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Daniel Bramich
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Variable Stars In Globular Clusters

I work as part of a collaboration which aims to study the variable stars in Galactic globular clusters. We routinely discover new variables in the crowded central regions of these clusters using difference image analysis (DIA) and we analyse the variable star light curves in order to study the properties of the variables themselves and of the cluster in which they reside. Below I list our variable star discoveries for the clusters that we have studied. The clusters are listed in alpha-numerical order. The information is up to date as of 01/04/2016.


  • NGC104 (47 Tucanae): Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      EM1 : Semi-regular variable
      EM2 : Semi-regular variable
      EM3 : Semi-regular variable
      EM4 : Semi-regular variable
      EM5 : Long-period irregular variable
      EM6 : Long-period irregular variable
      EM7 : Unclassified

    • We reclassified WF2-V34 as a long-period irregular variable.

    • We reclassified LW11 as a semi-regular variable.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC288: Click for details...

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    Our variable star discoveries from Arellano Ferro et al. (2013):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We did not discover any new variable stars, although we can be sure that there are no more RR Lyrae stars that are cluster members in the field of view of our study.

    • Our data are on CDS.

    Since our above publication:

    • Martinazzi et al. (2015) discovered the new variables:

      V11 : SX Phe
      V12 : SX Phe

      These two variables are of very low amplitude.



  • NGC1904 (M79): Click for details...

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    Our variable star discoveries from Kains et al. (2012):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variable:

      V14 : RR1

    • We classified V7 as a long-period irregular variable.

    • We speculated that V9 could be a RR01 (double mode) variable.

    • Our data are on CDS.

    Since our above publication:

    • Kopacki (2015) discovered the new variables:

      V15 : RR1
      V16 : SX Phe
      V17 : SX Phe
      V18 : SX Phe
      V19 : Long-period irregular variable
      V20 : Long-period irregular variable
      V21 : Long-period irregular variable
      V22 : Long-period irregular variable
      V23 : Long-period irregular variable
      V24 : Long-period irregular variable
      V25 : Long-period irregular variable
      V26 : Long-period irregular variable
      V27 : Long-period irregular variable
      V28 : Long-period irregular variable
      V29 : SX Phe
      V30 : SX Phe
      V31 : W UMa eclipsing binary
      V32 : Unclassified
      V33 : Long-period irregular variable
      V34 : Long-period irregular variable

      A number of these variables were outside the field-of-view of our previous study.

    • Kopacki (2015) reclassified V7 as a Population II Cepheid (W Virginis).

    • Kopacki (2015) classified V8 as a semi-regular variable. This star was saturated in our data.



  • NGC4147: Click for details...

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    Our variable star discoveries from Arellano Ferro et al. (2004):

    • We used DAOPhot to perform PSF photometry on the CCD images in order to extract the light curves. For the variable star search, we used the version of DanDIA described in Bramich et al. (2005) to perform difference image analysis.

    • We discovered the new variable:

      V18 : Tentatively classified as RR0

    • We reported that V5 and V15, previously thought to be variable, are in fact non-variable.

    • We classified V16 as RR1.

    • Our data are on CDS.

    Since our above publication:

    • Stetson et al. (2005) discovered the new variable:

      V19 : RR1

    • Stetson et al. (2005) found that V18 is non-variable.



  • NGC4590 (M68): Click for details...

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    Our variable star discoveries from Kains et al. (2015):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V49 : SX Phe
      V50 : SX Phe
      V51 : SX Phe
      V52 : SX Phe

    • We confirmed the variability of the standard star S28 (Walker 1994) and we assigned the name V53. The type of variability of this star remains unknown.

    • We confirmed that V40, V41 and V42 are non-variable stars.

    • We did not detect any variability above the noise in our light curves for the nine stars claimed to be variable by Sariya et al. (2014).

    • We are sure that there are no more RR Lyrae stars that are cluster members in the field of view of our study.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC5024 (M53): Click for details...

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    Our variable star discoveries from Arellano Ferro et al. (2011):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V91 : RR1
      V92 : RR1
      V93 : SX Phe
      V94 : SX Phe
      V95 : SX Phe
      V96 : SX Phe
      V97 : SX Phe
      V98 : SX Phe
      V99 : SX Phe
      V100 : SX Phe
      V101 : SX Phe
      V102 : SX Phe
      V103 : SX Phe
      V104 : SX Phe
      V105 : SX Phe

    • We reported that V81, V82 and V83, previously thought to be variable, are in fact non-variable.

