CRABTIME ivo://nasa.heasarc/crabtime NASA/GSFC HEASARC Lyne, Jordan, Roberts 2026-09-04 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Pulsar The CRABTIME database contains the Crab Pulsar Monthly Ephemeris covering the period from Feb 15 1982 (MJD=45015) to (close to) the present that was created Dr. Andrew Lyne and collaborators at Jodrell Bank Observatory. This database is periodically updated to include recent data as these become available. To assist astronomers, the HEASARC has created two new parameters which were not present in the original Jodrell Bank tables, the pulsar period and its first derivative, using the standard relations between period (P) and frequency 'Nu' (P=1./Nu) and their first derivatives (P_dot = -Nu_dot/Nu<sup>2</sup>). The assumed pulsar position used in the reductions is <pre> RA (1950.0) 05 31 31.406 DEC (1950.0) +21 58 54.391 RA (2000.0) 05 34 31.973 DEC (2000.0) +22 00 52.061 </pre> This HEASARC version of the "Jodrell Bank Crab Pulsar Timing Results, Monthly Ephemeris" is updated within one week of any changes to the tables available on the Web at <a href="http://www.jb.man.ac.uk/pulsar/crab.html">http://www.jb.man.ac.uk/pulsar/crab.html</a>. This is a service provided by NASA HEASARC . https://heasarc.gsfc.nasa.gov/W3Browse/all/crabtime.html Archive Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=crabtime& GET text/xml 180 99999 true 83.63322083 22.01446139 0.0833333333333333 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=crabtime GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_crabtime&Action=More+Options&Action=Parameter+Search&ConeAdd=1 STAR CATALOG 0.0833333333333333 Radio public crabtime Crab Pulsar Timing ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable mjd Modified Julian Date of Ephemeris mjd time.epoch int nullable nu Barycentric Frequency (Hz) Hz src.var.pulse double nullable nu_error Error in Frequency Hz stat.error;src.var.pulse double nullable period Period: 1/nu (s) s time.period double nullable period_dot Period Derivative: -nu_dot/nu^2 (s^2) s^2 arith.rate;time.period double nullable mit_time MIT Time (s) s time.epoch double nullable t_acc Accuracy (microseconds) micros stat.error;time.epoch short nullable "month" Month of Ephemeris time.epoch char nullable nu_dot_error Error in Frequency Derivative s^-2 stat.error;arith;src.var.pulse double nullable dm_flag Dispersion Measure Flag meta.code;phys.dispMeasure char nullable nu_dot Frequency Derivative (s^-2) s^-2 arith.rate;src.var.pulse double nullable dm Dispersion Measure (pc/cm^3) pc/cm^3 phys.dispMeasure double nullable "day" Day of Ephemeris time.epoch short nullable bii Galactic Latitude degree pos.galactic.lat double nullable jpl_time JPL Time (s) s time.epoch double nullable delay Delay (microseconds) micros time.interval int nullable note_number Note Number meta.note short nullable "year" Year of Ephemeris time.epoch short nullable lii Galactic Longitude degree pos.galactic.lon double nullable dm_dot Dispersion Measure Derivative (pc/cm^3/s) pc/cm^3/s arith.rate;phys.dispMeasure double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable