Photometric Observations and Rotation Periods of Asteroids 2376 Martynov, (7335) 1989 JA, 12923 Zephyr, and (85184) 1991 JG1

Photometric observations of asteroids 2376 Martynov, (7335) 1989 JA, 12923 Zephyr, and (85184) 1991 JG1 were conducted in order to determine their synodic rotation period, the absolute brightness with its amplitude, and estimate their diameter. For 2376 Martynov we found P = 11.133 ± 0.005 h, H = 11.07 ± 0.05 mag, A = 0.38 ± 0.05 mag, D = 47.583 ± 0.529 km (for albedo a = 0.0364) and D = 39.212 ± 0.588 km (for albedo a = 0.0536). For (7335) 1989 JA we found P = 5.177 ± 0.005 h, H = 17.48 ± 0.05 mag, A = 0.27 ± 0.05 mag, D = 0.849 ± 0.009 km (for albedo a = 0.25) and D = 0.748 ± 0.010 km (for albedo a = 0.322). For 12923 Zephyr we found P = 3.894 ± 0.002 h, H = 15.73 ± 0.05 mag, A = 0.21 ± 0.05 mag, D = 2.260 ± 0.025 km (for albedo a = 0.1764) and D = 2.072 ± 0.027 km (for albedo a = 0.21). For (85184) 1991 JG1 we found P = 24.14 ± 0.02 h, H = 18.37 ± 0.07 mag, A = 0.65 ± 0.07 mag, D = 0.631 ± 0.008 km (for albedo a = 0.20).