Optical Photometry of V404 Cyg (=GS2023+338)
ATel #56; R. M. Wagner (LBTO/U. Arizona), C. R. Shrader (NASA/GSFC), and S. G. Starrfield (Arizona State U.)
on 7 Mar 2000; 22:33 UT
Credential Certification: R. Mark Wagner (rmw@as.arizona.edu)
Subjects: Radio, Infra-Red, Optical, X-ray, Binary, Black Hole, Transient
In response to the request by Hjellming et al. in ATEL #54, Rose Finn (Steward Observatory/U. Arizona) obtained for us two R-band CCD images of V404 Cyg (=GS2023+338) on 2000 Mar 3.52 UT with the Steward Observatory Bok 2.3-m telescope and direct CCD (scale = 0.3 arcsec/pixel, airmass = 1.8, seeing = 1.7 arcsec FWHM). Photometry of V404 Cyg was obtained with respect to the comparison stars C1, C4, and C5 of Udalski and Kaluzny (1991, PASP, 103, 198), Casares et al. (1993, MNRAS, 265, 834), and our own photometry of C1 (R = 12.39). We find for V404 Cyg that R = (16.80 +/- 0.03) mag after correction for the contaminating star (R = 17.52; Casares et al. 1993) 1.4 arcsec north of V404 Cyg, which was not resolved from V404 Cyg at this high airmass. This magnitude is consistent with the quiescent magnitude of V404 Cyg after taking into account the intrinsic variability in quiescence which is typically ~+/-0.2 mag (Wagner et al., 1992, ApJ, 401, L97; Casares et al. 1993). The results indicate that there has not been a general optical brightening associated with the recent enhanced X-ray and radio activity which peaked on 2000 Feb 28 (Hjellming et al., ATEL #54). Given the level of intrinsic optical flickering, V404 Cyg would have to become brighter on average than perhaps V ~ 18 or R ~ 16 before a new optical outburst might be evident. However, our observations do not preclude the possibility that there have been changes in the amplitude of the optical fluctuations that might be correlated with the new X-ray and radio fluctuations. Photometric monitoring on short time scales during the next observing season might be worthwhile.
