A CCD detector at the prime focus of a 3.6 m telescope has been used to observe the BL Lacertae objects Markarian 501 and 421 in two bands of FWHM equaling approximately 700 A, centered at 5000 and 6500 A. The photometric profiles obtained for both objects are shown to be consistent with composite profiles from a point source and from an elliptical galaxy that obeys the de Vaucouleurs surface brightness law. The photometric parameters derived for the underlying galaxies show them to be apparently normal elliptical galaxies.

Publication Date



We are grateful to the CFHT staff for assistance at the telescope and to Ron Johnson for technical advice. This work was supported in part by the Natural Science and Engineering Research Council of Canada, and by a Canada Council Killam Scholarship and an NSERC University Research Fellowship to Paul Hickson.ISSN:1538-4357 Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)


RIT – Main Campus