NGC 6342 / C1718-195
RA: 17:21:10.08  DEC: -19:35:14.7  (J2000)

(Most recent updates: 
Membership probability flag - 2024; Remaining data - June 2013)
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Bytes  Format      Explanation
1-8      A8        Star ID
10-32  A11,1x,A11  Position
34-35    A2        Membership probability flag based on data published
                   by Prudil & Arellano Ferro (2024)
                    m1: prob >=0.85;  m2: prob >=0.7 and <0.85;
                    m3: prob >= 0.5 and <0.7; f: prob <0.5
                    u:  no data available
37-44   F8.4       Period  (days)
46-51   F6.3       Mean magnitude (or maximum magnitude if "max" 
                      is indicated in the remarks column)
53-57   F5.3       Light amplitude (range of variability)
59      A1         Colour for mean magnitude and amplitude
                    e.g.  B, V, R, I, J, K
                    or P (for photographic).
61-65   A5         Type of variable (draft 2006 GCVS classifications)
                      CST denotes non variable stars previously designated
                      as variables
67-80   A19        Notes and Remarks  (f denotes field star)
 
 "--" or "----" indicates no data available
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ID       Position               Mem   Period <mag>  ampl  C Type  Notes/
         RA          Dec        Flag                              Remarks
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No known variables.

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Supplementary Notes

A CM diagram based on VI photometry by Heitsch & Richtler (1999) shows
a pronounced red HB. 
According to the 2010 version of the Harris (1996) catalogue, NGC 6342
is a core collapsed cluster with [Fe/H] = -0.55.


PSR:  According to Paulo Freire's website at the Max Planck Institute 
      in Bonn (July 2024 version), there are 2 millisecond pulsars in 
      NGC 6342.

One of them has unusual properties, as described here.
A binary radio pulsar PSR B1718-19 was discovered in the field of 
NGC 6342 by Lyne et al. (1993). It has an unusally long period (1 sec)
for a binary pulsar associated with a globular cluster. (Pulsars in
binary systems in  globular clusters are usually millisecond pulsars.)
van Kerkwijk et al. (2000) and Janssen & van Kerkwijk (2005) discussed 
scenarios for the formation of such a system. Their preferred
explanation is that the system formed when a dormant pulsar in the 
cluster core had an interaction with a binary.
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References

Harris, W. E. 1996, AJ, 112, 1487

Heitsch, F. & Richtler, T. 1999, A&A, 347, 455

Janssen, T. & van Kerkwijk, M. H. 2005, A&A, 439, 433

Lyne, A. G., Biggs, J. D., Harrison, P. A., Bailes, M. 1993, Nature,
361, 47

Prudil Z., Arellano Ferro, A. 2024, MNRAS, 534, 3654

van Kerkwijk, M. H., Kaspi, V. M., Klemola, A. R., Kulkarni, S. R.,
Lyne, A. G., van Buren, D. 2000, ApJ, 529, 428
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