[vsnet-alert 9958] Re: CSS080130:021110+171624 is a confirmed UGSU type CV

[da55 at Safe-mail.net]

-------- Original Message --------
From: George Djorgovski <george at astro.caltech.edu>

> Hi, John,
> 
> 
> > thanks for your note.  I apologize for not citing everyone's relevant work.  We are guilty of ignorance as charged.

Ah, no need for that.  It just seems a bit of a shame everyone was just missing each other when a bit of liaison might make all the difference, that's why I also cc-ed to two lists.

> > I think that it is great that there is this community of  CV observers, and now that we are starting to find these objects in PQ and CSS surveys on a regular basis, it would be good if we can coordinate the information gathering and distribution.  We would be delighted to see them followed up, especially by the people who care and know.  VOEventNet should somehow ingest your contributions, and we can perhaps also help with the dissemination.  Instead of spamming everyone, could the right people please identify themselves, and we can start some email exchange?<

Hopefully the VSNET team leader and the CVNET people will be in touch with you about meaningful cross talk.

I'm no great expert on CVs, but one useful aspect is that certain subclasses have these diagnostic superhumps, wiggles in their photometric lighcurves, caused by precession of the circumstellar accretion disc during outburst if I remember rightly.

This could possibly save you time and effort (both no doubt at a premium) on occasions when you've a large number of transients to test spectroscopically, if an object is already confirmed as a cataclysmic variable independent of such information.

There are a couple of caveats, one is not all CVs have superhumps, though a lot of the higher amplitude ones can.  Also they do not necessarily start in the earliest phase of the outburst, and it has to be wait and see as to if they happen or not, and such waiting may lead to what turns out to be a necessary spectroscopic follow up being missed.

Also, as with the UGWZ object in ATEL 1418, it isn't always immediately clear if an object is a CV or a nova.

Hopefully those more expert on such things can advise on that with respect to timing.

Your group's ATELs appear to be regularly forwarded to both VSNET and CVNET, which covers things to some extent, it's just in this case things were circumvented via VOevents.

There is actually something of an almost rabid community of CV observers out there, both some professional groups and some dedicated amateurs, who are all too keen to point their CCD and 'scope at any new candidate object (at times using unfiltered photometry though, as this of course does not affect the detection of superhumps), so possibly requests for observations to vsnet

<http://ooruri.kusastro.kyoto-u.ac.jp/mailman/listinfo/vsnet-alert>

or cvnet

http://tech.groups.yahoo.com/group/cvnet-discussion/

or cc-ings/forwardings of announces may work, as discourse on recent events often occurs in these lists anyway.

I am not certain, but I think 16th magnitude and brighter objects would be the ones most likely to be covered.  Expert opinion may differ.

Finally, just for your information, although this object's progenitor wasn't in SDSS data, it was in likely in GALEX if the USNO B1.0 progenitor candidate is valid, see

http://galex.stsci.edu/GR2/?page=mastform

for an example search form.  Astrometric accuracy for GALEX is about 6 arcsecs, though it can be better than that.

This missions' cross correlation form

http://archive.stsci.edu/xcorr.php

can be coded to look only for GALEX specific objects via HTTP GET calls, just changing the RA and Dec as appropriate.

<http://archive.stsci.edu/xcorr.php?target=%2032.7924%2017.2735&missions[]=GALEX&radius_GALEX=0.2&outputformat=HTML_Table&max_records=10&action=Search>

then click in the object identifer code which is a hyperlink to a summary page.

The imminent release of the GALEX data release 4 All Sky Survey will mean 3/4 of the sky will have been covered.

However, this might not be of any practical use, as there is some serious overlap in colours between CVs and QSOs.

In this case though the galex object certainly has a white dwarf like FUV-NUV colour of +0.11

Cheers

John

John Greaves