Hessenstein also made his own visual and photoelectric observations of mu Cep in the 1930s---and luckily survived the War in order to publish it, despite the aerial pounding Potsdam got. The first list shows the visual observations, which were done with a spot photometer. The stars and a lamp comparison were projected as little patches of light rather than as star/star-like points, and the voltage on the lamp read-off to get a brightness. Often eight back-and-forth comparisons were averaged into a single observation, and the readings converted to magnitudes by calibrating the lamp against standard stars. I copied his raw delta-magnitudes (against two different stars), but also made the zero-point adjustment to 'mv' using modern V magnitudes for the two stars. I also compared the systematic difference of the two, and found that one was slightly brighter than the other. The night-to-night scatter, assuming the star doesn't change in that time, is perhaps 0.05 mag rms. This argues favorably for the use of a visual photometer per the recent topic on the discussion list. The second list shows photoelectric photometry done with a blue- sensitive photocell and without a filter. As noted below, the results seem to be very close to standard Johnson B (delta-)magnitudes. I thus applied a zero-point to make them B magnitudes and show that in the last column. Night-to-night rms here is about 0.03 mag. \Brian =============================================================================== mu Cephei historical photometric data sources: 1938POPot..29a...3H HASSENSTEIN W. Publ. Astrophys. Obs. Potsdam, 29, heft 1, 3 (1938) Untersuchungen uber den lichtwechsel von mu. Cephei. 1954POPot..29e...3H HASSENSTEIN W. Publ. Astrophys. Obs. Potsdam, 29, heft 5, 3 (1954) Photometrische beobachtungen von veranderlichen sterne. first list: 30cm refractor visual estimates using a spot photometer del(12) = magnitude difference wrt 12 Cep, derived mv assumes V=5.51; del(20) = magnitude difference wrt 20 Cep, derived mv assumes V=5.27. systematic offset of del(20) wrt del(12) = -0.04 +/- 0.05 (n=19, omitting two outliers). second list: 30cm refractor + potassium-argon photoelectric cell (no filter) delta = magnitude difference wrt 20 Cep (HD 209960). B mag. assumes B=6.68 for 20 Cep. magnitude difference of 12 Cep minus 20 Cep given as +0.353 +/- 0.030, which matches difference in Johnson B system. JD 2427926 - 2429086 from 1938POPot..29a...3H JD 2429110 - 2429677 from 1954POPot..29e...1H object JD del(12) mv del(20) mv CEPmu 2426615.43 -1.26 4.25 CEPmu 2426618.44 -1.71 3.80 CEPmu 2426624.41 -1.50 4.01 CEPmu 2426626.26 -1.32 4.19 CEPmu 2426631.27 -1.66 3.85 CEPmu 2426633.25 -1.43 4.08 CEPmu 2426636.41 -1.41 4.10 CEPmu 2426637.42 -1.43 4.08 