91   DO VULPECULAE   (UG)   Range: 16.0-20.7V
     Position:   19 52 10.74  +19 34 42.4 (J2000, A. Henden June 1999)
     Magnitude:  V=16.427  B-V=0.167      (A. Henden, single night)

a) Comparison star sequence

ID     RA (2000)    DEC       X    Y   N    V      ERR     B-V    ERR
     
1    19 52 10.9  +19 31 04     3 -218  3  11.205  0.178   1.203  0.165   
2    19 52 09.0  +19 36 35   -24  113  3  11.606  0.068   0.288  0.037   
3    19 52 04.6  +19 37 08   -87  145  3  12.167  0.005   0.624  0.013   
4    19 52 12.5  +19 36 51    25  129  4  12.606  0.005   0.730  0.018   
5    19 52 04.2  +19 32 04   -91 -158  3  12.884  0.005   0.574  0.016   
6    19 52 23.7  +19 35 39   184   56  3  13.219  0.006   0.697  0.018   
7    19 52 01.6  +19 35 34  -128   52  3  13.504  0.000   0.699  0.015   
8    19 52 09.2  +19 34 26   -21  -16  3  14.002  0.050   1.438  0.033   
9    19 52 15.2  +19 34 59    63   17  3  14.490  0.008   0.506  0.019   
10   19 52 16.7  +19 35 17    85   35  3  14.811  0.014   0.459  0.014   
11   19 52 16.7  +19 35 02    85   20  4  15.491  0.037   0.910  0.025   
12   19 52 09.8  +19 34 53   -12   11  3  15.719  0.016   1.642  0.019   
13   19 52 11.5  +19 35 22    11   40  3  16.053  0.006   0.841  0.018   
14   19 52 12.0  +19 34 26    18  -16  3  16.968  0.028   0.936  0.048   
15   19 52 12.5  +19 34 40    25   -3  2  18.069  0.027   1.023  0.072   
16   19 52 11.4  +19 34 02    10  -40  2  18.466  0.113   1.092  0.051   


b) Wide-colour extension for CCD calibration
 
     19 52 27.9  +19 35 42   243   60  3  12.113  0.000   0.220  0.032   
     19 51 48.6  +19 37 39  -312  177  3  12.802  0.008   0.275  0.011   
     19 51 52.3  +19 31 02  -261 -221  3  15.052  0.043   2.024  0.047   
     19 52 01.0  +19 30 38  -137 -244  3  16.010  0.026   2.034  0.033   


Notes:

1. Star #1 and #2 are saturated, and should be used with care. 
Their magnitudes are only accurate to about +/-0.2 magnitude.

2. DO Vul caught in outburst by Henden at V=16.427 in June 1999. 
This appears to be the first positive observation since Baade's 
discovery in 1927. 

3. AAVSO and vsnet report many negative observations of fainter than 
15.0 and often fainter than 15.5. From the available data it would 
appear that maximum is between 15.5 and 16.5, with a first guess 
near 16.0 probably being with half a magnitude of the truth.

4. A quiescent magnitude of V=20.73 has been determined by J. 
Thorstensen. His single UBVI set is as follows:

V   = 20.73 +/- 0.05
B-V = +0.08 +/- 0.10
U-B = -0.99 +/- 0.17
V-I = +0.64 +/- 0.10

5. DO Vul has a faint companion of about magnitude 20 located 
2.4 arcsec due east.


Bruce Sumner
Revised 1 July 1999
Second revision 5 June 2001