[vsnet-chat 3452] V348 Sgr sequence comparison

[Sebastián Otero <varsao@fullzero.com.ar>]

I was visually checking the sequence for the V348 Sgr field. Something is
clear: the PEP(V) magnitudes from Heck,et al. match exactly with what I saw.
As a conclussion, I think every other sequence not from PEP(V) must be used
with care. Some stars look in better agreement with UCAC1 than with Tycho 2;
some look better in Tycho 2 than in UCAC1 and some even look better in Tycho
than in Tycho 2.
So, although in general UCAC1 and Tycho 2 have better magnitudes, they
shouldn't be used if PEP(V) magnitudes are available.

I have added some stars to the sequence and I'd appreciate if Bruce could
complete the data.
Thanks. This is the table:


GSC(6858-..)--OBS. v -- PEP(V) -- UCAC1 -- Tycho2 --B-V


02674      100 -- --?--- -- ---?-- --  1003 -- 0.59 *
02162      103 -- --?--- -- ---?-- --  1037 -- 0.16
02724      104 -- --?--- -- ---?-- --  1053 -- 1.09 #
01673      104 -- --?--- -- ---?-- --  1037 -- 1.90
02278      105 -- ------- -- 1036 -- 1052 -- 1.26
02136      106 -- --?--- -- ---?--  -- 1091 -- 2.13
02176      106 -- ------- -- 1100 -- 1175-- -0.32
02252      108 -- 1075 -- 1077 -- 1049 -- 0.93 *
01964      110 -- 1105 -- 1119 -- 1087 -- 0.62
01727      111 -- 1106 -- 1076 --  ------  -- "red"
01487      114 -- --?--- --  --?--- -- 1077 -- 1.67
02438      115 -- 1148 -- 1172 -- 1141 -- 0.41 *
01715      115 -- --?--- --  --?--- -- 1153 -- 2.07
02920      115 -- 1154 -- 1173 -- 1123 -- 0.57
02962      117 -- --?--- --  --?--- -- 1170 -- 0.41
01425      118 -- ------- -- 1180 -- 1142 -- 0.54

# = Tycho 1 gives 10.38 and B-V 1.37
? = Data needed.
*  = These three stars were taken as reference stars for the estimates.

The two red stars   GSC 6858-02136 (1091T2) and GSC 6858-01487 (1077T2) look
the opposite as in Tycho 2. The latter is 0.6 magnitudes fainter. Maybe one
of them (or both) are variable.

I think this experiment has proven something we already knew: PEP(V) is the
best source for sequences.


Best regards,
Sebastián Otero.

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