Affiliation
American Association of Variable Star Observers (AAVSO)
Mon, 04/29/2013 - 14:02
I was just looking at some light curves of LPVs I follow and was wondering about TX And. The AAVSO chart gives a range of barely over 3 mags (10.4-13.8V) and the obs do not match this range. Also, the light curve is not that nice sexy sine-like curve characteristic of the Miras, so I couldn't even begin to guess at a period.
Walter-
Here's a link to a V light curve from VSNET from about 1997 to 2003 -
http://www.kusastro.kyoto-u.ac.jp/vsnet/gcvs2/ANDTX.html
The seasonal gaps give a somewhat misleading picture. There's a lot of scatter and the periodicity isn't that clear. Especially the last decade or so there are not all that many observations so it may simply be there is not enough information to properly characterize it. It certainly isn't on the Bulletin list.
Hmmm- Maybe I should put it on my observing list.
Clear skies and dark-
DaveM
There is a remark in GCVS: "Recent observations in the AAVSO database suggest type LB."
http://www.sai.msu.su/gcvs/cgi-bin/search.cgi?search=TX+And
LB description from VSX variabilty types:
LB
Slow irregular variables of late spectral types (K, M, C, S); as a rule, they are giants. This type is also ascribed, in the GCVS, to slow red irregular variables in the case of unknown spectral types and luminosities.
Example: CO Cyg.
Thanks for the replies, they are very interesting. The listed range is totally out of whack based on the AAVSO and VSNET light curves.
So the GCVS folks are saying TX And is LB: (based on AAVSO data), and this morning I see that someone updated the VSX entry for TX And just yesterday (this is not a coincidence, right?)--it is now shown as SR: (based on a 1910 paper in the AN). I guess we won't see it in the AAVSO Bulletin any time soon then. :)
I'll certainly keep it on my observing list--it only takes a minute or so to image it with my setup. If you and a handful of other observers were to add it to your observing list we could get perhaps get sufficient coverage for an answer.
The rather strange light curve may be at least partly due to the comparison sequence that was used. It was based on questionable photometry, had a big 117-126 gap, and included no color data for comps fainter than 126. I just finished revising the sequence using SRO photometry, and tried to decrease the amount of color variation. It will be interesting to see if that makes a difference.