Hello Bill,

is the remark of Jean Lecacheux in the last sentence of the forwarded mail
correct? FYI, this mail describes an occultation of an apparently nonexisting
star by a minor planet.

Clear skies
Bernd

------- Forwarded message follows -------


Le Mardi 6 Janvier 2015 19:44 GMT, Tim Haymes <tvh.observatory@...> a
écrit:

> 2015 Jan 06, 2053UT
> http://ocultacions.astrosabadell.org/IBEROC/20150106_005876_summary.html
> The prediction is for a star of mag 12.6, but there is nothing this bright at
> the position given. I looked in Aladin at 02 27 38 +27 34 38 (J2000) Regards,
>
> Tim Haymes
> http://www.stargazer.me.uk/

Hi.

Unfortunately phantom stars can be found in the UCAC4 catalog.

Through the following address

http://vizier.u-strasbg.fr/cgi-bin/VizieR-5?-ref=VIZ54ad00a913d9&-out.add=.&-sour
ce=I/322A/out&UCAC4===588-005876
you may verify that 4UC 588-00576 does have a detailed entry in VizieR !

However, despite the claimed 12.6 red magnitude, we remark there is no match with
the catalogs Tycho, UCAC2, AC2000, AGK2, 2MASS, etc., and moreover no APASS
photometry. One may find only one (apparent) positive match with the old Lick
Observatory Northern Proper Motion survey.

In addition the claimed proper motion of the putative star is fast : 71.6
mas/year in PA= 331.7 degrees.

Only one faint star lies in vicinity of the claimed position (red cross on the
attached 6'x 6' "Deep Space Survey" picture) : USNO-B1 1175-0040135 (whose
probable alias is USNO-B1 1175-0040137) = 2MASS 02273874+2734345. Its red
magnitude is about 18.0.

I remark that if we assume the above 71.6 mas/year proper motion, then the
claimed 4UC star had a close appulse with USNO-B1 1175-0040137 =
2MASS 02273874+2734345 in the year 1949, or with USNO-B1 1175-0040135
in the year 1965.

So according to me
1/ The fake 4UC 588-00576 actually is 2MASS 02273874+2734345 .
2/ Its actual proper motion very probably is small.
3/ Its reported magnitude 12.6 in the UCAC4 is entirely fanciful.


I already wrote in [planoccult] three times during the last three years that when
we read in the header of any UCAC4-based prediction something like
" Mv= *** Mp= *** Mr= *** " (i.e. three equal values)
then a thorough verification of the star from any independent source has to be
made absolutely.

Otherwise we get a probability
- about 10 % that the magnitude is false by more than 1.5 unit,
- perhaps 1 % that the star - and related occultation - does not exist.

J.Lecacheux


PS: I remark that my copy of 'Guide 9' displays 4UC 588-005875 and 588-005877
close to the claimed position, but that there is no trace of the 588-005876
label, although the 2MASS star is shown. So it seems that some kind of automatic
corrective already is incorporated in 'Guide'.

------- End of forwarded message -------
Bernd Klemt

Sternwarte Herne, MPC code A18
Herne, Germany

e-mail: info@...
http://www.sternwarte-herne.de