[vsnet-chat 5257] V4740 Sgr

[aah@nofs.navy.mil]

Doug West, as well as Seiichiro Kiyota, have indicated
that this fading nova appears to have unusual colors.  I have
calibrated the field at BVRcIc on one marginally photometric
night and with high airmass (the field currently transits
around sunrise), with the preliminary field photometry posted at
http://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/v4740sgr.dat
The expected external zeropoint error is about 3 percent,
though this is a *very* crowded, reddened field and you should take
care as to what stars you use for comparisons.

V4740 Sgr itself appears in that file with magnitudes/colors of:
    RA  (J2000) DEC         V     B-V    V-R    R-I
18:11:46.01  -30:30:51.5  12.776  0.859 -0.131 -0.535
The astrometry is with respect to UCAC1 and has approximately
100mas error.

This confirms Doug's results indicating a very blue object,
at least in the red filters.  I will acquire additional
calibration data as conditions permit (we have had a *very*
poor winter for all-sky photometry).

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