[vsnet-chat 1755] BVRI sequence for SN1999aa

[bas@lowell.Lowell.Edu (Brian Skiff)]

     Kevin Krisciunas (University of Washington) has provided a deep BVRI
sequence for stars close to NGC 2595, the host of SN 1999aa, obtained using
the Apache Point Observatory 3.5-m telescope.  Complete details are given at
his Web site starting at:

http://vsnet.astro.washington.edu/kevin/apo.html

For the list below, I have obtained USNO-A2.0 coordinates for all the objects,
and have rearranged the list in the format of my large photometric reference
file.  Each star has been observed several times on a total of five nights,
and errors are about 0.015 mag. in all colors except for the faint star 4.
I have omitted star 8 in the list because it is a faint galaxy (see the CCD
image at Kevin's site), and it's colors are inconsistent, so should not be used
for work on the supernova.  The center of NGC 2595, by the way, is at:
8 27 42.00  +21 28 44.2 (2000), which comes from the Lick Northern Proper
Motion Survey, and should be good to a few tenths of an arcsecond.
     I compared the APO B and R magnitudes against the USNO-A2.0 blue and red
magnitudes.  The USNO magnitudes are internally consistent.  Excluding the two
faintest stars, which have large errors in USNO-A, the offset for the red
magnitudes is zero +/- 0.3 mag. (per-star rms), while for the blue magnitudes
the offset is -0.5 +/- 0.3 (USNO-A2.0 too bright).
     Kevin tells me the values for the sequence stars may change slightly as
further data are obtained, but these should entirely adequate for now.
     Thanks Kevin!

\Brian



Name                  RA  (2000)  Dec    s     GSC       V    B-V   V-R   V-I
NGC 2995  2         8 27 43.3  +21 29 52 A             16.76  0.85  0.44  0.85
NGC 2995  3         8 27 38.2  +21 29 55 A  1391-0549  15.08  0.68  0.38  0.76
NGC 2995  4         8 27 43.4  +21 30 34 A             20.04  1.62  1.17  2.63
NGC 2995  5         8 27 40.7  +21 31 08 A             18.98  0.75  0.43  0.84
NGC 2995  6         8 27 37.3  +21 30 58 A             16.62  1.07  0.59  1.13
NGC 2995  7         8 27 35.2  +21 29 47 A             18.49  1.40  0.81  1.60
NGC 2995  9         8 27 32.5  +21 28 34 A             18.42  0.53  0.30  0.68
NGC 2995 10         8 27 35.7  +21 28 00 A             18.52  1.53  0.98  2.14
NGC 2995 11         8 27 36.9  +21 27 31 A             18.74  0.94  0.50  1.01
NGC 2995 12         8 27 40.8  +21 27 22 A             15.79  0.84  0.46  0.91

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