1995A&A...296..310M

From direct CCD imaging, BVR_CI_C photometry, low- and high-resolution spectrophotometry it is shown that PG 1136+581 is not a cataclysmic variable as reported in the Palomar Green survey, but a small and faint starburst galaxy at z=0.00280 identical to Markarian 1450. The emission line spectrum well conforms to the expectations of Case B under low electron densities. The emission lines are very narrow (<FWHM≳44km/s) and the forbidden ones particularly strong, with [O III]5007A/Hα=2. The reddening amounts to E_B–V=0.07. The narrowness of the emission lines and absence of photometric variability in excess of 0.1mag over the period 1983-1991 tends to exclude the presence of any AGN-like activity. In spite of some gaps in the photometric patrolling, it is quite possible that no supernova has exploded in PG 1136+581 during the period 1983-1991.