V4641 Sgr observations by D. West From: DWest61506@aol.com Date: Thu, 23 May 2002 10:47:05 -0400 Subject: [vsnet-obs 39956] V4641 Sgr CCD Observations V4641 Sgr observations taken with a 0.20m SCT + ST-9E CCD + V filter. Comparison star TYC 6848 3600 1 V=9.86. Estimated standard deviation of check star measurements = 0.03 magnitude. The signal-to-noise ratio (SNR) started at approximately 115 and ended the observing session at 40. The decreasing SNR is due to the increasing airmass and the approaching dawn. Variable, VSNET date, JD, unfiltered mag, Observer SGRV4641 20020522.4133 2452416.9133 11.91 JDW SGRV4641 20020522.4141 2452416.9141 11.94 JDW SGRV4641 20020522.4149 2452416.9149 12.08 JDW SGRV4641 20020522.4155 2452416.9156 12.23 JDW SGRV4641 20020522.4163 2452416.9164 12.19 JDW SGRV4641 20020522.4172 2452416.9173 12.26 JDW SGRV4641 20020522.4180 2452416.9180 12.36 JDW SGRV4641 20020522.4188 2452416.9188 12.38 JDW SGRV4641 20020522.4196 2452416.9196 12.35 JDW SGRV4641 20020522.4204 2452416.9204 12.30 JDW SGRV4641 20020522.4212 2452416.9212 12.34 JDW SGRV4641 20020522.4218 2452416.9219 12.21 JDW SGRV4641 20020522.4226 2452416.9227 12.29 JDW SGRV4641 20020522.4235 2452416.9235 12.47 JDW SGRV4641 20020522.4243 2452416.9243 12.53 JDW SGRV4641 20020522.4249 2452416.9250 12.44 JDW SGRV4641 20020522.4257 2452416.9258 12.42 JDW SGRV4641 20020522.4265 2452416.9266 12.37 JDW SGRV4641 20020522.4273 2452416.9274 12.54 JDW SGRV4641 20020522.4281 2452416.9281 12.39 JDW SGRV4641 20020522.4287 2452416.9287 12.32 JDW SGRV4641 20020522.4295 2452416.9295 12.45 JDW SGRV4641 20020522.4303 2452416.9303 12.48 JDW SGRV4641 20020522.4309 2452416.9310 12.43 JDW SGRV4641 20020522.4317 2452416.9318 12.27 JDW SGRV4641 20020522.4325 2452416.9326 12.43 JDW SGRV4641 20020522.4333 2452416.9334 12.37 JDW SGRV4641 20020522.4341 2452416.9341 12.47 JDW SGRV4641 20020522.4349 2452416.9349 12.45 JDW SGRV4641 20020522.4356 2452416.9357 12.37 JDW SGRV4641 20020522.4364 2452416.9365 12.14 JDW SGRV4641 20020522.4372 2452416.9372 12.15 JDW SGRV4641 20020522.4380 2452416.9380 12.21 JDW SGRV4641 20020522.4388 2452416.9388 12.28 JDW SGRV4641 20020522.4396 2452416.9396 12.37 JDW The observations were analyzed using the program AVE and periodicities were noted at 0.0081 and 0.012 day. Notice the greater than 0.6 magnitude decrease in approximately 20 minutes. I have unfiltered observations from 05/23/02 UT to reduce. I'll send them in tomorrow.