Dear colleagues, Ondrej Pejcha revealed that MisV1097 is a blue W UMa-type eclipsing variable. Please see the following web page for information in details on MisV1097. http://vsnet.aerith.net/misao/report/variable/MisV1097.html MisV1097, R.A. 01h15m28s.73, Decl. +41o19'59".3 (J2000.0), is a new variable star discovered in the course of the MISAO Project from Nobuo Ohkura's unfiltered CCD images between 2000 September and December. It is also recorded in the Guide Star Catalog 1.1 and the USNO-A2.0 as follows. GSC 2808-00139 01h15m28s.75 +41o19'59".1 Error:0.2" Mag:12.41 MagError:0.40 Band:6 Class:0 Plate:02RY Flag:F Epoch:04 AUG 1984 USNO-A2.0 1275.00747331 01h15m28s.736 +41o19'59".40 Mag(R):12.5 Mag(B):13.1 The observations suggest that it is a short periodic variable with a range of 12.4 - 13.2 mag. Seiichi Yoshida investigated the DSS images and found that MisV1097 is bright in any bands on the DSS 1 and the DSS 2 images. Especially, it is very bright on the DSS 2 Bj-band image, which implies that MisV1097 is blue. MisV1097 is also recorded in the 2MASS catalog. The 2MASS J-Ks color is 0.160 mag. This is the bluest value among all MisV stars recorded in the 2MASS catalog until MisV1118. John Greaves reported that the USNO-B1.0 B1-R1 color is 0.4 mag, which implies that Johnson B-V color is around 0.2 mag. It means the spectral class of MisV1097 may be A or early F. Ondrej Pejcha observed MisV1097 in V and I bands for 4 hours on Feb. 14, 2003 at Brno Observatory, and succeeded to obtain the light curves. The curves show a nice symmetric minimum of an eclipse, and revealed that MisV1097 is a W UMa-type (EW) eclipsing variable. Based on these light curves, John Greaves pointed out that the period is probably about 0.5 to 0.6 days. The difference between V and I from Ondrej Pejcha's observations shows that MisV1097 is much bluer than the comparison star and two check stars. Here are the relative V-I color of MisV1097 and the comparison star against the two check stars at Feb. 14.7335. V-I against V-I against check star 1 check star 2 -------------------------------------- MisV1097 -0.588 -0.152 Comp. star +0.356 +0.792 The GCVS description on EW type says, "The components generally belong to spectral types F-G and later." But it also says on KE subgroup of EW-type stars as, "Contact systems of early (O-A) spectral type, both components being close in size to their inner critical surfaces." Therefore MisV1097 is probably an EW/KE type variable star. Note that the color of MisV1097 in standard system is not obtained. Multi-color photometry using standard filters is encouraged. Best regards, -- Seiichi Yoshida comet@aerith.net http://vsnet.aerith.net/
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