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AAVSO Alert Notice 529
October 1, 2015
Observing campaign on 5 variables in Cygnus
Dr. George Wallerstein (University of Washington) hasrequested AAVSO assistance in monitoring 5 variable stars in Cygnus now throughDecember 2015. He is working to complete the radial velocity curves for thesestars, and needs optical light curves for correlation with the spectra he willbe obtaining.
Dr. Wallerstein writes: "I need to know the time ofmax or min so I can assign a phase to each spectrum. Most classical cepheidsare quite regular so once a time of max or min can be established I can derivethe phase of each observation even if my obs are several cycles away from theestablished max or min. MZ Cyg is a type II cepheid and they are less regularthan their type I cousins." SZ Cyg, X Cyg, VX Cyg, and TX Cyg are allclassical Cepheids.
The target list is given below.
Star R.A.and Dec. (2000.0) Range Period (d) SZ Cyg 20 32 54.29+46 36 04.6 8.92-9.84 V 15.10965 X Cyg 20 4324.19 +35 35 16.1 5.85-6.91 V 16.386332 VX Cyg 20 57 20.83+40 10 39.0 9.54-10.55 V 20.133407 TX Cyg 21 00 06.38+42 35 51.2 8.59-10.02 V 14.7098 MZ Cyg 21 21 54.73+37 27 33.1 10.76-12.68 V 21.4*
*MZ Cyg is in the fuzzy area between Type II Cepheids andRV Tauri stars. 21.4 d is the period for CWA classification, 42.8 d for RVA (revised by S. Otero October 2015).
All targets will be observed by Dr. Wallerstein on thefollowing dates:
0100-0300 UT 2015 October 2, 4 0200-0400 UT 2015 November 3, 4, 30 0200-0400 UT 2015 December 2, 30, 31
V and visual observations are requested. These are long-periodCepheids, so nightly observations are sufficient; many observations made overone night are not necessary.
All observations made during this campaign will beimportant in determining the times of maxima and minima of these stars.
Charts with comparison star sequences for these objectsmay be created using the AAVSO's Variable Star Plotter (VSP, https://www.aavso.org/vsp).
Please submit observations to the AAVSO InternationalDatabase using the names shown in the table.
This AAVSO Alert Notice was compiled by Elizabeth O.Waagen.
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發表於 2015-10-2 08:48:28