    • We announced the variable star candidates S1, S2, S3, S4 and S5.

    • Our data are on CDS.

    Our variable star discoveries from our follow-up paper Arellano Ferro et al. (2012):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We concluded that the rate of incidence of the Blazhko effect in this cluster is at least 37% and 66% for the RR0 and RR1 variables, respectively.

    • Our data are on CDS.

    Since our above publications:

    • Safonova & Stalin (2011) presented 74 candidate variable stars in NGC5024.

    We followed up on the results presented in the Safonova & Stalin (2011) paper. We made the following variable star discoveries in Bramich et al. (2012):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We confirmed the variability and classification of three of the Safonova & Stalin (2011) variable star candidates:

      V106 : SX Phe
      V107 : SX Phe
      V108 : SX Phe

    • We tentatively confirmed the variable nature of the Safonova & Stalin (2011) variable star candidates W11 and SX12.

    • We discovered the new variable:

      V109 : Semi-regular variable

    • We found that 10 of the Safonova & Stalin (2011) variable star candidates are already known variables and that 54 candidates are false positive detections.

    • Our data are on CDS.

    Since our last publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC5053: Click for details...

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    Our variable star discoveries from Arellano Ferro et al. (2010):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We announced the variable star candidates BS4, BS5, BS19, BS22, BS23, BS25, BS28, BS29, BS30, BS31 and NV1.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC5139 (Omega Centauri): Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V457 : Unclassified
      V458 : Long-period irregular variable
      V459 : Long-period irregular variable

    • Our data are on CDS.

    Since our above publication:

    • Lebzelter & Wood (2016) discovered the new variables:

      LW1 : Long-period irregular variable
      LW2 : Long-period irregular variable
      LW3 : Long-period irregular variable
      LW4 : Long-period irregular variable
      LW5 : Long-period irregular variable
      LW6 : Long-period irregular variable
      LW7 : Long-period irregular variable
      LW8 : Long-period irregular variable
      LW9 : Long-period irregular variable
      LW10 : Long-period irregular variable
      LW11 : Long-period irregular variable
      LW12 : Long-period irregular variable
      LW13 : Long-period irregular variable
      LW14 : Long-period irregular variable
      LW15 : Long-period irregular variable
      LW16 : Long-period irregular variable
      LW17 : Long-period irregular variable
      LW18 : Long-period irregular variable
      LW19 : Long-period irregular variable
      LW20 : Long-period irregular variable
      LW21 : Long-period irregular variable
      LW22 : Long-period irregular variable
      LW23 : Long-period irregular variable
      LW24 : Long-period irregular variable
      LW25 : Long-period irregular variable
      LW26 : Long-period irregular variable

      All of these variables are outside the field-of-view of our previous study.



  • NGC5286: Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V63 : SX Phe
      V64 : RR1
      V65 : RR0
      V66 : Semi-regular variable
      V67 : Semi-regular variable
      V68 : Semi-regular variable
      V69 : Long-period irregular variable
      V70 : Long-period irregular variable
      V71 : Long-period irregular variable
      V72 : Long-period irregular variable
      V73 : Long-period irregular variable

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC5466: Click for details...

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    Our variable star discoveries from Arellano Ferro et al. (2008):

    • We used the version of DanDIA described in Bramich et al. (2005) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V37 : Semi-regular variable
      V38 : Semi-regular variable

    • We announced the variable star candidates CV1, CV2 and CV3.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC5904 (M5): Click for details...

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    Our variable star discoveries from Arellano Ferro et al. (2015):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V170 : SX Phe
      V171 : Semi-regular variable
      V172 : Semi-regular variable
      V173 : Semi-regular variable
      V174 : Semi-regular variable
      V175 : Semi-regular variable
      V176 : Semi-regular variable
      V177 : Semi-regular variable
      V178 : Semi-regular variable
      V179 : Semi-regular variable
      V180 : Semi-regular variable
      V181 : Semi-regular variable

    • We reported that V23, V46, V48, V49, V51, V124, V136, V138, V140, V143, V144, V145, V146, V147, V148, V149, V150, V151, V152, V153 and V154, previously thought to be variable, are in fact non-variable.

    • We reclassified V155 as a W UMa eclipsing binary.

    • Our data are on CDS.

