Suzaku Observation : 406046010

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Fits Header

TELESCOP= 'SUZAKU  '           / Telescope (mission) name
OBS_ID  = '406046010'          / Observation identification string
OBSERVER= 'TERUAKI ENOTO'      / Principal Investigator
OBJECT  = '4U 1954+31'         / Name of observed object
OBS_REM = '        '           / remark on observation
RA_OBJ  =             298.9263 / planned target R.A.(deg)
DEC_OBJ =              32.0970 / planned target DEC.(deg)
RA_NOM  = 2.989334000000000E+02 / Right Ascension of target (deci. deg)
DEC_NOM = 3.208030000000000E+01 / Declination of target (deci. deg)
PA_NOM  =             261.2562 / nominal position angle from north to DETY(deg)
MEAN_EA1=     298.933364767970 / mean of the 1st ZYZ-Euler angle (deg)
MEAN_EA2=      57.919725909573 / mean of the 2nd ZYZ-Euler angle (deg)
MEAN_EA3=     188.743802489811 / mean of the 3rd ZYZ-Euler angle (deg)
DATE-OBS= '2011-10-23T08:05:45' / Start date of observations
DATE-END= '2011-10-24T17:17:14' / End date of observations
TSTART  = 3.726752940000000E+08 / time start
TSTOP   = 3.727918175698847E+08 / time stop
TELAPSE = 1.165235698846579E+05 / elapsed time
ONTIME  = 6.023193619811535E+04 / On-source time
EXPOSURE= 6.023193619811535E+04 / Exposure time
MJD-OBS = 5.585737220120370E+04 / MJD of data start time
FILIN001= 'ae406046010xi0_0_3x3n066l_cl.evt.gz' / Input file name
SEQPNUM =                    2 / Number of times this dataset processed
PROCVER = '3.0.22.44'          / Processing script version
MK1STVER= 'mk1stfits20120530'  / Version of mk1stfits used
SOFTVER = 'Hea_08Feb2016_V6.18_Suzaku_14Nov2013_V22' / Version of HEADAS used
CALDBVER= 'hxd20110913_xis20160607_xrt20110630_xrs20060410' / Version of CALDB u
FILIN002= 'ae406046010xi0_0_5x5n066h_cl.evt.gz' / Input file name
FILIN003= 'ae406046010xi0_0_5x5n066l_cl.evt.gz' / Input file name
FILIN004= 'ae406046010xi1_0_3x3n130b_cl.evt.gz' / Input file name
FILIN005= 'ae406046010xi1_0_5x5n130b_cl.evt.gz' / Input file name
FILIN006= 'ae406046010xi3_0_3x3n066a_cl.evt.gz' / Input file name
FILIN007= 'ae406046010xi3_0_5x5n066a_cl.evt.gz' / 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:

We propose the first Suzaku observation of a symbiotic X-ray binary 4U 1954+31. This object has an extraordinarily long spin period, ~5 hour, attributed to the neutron star (NS) rotation, making 4U 1954+31 the slowest-rotating accreting NS binary. It raises a question about its binary evolution, since a slowly rotating NS orbiting an M-type giant is quite unique. As to its large variability, the popular clumpy wind model has not yet become a smoking-gun, and we propose an alternative hypothesis that the NS is a magnetar descendent captured by an M-type giant in their closer encounter. Known X-ray properties of 4U~1954+31 will be revisited in a view of gated accretion onto the strongly magnetized NS. A 60 ks Suzaku observation can examine these scenarios.