The Hipparcos and Tycho catalogues contain the results of around 100 photometric measurements per star over a 3 year period. These can be used to give an indication of whether suspected variables are truly variable.
The following table gives the quoted V magnitudes and the corresponding scatter in the Hipparcos (Hp) and Tycho (Vt) measurements for a number of suspected variables.
Photometric
scatter Var
Variable HIP V Hp Vt Annex Type Other Name Notes
Tau Cas 117301 4.88 0.02 0.05 N NSV 14707
NSV 14260 Lac 111795 5.11 0.13 0.09 Y U/I V416 Lac
NSV 13857 Cyg 107235 5.51 0.04 0.08 Y U/LB
NSV 2917 Ori 30099 5.67 0.04 0.08 Y U/LC
NSV 14213 Lac 111362 5.72 0.03 0.08 N
NSV 12088 Aql 95898 6.08 0.04 0.09 Y U
NSV 13729 Cep 105949 6.11 0.15 0.12 Y U/I V426 Cep
69 Dra 98401 6.20 0.06 - N
SAO 37607 And 8922 6.25 0.02 0.08 N
NSV 13784 Cyg 106420 6.27 0.05 0.10 Y U
NSV 13656 Cep 105193 6.43 0.14 0.15 Y U/I V422 Cep
SAO 19521 Cep 106604 6.47 0.06 0.09 Y P V431 Cep (1)
+49o2165 CVn 62600 6.50 0.03 0.09 N NSV 5976
NSV 2967 Gem 30722 6.57 0.05 0.09 Y U PZ Gem (2)
SAO 44590 CVn 65309 6.64 0.32 0.34 Y U/L BR CVn (3)
NSV 3597 Lyn 36334 6.66 0.10 0.13 Y U/SR BY Lyn (4)
SAO 77971 Gem 28969 6.67 0.03 0.11 N (5)
+20o1156 Ori 27829 6.70 0.02 0.12 N
SAO 21020 Cas 181 6.77 0.09 0.15 Y U/SR V822 Cas (6)
NSV 1280 Tau 17572 6.85 0.02 0.09 N
NSV 1702 Tau 22013 6.91 0.03 0.12 N
+47o2801 Cyg 94813 7.26 0.03 0.13 N
NSV 12247 Cyg 96533 7.29 0.11 0.19 Y U/I V2085 Cyg
NSV 13150 Del 101512 7.29 0.13 0.19 Y P/SR MV Del (7)
NSV 650 Cas 8896 7.31 0.04 0.13 N
SAO 78074 Gem 29360 7.41 0.04 0.17 N NSV 2859
NSV 12439 Cyg - 7.50 - 0.15 N
NSV 14680 Cep 116945 7.70 0.05 0.17
+18o4586 Del - 7.85 - 0.22
+61o0668 Cam 19122 7.91 0.04 0.21 N
TAV 0136+60 7755 7.97 0.68 0.73 Y U/LB V770 Cas (8)
SAO 15926 Dra 62839 8.65 0.06 0.34 N (9)
NSV 3369 Gem - 9.11 - 0.76 N
The Var Annex column indicates whether additional information is
included in the catalogues variability annex (Types: U=Unsolved ,
P=Periodic)
As can be seen, there is a tendency for the scatter to be larger in the Tycho measures and also for it to be slightly larger for fainter stars.
The scatter is very low for most of these stars - no larger than that found in non-variable stars. However, there are a few for which the scatter is somewhat larger and many of these have now been given permanent designations.