    Our variable star discoveries from Arellano Ferro et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We reclassified V104 and V127 as RR0 stars.

    • We classified V158 as an RR1 star.

    • Our data are on CDS.

    Since our above publications, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6093 (M80): Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V35 : Long-period irregular variable
      V36 : Long-period irregular variable
      V37 : Long-period irregular variable
      V38 : Long-period irregular variable
      V39 : Long-period irregular variable
      V40 : Long-period irregular variable

    • The star T Scorpii underwent an outburst on May 21st 1860 and consequently it became the first variable star discovered in the field of a globular cluster. We observed the first outburst of this Nova since the 1860 outburst, and therefore we have named this variable as V34. The Nova seems to be a cluster member from its position in the CMD.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6121 (M4): Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We did not discover any new variable stars, although we can be sure that there are no more RR Lyrae stars that are cluster members in the field of view of our study.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6229: Click for details...

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    Our variable star discoveries from Arellano Ferro et al. (2015):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V49 : RR0
      V50 : RR0
      V51 : RR0
      V52 : RR0
      V53 : RR0
      V54 : RR0
      V55 : RR0
      V56 : RR0
      V57 : RR0
      V58 : RR0
      V59 : RR1
      V60 : RR1
      V61 : RR1
      V62 : RR1
      V63 : RR1
      V64 : Semi-regular variable
      V65 : Semi-regular variable
      V66 : Semi-regular variable
      V67 : Population II Cepheid (BL Herculis)
      V68 : SX Phe
      V69 : Unclassified
      V70 : Semi-regular variable
      V71 : Semi-regular variable
      V72 : Semi-regular variable
      V73 : Tentatively classified as a Population II Cepheid

    • We reported that V25, V26 and V28, previously thought to be variable, are in fact non-variable.

    • We confirmed the variability of V29 and V30, both of which we classified as RR0 variables.

    • We reclassified V31 and V32 as RR0 variables.

    • We reclassified V39 and V48 as RR1 variables.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6333 (M9): Click for details...

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    Our variable star discoveries from Arellano Ferro et al. (2013):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V22 : RR1
      V23 : RR1
      V24 : W UMa eclipsing binary
      V25 : Algol-type eclipsing binary
      V26 : Long-period irregular variable
      V27 : Long-period irregular variable
      V28 : Long-period irregular variable
      V29 : Long-period irregular variable
      V30 : Long-period irregular variable
      V31 : Long-period irregular variable
      V32 : W UMa eclipsing binary
      V33 : RR0
      V34 : Long-period irregular variable

    • We reclassified V12 as an anomalous Cepheid pulsating in the fundamental mode and we conjectured that it is a cluster member.

    • We reclassified V19 as a RR01 (double mode) variable.

    • We confirmed the W UMa eclipsing binary classification for V21.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6366: Click for details...

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    Our variable star discoveries from Arellano Ferro et al. (2008):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V3 : Tentatively classified as an Anomalous Cepheid or a Population II Cepheid (W Virginis)
      V4 : Long-period irregular variable
      V5 : Long-period irregular variable
      V6 : SX Phe
      V7 : Long-period irregular variable
      V8 : Eclipsing binary

    • We announced the variable star candidates C1, C2, C3, C4, C5, C6, C7, C8, C9, C10 and C11.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6388: Click for details...

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    Our variable star discoveries from Skottfelt et al. (2015):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V74 : Tentatively classified as RR1
      V75 : RR1
      V76 : RR0
      V77 : Anomalous Cepheid
      V78 : Semi-regular variable
      V79 : Semi-regular variable
      V80 : RV Tauri
      V81 : Semi-regular variable
      V82 : RV Tauri
      V83 : Semi-regular variable
      V84 : Semi-regular variable
      V85 : Semi-regular variable
      V86 : Semi-regular variable
      V87 : Semi-regular variable
      V88 : Semi-regular variable
      V89 : Semi-regular variable
      V90 : Semi-regular variable
      V91 : Semi-regular variable
      V92 : Semi-regular variable
      V93 : Semi-regular variable
      V94 : Semi-regular variable
      V95 : Semi-regular variable
      V96 : Long-period irregular variable
      V97 : Long-period irregular variable
      V98 : Long-period irregular variable
      V99 : Long-period irregular variable
      V100 : Long-period irregular variable
      V101 : Long-period irregular variable
      V102 : Long-period irregular variable
      V103 : Long-period irregular variable
      V104 : Long-period irregular variable
      V105 : Long-period irregular variable
      V106 : Long-period irregular variable
      V107 : Long-period irregular variable
      V108 : Long-period irregular variable
      V109 : Long-period irregular variable
      V110 : Long-period irregular variable
      V111 : Long-period irregular variable
      V112 : Long-period irregular variable
      V113 : Long-period irregular variable
      V114 : Long-period irregular variable
      V115 : Long-period irregular variable
      V116 : Long-period irregular variable
      V117 : Long-period irregular variable
      V118 : Long-period irregular variable
      V119 : Tentatively classified as a long-period irregular variable
      V120 : Unclassified
      V121 : Unclassified

