[vsnet-alert 12390] Re: two new CV candidate detected by Itagaki

[F L]

"Hi all,

  Itagaki-san reports his detection of two brightened objects. 

OT_J085228.5-084411     20101111.72596       14.5C       KIt

  There is no definite quiesient counterpart on the DSS or 2MASS
images.  

OT_J092001.0-110302     20101111.74132       14.9C       KIt

  The quiesient counterpart has been observed as a mag 19 blue star.
Though it is cataloged in the QSO candidate (Atlee et al., 2007, ApJ,
664, 53), it is possibly a new CV.

  Confirmation and time-resolved photometry is urgently encouraged.

With regards,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka at phys.kyushu-u.ac.jp"

The first mentioned object has a J plate detection of mag 22.1 logged in GSC 2.3.2

The second mentioned object is a GALEX source, and that's why it is mentioned in the QSO candidacy list, because the related paper is involved in searching for QSOs using GALEX and USNO POSS digitisation "photometry".

Stellar appearing objects in optical and GALEX colour space can not be used to distinguish between QSOs, cataclysmic variables, white dwarfs or even B subdwarfs for that matter in any unique way.  Having said that, the fainter the object the more likely it will be a field QSO, yet still such candidacy lists will have a significant number of false alarms.

Therefore something appearing in a QSO candidate list based on such criteria has a chance of being a QSO, but in no way has to be (well, unless backed up by some independent data, but then that is information outside the initial selection criteria).

At least this paper is honest enough to describe the table as one of candidates.  Many survey based lists appear of late, some often forgetting to carry the word candidate, which can carry up to half or even more of the list as being false alarms, which pretty much negates their applicability, but still they appear in the mainstream journals readily enough.


Possibly of more interest is that as far as I can tell these two objects do not even rise until after local midnight at the moment, transiting nearer local dawn than local midnight too, all probably reducing the number of cycles detectable by any one observer significantly.

Given the sheer amount of demand upon amateur photometrists for time series runs on anything that may or may not have a hint of a superhump, whether the object be of some significance like OT_011013.12+600435.7 (=HT Cas) or just another cataclysmic binary in outburst, does the discipline need any further deplenishment given the plethora of these targets already demanding followup?

I can see that the surveys make it difficult for the amateur discoverer, such that like comet and asteroid hunters in the past, the nova and outburst detecting amateur has to aim at the peripheral times of night in order to find something first, but as there are lots of objects already, discovery for discoveries sake, and the need for confirmation irrespective of any potential import seems like a massive waste of resource.

Meanwhile let us hope someone somewhere has heeded the alerts and spectral tomopgraphy is being conduc

Cheers

John