Terzan 1 / HP2 / C1732-304 (Updated August 2019) RA: 17:35:47.2 DEC: -30:28:54 (J2000) *See comment about RA, dec below. ============================================================ Bytes Format Explanation 1-8 A8 Star ID 10-32 A11,1x,A11 Position 34-35 A2 Units for position R0 denotes RA, DEC in the J2000 coordinates R5 denotes RA, DEC in the 1950 coordinates XA denotes X, Y in arcseconds XP denotes X, Y in pixels 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 ========================================================================= ID Position Period ampl C Type Notes/ RA/X Dec/Y Units Remarks ========================================================================= 1 17:35:47.71 -30:28:49.5 R0 ---- -- -- ? 2 17:35:47.50 -30:27:50.6 R0 ---- -- -- ? Note 3 17:35:53.41 -30:29:21.9 R0 ---- -- -- ? 4 17:35:55.20 -30:29:48.4 R0 ---- 16.2 2.0 R M? Note 5 17:35:46.15 -30:29:03.4 R0 18.8351 14.569 0.917 I CW Note 6 17:35:44.37 -30:29:48.2 R0 0.5279 17.826 0.697 I RR0 Note 7 17:35:45.17 -30:29:01.5 R0 0.5309 18.115 0.653 I RR0 8 17:35:45.60 -30:28:56.6 R0 0.3073 17.752 0.218 I RR1 9 17:35:45.83 -30:28:57.3 R0 0.6422 17.850 0.389 I RR0 10 17:35:45.94 -30:29:15.9 R0 0.6069 17.827 0.431 I RR0 11 17:35:46.01 -30:28:48.5 R0 0.5326 17.252 0.330 I RR0 12 17:35:46.23 -30:28:33.3 R0 0.6183 17.456 0.473 I RR0 13 17:35:46.88 -30:29:27.9 R0 0.3196 18.125 0.275 I RR1 Note 14 17:35:48.40 -30:28:36.7 R0 0.5436 17.863 0.661 I RR0 15 17:35:48.74 -30:27:32.0 R0 0.5203 17.845 0.602 I RR0 Note 16 17:35:50.95 -30:28:41.8 R0 0.2916 18.095 0.364 I RR1 17 17:35:53.52 -30:29:05.6 R0 0.7503 17.755 0.361 I RR0 Note 18 17:35:45.88 -30:29:08.7 R0 9.9442 15.263 0.182 I CW 19 17:35:48.06 -30:29:38.1 R0 2.4932 16.940 0.536 I CW 20 17:35:48.77 -30:28:49.0 R0 2.4932 17.000 0.813 I CW 21 17:35:53.47 -30:28:52.1 R0 16.6981 17.706 0.285 I E ======================================================================= Supplementary Notes Terzan 1 is a highly obscured cluster located in a crowded field in the Galactic bulge. CM diagrams published by Ortolani et al. (1999), based on VI photometry and by Valenti et al. (2010), based on JK photometry both show a red HB. Valenti et al (2015) derived a metal abundance, [Fe/H]=-1.26. The cluster has core radius: 0.04' (arcminutes), half-light radius: 3.82' and tidal radius: 12.6' acccording to Harris (1996 - 2010 update), However, the Valenti et al. (2010) CM diagrams show there is significant contamination from field stars, particularly at distances greater that 1.5' from the cluster centre. Therefore it is unlikely that stars beyond this limit are cluster members. Terzan 1 and its surrounding field were observed in the OGLE IV Galactic Bulge survey. Results from this survey have been reported by Soszynski et al. (2014) for RR Lyrae variables, Soszynski et al. (2016) for eclipsing binaries, and by Soszynski et al. (2017) for type II Cepheids. The OGLE data are available by "Data Download" from the OGLE website: ogle.astrouw.edu.pl In the above table: V1-4 The RA and dec for V1-4 are from Samus et al. (2009). Otherwise, there is not much information availble for these stars, apart from what has been indicated in the notes on individual stars. V5-21 The data for V5-21 in the above table are from the OGLE IV survey. Only variables that are located less than 1.4 arcminutes from the centre have been listed. Soszynski et al. (2014) adopted a radius of 1.2 arcminutes for Terzan 1, but in this catalogue, the adopted radius has been set at 1.4 arcminutes. The Note below for V15 explains why. *The RA and dec listed here for the cluster centre are from the 2003 version of the Harris (1996) catalogue. The dec Harris listed in 2010 (-30:28:11) is too far north. He based his 2010 coordinates on the values published by Terzan (1971) but it appears they were incorrect. Infra-red and X-ray images of Terzan 1 published by Cackett et al. (2006) show that Harris's 2003 coordinates are more accurate. Furthermore, according to ID chart published Terzan & Rutily (1975) in their discovery paper, V1's declination should be a few arcseconds north of the cluster centre. This is consistent with Harris' 2003 position. ======================================================================= Notes on individual stars V2: The y coordinate that Terzan & Rutily (1975) listed for V2 does not correspond to the position labelled on their ID chart. The dec listed in the above table is based on the position on the ID chart. V4: According to Samus et al. (2009), V4 is NSV 22828 in the GCVS. V4 is located 1.95 arcminutes from the cluster centre. The magnitude and amplitude listed in the above table are the values reported in the GCVS and are from Terzan & Ounnas (1988) who listed it as V1812. The star appears to be a Mira variable, based on