2.0,
MPexposure pushes livetime
correction to timescales below 1 s, allowing livetime-corrected timing
analysis above 1 Hz. The feature is under testing
License and notes for the users¶
This software is released with a 3-clause BSD license. You can find
license information in the
If you use this software in a publication, please refer to its Astrophysics Source Code Library identifier:
- Bachetti, M. 2015, MaLTPyNT, Astrophysics Source Code Library, record ascl:1502.021.
In particular, if you use the cospectrum, please also refer to:
- Bachetti et al. 2015, ApJ , 800, 109.
I listed a number of open issues in the Issues page. Feel free to comment on them and propose more. Please choose carefully the category: bugs, enhancements, etc.
I would like to thank all the co-authors of the NuSTAR timing paper and the NuSTAR X-ray binaries working group. This software would not exist without the interesting discussions before and around that paper. In particular, I would like to thank Ivan Zolotukhin, Francesca Fornasini, Erin Kara, Felix Fürst, Poshak Gandhi, John Tomsick and Abdu Zoghbi for helping testing the code and giving various suggestions on how to improve it. Last but not least, I would like to thank Marco Buttu (by the way, check out his book if you speak Italian) for his priceless pointers on Python coding and code management techniques.
- Installation Instructions
- Preliminary info
- Loading event lists
- Calibrating event lists
- Producing light curves
- Joining, summing and “scrunching” light curves
- Producing power spectra and cross power spectra
- Rebinning the spectrum
- Calculating the cospectrum and phase/time lags
- Saving the spectra in a format readable to XSpec
- Open and fit in XSpec!