AstroNote 2019-60

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2019-08-01 16:45:23
Type: Announcement-Tool/Utility
Revising the astrometric accuracy values on the TNS and merging of objects
Authors: Ofer Yaron (Weizmann)
We further revise the astrometric accuracies of several surveys by rounding up the values, in order to decrease the occurrence of situations where separate objects are created on the TNS that are actually for the same transient/event. We list the objects that have been recently merged on the TNS.

As some are aware, since we've deployed the new astrometric accuracies mechanism on 2019-06-23 (AstroNote 2019-37), and although we've applied "conservative" values (for the accuracy values), based on statistical analysis of real data from the TNS with addition of safety buffers, several objects were created as separate ones although they are actually for the same transient (event), thus require merging.

As a quick immediate measure (to be further examined in the future) to improve the situation, we decided to increase and round up the astrometric accuracy values of several surveys, for which there seems to be a larger astrometric scatter. All other details remain exactly as is described in AstroNote 2019-15 and AstroNote 2019-37. (As has been mentioned, the up-to-date values of the astrometric accuracy can always be viewed on the TNS Groups page.) 

The accuracies of the following surveys were revised:

Survey 0.95 quantile Previous Accuracy (30% margin rounded) New value
GaiaAlerts ----- 0.2 0.3
Pan-Starrs1 0.38 0.5 0.9
OGLE 0.43 0.6 1.0
ZTF 0.44 0.6 1.0
ATLAS 0.83 1.1 1.5
POSS 1.34 1.7 2.0


The following objects were merged and removed on 2019-08-01:

  • 2019kko (ZTF) removed and merged with 2019kan (ATLAS).
  • 2019jky (PS1) removed and merged with 2019agn (ZTF).
  • 2019lue (ATLAS) removed and merged with 2019lmd (ZTF).
  • 2019lvg (ZTF,PS1) removed and merged with SN 2019lpu (ATLAS).
  • 2019mcc (ATLAS) removed and merged with 2019lnc (PS1).
  • 2019lwd (Gaia) removed and merged with SN 2019ltx (ATLAS).
  • 2019kkh (ZTF) removed and merged with SN 2019zc (ATLAS).
  • 2019kif (Gaia) removed and merged with 2019hyv (ATLAS).
  • 2019jil (PS1) removed and merged with 2019aqj (ATLAS).
  • 2019klo (ATLAS) removed and merged with 2019jzx (ZTF).
  • 2019jzi (ZTF) removed and merged with 2019ilp (ATLAS).
  • 2019kln (ATLAS) removed and merged with 2019hoh (PS1).
  • 2019kad (ATLAS) removed and merged with 2019ihk (ZTF).
  • 2019lpm (ATLAS) removed and merged with SN 2019lks (ZTF).
  • 2019kam (ATLAS) removed and merged with SN 2019lqn (Gaia).

For all merged objects, comments are added to the object pages, emails are sent to the relevant surveys group owners and updates are sent for the ADS indexes.