Erratum: A 22-yr southern sky survey for transient and variable radio sources using the Molonglo Observatory Synthesis Telescope

Authors

Errata

This article corrects:

  1. A 22-yr southern sky survey for transient and variable radio sources using the Molonglo Observatory Synthesis Telescope Volume 412, Issue 1, 634–664, Article first published online: 13 January 2011

E-mail: k.bannister@physics.usyd.edu.au

The paper ‘A 22-yr southern sky survey for transient and variable radio sources using the Molonglo Observatory Synthesis Telescope’ was published in Mon. Not. R. Astron. Soc. 412, 634–664 (2011). We wish to correct a number of typographical and data processing errors in our original paper.

First, the header in table 2 of Bannister et al. (2011) should read ‘Semi-minor axis (a0/2)’.

Secondly, the NVSS (Condon et al. 1998) identifications for four transient sources were incorrectly specified as ‘not detected’ (ND) in the original paper, as an incorrect matching radius was used. Also, the quoted NVSS measurements for all sources were not bias-corrected. The bias correction is small, and not significant to the overall result. The correct NVSS flux densities for the transient sources are shown in Table 1. The radio light curves of sources with the previously ‘not detected’ NVSS fluxes are shown in Fig. 1 and comments on the same are shown in Table 2.

Table 1.  Abbreviated, corrected version of table 6 from Bannister et al. (2011). Radio sources not detected by MOST at least once, with revised NVSS fluxes. ‘ND’ indicates the source was not detected in NVSS. * indicates this source was classified ‘ND’ in the original paper. ‘–’ indicates the source position is not covered by NVSS.
Source nameNVSS flux density (inline image)
SN1987A
SUMSS J0557123811065.9
J060938333508ND
J0610513424045.5*
SUMSS J062636425807
J0627163717363.2
J0641493717064.1*
SUMSS J10264133361510.0*
SUMSS J1126103302167.5
Nova Muscae 1991
J1210323814399.9
J1353043637265.3
J1536133329158.2
GRO 165540ND
SUMSS J2241523008235.5*
Figure 1.

Abbreviated, corrected version of fig. B1 from Bannister et al. (2011). Light curves of transient sources with corrected NVSS fluxes.

Table 2.  Abbreviated, corrected version of table 7 from Bannister et al. (2011). Summary and classifications of the four transient radio sources with revised NVSS flux density measurements.
SourceRadio light curveCounterparts atClassification
  other wavelengths 
J061051342404Non-detection betweenNo known counterparts.Possible scintillating AGN appearing
 two MOST detections; above the noise threshold.
 also detected in NVSS.  
J064149371706Single detection; alsoNo known counterparts.Possible scintillating AGN appearing
 detected in NVSS. above the noise threshold.
SUMSS J102641333615Single detection; alsoNo known counterparts.Possible scintillating AGN appearing
 detected in NVSS. above the noise threshold.
SUMSS J224152300823Single detection; alsoNVSS source is 10 arcsec fromPossible scintillating AGN appearing
 detected in NVSS.a blue point-like optical source,above the noise threshold.
  but probably not associated. 

The change in NVSS identifications does not impact on our formal definition of a transient source, but it does imply a change in the blind survey transients rate. As described in section 3.6 of the original paper, we define a transient source as one that is not detected by MOST at least once. As described in section 4.3, there are 15 such transient sources, implying a completeness-corrected rate of 1.1 × 10−2 deg−2 in two epochs. If we now add the requirement that a transient source was also not detected in NVSS, there are only five such transients, with an implied rate 1/3 of the original rate, i.e. 3.7 × 10−3 deg−2 in two epochs. Of these five transients, three were initially detected at other wavelengths (SN1987A, GRO 165540, Nova Muscae 1991), so only two were detected in a truly blind survey, implying a rate of 2/15 the original, i.e. 1.5 × 10−3 deg−2 in two epochs.

ACKNOWLEDGMENTS

We thank Geoffrey Bower for bringing the incorrect NVSS identifications to our attention and Kate Randall for noting the incorrect table header. KWB acknowledges the support of an Australian Postgraduate Award.

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