Galaxy NGC 2403
The galaxy NGC 2403 was discovered on 1 November 1788 by William Herschel with his 18.7 inch reflecting telescope. He cataloged it as V 44 (class V = very large nebulae) and described it: «Considerably bright, round, very gradually brighter in the middle, bright nucleus 6 or 7' diameter with a faint branch extending a great way to the northern preceeding side not less than 1/2 degree, and to the north or north following the nebulosity diffused over a space not less than a whole degree.»  On 2 February 1886 the french astronomer Guillaume Bigourdan pointed the 12.4 inch refractor of the Paris Observatory to this nebula and found within a «very faint, very small» knot, which later became NGC 2404. 
Distance determinations range from 3.1 Mpc to 4.2 Mpc.  The galaxy belongs to the M 81 galaxy group. It is home to several H-II star-forming regions, the brightest of which has its own NGC designation: NGC 2404.
|Name||RA||Dec||Type||bMag||vMag||Dim||Dreyer Description||Identification, Remarks|
|NGC 2403||07 36 50.6||+65 36 06||Gx (SBc)||8.9||8.5||23.4 × 11.8||!! cB, eL, vmE, vgmbMN||UGC 3918, MCG 11-10-7, CGCG 309-40, IRAS 07321+6543, KARA 197, CGCG 310-3|
|NGC 2404||07 37 07.0||+65 36 40||GxyP||14.5||0.4||vF, vS||HII/Association in N 2403|
Die Galaxie NGC 2403 befindet sich im Sternbild Camelopardalis (Giraffe). Die beste Beobachtungszeit ist September bis März, wenn es nachts am höchsten steht.