Date: very important.

[Sebastian Otero <varsao@fullzero.com.ar>]

Dear colleagues,

As most of you know, some of us are making intensive use of the publicly
available databases to do systematic searches of variables.
Last week, large discrepances between TASS and NSVS data for an eclipser
were noted and Patrick Wils said that it was a date error. I sent a
lightcurve confirming that and other people also noted the same situation in
other cases.

While other people continue to use words as "alleged" regarding this
problem, my colleague Pavol Dubovsky sent me some stars that he analysed and
one of them --using TASS observations besides NSVS-- had a very important
remark: "period change according to TASS data".
I inmediately downloaded the data and made lightcurves only to confirm that
all TASS eclipses are 1 and 2 days off (YES, TWO).
This is going out of hand. All dates are a chaos recently.
Please take this example and stop trying to explain the unexplainable:

NSV 5040 is a 3.02405 d. period eclipser. "NSV5040_shame" shows how all TASS
eclipses fall outside the expected phases. These are the HJD (2450000+)
dates and the difference with the real world:

3085.6800 12.591 ?
3096.6637 12.710 ?
3096.6654 12.714 ?
3098.6460 12.754 +1 or +2
3098.6477 12.609 +1 or +2
3099.6488 12.899 +2
3099.6505 12.859 +2
3103.6348 13.308 +1
3103.6364 13.027 +1
3105.6293 12.753 +1
3105.6310 12.763 +1
3106.6237 13.347 +1
3106.6253 13.341 +1
3109.6150 13.181 +1
3109.6167 13.125 +1
3112.6164 13.030 +1
3112.6181 12.928 +1
3114.6136 12.629 +1
3120.5919 12.686 +1
3120.5936 12.711 +1
3121.5803 12.705 +1
3121.5820 12.720 +1

So it's not a 1-day problem. It's not day 3109 alone.

"?" means that the date could be whatever. ((Maybe TASS is an online version
of the lotto??))
"+1 or +2" means that the date is wrong but it might be corrected by adding
1 or 2
"+1" means that the dates are corrected by adding 1 day.
"+2" means that the dates are corrected by adding 2 days.

"NSV5040_realworld" is the lightcurve with these corrections applied. The
revelation of the 2 points of day 3099 matching exactly in the ascending
branch by adding 2 is astonishing.
I don't know if I should make jokes about this or simply cry....

I urge that you inmediately hold back from the web all TASS data at least
for these year 2004, because it's a total lack of respect to people having
this data avaliable online. Not all researchers are subscribed to the TASS
list and know what is happening. But if the data is not taken off as soon as
possible, I will take care of publishing this real shame in every way I can
so they become aware.
Furthermore, I think that if you are responsible enough, you should make the
web access unavailable until you completely fix this embarrassing problem.

The TASS database is completely useless right now.

Sebastian Otero.

NSV5040_realworld.gif

NSV5040_shame.gif