4 The catalogue

The catalogue is composed of two tables containing objects with periods P smaller or larger than 30 days, respectively. The identifier of each star is given according to the recommendations of the IAU Commission 5 in The Rules and Regulations for Nomenclature (see the Annual Index of A&A). The general acronym used in the catalogue is EROS2 GSA followed by J2000 equatorial coordinates in the format $\rm JHHMMSS\pm DDMMSS$. The remainder of the identifier in parentheses gives some information relating to the internal organisation of the EROS database: gnnnn or tmnnn is the name of the field, followed by the CCD number and the location on the image following the EROS II nomenclature. The remaining number is the star identifier used in the EROS database. As an example, J132630-630945(tm5504m12359) is the name of the 12359th star observed in quarter m of CCD 4 in the field tm550. The J2000 equatorial coordinates of this star are 13:26:30.11, -63:09:45.66.

The equatorial coordinates (J2000) of individual stars have been obtained as follows. First, we have inserted the suitable WCS keywords into the header of the EROS II reference images using the WCSTOOLS package (Mink 1999). Whenever possible, the cross-identification of each star with previously known objects within a 10$\arcsec$ search radius has been done using the SIMBAD and VIZIER databases available at the CDS, Strasbourg.

Figure 7: Distinction between classical Cepheids, s-Cepheids and miscellaneous pulsating stars in the R21-P and $\Phi _{21}-P$ planes. The individual uncertainties are reported. The cloud of points represent the Cepheids observed in the LMC (adapted from Afonso et al. 1999). The curve corresponds to the empirical function $R_{21}^{\rm cut}(P)=0.4 - (P/30$ days) used to distinguish between s and classical Cepheids.

The tables contain the following information:

1.

Identifier;

2.

Right ascension $\alpha$ (J2000);

3.

Declination $\delta$ (J2000);

4.

$\langle R_{\rm E} \rangle$ mean magnitude in EROS-red;

5.

$\Delta R_{\rm E}$ amplitude peak to peak in $R_{\rm E}$;

6.

$\langle V_{\rm E} \rangle$ mean magnitude in EROS-visible;

7.

$\Delta V_{\rm E}$ amplitude peak to peak in $V_{\rm E}$;

8.

Period in days. Note that periods longer than 30 days are given with less accuracy since the time span of the measurements does not allow a precise determination. Measured periods which are longer than 60 days (i.e. 2/3 of the observation period) are flagged by writing "P>60 d'' and have no warranty to be true periodic variable stars. The peak to peak amplitude of these stars could be meaningless and the mean magnitude is determined with low accuracy.

For Cepheids and RR Lyræ the results of the Fourier fit are given:

9.

Fourier coefficient ratio R₂₁;

10.

Fourier coefficient ratio R₃₁;

11.

Phase difference $\phi_{21}$ (in rad);

Also given when possible:

13.

Type of variability (C = classical Cepheids, S = s-Cepheids, puls. = miscellaneous pulsating stars, EA, EB, EW = eclipsing binaries, misc = miscellaneous variable stars, SR = Semi-Regular variables, M = Miras, LPV = long period variables);

14.

Name of cross-identified object(s) within a search radius of 10$\arcsec$.

Tables 4 and 5 show a sample of the catalogue that we plan to install at the CDS (see also our Web site http://eros.in2p3.fr/).

Figure 8: Colour-magnitude diagrams ($I_{\rm C}$ vs. $V_{\rm J}$-$I_{\rm C}$) for the Miras (represented by dots $\bullet$), Semi-Regular variable stars (diamonds $\diamond$) and eclipsing binaries (open circles $\circ$). The dotted line corresponds to cut 2 on the luminosity of the stars.

 

 

Table 4: Catalogue of stars with P<30 days (sample).

EROS2 GSA ID	RA(J2000)	DEC(J2000)	$\langle R_{\rm E} \rangle$	$\Delta R_{\rm E}$	$\langle V_{\rm E} \rangle$	$\Delta V_{\rm E}$	P(days)	R21	$\sigma_{R_{21}}$	R31	$\sigma_{R_{31}}$	$\phi_{21}$	$\sigma_{\phi_{21}}$	Type	Note
J132357-631158(tm5504k673)	13:23:57.99	-63:11:58.88	14.73	0.58	15.7	0.64	2.5367							EA
J132402-633439(tm5506k1244)	13:24:02.90	-63:34:39.66	14.20	0.57	16.03	0.70	8.8020	0.224	0.004	0.215	0.002	5.41	0.06	C
J132433-624202(tm5500l6773)	13:24:33.35	-62:42:02.40	12.69	0.65	13.37	0.50	1.7601							EA	V* NX Cen
J132449-631304(tm5504k9109)	13:24:49.24	-63:13:04.60	14.56	1.24	15.72	1.41	3.5099							EA
J132457-633032(tm5506k8804)	13:24:57.51	-63:30:32.00	12.55	0.54	13.66	0.52	1.5775							EA
J132500-631337(tm5504k10856)	13:25:00.23	-63:13:37.21	14.64	0.22	15.91	0.31	14.8285	0.405	0.036	0.151	0.008	-0.06	0.03	puls
J132531-633526(tm5506m1888)	13:25:31.96	-63:35:26.48	14.96	1.36	16.15	1.47	1.6274							EA
J132554-631029(tm5504m6315)	13:25:54.62	-63:10:29.34	13.71	0.25	14.71	0.20	0.4349							misc
J132630-630945(tm5504m12359)	13:26:30.11	-63:09:45.66	10.18	0.52	11.77	0.64	12.8941	0.129	0.001	0.146	0.001	4.33	0.23	C	V* OO Cen
J132721-630110(tm5503l3554)	13:27:21.68	-63:01:10.80	10.98	0.80	12.67	0.97	15.2278	0.286	0.006	0.219	0.003	4.39	0.15	C	V* V881 Cen

   

Table 5: Catalogue of stars with P>30 days (sample).

