[vsnet-outburst 22397] MASTER OT J172758.09+380021.5: new SU UMa type dwarf nova - updated sueprhump period

Wed Jul 25 05:27:25 JST 2018

Dear colleagues,

Further to my message of yesterday regarding the detection of superhumps in the light curve of MASTER OT J172758.09+380021.5, I have now analysed both my 2018, Jul 22/23 and Jul 23/24 unfiltered CCD photometry sessions of this target. Observations were made at CBA Extremadura Observatory (Spain),  using a 0.40-m f/5.1 telescope and SX-46 CCD camera, under a very clear sky. 

The detrended light curve of Jul 23/24 continues to show superhumps with an amplitude of 0.10 mag, but the object has faded to mag 16.1 (CV) on Jul 24th. A period analysis of both nights’ datasets using the ANOVA, Lomb-Scargle and PDM methods (Peranso), yields a combined updated superhump period of 0.0565 +/- 0.0002d. 

Astrometry of this target (J2000.0, UCAC4 based): RA = 17h 27m 58.13s, Dec = +38° 00’ 22.5” (residual 0.3”)

Observations will be sent to AAVSO, CBA and VSNET for further analysis.

Best regards
Tonny

Tonny Vanmunster
CBA Belgium Observatory
CBA Extremadura Observatory
 <http://www.cbabelgium.com> www.cbabelgium.com
 <http://www.peranso.com> www.peranso.com

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