Z cam Stars in the Twenty-First Century Mike Simonsen

3. Bona fide Z Cam stars
After four years of Z CamPaign observations and an exhaustive examination 
of the AAVSO International Database, nineteen bona fide Z Cam type systems 
have been identified out of the sixty-five stars listed in the literature at one time 
or another as Z Cam stars. Some of these have been known to be Z Cams for 
decades. Others are newly classified or re-classified as Z Cams.
All light curves (Figures 1–21) in this section were created using 
VSTAR
(Benn 2012). Black dots are AAVSO visual data; green dots [gray in black/
white version] are AAVSO Johnson V data (AAVSO 2013). Except for the 
prototype star Z Cam, the stars are listed here in order of R.A. Each star's 
position, maximum and minimum, and type is given in Table 1.
The entire set of AAVSO data for each star was downloaded and the 
light curve was examined visually, both in gross, multi-year displays and in 
close detail, cycle-by-cycle. Start dates of the data set and the beginnings and 
endings of outbursts and standstills could be determined by selecting individual 
data points on the 
VSTAR
light curve and viewing the complete observational 
information on the 
VSTAR
information screen. 
Table 1: Bona fide Z Cam–type variable stars.
 
Name 
R.A. (2000) 
Dec. (2000) 
Max 
Min 
Type
 
h m 
s 
° 
' 
"
WW Cet
00 11 24.78 
–11 28 43.1 
10.4V 
15.8V 
UGZ
V513 Cas 
00 18 14.91 
66 18 13.6 
14.9V 
18.9V 
UGZ*
IW And 
01 01 08.91 
43 23 25.7 
13.8V 
17.7V 
UGZ*
RX And 
01 04 35.54 
41 17 57.8 
10.2V 
15.1V 
UGZ
AY Psc 
01 36 55.45 
07 16 29.3 
15.3V 
17.0V 
UGZ+E
TZ Per 
02 13 50.97 
58 22 52.3 
12.0V 
15.6V 
UGZ
HL CMa 
06 45 17.22 
–16 51 34.7 
10.6V 
14.9V 
UGZ*
BX Pup 
07 54 15.57 
–24 19 36.5 
13.8V 
18.0V 
UGZ
Z Cam 
08 25 13.20 
73 06 39.2 
10.0V 
14.5V 
UGZ*
AT Cnc 
08 28 36.93 
25 20 03.0 
12.7V 
15.2V 
UGZ*
SY Cnc 
09 01 03.32 
17 53 56.2 
11.1V 
14.5V 
UGZ
Leo5 
10 28 00.08 
21 48 13.7 
15.2V 
17.7V 
UGZ+E*
ES Dra 
15 25 31.81 
62 01 00.0 
14.1V 
17.5V 
UGZ
HP Nor 
16 20 49.59 
–54 53 22.9 
12.8v 
16.4V 
UGZ
AH Her 
16 44 10.01 
25 15 02.0 
11.3v 
14.7V 
UGZ*
UZ Ser 
18 11 24.90 
–14 55 33.9 
12.4V 
17.2V 
UGZ*
EM Cyg 
19 38 40.11 
30 30 28.4 
12.0V 
14.3V 
UGZ+E
VW Vul 
20 57 45.07 
25 30 25.7 
13.1V 
17.0V 
UGZ
HX Peg 
23 40 23.70 
12 37 41.8 
12.9V 
16.6V 
UGZ*
*Outbursts from standstills have been observed.

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Simonsen et al., JAAVSO Volume 42, 2014
6
Average cycle times were determined using a custom-designed tool in 
VSTAR
. 
Maxima could be hand selected individually, and the mean magnitude and 
average time between selections were automatically calculated. The averages 
of the densest data sets were then calculated to derive the mean time between 
selections and the mean magnitude of maxima. 
3.1. Z Cam (the prototype star) 
Figure 1.AAVSO light curve for Z Cam, the prototype of the class, showing the normal rapid 
succession of outburst to quiescence interrupted by a standstill from JD 2452896 to 2453381 
(September 2003 to January 2005). There is then a drop to quiescence followed by an irregular 
pattern of outbursts. 
3.2. WW Cet
Figure 2. The AAVSO light curve of WW Cet shows a normal pattern of outbursts and minima, 
followed by the first standstill in AAVSO records, from JD 2455359 to 2455826 (June 2010 to 
September 2011). This is followed by a weaker pattern of outbursts with progressively fainter 
minima. Recently classified as Z Cam in Simonsen and Stubbings (2011).

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