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Follow-up observations of transients Gaia17dcx and Gaia17ddg

ATel #11053; V. Reshetnyk, A. Simon, V. Vasylenko (Taras Shevchenko National University of Kyiv, Ukraine), I. Sokolov (INASAN RAS, Russia), V. Godunova, O. Sergeev (ICAMER Observatory, Ukraine)
on 12 Dec 2017; 20:38 UT
Credential Certification: Andrew Simon (skazhenijandrew@gmail.com)

Subjects: Optical, Transient

We report optical observations of two blue transients near the Galactic plane, Gaia17dcx and Gaia17ddg, which are assumed to be CVs. BVRI photometry of the objects was performed with the 2-m RCC telescope at the Terskol Observatory early December 2017, just after the alerts were published.

Gaia17dcx was detected by Gaia on 2017-11-29 at magnitude G = 17.48. No progenitor of this transient was found on archival images. Our CCD images were taken on 2017-12-01 and 2017-12-02. Using the AAVSO catalogue for photometric calibration we derived the following magnitudes of Gaia17dcx (not corrected for the Galactic foreground extinction):

MJDBeBVeVReRIeI
58088.98518.170.1017.880.0517.980.0718.310.08
58089.97518.230.1217.930.0518.070.0618.350.12

These results suggest that the source brightness remained approximately constant over the observed one-day period.

Gaia17ddg was discovered on 2017-11-30 at magnitude G = 17.15; on the Gaia Photometric Alerts page, it was announced as a declining source. There was no progenitor object on archival images. We detected Gaia17ddg on the images taken on 2017-12-03 (MJD 58090.0). By using the AAVSO catalogue for photometric calibration, we obtained the following magnitudes of the source (not corrected for the Galactic foreground extinction): B = 17.70 ± 0.05, V = 17.58 ± 0.04, R = 17.67 ± 0.05, I = 17.94 ± 0.05.

We acknowledge ESA Gaia, DPAC and the Photometric Science Alerts Team (http //gsaweb.ast.cam.ac.uk/alerts).