  We present the first full-disk solar images obtained with the Atacama Large
Millimeter/submillimeter Array (ALMA) in Band 7 (0.86 mm; 347 GHz). In spite of
the low spatial resolution (21"), several interesting results were obtained.
During our observation, the sun was practically devoid of active regions. Quiet
Sun structures on the disk are similar to those in Atmospheric Imaging Assembly
(AIA) images at 1600 A and 304 A, after the latter are smoothed to the ALMA
resolution, as noted previously for Band 6 (1.26 mm) and Band 3 (3 mm) images;
they are also similar to negative H$\alpha$ images of equivalent resolution.
Polar coronal holes, which are clearly seen in the 304 A band and small
H$\alpha$ filaments, are not detectable at 0.86 mm. We computed the
center-to-limb variation (CLV) of the brightness temperature, $T_b$, in Band 7,
as well as in Bands 6 and 3, which were obtained during the same campaign, and
we combined them to a unique curve of $T_b(\log\mu_{100})$, where $\mu_{100}$
is the cosine of the heliocentric angle reduced to 100 GHz. Assuming that the
absolute calibration of the Band 3 commissioning observations is accurate, we
deduced a brightness temperature at the center of the disk of 6085 K for Band
7, instead of the value of 5500 K, extrapolated from the recommended values for
Bands 3 and 6. More importantly, the $T_b(\log\mu_{100})$ curve flattens at
large values of $\mu_{100}$, and so does the corresponding
$T_e(\log\tau_{100})$ at large $\tau_{100}$. This is probably an indication
that we are approaching the temperature minimum.
