[vsnet-alert 10039] FWD [CVNET-DISCUSSION 1130] likey new CV in Hydra - CSS080409:081419-005022

[csscvs at Safe-mail.net]

One of the PIs (Andrew Drake) at the Catalina Sky Survey Transient project has sent this note to CVNET regarding a likely CV.

http://tech.groups.yahoo.com/group/cvnet-discussion/message/1130

Also of note is the the GALEX Far UV and Near UV magnitudes are also 19.0, so the quiescent colours are very white indeed.  This seems to be quite common for these faint CVs, with little if any hint of the red dwarf in the colours whatsoever.

It's also useful circumstantial confirmation of the SDSS u' magnitude, which latter can be problematic, as outlined on the SDSS data release pages.

GALEX :- http://galex.stsci.edu/GR2/?page=explore&objid=2735560766478355596


Another somewhat pedantic point is that the true bibliographic identity is the discovery identity, CSS080409:081419-005022, yet that identity itself is pedantically problematic because it contravenes IAU guidelines because the coordinate part is _rounded_ whereas it should be truncated, ie CSS080409:081418-005022.


Another potential source of archival outburst information is the NSVS Orphan database, little utilised.  It mostly consists of objects that belong to known stars but were outside the match radius when epoch photometry was lumped into object synonyms.  However it may contain transitory events at times, but it's use is nontrivial.

Going to this url http://skydot.lanl.gov/nsvs/nsvs.php and using the SQL search box that says 'select * from object limit 10' the following simple SQL route can be taken

Clear the SQL box and enter

select a.* from orphan as a
where a.rao between 123.57 and 123.59 and a.deco between -0.85 and -0.83

and click the 'submit query' button _under_ the sql box.  This will be a little slow, possibly ten minutes.  The above are decimal RA and Declinations chosen to surround the object's position, ie a search box.  This is a simple formulation, more sophisticated cone searches are possible.

This particular search returns

Row #	frame_id	rao	deco	mag	err	flags	htm_id
1	148265	123.58213	-0.83639	12882	32	256	2464208823
2	148271	123.58231	-0.83155	12835	94	256	2464208822

That's instrumental magnitudes 12.882 error 0.32 and 12.835 error 0.94 both a quarter and a half an arcminute of the CV position respectively, reasonable enough for this wide field survey's resolution (~15" per pixel) and with no nearby 13th magnitude star fitting as alternate candidate source.

However, this is not rigorous.  Just suggestive.  Other things like ccd hotspots etc can cause orphans.

Observation dates can be found the following way, again using the SQL box and the 'submit query' button _under_ it (if you use the button above the example coordinate search details are returned instead) :-

select a.* from frame as a
where id = 148265

and

select a.* from frame as a
where id = 148271

which return 1999-10-15T10:01:22.18 and 1999-11-05T08:23:37.30 UT respectively, and which are possibly a little unlikely for a CV even if part of a same superoutburst, although the errors are large on the second measure.

The nearest similar mag star lies 2' away and has this lightcurve

http://skydot.lanl.gov/nsvs/star.php?num=12807142&mask=18708

But for a faint star to have orphans up to 2 arcminutes away even in this wide field survey would be a bit peculiar.

So the orphans don't really help in this instance, merely being slightly suggestive, especially as they are so few in number.

But the general principle can be seen.

More efficient SQL queries may expedite the searches better and other objects may be better covered.  Certainly several novae, one previously unknown, and at least one previously unknown CV amongst other infrequent outburters lie within the NSVS main dataset.

John Greaves