VZ TUC

Hi Stephen, Looking at LCGv2, there are a bunch of visual obs by Tom Cragg and Al Jones, over a substantial range of magnitudes, 13-15, and spread out over 5 years span in the mid-90's. A nova outburst would be expected to show a single sharp curve, of rapid rise and fall over a relatively short period of time.

So, it appears odd. Looking at the VSP chart, I notice a strange effect, when I plot the DSS background, the chart shows a sharp discontinuity in the stars visible. So, its possible there is/was a chart issue and/or misidentification of the variable back then? Too bad neither JA nor CR are with us anymore to shed further light on this mystery!

Looking further, it seems some of the obs then were made using RASNZ charts. I do not have access to these, so maybe someone could look at the older ones and compare to the current VSP, to see what's up? Also, I found an obs by Peter Nelson in 1991, and he certainly is still around, maybe he could give us some thoughts about whether this was a real outburst or misidentification?

Mike

Hi,

Don't see any references in the online literature for VZ Tuc that mentions NR. Could be though. Min would likely be <19, at least. More likely to be NA as in VSX. Those multiple positives in the DB by some of the most renowed VSO'ers in history is somewhat curious however keeping in mind that the charting and reference apps and tech we use nowadays to assist us in our pursuits through what was once termed the 'inner sanctum' was only starting to come on, I find it easier to understand how possible misidentifications could have been made, especially in crowded areas. The present day 146 and 159 comps are the two brightest stars near the VSX position for VZ Tuc. Everything else thats' closer in is mag 16 or fainter. I found a file in my image archives that covers that part of the SMC taken last October showing the VSX position empty (<180V). In SIMBAD, the default 2x2 arc-min DSS JPEG shows a REALLY faint object(s) (21-22m?) at the VSX position. The Downes 2006 ref  and image suggests a tight smattering of <mag20 stars at or extremely close to position.  As this area is fairly close to another var I'm interested in (RAW 21) I will randomly check for VZ Tuc as well . You never know, perhaps our mentors really did see a recurrance.

Thanks guys for bringing up this interesting star !

Steve

Thanks for your comments. Here is part of the old RASNZ Chart 1005 for VZ TUC. The star just below VZ TUC is our 146 and the two dots above are about 152-156. But even if one of these were misidentified as the variable, it doesn't account for the 12-13th magnitude observations. And they were made by very capable observers. Anyway, I will keep watch.

Thanks Stephen for posting part of the older RASNZ chart for VZ Tuc. To me, the indicated position is very accurate. As you mentioned, the dot (at 4 o'clock) is the 146. The faint point (at 10 o'clock) is the 159. And VZ is on a straight line between them. The dot due N of VZ is a faint double on DSS. There is an additional, fainter field star closer to VZ (almost due N of VZ at 14" which is no brighter than 16.5). If our experienced observers in the 1990's were using the chart you posted, I find it hard to imagine them misidentifying in this case. Especially, as you pointed out, some of the positives were quite bright. I am going to look over those obs from years gone by. Were folks simply forgetting a (< fainter than) or do we have a bonefide NR here ?  btw, there is no bright 2MASS counterpart as with V745 Sco.

Cheers,

Steve         

Hi all

i have an old RASNZ VSS Circular for Feb 1991 which covers one of Albert Jones' positive observations of VZ Tuc. It was listed as a "class 3" observation which means that it's uncertain. Also there's a negative observation (<14.7) by Bill Goltz one day after Albert's observation.

So for this occasion, I think it's a reasonable assumption that it was not in outburst.

Unfortunately I don't have Circulars covering the later positive observations in the AID.

Regards

Andrew Pearce