[vsnet-obs 20457] [FWD] KAIT calibration of SN 1999by magnitures

[Hitoshi YAMAOKA <yamaoka@rc.kyushu-u.ac.jp>]

[FWD] KAIT calibration of SN 1999by magnitures

Dr. Weidong Li, a member of LOSS KAIT team, has kindly provided their
revised magnitudes of SN 1999by using Brian's sequence [vsnet-alert
2919].  Note that he used the star 3, 4, and 5, then the revision in
[vsnet-alert 2937] does not affect his results.

Dr. Li wrote:
>First, I  used the Hubble Space Telescope Guide Star Catalog to
>get positions and magnitude info for all the stars in the field
>of NGC 2841, and I don't know the correlation between the HSTGSC
>magnitudes and GSC or UNSO ones. Comparing the V magnitudes for 
>3 stars that you provided which are also included in the HSTGSC
>catalog, I found an offset of about 0.2 mag between the two 
>catalogs, with the HSTGSC brighter. Thus the unfiltered magnitude
>for our discovery images should be something like this, if I 
>used the V magnitude you provided (the clear filter is indeed 
>very close to V band anyway),
>
>Apr 30.2 UT,   15.9 
>May 01.2 UT,   15.3
>May 02.2 UT,   14.8
>
>We had UBVRI observations for 99by on May 2 UT, and using the 
>BVRI sequence you provided, I got the magnitudes for the SN
>as listed in the following. These results used 3 stars in the 
>catalog you provided, namely star 3 (13.51), 4 (13.77) and 5
>(14.19). I think the sequence is pretty good as the RMS for the 
>results is pretty small.
>
>SN 1999by on May 2.2 UT,
>
>B = 14.97 +/- 0.07
>V = 14.63 +/- 0.03
>R = 14.52 +/- 0.03
>I = 14.38 +/- 0.04
>
>Please let me know if you have other questions.
>
>By the way, the weather has been bad for the past two days
>here, but we may have observations in the next couple of 
>days.
>
>Sincerely yours,
>
>Weidong Li, University of California, Berkeley

Reformatted:

SN1999by 990430.2     159C KAIT
SN1999by 990501.1     153C KAIT
SN1999by 990502.2     148C KAIT
SN1999by 990502.2   14.97B KAIT
SN1999by 990502.2   14.63V KAIT
SN1999by 990502.2   14.52R KAIT
SN1999by 990502.2   14.38I KAIT

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