Very high energy observations of the BL Lac objects 3C 66A and OJ 287

TL;DR

This study used the STACEE telescope to observe two low-frequency-peaked BL Lac objects, 3C 66A and OJ 287, setting upper limits on their very high energy gamma-ray emissions, with no detections made.

Contribution

First observational upper limits on VHE gamma-ray emission from 3C 66A and OJ 287 using STACEE, testing predictions for these LBLs as potential sources.

Findings

No detections of VHE gamma rays from 3C 66A and OJ 287.

Established 99% CL upper limits of 0.15 and 0.52 Crab flux units.

Limits assume Crab-like spectrum at 185 GeV threshold.

Abstract

Using the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE), we have observed the BL Lac objects 3C 66A and OJ 287. These are members of the class of low-frequency-peaked BL Lac objects (LBLs) and are two of the three LBLs predicted by Costamante and Ghisellini to be potential sources of very high energy (>100 GeV) gamma-ray emission. The third candidate, BL Lacertae, has recently been detected by the MAGIC collaboration. Our observations have not produced detections; we calculate a 99% CL upper limit of flux from 3C 66A of 0.15 Crab flux units and from OJ 287 our limit is 0.52 Crab. These limits assume a Crab-like energy spectrum with an effective energy threshold of 185 GeV.