Z CamPaign Update February 4, 2014

American Association of Variable Star Observers (AAVSO)
Tue, 02/04/2014 - 23:22

The first news item is the acceptance by JAAVSO of two papers based on Z CamPaign observations - Z Cam Stars in the Twenty-First Century

and - ST Chamaeleontis and BP Coronae Australis: Two Southern Dwarf Novae Confirmed as Z Cam Stars

A big thank you to all the observers who have contributed to the campaign since 2009.

Other news- 

It looks like we have another bona fide Z Cam to add to the list. PY Per has been in standstill, hovering around 15.6V, since January 11, 2014. 

This is an interesting dwarf novae that used to have quite normal UGSS like outbursts to 13.8 every 43 days or so. Then in December 2008 it went into a deep VY Scl-like fade, biding its time in the low 17th mag range, reaching a minimum of 18.2 in December 2009,  until March 2010 when it came back to life for a short time.

Its had a handful of outbursts since then and two more VY Scl-like fades. Since September 2013 it has been averaging outbursts every 21.7 days with a mean maximum magnitude of 14.79. In January it halted its descent to minima and has been stuck around 15.6 ever since. PY Per is well placed for northern observers. Visual and once per night snapshots in V are adequate for our purposes, so please add this to your program if you are not observing it already. The longer we can confirm PY Per 'stuck in the middle with us', the more sure the classification is. Whatever happens next is anyone's guess. Lots of data gets you listed as co-author on the next paper.

A southern dwarf nova that has tantalizing visual data from Rod Stubbings in 2011 is TT Ind. It looks like it was in standstill in August and September that year…maybe. It has a rather long outburst cycle for a Z Cam, somewhere between 128 and 160 days, but that may just be lack of coverage. The mean maximum magnitude is 12.7. I would expect standstills to occur around the 14.2 range. Rod's observations in August and September 2011 center around 15.1 and range from 14.4 to 15.7. With minimum magnitudes now measured around 17.6, it would be at the top of the amplitude range for a Z Cam system. Nevertheless, I think this one is worthy of extra scrutiny over the next two years. If you live in the southern hemisphere or have access to telescopes there, please add this interesting DNe to your program. Nightly snapshots and visual data are adequate for our needs.

3 stars have been removed from the candidates list.

V368 Per - This is a known UGSU. Kato et al, 2013, 2013arXiv1310.7069K demonstrates it has super humps and a period of 0.07902 days.
V991 Aql - J-K 1.83, too red for a CV. This is an UXOR.
V735 Sgr - J-K 2.73, too red to be a CV. This is an ISB or an UXOR.

Z Cams - 21 (excluding PY Per)
Impostors - 27 (including many long time misclassified systems)
Candidates - 19 (including PY Per)
Total Z CamPaign stars - 67

An up to date full listing of the status of the Z CamPaign stars and their status can be found at The Z Cam List website - https://sites.google.com/site/thezcamlist/the-list

Mike Simonsen