[vsnet-alert 9000] Nova Camelopardalis 1999 ? Image request

[ncam1999 at yahoo.com]

Well, this is a kind of "non-alert".  Basically it's a
request for images of a field to show the _absence_ of
something.  It looks likely that there was a missed
faint nova near the North Celestial Pole in spring to
summer 1999.  By now it should be long gone, but it
would be fairly interesting if someone could take an
image of the field, at least 5 arcmin or so across, 
reasonably deep (no need to get rabid over it though),
and make it readily available online somewhere, with a
note to the list of where, as such an image should
hopefully show nothing at the position noted below at
the current time, just as nothing existed there before
the event.  Or possibly there might just be a very
faint object from really deep imaging.  It's near the
Pole so it'll be tricky for most 'scope mounts, no
doubt.  Archival images around the time might show it
during outburst, too.


Thanks in advance to those interested in image follow
up.



A potted summary of details follows:-

---------------------------------------------------------------------------
NSVS J1357306+812719 appears to be a nova that was
missed at the time of outburst, detected on three
independent cameras of the ROTSE1 survey system
contemporaneously. The three camera results are shown
here.

http://skydot.lanl.gov/nsvs/star.php?num=918725&mask=15636
http://skydot.lanl.gov/nsvs/star.php?num=952593&mask=15636
http://skydot.lanl.gov/nsvs/star.php?num=1037109&mask=15636

the first detection was of instrumental red sensitive
magnitude (calibrated against Tycho2 V...) 12.4 on the
6th of April 1999 (JD 2451274.67), in all three
cameras.  It should be noted that ROTSE1 data for
several stars within a few arcminutes of this one have
their first observations at the same date and time as
this object, so detection date is likely to have no
meaning in terms of maximum outburst date.

The object is confirmed by existance in 2MASS on an
overlapping date (below), but otherwise is not seen in
any other survey or catalogue.

No object appears in USNO B1.0 or GSC2.3 at this
position, nor on POSS II plates dated 1997.2717,
1998.0602 and 1998.2245 for J, N and F plates
respectively, down to the limiting magnitude, ie
POSS_J ~21 and POSS_F ~21, or more generally, the
progenitor was fainter than red mag 21.  Nor is it on
1955 POSS I red and blue plates.


However, the object _is_ in 2MASS as 2MASS
J13573022+8127188, for which the far more accurate
astrometry of 

J2000 RA 13h57m30.22s Dec +81d27'18.8"

is given.

Comparison of 2MASS images from June 10th 1999 with
the POSS II images, all taken within two and a bit
years of each other, makes the situation plain, and by
happy coincidence the date of the 2MASS images is June
10th 1999, which is pretty much the same date as when
the last more or less contiguous run of ROTSE1
datapoints occured, ie MJD ~2451340 (see lightcurves'
links above).

This gives contemporaneous colours.  Red mag was 14.3
(error will be around +/- 0.2) and J-Ks colour was
+0.30, so the V magnitude would not have been far 
different from the red (2MASS J was 13.41 and Ks
13.11).  E(B-V) here is 0.04 according to
http://irsa.ipac.caltech.edu/applications/DUST/ , ie
interstellar extinction is negligible, so for any
outburst the expanding pseudophotosphere was akin to
the colour/temperature of a mid spectral type G star
at that time, 65 days after detection, that is it was
not very red even at this late stage.

The drop in magnitude of 2 magnitudes during this time
suggests that the object was a slow nova.  

The time since outburst is likely long enough for the
object to have returned to near quiessence by now,
even given that the rate of decline would have
decreased dramatically, quiessence has either been
reached or 
will be being exponentially approached.

Original instinct, based on the newness of the object
(ROTSE1 survey and 2MASS only appearance) and the
profile and slow rate of the decline, and 
given angular distance from the Galactic Plane, led me
to think it might just be a symbiotic nova, which
might have been of some interest, but as it is likely
merely a missed faint nova, it is probably not of any
importance in terms of nova studies, and of course it
is too late to spectroscopically confirm it.

The outburst amplitude, ie POSS red mag fainter than
21 for any progenitor, ROTSE1 red mag 12.4 at
discovery, and overall colour, even 65 days after
detection, and 
probably longer since maximum outburst luminosity, fit
a nova better though, and the slow decline and
outburst amplitude also precludes most if not all
classes of cataclysmic variable.

A post ROTSE1 levelling off of the lighcurve could
have left a findable quiescent object, however that
can be guesstimated at being around magnitude 18ish at
the very brightest by now.  No online archival image
service appears to have anything at this declination
from dates subsequent to this event.



All surveys and services noted herein are hereby
acknowledged for making their data publicly and often
readily available.  This message can be
cited/forwarded/ignored.
----------------------------------------------------------------------------------


John Greaves


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