H i moment maps of NGC 2403. Top-left: integrated H i map derived from the GBT data. Thick dark-gray contours show the H i distribution of the entire galaxy. Contour levels are 5 × 10¹⁷, 5 × 10¹⁸, 5 × 10¹⁹, and 5 × 10²⁰ cm^-2. The gray-scale runs from 5 × 10¹⁷ (white) to 1.5 × 10²¹ cm^-2 (black). Thin, black contours show the H i distribution of the cloud. Contour levels are (6.25, 12.5, 25, 62.5) × 10¹⁷ cm^-2. White contours indicate the location of the 8 kpc filament. The GBT beam is shown in the bottom-left corner. Top-right: integrated H i map derived from the 30′′ VLA data from Fraternali et al. (2002). The gray-scale runs from 2 × 10¹⁹ (white) to 2 × 10²¹ cm^-2 (black). Contours are as in the top-left panel. The VLA beam is indicated in the bottom-right corner. Bottom-left: intensity-weighted mean velocity field derived from the GBT data. The thick black contour indicates v = 130 km s^-1. White contours decrease with respect to this value in steps of 20 km s^-1. Black contours increase in steps of 20 km s^-1. Bottom-right: intensity-weighted mean velocity field derived from the 30′′ VLA data. Contours are as in the bottom-left panel.