# IBVS 5441-t1.txt #Observer: A. Henden, B. Sumner #Field: AY Lac #IBVSdataKey: sequence # URL: ftp://ftp.nofs.navy.mil/pub/outgoing/aah/sequence/sumner/aylac.seq 157 AY LACERTAE (NR:/WZ:) Range: 14.0v-~21B Position: 22 22 22.18 +50 23 40.0 (DSS, IBVS 5441) Magnitude: ID RA (2000) DEC X Y N V ERR B-V ERR a) Comparison star sequence 1 22 22 20.5 +50 24 36 -16 56 1 10.539 0.000 0.744 0.001 2 22 21 55.8 +50 27 31 -252 232 1 11.079 0.001 0.125 0.001 3 22 22 39.9 +50 21 00 169 -160 1 11.577 0.001 0.776 0.001 4 22 22 31.4 +50 24 37 88 57 1 12.164 0.001 0.356 0.001 5 22 22 16.5 +50 23 47 -54 7 1 12.950 0.001 0.470 0.001 6 22 22 09.2 +50 19 21 -125 -258 1 13.520 0.002 0.432 0.003 7 22 22 30.6 +50 24 28 80 48 1 13.948 0.002 0.756 0.004 8 22 22 36.1 +50 20 17 133 -203 1 14.316 0.003 0.542 0.004 9 22 22 26.7 +50 23 25 44 -15 3 14.722 0.005 0.723 0.004 10 22 22 26.6 +50 23 54 42 14 3 15.005 0.006 0.982 0.004 11 22 22 23.6 +50 23 26 13 -14 3 15.566 0.006 0.685 0.006 12 22 22 26.5 +50 23 41 41 1 2 16.590 0.000 0.873 0.009 13 22 22 24.7 +50 23 30 24 -10 2 17.345 0.008 0.846 0.006 14 22 22 24.5 +50 23 44 22 4 2 17.863 0.008 1.049 0.011 15 22 22 22.7 +50 23 54 5 14 2 18.811 0.022 0.972 0.018 b) Wide-colour extension for CCD calibration 22 22 45.3 +50 24 01 221 21 1 12.317 0.001 0.292 0.001 22 22 24.5 +50 21 34 22 -126 1 12.333 0.001 1.453 0.002 22 22 46.0 +50 24 21 228 41 1 12.102 0.001 1.660 0.002 22 22 39.1 +50 20 30 162 -190 1 13.488 0.002 1.781 0.004 Notes: 1. The first four bright stars in this sequence, all brighter than magnitude 12.5, are saturated and their magnitudes are only approximate. They should be used for guidance only until their magnitudes are correctly determined. Star #1 has a reliable Tycho-2 magnitude of 10.12+/-0.03. 2. The 4th edition of GCVS (Kholopov, 1985) gives the type as M (Mira), however the online catalogue and atlas of cataclysmic variables (Downes, et. al., 2003) lists the star as UG:/M and quotes this author with the comment from the first edition of this sequence that this variable is still considered a possible UG. Non-detection on POSS images between 1952 and 1990 confirms this possibility. 3. This possibility was confirmed in IBVS 5441 of 14 July 2003 where outbursts of this variable in the Sonneberg Observatory plate stacks are discussed, one in August 1927 (the discovery), another long outburst of at least 6 weeks duration in August 1962 (originally identified by H. Gessner in 1966). A third unconfirmed visual observation at 14.0v in August 1943 is also discussed. An accurate position was determined from a POSS-II blue image (given above) and approximate limiting magnitudes were also provided (also shown above). 4. The IBVS 5441 authors Kroll, Samus and Volkov conclude that AY Lac is a definite cataclysmic variable, most probably a recurrent nova, although they also also admit that a classification of type WZ Sge is also possible. The recurrence time may be in the order of 17 to 19 years. Bruce Sumner 15 September 2000 Revised 1 August 2003