    • We classified V29, V63 and V69 as Population II Cepheids (BL Herculis).

    • We classified V70, V72 and V73 as Population II Cepheids (W Virginis).

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6401: Click for details...

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    Our variable star discoveries from Tsapras et al. (2017):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V38 : Long-period variable
      V39 : Long-period variable
      V40 : Long-period variable
      E1 : Eclipsing binary
      LPV2 : Long-period variable
      LPV4 : Long-period variable
      LPV5 : Long-period variable
      LPV6 : Long-period variable
      LPV7 : Long-period variable
      LPV8 : Long-period variable
      LPV9 : Long-period variable
      LPV10 : Long-period variable
      LPV11 : Long-period variable

    • We reported that V1, V20 and OGLE-BLG-RRLYR-23724, previously thought to be variable, are in fact non-variable.

    • We classified V3 as a Population II Cepheid (W Virginis).

    • We classified V8 as RR1.

    • We classified V10 and V14 as RR0.

    • We detected double mode pulsations in the RR Lyrae star V12 and identified that at least one of the modes is non-radial.

    • Our data are on CDS.

    Since our above publication:

    • Soszynski et al. (2016) discovered the new variables:

      V41 : Eclipsing binary
      V42 : Ellipsoidal variable
      V43 : Eclipsing binary
      V44 : Ellipsoidal variable
      V45 : Ellipsoidal variable
      V46 : Ellipsoidal variable
      V47 : Ellipsoidal variable
      V48 : Ellipsoidal variable
      V49 : Eclipsing binary
      V50 : Eclipsing binary
      V51 : Ellipsoidal variable
      V52 : Ellipsoidal variable
      V53 : Eclipsing binary
      V54 : Eclipsing binary

      These variables are all too faint to have been detected in our data.



  • NGC6441: Click for details...

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    Our variable star discoveries from Skottfelt et al. (2015):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V151 : RR0
      V152 : Tentatively classified as RR0
      V153 : Population II Cepheid (W Virginis)
      V154 : Population II Cepheid (W Virginis)
      V155 : Unclassified
      V156 : Semi-regular variable
      V157 : Semi-regular variable
      V158 : Semi-regular variable
      V159 : Semi-regular variable
      V160 : Semi-regular variable
      V161 : Semi-regular variable
      V162 : Semi-regular variable
      V163 : Tentatively classified as a semi-regular variable
      V164 : Unclassified
      V165 : Semi-regular variable
      V166 : Semi-regular variable
      V167 : Semi-regular variable
      V168 : Semi-regular variable
      V169 : Long-period irregular variable
      V170 : Long-period irregular variable
      V171 : Long-period irregular variable
      V172 : Long-period irregular variable
      V173 : Long-period irregular variable
      V174 : Long-period irregular variable
      V175 : Long-period irregular variable
      V176 : Long-period irregular variable
      V177 : Long-period irregular variable
      V178 : Long-period irregular variable
      V179 : Long-period irregular variable
      V180 : Long-period irregular variable
      V181 : Long-period irregular variable
      V182 : Long-period irregular variable
      V183 : Long-period irregular variable
      V184 : Long-period irregular variable
      V185 : Long-period irregular variable
      V186 : Long-period irregular variable
      V187 : Long-period irregular variable
      V188 : Long-period irregular variable
      V189 : Long-period irregular variable
      V190 : Long-period irregular variable
      V191 : Long-period irregular variable
      V192 : Long-period irregular variable
      V193 : Long-period irregular variable
      V194 : Long-period irregular variable
      V195 : Long-period irregular variable
      V196 : Long-period irregular variable
      V197 : Long-period irregular variable
      V198 : Long-period irregular variable
      V199 : Long-period irregular variable

    • We classified V118 as RR0.

