Suzaku Observation : 403063010

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Fits Header

TELESCOP= 'SUZAKU  '           / Telescope (mission) name
OBS_ID  = '403063010'          / Observation identification string
OBSERVER= 'EDWARD M CACKETT'   / Principal Investigator
OBJECT  = 'CYG X-2 '           / Name of observed object
OBS_REM = '        '           / remark on observation
RA_OBJ  =             326.1717 / planned target R.A.(deg)
DEC_OBJ =              38.3217 / planned target DEC.(deg)
RA_NOM  = 3.261609000000000E+02 / Right Ascension of target (deci. deg)
DEC_NOM = 3.832930000000000E+01 / Declination of target (deci. deg)
PA_NOM  =              51.1203 / nominal position angle from north to DETY(deg)
MEAN_EA1=     326.160888492071 / mean of the 1st ZYZ-Euler angle (deg)
MEAN_EA2=      51.670668753686 / mean of the 2nd ZYZ-Euler angle (deg)
MEAN_EA3=      38.879667180840 / mean of the 3rd ZYZ-Euler angle (deg)
DATE-OBS= '2008-07-01T01:36:21' / Start date of observations
DATE-END= '2008-07-03T14:46:14' / End date of observations
TSTART  = 2.681942123173913E+08 / time start
TSTOP   = 2.684115467884271E+08 / time stop
TELAPSE = 2.173344710357189E+05 / elapsed time
ONTIME  = 2.434800000017881E+04 / On-source time
EXPOSURE= 2.434800000017881E+04 / Exposure time
MJD-OBS = 5.464810042246980E+04 / MJD of data start time
FILIN001= 'ae403063010xi1_0_3x3b109b_cl.evt.gz' / Input file name
SEQPNUM =                    7 / Number of times this dataset processed
PROCVER = '3.0.22.43'          / Processing script version
MK1STVER= 'mk1stfits20120530'  / Version of mk1stfits used
SOFTVER = 'Hea_08Feb2016_V6.18_Suzaku_14Nov2013_V22' / Version of HEADAS used
CALDBVER= 'hxd20110913_xis20151005_xrt20110630_xrs20060410' / Version of CALDB u
FILIN002= 'ae403063010xi3_0_2x2b106a_cl.evt.gz' / Input file name
FILIN003= 'ae403063010xi3_0_3x3b106a_cl.evt.gz' / Input file name
FILIN004= 'ae403063010xi3_4_3x3b106z_uf.evt' / Input file name
COMMENT -------------------------
COMMENT BITPIX compressed from 32 to 8.
COMMENT Pixel values greater than 255 was set to 255.
COMMENT This file was made for JUDO-Suzaku.
COMMENT -------------------------
COMMENT   FITS (Flexible Image Transport System) format is defined in 'Astronomy

Abstract:

The nature of ultra-dense matter in neutron stars remains enigmatic. To probe this requires accurate neutron star radii and masses. We recently showed that broad iron lines in neutron star low-mass X-ray binaries (LMXBs) constrain the neutron star radius. LMXBs also provide us with another tool, kHz quasi-periodic oscillations (QPOs). Combining the inner disk velocity (from modeling the iron line) and the frequency of the kHz QPOs gives a method to measure the neutron star mass. We propose a 100 ks observation of Cyg X-2 with Suzaku to provide a detailed iron line profile. Combined with simultaneous observations with RXTE to determine the kHz QPO frequency, we will measure the neutron star mass. Cyg X-2 is the perfect test case as it already has a known mass from optical observations.