Short-period variables in the July, 2002 dataset

Patrick Wils
Aug 5, 2002

I have been working on similar lines. Besides the WS statistic, I look at the value of Spearman's rank correlation coefficient (SRCC) for the data within a night. This measures basically whether magnitudes are more or less randomly spread over a night, or whether e.g. bright and faint mags tend to lie together. The latter is an indication of regular variation. Short period variables have a large WS statistic and a highly significant SRCC for all (or most) nights in V and I. Some new short period variable stars in the July data set, found this way (I have not checked all possible variables at this moment, I haven't paid much attention to the WS < 4 range yet):

  1. GSC00380-00247, observed on 4 nights (WS=47): 2 clear minima and a descending branch (4th night is too short, but shows a slight fading), frequency 8.3 cycles/day ? (already featured in a "fresh meat" post from Tom).

  2. NSV 7901 = GSC00395-01818, 3 nights (WS=15): one night no variability (near maximum ?), one night fading, one night rising. NSV gives type L (slow irregular).

  3. GSC00396-00073, 4 nights (WS=13): 2 nights near maximum, a descending branch + minimum, and a minimum + ascending branch.

  4. HD 153586 = GSC00410-02004 (WS=12), 2 nights: an ascending and a descending branch.

  5. GSC00410-02795, observed on 2 nights (WS=64): a descending branch and a pronounced minimum.

At lower amplitudes (and lower WS), there is HIP 83986 = HD 155229 = GSC00407-00415 (WS=4), with an ascending and descending branch.

In this way I also found the known variable V2377 Oph (WS=7) = HIP 85944 = HD 159356 = GSC00992-01402, 2 nights: an ascending and a descending branch.

In contrast, for the Mira star SS Her (WS=70), the significance of SRCC for the I mags is low on the two nights, indicating long term variability.