Survey observations of emission-line stars in the Orion region. I. The KISO area A-0904.

Survey observations for H-alpha emission stars in the Orion region have been conducted using the Kiso Schmidt telescope and partly the CTIO Curtis Schmidt telescope. In the Kiso sky area A-0904 of 5 deg x 5 deg, centered at alpha = 5 h 40 m and delta = 0.0 deg, 236 H-alpha-emission objects are detected among which 155 are new, including 6 nonstellar objects. The celestial coordinates and V-magnitude are measured for the detected objects. Eye estimation of the H-alpha emission intensity is also made at three epochs in a time span of about one and a half years. A notable variation of the H-alpha intensity is found in 68 out of 236 objects. Besides a remarkable concentration along the northern dark cloud complex, a loose clustering is noticed near the Orion belt region, nearly coinciding with the distribution of the Orion OB1b association members.