[vsnet-campaign-dn 6889] Lanning 420 superhump period

[Taichi Kato]

Lanning 420 superhump period

   Enrique de Miguel, Maehara-san and Kyoto team (Ohshima-san) have reported
observations.  The data confirm Enrique's identification of the superhump
period.  The mean period has been 0.06155(6) d.  We did not, however,
confirm the significant period derivative, possibly suggesting that
the outburst has already entered "stage C" evolution.
Since this estimation was based on a relatively short baseline, further
observations are of course necessary to confirm the absence of the
period change.

Enrique's comment:
===

Comments:     Clear skies. High humidity, particularly by
              the end of the run. As I did yesterday, 
              images are grouped together to improve S/N,
              with an effective exposure time of 180 s.
              On average, this object is 0.16 mags fainter than
              yesterday. From a casual inspection of the 
              light curve, there seems to be no well-defined
              superhump structure; however, both ANOVA and
              PDM analysis show a periodic signal at 0.0626(30) d
              which is clearly related to Psh.
              Combining all three runs,

                     Psh = 0.06159(21) d

              The results seem to suggest a positive Pdot.