its amplitude. It is near the RG tip in the (K, J-K) CM diagram published by Valenti et al. (2010). V5: The data listed above are from OGLE IV (Soszynski et al. 2017). Matsunaga et al. (2006) published K=10.61, J-K=1.36. These values place it on the Valenti et al. (2010) CM diagram at a location expected for a type II Cepheid that belongs to the cluster. V6, V13, V17: These three variables were not included in the Soszynski et al. (2014) list of RR Lyrae in Terzan 1, but they are all less than 1.4 arcminutes from the cluster centre when the calculation is based on the corrected (Harris's 2003) coordinates. Their radial distances are 1.09, 0.57 and 1.38 arcminutes respectively. V15: When the coordinates from the 2010 update to the Harris (1996) catalogue are used to calculate the distance from the cluster centre, V15 is at a distance of 0.68 arcminutes. However, the 2010 coordinates are incorrect. Based on the correct values, V15 is at a distance 1.41 arcminutes from the cluster centre. Since V15 appears to be a cluster member, the cluster radius adopted in this catalogue is 1.4 arcminutes. This is also the radius that Cackett et al. (2006) adopted in their study of Chandra X-ray sources in Terzan 1. ======================================================================== Discovery of the variable stars in Terzan 1: V1-4 Terzan & Rutily (1975) with x,y coordinates and an ID chart Samus et al. (2009) later derived RA and dec for these stars. All four variables lie near the red giant tip in the CM diagram in CM diagram of Valenti et al. (2010). The radial distances of V1, V2 and V3 are 0.13, 1.06 and 1.42 arcminutes respectively; V4 is more distant (1.95 arcmin). According to the VizieR Service, V2, V3 and V4 are listed in the catalog of VISTA Variables in the Via Lactea Survey DR2 (Minniti et al. 2017), as VVVJ173547.9-302750.46, VVVJ1173553.42-302921.63 and VVVJ173555.19-302948.42 respectively. No periods were published by the VVV group. V5 Matsunaga et al. (2006) with RA and dec This variable was later recovered as OGLE-BLG-T2CEP-0479 in the OGLE IV survey (Soszynski et al. 2017). V6-17: These are RR Lyrae variables in the Galactic Bulge detected in the OGLE IV survey and discussed by Soszynski et al. (2014). The numbers V6-17 were assigned by Clement et al. (2001) in the 2016 update as follows: V6=OGLE-BLG-RRLYR-22087, V7=OGLE-BLG-RRLYR-22095, V8=OGLE-BLG-RRLYR-22102, V9=OGLE-BLG-RRLYR-22104, V10=OGLE-BLG-RRLYR-22107, V11=OGLE-BLG-RRLYR-22108, V12=OGLE-BLG-RRLYR-22112, V13=OGLE-BLG-RRLYR-22118, V14=OGLE-BLG-RRLYR-22135, V15=OGLE-BLG-RRLYR-22139, V16=OGLE-BLG-RRLYR-22170, V17=OGLE-BLG-RRLYR-22196 V6-17 are located within 1.4 arcminutes of the cluster centre based on Harris's 2003 position. There are an additional 11 RR Lyrae variables located between 1.4' and the half light radius, 3.82' (arcminutes), OGLE-BLG-RRLYR: 21979, 22033, 22042, 22051, 22063, 22199, 22205, 22228, 22234, 22246, 22258. V18-20: These are type II Cepheids in the Galactic Bulge detected in the OGLE IV survey and discussed by Soszynski et al. (2017). Their distances from the cluster centre are 0.37, 0.76 and 0.35 arcminutes respectively, indicating they all probably belong to the cluster. The numbers V18-20 have been assigned in this catalogue: V18=OGLE-BLG-T2CEP-0478, V19=OGLE-BLG-T2CEP-0480, V18=OGLE-BLG-T2CEP-0481. Soszynski et al. (2017) also confirmed the variability of V5 which is OGLE-BLG-T2CEP-0479 with r=0.27 arcminutes. Another type II Cepheid identified in the Ogle IV survey is OGLE-BLG-T2CEP-0485 at a distance 2.37' from the cluster centre, with period = 2.46 days and I= 16.921 mag. V21 = OGLE-BLG-ECL-040507: This is an NC eclipsing binary in the Galactic Bulge detected in the OGLE IV survey (Soszynski et al. 2016). Its distance from the cluster centre is 1.35' (arcminutes). The number V21 has been assigned in this catalogue. It could belong to the cluster, but its location on the CM diagram is difficult to determine. There are 3 other NC eclipsing binaries located between 1.4' and the half light radius, 3.82' (arcminutes), OGLE-BLG-ECL: 039460 (r=2.41'), 039648 (r=2.67') and 039705 (r=1.49'). ======================================================================= References Cackett, E. M., Wijnands, R., Heinke, C. O., Pooley, D., Lewin, W. H. G., Grindlay, J. E., Edmonds, P.D. and 2 co-authors, 2006, MNRAS, 369, 407 Clement, C. M., Muzzin, A., Dufton, Q., Ponnampalam, T., Wang, J., Burford, J., Richardson, A., Rosebery, T. 2001, AJ, 122, 2587 Harris, W. E. 1996, AJ, 112, 1487 Minniti, D., Lucas, P. and the VVV Team, 2017, Vizier Online Catalog: VISTA Variables in the Via Lactea Survey DR2 Matsunaga, N., Fukushi, H., Nakada, Y., Tanabe, T., Feast, M. W., Menzies, J. 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