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[vsnet-chat 907] SN1998bn
- Date: Tue, 05 May 1998 11:46:02 +0300
- To: lagmonar@csir.co.za, vsnet-chat@kusastro.kyoto-u.ac.jp, aah@nofs.navy.mil
- From: Berto Monard <lagmonar@csir.co.za>
- Subject: [vsnet-chat 907] SN1998bn
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- Sender: owner-vsnet-chat@kusastro.kyoto-u.ac.jp
Further on my recent posting and refering to previous ones, I must admit that I had the intention to in future modify my 13.5 mag estimates for SN 1998bn to somewhere around 13.7, based on an 'improved' visual estimate of star 'd' vs the near GSPC field. Did you by any chance measure that field against 'your' standards, Arne?
I still feel that 13.7 was the better v measure for the SN, as compared to V.
Where my original 13.5 estimate came from? To tell the truth: it was an 'absolute' eyeball measurement without the direct use of comparison sequences. It was based on an established 'feel' for the limiting magnitude of my telescope for that region at that time using different magnifications.
From that 13.5 mag value for the SN I then derived 13.2 for star 'd' which was to be used as the 'reference' for future observations.
The above method I have applied to measure 'v-sequences' for numerous stars in my program, those without official charts or sequences. So far they stood the test of comparison to other sources. I can only validate them via intercomparisons as in this case.
Therefore I also wish to thank you for those sequence measurements in the NGC 4462 region.
Berto Monard
>>> Berto Monard <lagmonar@csir.co.za> 05/05 8:26 AM >>>
Arne,
that's why my SN measures, although rounded to a lower resolution, agree with yours....
Visual observations especially under the 'cloud' of uncertain sequences cannot determine the exact time of peak brightness of a 'slowish' event as a SN near maximum. One needs those 0.01 mags to determine that. I hope you or someone else keep(s) providing those...
Regards,
Berto
>>> <aah@nofs.navy.mil> 05/04 11:37 PM >>>
Reading Berto Monard's note from [vsnet-alert 1729], he used a star 'd',
positioned 20" S and 1' E of the bright star in the NGC4462 field. If
I have my identifications correct, this star is listed in my master
sequence (http://ftp.nofs.navy.mil/pub/outgoing/aah/vsnet/ngc4462.seq)
as V=13.171 (B-V=0.681), so very close to the provisional magnitude of
V=13.2 that Berto used.
Arne
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