Subject: JEM-X Monday Meeting 2005-12-05

Present: CBJ, SB, JC, ILR, CAO, NL, NJW.

JEM-X status: Fine. Hotspot acitivity is low. INTEGRAL is in eclipse season
which causes larger temperature changes. Generally the gain relaxation
from the beginning of an orbit takes longer time: now 6-8 hours.
SB checks if the JMX1 HV should be stepped down again.

Spectral extraction (NL, NJW): j_ima_iros has been split up into
a specific part and a common part that can also be used by j_src_properties.
In this process an error in j_ima_iros was discovered (too large 'clouds'
in the detector from interactions).
Stephane P. has sent a plot with ratios between fluxes from LCR and
IMA. The ratios are constant but not unity. Could possibly be caused by
differences in the applied position resolution of the detector,
which is more important at low energy.

Position results (NJW, CBJ): Crab position ameliorated for the new
j_ima_iros version (1.5.3) though not quantified yet. CBJ gets mean
position deviation from SIMBAD positions (four digits after decimal
point) for 20 selected sources of 3 arcsec. Temperature correction has
been applied. The temperature of the mask has been used as an input
parameter for the neural analysis and the position deviations are
correlated with this temperature and hence the Sun-angle.

Detector sensitivity (CBJ): The thermal blanket on the mask absorbs
about 15% at 3 keV. The electronic sensitivity has been derived from
the nominal/low gain observations in revol. 365 which extends the
investigations by SB to a higher energy range. The unfolded Crab
spectrum (simplified assumptions and no model fitting) comes out
with a photon index of 1.99 and looks definitely as a power law.
This result is to be combined with earlier results of SB.

Mosaicking (JC): 4 sources have been selected in mosaic images
and their 'number of sigmas' detection levels have been estimated
and plotted as a function of 'Effective Observation Time' (exposure
time corrected for vignetting). A comparison of the detection
significance level should be made between the mosaic image from
the variance map and counting statistics.

GRS1915 (JC): There is now a mosaic image and we are looking
for new sources. Should one be sampling below j_ima_iros pixel
size for better verification?

Positioning (CBJ): It looks as if source 1608-522 has a bad position in
gnrl_refr_cat_0023.

SWIFT conference (SB): In september a burst with a redshift of about 6.
Seen optically and spectral analysis.
Long duration bursts come from star formation regions. Can be valuable
tool in cosmology. More short busts have been observed - probably NS-BH
or NS-NS mergers.

/NJW

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Niels J. Westergaard
Danish National Space Center
Juliane Maries Vej 30, DK 2100 Copenhagen O
Phone: +45 35325705; FAX:  +45 35362475