[vsnet-chat 2855] Brighter stars near CH UMa

[Brian Skiff <bas@lowell.edu>]

     As a check on the magnitudes for some brighter stars appearing on the 
AAVSO (d)-scale chart for CH UMa, tonight I measured several of them with the
Lowell 53 cm telescope.  I used a 19" diaphragm and calibrated against a dozen
observations of nine standards.  Of particular interest are the four fainter
stars that bracket the brightness of the recent bright outburst.
     The first column in the list shows the magnitude indicated on the current
AAVSO on-line chart (dated April 1993, evidently derived from a BAA sequence),
then the "real" name, followed by the Johnson V magnitude and Stromgren b-y
color.  As can be seen, the chart magnitudes are roughly correct.
     I also show observed or approximate spectral types and corrected Tycho-2 V
magnitudes.  Note that for the two fainter stars, the Tycho-2 magnitudes aren't
so hot, being off by several times their quoted uncertainty.
     For fainter stars close to the CV, one should use Arne Henden's deep
sequence at: http://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/sumner/chuma.seq

\Brian


AAVSO  Name               V    b-y   spec      V (Tyc2)       Remarks
 68    HD 87043          7.04  0.67  K0       7.06 +/- 0.01
 86    HD 87126          8.75  0.96  M0       8.77 +/- 0.02   DO 33138
100    BD+68 591        10.06  0.46  (g5v)    9.98 +/- 0.03   GSC 4143-0761
103    BD+68 592        10.20  0.40  (g0v)   10.29 +/- 0.03   GSC 4384-0235
106    GSC 4383-0037    10.67  0.75  (k2iii) 10.92 +/- 0.06
110    GSC 4143-0698    11.09  0.58  (g8iii) 10.85 +/- 0.06

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