The Astronomical Journal
We present BVRI observations of BL Lacertae during its recent outburst. These observations, made during a 3 month period, cover a significant portion of the optical flare. The reduced data are displayed as light curves and broadband spectra. Changes in the spectral index are analyzed, and the results are compared with previous BL Lac observations. We find that the variations are simultaneous in the optical bands, but the higher frequency bands show a higher amplitude of variability. The spectral index is variable during the active period, and there is marginal evidence that the spectrum flattens as the source gets brighter.
Oswalt, Terry D.; Marshall, Daniel; and Robishaw, Tim, "Broadband Optical Observations Of BL Lacertae During The 1997 Outburst" (1998). Aerospace, Physics, and Space Science Faculty Publications. 278.