Tales of Cataloguing XVI -- 6 positional fixes of faint legacy quasars

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Eric Flesch

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Oct 31, 2021, 2:46:43 AMOct 31
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The Million Quasars (MILLIQUAS) catalogue v7.3 has been released,
which has all quasars published to 31 October 2021. It and its ReadMe
are available at
http://quasars.org/milliquas.htm
and at NASA HEASARC at
http://heasarc.gsfc.nasa.gov/W3Browse/all/milliquas.html

Part of its updates were tweaks of the J2000 for very faint (r>22)
legacy quasars, i.e., those inherited from the Veron-Cetty & Veron
(VCV) quasar catalogue, 13th edition. I've checked about 300 of these
against Pan-STARRS and DES charts, resources which were not available
until recent years. I've corrected positional discrepancies which
were usually in the range of 0.5 - 2.5 arcsec. But there were a few
farther offset because of errors made by the authors or by VCV. In
line with previous postings in this "Tales of Cataloguing" series, I
present here 6 corrections of > 10 arcsec in order of greatest
offsets; 3 of these are basically lost objects, now recovered.

(1) CXOPS J042155.0+330037, z=1.125, is at 04 21 55.04 +33 00 36.3
(J2000), it was published by Rogel+ 2006-ApJS-163-160. Somehow, VCV
wrote RA as 042105.0 (05 instead of 55), resulting in a 629 arcsec
offset (50 time sec) from the true. Now fixed, but NED does have the
correct position.

(2 & 3) AMS03, z=2.698 at 17 13 40.19 +59 27 45.8, and AMS04, z=1.782
at 17 13 40.57 +59 49 17.0, are both type-II objects from
Martinez-Sansigre+ 2006-MNRAS-370-1479. Somehow, VCV wrote their
time-seconds as 14 instead of 40, so both objects were offset about
200 arcsec from the true. Now fixed, but NED does have the correct
positions.

(4) ISO J1324-2016, z=1.50, is at 13 24 47.25 -20 16 12.0 (J2000)
which is from Pierre+ 2001-A&A-372-L45 -- which is to say, from the
authors' finding chart. What the authors actually wrote as the
position was 13 24 45.67 -20 16 11.3 (J2000), which points to nothing
and is 21.3 arcsec offset from the true. The false position was
faithfully reported by VCV and NED. This correction recovers this
quasar after 20 years MIA.

(5) Q 03022-0023, z=2.14, is at 03 04 46.11 -00 11 27.5 (J2000) and
is from Jakobsen+ 2003-A&A-397-891. The paper was focused on another
object and briefly stated (end of section 2) a faint emission QSO at
03 04 45.94 -00 11 38.2. Nothing is seen there on DES or Pan-STARRS
-- clearly the astrometry was done hurriedly. NED reports the false
position. 10.8 arcsec to the NE is a flat-spectrum object, r=22.14,
g=22.28, with 97% x-ray 4XMM J030446.0-001127. It is the quasar,
salvaged after 18 years MIA.

(6) PC 0027+0525, z=4.099, r=21.7, g=24.7, is from
Schneider/Schmidt/Gunn 1997-AJ-114-36; they wrote the position as
00 27 15.4 +05 25 30 (B1950) which converts to 00 29 49.96 +05 42 04.4
in J2000. However, nothing is seen there, and NED reports this false
position. However, the authors also gave a finding chart on which the
quasar is seen at the true position of 00 29 49.99 +05 42 14.5 (J2000)
at 10.6 arcsec offset. Thus it is recovered after 24 years MIA.

Eric Flesch
New Zealand
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