It reached a peak brightness of magnitude 3.5 on 13 December 1967, making it easily visible to the naked eye around that time.

[6][7] Pre-outburst photographs taken with the Samuel Oschin telescope showed it as a ~12th magnitude star which might have been variable.

[3] It took 230 days for HR Delphini to fade from its peak by 3 magnitudes, which makes it a "slow" nova.

[2] Its decline from peak brightness showed several brief outbursts, leading to its light curve being classified as type "J" (for "jitters").

[11] HR Delphini is surrounded by a bipolar nova remnant emission nebula, visible in Hα, Hβ as well as forbidden lines of oxygen and nitrogen.