    • We classified V132 as a Population II Cepheid (BL Herculis).

    • We classified V126, V127, V128 and V129 as Population II Cepheids (W Virginis).

    • We reclassified V139 as a semi-regular variable.

    • We reclassified V145 as a RR01 (double mode) variable.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6528: Click for details...

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    Our variable star discoveries from Skottfelt et al. (2015):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V1 : RR1
      V2 : Tentatively classified as RR0
      V3 : Long-period irregular variable
      V4 : Long-period irregular variable
      V5 : Long-period irregular variable
      V6 : Long-period irregular variable
      V7 : Tentatively classified as an eclipsing binary

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6541: Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V21 : RR0
      V22 : Long-period irregular variable

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6638: Click for details...

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    Our variable star discoveries from Skottfelt et al. (2015):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V64 : RR1
      V65 : RR1
      V66 : RR0
      V67 : RR0
      V68 : RR0
      V69 : Semi-regular variable
      V70 : Semi-regular variable
      V71 : Long-period irregular variable

    • We classified V25, V26, V27, V30, V31 and V32 as RR0.

    • We classified V29 and V33 as RR1.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6652: Click for details...

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    Our variable star discoveries from Skottfelt et al. (2015):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V13 : Unclassified
      V14 : Eclipsing binary (blue straggler) or field RR1

    • We detected ~1.1 magniutude variations in the optical light curve of V11.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6656 (M22): Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We did not discover any new variable stars, although we can be sure that there are no more RR Lyrae stars that are cluster members in the field of view of our study.

    • We observed an outburst of the dwarf nova CV1.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6681 (M70): Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variable:

      V6 : RR1

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6715 (M54): Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V212 : Eclipsing binary
      V213 : RR1
      V214 : RR1
      V215 : RR1
      V216 : RR1
      V217 : RR1
      V218 : RR1
      V219 : RR1
      V220 : RR1
      V221 : RR01 (double mode)
      V222 : Tentatively classified as RR0
      V223 : RR0
      V224 : Tentatively classified as RR0
      V225 : Tentatively classified as RR1
      V226 : Tentatively classified as RR0
      V230 : RR0
      V231 : RR0
      V232 : RR0
      V234 : RR0
      V235 : RR0
      V238 : RR0
      V239 : RR0
      V241 : RR0
      V242 : RR0
      V243 : RR0
      V245 : RR0
      V247 : RR0
      V248 : RR0
      V249 : RR0
      V254 : RR0
      V255 : RR0
      V256 : Population II Cepheid (W Virginis)
      V257 : Semi-regular variable
      V258 : Semi-regular variable
      V259 : Semi-regular variable
      V260 : Long-period irregular variable
      V261 : Long-period irregular variable
      V262 : Long-period irregular variable
      V263 : Long-period irregular variable
      V264 : Long-period irregular variable
      V265 : Long-period irregular variable
      V266 : Long-period irregular variable
      V267 : Long-period irregular variable
      V268 : Long-period irregular variable
      V269 : Long-period irregular variable
      V270 : Long-period irregular variable
      V271 : Long-period irregular variable
      V272 : Long-period irregular variable
      V273 : Long-period irregular variable
      V274 : Long-period irregular variable
      V275 : Long-period irregular variable
      V276 : Long-period irregular variable
      V277 : Long-period irregular variable
      V278 : Long-period irregular variable
      V279 : Long-period irregular variable
      V280 : Long-period irregular variable
      V281 : Unclassified
      V282 : Unclassified
      V283 : Unclassified
      V284 : Unclassified
      V285 : Unclassified
      V286 : Unclassified
      V287 : Unclassified
      V288 : Unclassified
      V289 : Unclassified
      V290 : Unclassified
      V291 : Unclassified

    • We reclassified V112 as a semi-regular variable.

    • Montiel & Mighell (2010) presented 33 RR Lyrae star candidates that lie within the field-of-view of our study. We found that 3 of these stars are previously known RR Lyraes, and we confirmed the variable nature of a further 22 candidates. However, we did not detect variability in the remaining 8 candidates.

    • McDonald et al. (2014) presented 18 variable star candidates that lie within the field-of-view of our study. We confirmed the variable nature of 2 of these candidates, but we did not detect variability in the others.

    • Our data are on CDS.

