[vsnet-obs 41371] [vsnet-obs] SN Data Correction vsnet-obs 41218

["Jean marie Llapasset" <jean-marie.llapasset@wanadoo.fr>]

Please correct following observation in [vsnet-obs 41218 ]

SN2002er 20020902.907 147CR Van

Should be

SN2002er 20020902.907 143CR Van

A large discrepancy appeared between the measures published by J. Nicolas and J.
B. de Vanssay, members of the groupe CCD-Web
(http://fr.groups.yahoo.com/group/CCD-Web/).

As members of the group always report the star they used as reference, it
appeared that J. B. de Vanssay used the star referenced as 143R on O. Trondall
image, while J. Nicolas used the star referenced 150R and, in a further study,
J. C. Pelle ( mailto:jcpelle@mail.pf ), taking into account color term and
magnitude term in the USNO magnitudes, concluded that both stars where in error
with a total discrepancy of 0.57 mag.

J. C. Pelle proposes the following corrections

OT 143 -0.20 mag i.e. 14.10
OT 150 +0.27 mag i.e. 15.27

This accounts for a 0.47 mag difference.

J. C. Pelle explains the remaining 0.10 magnitude as follow

Color term	 +0.025 mag
Magnitude term	 +0.077 mag


J. C. Pelle also recommends using as reference the USNO star at the East of the
SN

    RA         DC    Mag_B   Mag_R   V-R   Dist(°)
17 11 43.4 +08 00 33 16.30B  15.20R +0.40   0.057

which appears to have a magnitude in good accordance with the remaining of the
field.

Software SNWeb provided by Jean-Claude PELLE ( jcpelle@mail.pf )

Jean-Marie LLAPASSET
Obs 635 Perpignan (France)
http://perso.wanadoo.fr/jm.llapasset
http://vsnet.astrosurf.com/snweb/

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