Following tentative detection of cyclopropene (C_3_H_4_) in Sgr B2 through its transition 3_22_-2_21_, several attempts to confirm the presence of cyclopropene in astronomical objects (including Sgr B2 itself) have been made. We suggest that cyclopropene may be observed in astronomical objects through its transition 2_20_-2_21_ at 3.67218GHz, in absorption, even against the cosmic 2.7K background, in a region having low density and low kinetic temperature.