[vsnet-chat 2344] SN 1999ee sequence

["Berto Monard" <lagmonar@csir.co.za>]

Dear Kato-san and readers,

I would like to point at the unfortunate incorrectness of the converted USNO-A1.0 sequence for SN 1999ee as provided with the VSNET chart.

I have made an independent sequence by using USNO-A2.0 data and calibrating them against a GSPC field 3 degrees away and a LONEOS field 1 degree away. Both calibrations agreed to within 0.1 magnitude which is better than usual....

However the derived sequence is about 1 full magnitude different from the VSNET reported one, with the latter having too bright magnitudes. 
If SN 1999ee would be measured against a sequence that is 1 magnitude off this would give discrepant results regarding absolute magnitudes of SNe Ia or incorrect derived distances!

Therefore I would urge observers to rather use the 'berto' sequence, which I have checked at the eyepiece (SN 1999ee is close to zenith at a convenient observing time here...) and it really looked OK. A pity Arne can't measure that far South to confirm.

Please receive here-under my derived sequence and comparison with the magnitudes from the VSNET data.

coord 2000; berto; vsnet

221610.5-365158;122;111
221610.2-364820;131;119
221556.1-364955;157;151
221625.7-365047;144;136
221605.2-364715;150;139
221609.8-365453;144;135
221617.1-365619;131;121

additional valuable magnitudes a bit further away

221626.5-364746;148;-
221626.5-364719;151;-
221534.6-364720;140;-

Note: the star with VSNET magnitude 1354 at 221557.1-364654 is a galaxy (14.6)

Regards (and no offence, Taichi!),

Berto

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