CEPmu 2426641.40 -1.42 4.09 CEPmu 2426646.40 -1.44 4.07 CEPmu 2426650.39 -1.54 3.97 CEPmu 2426656.34 -1.70 3.81 CEPmu 2426675.37 -1.66 3.85 CEPmu 2426681.27 -1.67 3.84 -1.43 3.84 CEPmu 2426691.44 -1.68 3.83 CEPmu 2426706.35 -1.61 3.90 CEPmu 2426707.25 -1.45 4.06 -1.51 3.76 CEPmu 2426721.35 -1.59 3.92 CEPmu 2426726.25 -1.55 3.96 -1.39 3.88 CEPmu 2426735.22 -1.70 3.81 -1.37 3.90 CEPmu 2426744.25 -1.59 3.92 -1.45 3.82 CEPmu 2426753.25 -1.61 3.90 -1.38 3.89 CEPmu 2426766.26 -1.58 3.93 -1.42 3.85 CEPmu 2426782.27 -1.61 3.90 -1.30 3.97 CEPmu 2426790.44 -1.69 3.82 -1.47 3.80 CEPmu 2426811.39 -1.53 3.98 -1.33 3.94 CEPmu 2426825.40 -1.66 3.85 -1.45 3.82 CEPmu 2426844.42 -1.51 4.00 -1.38 3.89 CEPmu 2426856.46 -1.57 3.94 CEPmu 2426861.41 -1.59 3.92 -1.34 3.93 CEPmu 2426869.40 -1.53 3.98 -1.34 3.93 CEPmu 2426881.44 -1.62 3.89 -1.38 3.89 CEPmu 2426893.42 -1.61 3.90 -1.42 3.85 CEPmu 2426898.39 -1.43 3.84 CEPmu 2426937.34 -1.36 3.91 CEPmu 2426943.38 -1.38 3.89 CEPmu 2426960.31 -1.36 3.91 CEPmu 2426979.46 -1.63 3.88 -1.48 3.79 CEPmu 2426987.44 -1.69 3.82 -1.48 3.79 CEPmu 2426998.43 -1.45 3.82 CEPmu 2427021.32 -1.60 3.67 CEPmu 2427024.35 -1.85 3.66 -1.64 3.63 CEPmu 2427026.36 -1.70 3.57 CEPmu 2427039.32 -1.80 3.71 -1.53 3.74 CEPmu 2427051.28 -1.86 3.65 CEPmu 2427057.37 -1.52 3.75 CEPmu 2427061.26 -1.77 3.50 CEPmu 2427072.21 -1.87 3.64 CEPmu 2427079.24 -1.87 3.64 CEPmu 2427106.22 -1.88 3.63 CEPmu 2427115.26 -1.90 3.61 CEPmu 2427132.28 -1.82 3.69 CEPmu 2427143.26 -1.77 3.74 CEPmu 2427159.33 -1.79 3.72 CEPmu 2427176.36 -1.73 3.78 CEPmu 2427189.34 -1.73 3.78 CEPmu 2427213.45 -1.89 3.62 CEPmu 2427280.39 -1.66 3.85 CEPmu 2427281.36 -1.45 3.82 CEPmu 2427320.32 -1.67 3.84 CEPmu 2427321.32 -1.63 3.88 CEPmu 2427327.31 -1.67 3.84 CEPmu 2427342.27 -1.62 3.89 CEPmu 2427352.40 -1.58 3.93 CEPmu 2427368.38 -1.58 3.93 CEPmu 2427384.34 -1.59 3.92 CEPmu 2427399.33 -1.41 4.10 CEPmu 2427415.26 -1.46 4.05 CEPmu 2427442.25 -1.36 4.15 CEPmu 2427449.21 -1.46 4.05 CEPmu 2427460.21 -1.42 4.09 CEPmu 2427483.25 -1.41 4.10 CEPmu 2427514.30 -1.23 4.28 CEPmu 2427530.42 -1.28 4.23 CEPmu 2427549.40 -1.38 4.13 -1.35 3.92 CEPmu 2427567.43 -1.45 4.06 CEPmu 2427581.39 -1.47 4.04 CEPmu 2427590.41 -1.54 3.97 CEPmu 2427601.41 -1.57 3.94 CEPmu 2427611.42 -1.60 3.91 CEPmu 2427616.45 -1.51 4.00 CEPmu 2427657.38 -1.67 3.84 CEPmu 2427665.39 -1.70 3.81 CEPmu 2427689.31 -1.66 3.85 CEPmu 2427699.30 -1.76 3.75 CEPmu 2427717.42 -1.59 3.92 CEPmu 2427733.39 -1.61 3.90 CEPmu 2427745.46 -1.43 4.08 CEPmu 2427755.36 -1.61 3.90 CEPmu 2427785.25 -1.64 3.87 CEPmu 2427806.40 -1.58 3.93 CEPmu 2427832.45 -1.55 3.96 CEPmu 2427840.26 -1.50 4.01 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ object JD delta B CEPmu 2427926.43 -0.360: 6.32 CEPmu 2427927.48 -0.360: 6.32 CEPmu 2427928.47 -0.332 6.35 CEPmu 2427929.39 -0.355: 6.33 CEPmu 2427934.49 -0.340 6.34 CEPmu 2427943.45 -0.359 6.32 CEPmu 2427944.45 -0.324 6.36 CEPmu 2427950.45 -0.346 6.33 CEPmu 2427951.45 -0.364 6.32 CEPmu 2427954.45 -0.354 6.33 CEPmu 2427964.44 -0.367 6.31 CEPmu 2427966.44 -0.348 6.33 CEPmu 2427973.47 -0.331 6.35 CEPmu 2427975.49 -0.346 6.33 CEPmu 2427976.43 -0.288 6.39 CEPmu 2428021.39 -0.284 6.40 CEPmu 2428025.40 -0.240 6.44 CEPmu 2428026.40 -0.242 6.44 CEPmu 2428044.36 -0.252: 6.43 CEPmu 2428047.35 -0.200 6.48 CEPmu 2428055.49 -0.180 6.50 CEPmu 2428056.46 -0.136: 6.54 CEPmu 2428063.46 -0.185: 6.50 CEPmu 2428064.48 -0.207 6.47 CEPmu 2428069.29 -0.173 6.51 CEPmu 2428070.29 -0.218 6.46 CEPmu 2428081.45 -0.149 6.53 CEPmu 2428084.27 -0.164 6.52 CEPmu 2428088.26 -0.142 6.54 CEPmu 2428094.24 -0.132 6.55 CEPmu 2428107.34 -0.072 6.61 CEPmu 2428111.21 -0.079 6.60 CEPmu 2428121.29 -0.034 6.65 CEPmu 2428138.42 -0.018 6.66 CEPmu 2428143.36 +0.065: 6.75 CEPmu 2428145.37 +0.020: 6.70 CEPmu 2428153.22 +0.004 6.68 CEPmu 2428173.22 +0.020 6.70 CEPmu 2428180.22 +0.016 6.70 CEPmu 2428183.31 +0.010 6.69 CEPmu 2428192.42 +0.070: 6.75 CEPmu 2428205.40 -0.048 6.63 CEPmu 2428209.26 +0.012 6.69 CEPmu 2428228.31 +0.005 6.69 CEPmu 2428247.29 +0.006 6.69 CEPmu 2428267.35 -0.015 6.66 CEPmu 2428270.53 -0.036 6.64 CEPmu 2428280.37 -0.024: 6.66 CEPmu 2428285.39 -0.003: 6.68 CEPmu 2428298.51 -0.139 6.54 CEPmu 2428303.54 -0.076 6.60 CEPmu 2428305.51 -0.089 6.59 CEPmu 2428308.44 -0.098 6.58 CEPmu 2428322.49 -0.150 6.53 CEPmu 2428332.47 -0.208 6.47 CEPmu 2428333.48 -0.164: 6.52 CEPmu 2428338.50 -0.140 6.54 CEPmu 2428373.39 -0.227 6.45 CEPmu 2428376.45 -0.202: 6.48 CEPmu 2428389.46 -0.248 6.43 CEPmu 2428397.36 -0.277: 6.40 CEPmu 2428398.38 -0.224 6.46 CEPmu 2428407.35 -0.214 6.47 CEPmu 2428417.36 -0.210 6.47 CEPmu 2428424.32 -0.219 6.46 CEPmu 2428429.31 -0.259 6.42 CEPmu 2428435.28 -0.253 6.43 CEPmu 2428441.27 -0.247 6.43 CEPmu 2428453.44 -0.263 6.42 CEPmu 2428471.23 -0.326 6.35 CEPmu 2428480.49 -0.339 6.34 CEPmu 2428496.30 -0.325 6.36 CEPmu 2428514.24 -0.347 6.33 CEPmu 2428522.28 -0.328 6.35 CEPmu 2428528.27 -0.350 6.33 CEPmu 2428534.27 -0.322 6.36 CEPmu 2428542.31 -0.326 6.35 CEPmu 2428554.31 -0.337 6.34 CEPmu 2428578.53 -0.263: 6.42 CEPmu 2428590.32 -0.277 6.40 CEPmu 2428603.49 -0.306 6.37 CEPmu 2428617.45 -0.318 6.36 CEPmu 2428633.52 -0.296 6.38 CEPmu 2428645.52 -0.323 6.36 CEPmu 2428655.43 -0.264 6.42 CEPmu 2428662.48 -0.309 6.37 CEPmu 2428666.45 -0.283 6.40 CEPmu 2428677.47 -0.272 6.41 CEPmu 2428683.50 -0.277 6.40 CEPmu 2428691.46 -0.317 6.36 CEPmu 2428695.50 -0.262 6.42 CEPmu 2428703.46 -0.346 6.33 CEPmu 2428707.47 -0.365 6.32 CEPmu 2428711.44 -0.349 6.33 CEPmu 2428718.43 -0.362 6.32 CEPmu 2428752.41 -0.335 6.35 CEPmu 2428757.39 -0.342 6.34 CEPmu 