RR Lyr stars found from SDSS imaging

RR Lyr stars have distinct colors in the passbands of the Sloan Digital Sky Survey (SDSS). See Krisciunas, Margon, and Szkody (1998 PASP 110 , 1342). Beth Willman and Scott Anderson wrote some software to dig through preliminary SDSS commissioning data and identify RR Lyr candidates on the basis of their colors and two-epoch variability. Six of these were measured in the fall of 1999 with the Manastash Ridge Observatory 30-inch telescope in central Washington. All six seem to be RR Lyr stars.

V-band photometry is from Manastash Ridge Observatory 30-inch telescope by Kevin Krisciunas, Chris Schaber, Dawn Erb, and Chelsey Logan. We have also used, where possible, data from the Lowell Observatory Near Earth Object Search (LONEOS) to refine the periods. Since LONEOS uses an unfiltered CCD which has its peak QE in the R-band, we would expect the amplitude of the light variations to be less in "LONEOS-R" than in Johnson V, and in fact it is.

Here are the finder charts and folded light curves for six RR Lyrae stars, with identifications for comparison stars in each field.

       Comparison Star Sequences

 Star      V      +/-     B-V    +/-   N

b1110-1  15.434  0.010   0.580  0.030  3
b1110-2  14.946  0.005   1.113  0.014  3
b1110-3  15.861  0.005   0.727  0.012  3
b1110-4  16.204  0.003   0.500  0.006  3

b2771-1  14.454  0.001   0.751  0.001  1
b2771-2  14.333  0.001   0.629  0.001  1
b2771-3  17.767  0.013   0.746  0.018  1
b2771-4  14.594  0.001   0.563  0.001  1
b2771-5  15.779  0.003   0.787  0.004  1

b2774-1  14.726  0.003   0.956  0.009  1
b2774-2  15.325  0.005   0.765  0.014  1
b2774-3  15.502  0.005   1.107  0.018  1
b2774-4  13.980  0.002   0.654  0.005  1

b2838-1  14.517  0.003   0.597  0.006  1
b2838-2  17.294  0.022   0.721  0.061  1
b2838-3  15.039  0.004   0.695  0.011  1

b3069-1  15.180  0.006   1.428  0.025  1
b3069-2  16.375  0.015   1.048  0.054  1
b3069-3  16.194  0.013   1.402  0.056  1
b3069-4  13.808  0.002   0.612  0.005  1

b3210-1  14.859  0.003   0.621  0.006  1
b3210-2  16.404  0.009   0.687  0.021  1
b3210-3  16.689  0.011   0.642  0.027  1
b3210-4  16.144  0.007   0.902  0.021  1

The b2771 stars were calibrated by Arne Henden (USNO)
from images on 5 November 1999 UT.  The other fields
were calibrated by Kevin Krisciunas from 4 September
through 18 October 1999 UT with the MRO 30-inch telescope.

              Differential Photometry of Field Stars

Field     Comparison vs. Check Star  mean delta v   sigma     N

b1110              1 vs. 2             0.510(2)     0.013     28

b2771              3 vs. 5             1.971(9)     0.047     29

b2774              1 vs. 2            -0.619(2)     0.009     25

b2838              1 vs. 3            -0.520(2)     0.009     20

b3069              1 vs. 4             1.334(3)     0.011     18

b3210              1 vs. 2            -1.533(4)     0.019     21

This indicates that the comparison stars are acceptably constant
for the differential photometry of the RR Lyr candidates.