I performed unfiltered time series photometry on DV UMa at CBA Belgium Observatory last night (April 9/10, 1997), during 4.8 hours.
The resulting light curve shows three eclipses and very prominent superhumps. These observations thus establish DV UMa as a new member of the UGSU-type dwarf novae.
I will determine an exact superhump period value shortly, using the PDM method. A rough inspection of the data already yields a value of 0.0837 d.
I will also shortly calculate the mid-eclipse times, allowing me to check the eclipse timing ephemeris published by Taichi Kato in an earlier VSNET message.
We (Ouda Team) have detected superhumps with a quite large amplitude (~0.6 mag!) in DV UMa during the last night 5-hr run. The preliminary period analysis with the PDM method give the best estimated period of 0.090 (+- 0.002) day.
(from CVC 843, vsnet-alert 843)
DV UMa [UGSU, 15.4v - 20.6v] ============================In a recent VSNET message, Tonny Vanmunster, CBA Belgium Observatory announced the discovery of superhumps in this system, hence classifying it as a UGSU type dwarf nova : "I performed unfiltered time series photometry on DV UMa at CBA Belgium Observatory last night (April 9/10, 1997), during 4.8 hours. The resulting light curve shows three eclipses and very prominent superhumps. These observations thus establish DV UMa as a new member of the UGSU-type dwarf novae."
Joe Patterson, CBA (Columbia University), NY communicates following precise data on the superhump period : "I received a lot of data on DV UMa, coming from CBA Denmark (Lasse Jensen), CBA West (Dave Harvey) and CBA Belgium (Tonny Vanmunster), and the star now shows very large superhumps at nu = 11.22 +- 0.05 c/d. The superhump amplitude is about 0.35 mag. One very large run on JD 548 has an obvious signal at 23.52 c/d, which I take to be the first harmonic of nu-orb, a la AL Com and WZ Sge."
In CVC 133, we listed a mid-eclipse ephemeris for DV UMa, published by Taichi Kato, consisting of two possible alternatives. An analysis by T. Vanmunster of a set of DV UMa time series photometry data, obtained on April 9/10 at the Center for Backyard Astrophysics of Dave Skillman (CBA East) and CBA Belgium, clearly indicates that the best fit ephemeris is the first one :
Min.HJD = 2446854.7487 + 0.085852614 E (1),The observed eclipses fit within the 0.002 day error mentioned by Taichi Kato [CVC 133].
I've just reduced observing run from yesterdays evening (13.4.97) of DV UMa. Quite suitable light curve shows some eclipse and one hump. Second hump is not full because I stoped observations very soon :-( (Been interested in Mark 501, shame...) If anyone is interested in this dataset please feel free to contact me at firstname.lastname@example.org Have a nice day and clear sky
RudolfP.S. New telescope - new age of superhumps at our observatory :-)
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