    Since our above publication:

    • Hamanowicz et al. (2016) independently discovered the variables V213, V214, V215, V217, V219, V220, V223, V230, V231, V234, V239, V241, V242, V247, V254, V255, V256, V262, V263, V270, V271, V273, V274, V275, V279, V280, V284, V285, V286, V287, V289, V290 and V291.

    • Hamanowicz et al. (2016) classified some of their independently discovered variables differently to our classifications for the same stars. Specifically, they classified V214, V220, V263, V284, V285 and V289 as RR0 stars. They classified V291 as an RR1 star. They classified V230 as a Population II Cepheid (BL Herculis). Finally, they classified V271, V273, V274, V275, V279, V280, V286 and V287 as semi-regular variables.

    • Hamanowicz et al. (2016) discovered the new variables V292-V347. Most of these variables were outside the field-of-view of our previous study.



  • NGC6723: Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We did not discover any new variable stars, although we can be sure that there are no more RR Lyrae stars that are cluster members in the field of view of our study.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6752: Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2016):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We did not discover any new variable stars, although we can be sure that there are no more RR Lyrae stars that are cluster members in the field of view of our study.

    • We observed an outburst of the dwarf nova V26.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC6981 (M72): Click for details...

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    Our variable star discoveries from Bramich et al. (2011):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V43 : RR1
      V44 : Tentatively classified as RR0
      V45 : Tentatively classified as RR0
      V46 : RR1
      V47 : RR0
      V48 : RR0
      V49 : RR0
      V50 : RR0
      V51 : Tentatively classified as RR0
      V52 : RR0 or RR1
      V53 : RR0 or RR1
      V54 : SX Phe
      V55 : SX Phe
      V56 : SX Phe

    • We reported that V6, V19, V22, V26, V30, V33, V34, V37, V39, V40, V41, S1, S2, S4, S6, R1, R2, R5, R6 and R7, previously thought to be variable, are in fact non-variable.

    • Our data are on CDS.

    Our variable star discoveries from our follow-up paper Skottfelt et al. (2013):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the EMCCD images in order to extract the light curves.

    • We discovered the new variables:

      V57 : RR1
      V58 : Unclassified

    • Our data are on CDS.

    Since our above publications:

    • Amigo et al. (2013) discovered the new variables:

      V59 : RR0
      V60 : RR0

      These variables were all outside the field-of-view of our previous studies.

    • Amigo et al. (2013) found that V38 is a non-variable star. We had not been able to study this star because it was close to a brighter saturated star in our data.

    • Amigo et al. (2013) found that V39 is a field RR0 variable star behind the cluster. We had not detected variability in this star.

    • Amigo et al. (2013) found that V42 is a variable star but they were unable to classify it. This star was saturated in our data.

    • Amigo et al. (2013) confirmed our classification of V44 and V51 as RR0 stars.

    • Amigo et al. (2013) reclassified V45 as an RR1 star. We had tentatively classified this variable as an RR0 star.

    • Amigo et al. (2013) confirmed our classification of V52 and V53 as RR Lyrae stars and further classified them as RR0 stars.



  • NGC7089 (M2): Click for details...

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    Our variable star discoveries from Lazaro et al. (2006):

    • We used the version of DanDIA described in Bramich et al. (2005) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V35 : RR1
      V36 : RR1
      V37 : RR0
      V38 : RR0
      V39 : RR0
      V40 : RR0
      V41 : RR0
      V42 : RR1

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC7099 (M30): Click for details...

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    Our variable star discoveries from Kains et al. (2013):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V14 : RR1
      V16 : RR1
      V17 : Tentatively classified as SX Phe
      V18 : Eclipsing binary (blue straggler)
      V20 : SX Phe
      V21 : Unclassified

    • We reported that V5, V6, V7, V8, V9, V10, V11, V12 and V13, previously thought to be variable, are in fact non-variable.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.


  • NGC7492: Click for details...

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    Our variable star discoveries from Figuera Jaimes et al. (2013):

    • We used the version of DanDIA described in Bramich (2008) to perform difference image analysis on the CCD images in order to extract the light curves.

    • We discovered the new variables:

      V5 : Long-period irregular variable
      V6 : SX Phe
      V7 : SX Phe

    • We announced the variable star candidate CSX1 which we tentatively classify as an SX Phe star.

    • We can be sure that there are no more RR Lyrae stars that are cluster members in the field of view of our study.

    • Our data are on CDS.

    Since our above publication, there has been no new work published in the literature on the variable stars in this cluster.




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