NGC 6544 / C1804-250
RA: 18:07:20.64  DEC: -24:59:50.4  (J2000)

(Most recent updates: 
Membership probability flag - 2024; Remaining data - March 2016)
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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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1        18:07:16.11 -25:00:48.9 f  ----     18.15  0.5   B E?    
2        18:07:28.37 -25:01:52.7 m1   0.5723 15.85  1.5   B RR0   Note
PSR      -- -- --     -- -- --   u  ----     --     --            3 msPs
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Supplementary Notes 

A CM diagram by Cohen et al. (2014) shows a well populated blue HB with 
an extended tail and a centrally concentrated blue straggler population.
The 2010 update to the Harris (1996) catalogue lists [Fe/H] = -1.40. 

In the above table, the RA and dec are from Samus et al. (2009).  The 
data for V1 are from the discovery paper by Hazen (1993).
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Notes on individual stars

V2: This variable was also recovered in the OGLE III survey of
    RR Lyrae Star in the Galactic Bulge (Soszynski et al. 2011) where 
    it is listed as OGLE-BLG-RRLYR-13867. The period listed in the 
    above table is from the OGLE IV study (Soszynski et al 2014).  The 
    remaining data are from Hazen (1993).
    According to Hazen, the star's membership status is uncertain. 
    At r ~ 2.7 arcminutes from the cluster centre, it is beyond the
    tidal radius which is ~ 2.15 arcminutes according to the 2010 update
    to the Harris (1996) catalogue.
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Discovery of the variable stars in NGC 6544:

  V1-2 
     Hazen (1993) with x,y coordinates, 1950 RA & dec, and an ID chart
     She also identified two field variables: F1 and F2. 

  PSR:  According to Paulo Freire's website at the Max Planck 
        Institute in Bonn (July 2024 version), there are 
        3 millisecond pulsars in NGC 6544.
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References

Cohen, R. E., Mauro, F., Geisler, D., Moni Bidin, C., Dotter, A.,
Bonatto, C. 2014, AJ, 148, 18

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

Hazen, 1993, AJ, 106, 1055 

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

Samus, N. N., Kazarovets, E. V., Pastukhova, E. N., Tsvetkova, T. M.,
Durlevich, O. V. 2009, PASP, 121, 1378

Soszynski, I., Dziembowski, W. A., Udalski, A., Poleski, R., Szymanski,
M. K., Kubiak, M., Pietrzynski, G. and 4 coauthors, 2011a, Ac. A., 61, 1

Soszynski, I., Udalski, A., Szymanski, M. K., Pietrukowicz, P., Mroz,
P., Skowron, J., Kozlowski, S. and 6 coauthors,  2014, Ac. A. 64, 177

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