With the objective of measuring the intensity of the cosmic X-ray
background (CXB), INTEGRAL performed another set of Earth-occultation
observations on 10 November 2015 (see also
INTEGRAL POMs
of
March 2006,
November 2013,
February and
December 2014).
These observations were,
however, contaminated by auroras which emitted hard X-rays (see
"INTEGRAL X-rays Earth's aurora").
During Earth-occultation observations on 17 December 2013, the Optical
Monitor Camera (OMC) shot its first image of the Earth. On UT 10 November 2015,
16:00 it took its second chance, as shown in the displayed 10-sec exposure
image.
The OMC has a much smaller field of view than the IBIS/ISGRI instrument
and as such does not show the aurora seen in complementary images
captured by that instrument. The colour (i.e., false colour since the
instrument observes only at one wavelength, the optical V-band) is a
representation of flux intensity. That is, the variation of blue/green
along the limb means that the emission of the atmosphere has different
intensity in the optical range observed by OMC: brighter for green and
even more so for yellow and orange.
The region showing a brighter atmosphere is the nearest to the day side
of the Earth after sunset. A number of features can be seen: the haze of
the atmosphere along the limb of the Earth, background stars, and the
lights of cities including Bangkok, Singapore, Jakarta, Ho Chi Minh.
Lights at sea can also be picked out. In the version on the right, the
outlines of the coast have been added to guide the eye.
Credits: A. Domingo (CAB-CSIC/INTA, INTEGRAL/OMC team)