2428762.41 -0.378 6.30 CEPmu 2428770.37 -0.336 6.34 CEPmu 2428777.38 -0.335 6.35 CEPmu 2428795.29 -0.347 6.33 CEPmu 2428801.28 -0.346 6.33 CEPmu 2428810.26 -0.413: 6.27 CEPmu 2428826.25 -0.353 6.33 CEPmu 2428829.25 -0.363 6.32 CEPmu 2428834.44 -0.323: 6.36 CEPmu 2428835.39 -0.335 6.34 CEPmu 2428848.46 -0.320 6.36 CEPmu 2428859.34 -0.332 6.35 CEPmu 2428865.34 -0.287 6.39 CEPmu 2428881.33 -0.337: 6.34 CEPmu 2428890.40 -0.299: 6.38 CEPmu 2428903.45 -0.307 6.37 CEPmu 2428924.22 -0.365 6.32 CEPmu 2428929.26 -0.307 6.37 CEPmu 2428935.29 -0.280 6.40 CEPmu 2428946.25 -0.262 6.42 CEPmu 2428951.27 -0.243 6.44 CEPmu 2428963.28 -0.274 6.41 CEPmu 2428969.30 -0.297 6.38 CEPmu 2428973.29 -0.336 6.34 CEPmu 2428977.30 -0.265 6.42 CEPmu 2428998.35 -0.303 6.38 CEPmu 2429003.40 -0.305 6.38 CEPmu 2429016.46 -0.274 6.41 CEPmu 2429022.50 -0.315 6.37 CEPmu 2429026.52 -0.284 6.40 CEPmu 2429030.47 -0.326 6.35 CEPmu 2429032.46 -0.325 6.36 CEPmu 2429042.46 -0.308 6.37 CEPmu 2429054.47 -0.366 6.31 CEPmu 2429070.44 -0.406 6.27 CEPmu 2429079.44 -0.432 6.25 CEPmu 2429086.40 -0.411 6.27 CEPmu 2429110.401 -0.471 6.21 CEPmu 2429114.416 -0.506 6.17 CEPmu 2429120.385 -0.501 6.18 CEPmu 2429130.378 -0.523: 6.16 CEPmu 2429130.531 -0.503 6.18 CEPmu 2429152.331 -0.503 6.18 CEPmu 2429157.306 -0.468 6.21 CEPmu 2429162.297 -0.452 6.23 CEPmu 2429168.292 -0.421 6.26 CEPmu 2429175.468 -0.451 6.23 CEPmu 2429186.473 -0.461 6.22 CEPmu 2429192.489 -0.398 6.28 CEPmu 2429193.248 -0.436 6.24 CEPmu 2429204.224 -0.427 6.25 CEPmu 2429214.421 -0.385 6.30 CEPmu 2429231.295 -0.370 6.31 CEPmu 2429234.346 -0.339 6.34 CEPmu 2429245.301 -0.292 6.39 CEPmu 2429274.279 -0.315: 6.37 CEPmu 2429278.262 -0.263: 6.42 CEPmu 2429287.237 -0.211: 6.47 CEPmu 2429289.336 -0.339: 6.34 CEPmu 2429293.278 -0.278 6.40 CEPmu 2429301.241 -0.283 6.40 CEPmu 2429314.171 -0.272 6.41 CEPmu 2429323.308 -0.207: 6.47 CEPmu 2429325.274 -0.247 6.43 CEPmu 2429339.327 -0.282 6.40 CEPmu 2429354.316 -0.254 6.43 CEPmu 2429365.351 -0.216: 6.46 CEPmu 2429374.446 -0.277: 6.40 CEPmu 2429388.383 -0.284: 6.40 CEPmu 2429400.427 -0.293 6.39 CEPmu 2429410.410 -0.267 6.41 CEPmu 2429414.458 -0.252 6.43 CEPmu 2429422.446 -0.235 6.45 CEPmu 2429429.466 -0.230 6.45 CEPmu 2429438.449 -0.220 6.46 CEPmu 2429445.488 -0.265 6.42 CEPmu 2429481.403 -0.225 6.46 CEPmu 2429492.392 -0.186 6.49 CEPmu 2429495.419 -0.194 6.49 CEPmu 2429505.370 -0.223 6.46 CEPmu 2429514.307 -0.175 6.51 CEPmu 2429536.274 -0.172: 6.51 CEPmu 2429537.267 -0.152 6.53 CEPmu 2429553.417 -0.140 6.54 CEPmu 2429574.358 -0.123 6.56 CEPmu 2429588.354 -0.114 6.57 CEPmu 2429606.425 -0.065 6.62 CEPmu 2429612.259 -0.047: 6.63 CEPmu 2429618.375 -0.069 6.61 CEPmu 2429635.250 -0.047 6.63 CEPmu 2429647.231 -0.102 6.58 CEPmu 2429659.269 -0.131 6.55 CEPmu 2429677.367 -0.100 6.58