Detail of the constellation Bootes (see Fig. B.5), showing the relative positions of the stars in UlughBeg (red), Ptolemaios (light blue, epoch 137), and Ptolemaios after correction to the epoch of Hipparcos (−128), by subtraction of 2°40′ from the longitude (dark blue). Stars from the modern Hipparcos Catalogue are indicated with black open circles. For illustrative purposes, the positions of these stars and of the stars from both epochs of Ptolemaios were converted with modern precession equations to the epoch of Ulugh Beg, 1437. It is seen that the catalogue positions as given by Ptolemaios for 137 are systematically too low. Our identifications are indicated with solid lines; those by Knobel (1917) and Toomer (1998) with dash-dotted lines, when different from our identifications. For the projection used see Sect. B.