Check out an AMRAAM or Harpoon for reference, not a space craft.
A cursory search wasn't able to find the rate of acceleration of the air defense missiles.
My vague recollection, was that the Whidby launch was ostensibly an anti-air missile of unknown provenance, more or less in the general vicinity of a certain high-priority wide-body jet carrying a VIP. This would argue, if true, for a much lower maximum speed for the missile in the picture. But, again, the length of the boost stage and the duration of the stage, for an unknown missile type, is perforce uncertain...