EROS2 GSA ID	RA(J2000)	DEC(J2000)	$\langle R_{\rm E} \rangle$	$\Delta R_{\rm E}$	$\langle V_{\rm E} \rangle$	$\Delta V_{\rm E}$	P(days)	Type	Note
J132359-623229(tm5500l1488)	13:23:59.86	-62:32:29.63	10.83	0.14	14.18	0.22	52.04	SR	MSX5C G306.6758+00.0933
J132400-632057(tm5504l1003)	13:24:00.60	-63:20:57.82	12.34	0.20	16.06	0.38	45.83	SR	[CKS91] 13206-6305
J132419-632717(tm5506k3687)	13:24:19.25	-63:27:17.42	11.56	0.34	14.94	5.43	>60 d	LPV	MSX5C G306.5942-00.8179
J132427-631542(tm5504k5591)	13:24:27.10	-63:15:42.08	11.75	0.18	14.88	0.33	>60 d	LPV	[CKS91] 13211-6300
J132431-630539(tm5504k6408)	13:24:31.78	-63:05:39.51	15.34	0.27	17.19	0.50	55.70
J132433-632201(tm5504m10330)	13:24:33.05	-63:22:01.64	11.96	0.24	9.49	0.43	58.46		[CKS91] 13229-6252
J132437-623119(tm5500k7345)	13:24:37.80	-62:31:19.09	12.4	0.21	15.94	0.47	>60 d
J132440-633236(tm5506k6457)	13:24:40.22	-63:32:36.78	11.67	0.34	15.46	0.42	>60 d		MSX5C G306.6222-00.9099
J132444-632224(tm5504l7786)	13:24:44.82	-63:22:24.20	10.79	0.44	14.13	1.19	55.00		IRAS 13214-6306; MSX5C G306.6524-00.7426
J161332-541002(gn4590k724)	16:13:32.50	-54:10:02.22	13.14	0.84	16.49	1.79	>60 d	LPV	2MASS 1613326-541004
J161332-541453(gn4590k673)	16:13:32.45	-54:14:53.91	13.87	0.18	16.12	0.26	38.29	SR	2MASS 1613325-541454

Figure 9: Colour-magnitude diagrams ($I_{\rm C}$ vs $V_{\rm J}$-$I_{\rm C}$) for the classical Cepheids (represented by stars $\star$), s-Cepheids (dots $\bullet$), and RR Lyræ (open circles $\circ$).

A by-product of such a survey is the possibility to update the coordinates given in older catalogues. As an example, it was found that the well known classical Cepheid OO Cen with the SIMBAD identifier V*OO Cen was 20$\arcsec$ away from an EROS object, namely J132630-630945(tm5504m12359), as shown in the finding chart of Fig. 10.

 

 

Table 6: Period and coordinates obtained on OO Cen by SIMBAD, GCVS and this study.

Source	SIMBAD	GCVS	This study
object	V* OO Cen	OO Cen	J132630-630945(tm5504m12359)
P (days)	n/a	12.8805	12.894
$\alpha$ (B1950)	13:23:06.85	13:23:09	13:23:08.8
$\delta$ (B1950)	-62:54:24.9	-62:54.0	-62:54:11

 

 

Table 7: Previously known variable stars recovered by this survey. For each star we give its name, the original catalogue, the type of variability, the period and the I magnitude given (if any) in the catalogue and in this survey.

Object	Catalogue	Type	P(days)	I	EROS ID	P(days)	$I_{\rm c}$
OO Cen	GCVS	C	12.8805	9.96	J132630-630945	12.8941	10.20
					(tm5504m12359)
V881 Cen	GCVS	C	-	10.57	J132721-630110	15.2278	10.97
					(tm5503l3554)
V608 Cen	GCVS	EB	1.6287	12.95	J132948-630634	1.7601	12.05
					(tm5505m13922)
CKS91	CKS91	EA	-	13.29	J132758-631449	5.4918	13.03
13246-6259					(tm5505l9598)
CKS91	CKS91	E	-	13.05	J133311-630023	0.2141	13.20
13297-6244				1	(tm5511m5801)
CKS91	CKS91	SR	-	12.35	J132400-632057	45.83	12.34
13206-6305					(tm5504l1003)
CKS91	CKS91	LPV	-	11.73	J132427-631542	P>60	11.75
13211-6300					(tm5504k5591)
CKS91	CKS91	SR	-	10.51	J132444-632224	55.00	10.79
13214-6306					(tm5504l7786)
CKS91	CKS91	SR	-	12.85	J132447-631201	52.39	12.77
13214-6256					(tm5504k8841)
CKS91	CKS91	LPV	-	10.43	J132454-631437	P>60	10.23
13215-625					(tm5504k9938)
CKS91	CKS91	LPV	-	11.81	J132519-631720	P>60	13.00
13219-6301					(tm5504l13138)
CKS91	CKS91	LPV	-	12.51	J132433-632201	58.46	11.96
13229-6252					(tm5504m10330)
CKS91	CKS91	LPV	-	12.48	J132625-630645	P>60	12.41
13230-6251					(tm5504m11603)
CKS91	CKS91	LPV	-	12.63	J132714-634338	P>60	10.78
13238-6227					(tm5507l1058)
CKS91	CKS91	LPV	-	12.21	J132719-633644	P>60	11.91
13238-6254					(tm5507l1752)
CKS91	CKS91	M	-	12.46	J132803-632200	P>60	13.99
13246-6306					(tm5505l10106)
CKS91	CKS91	SR	-	12.66	J132813-630013	44.80	12.72
13247-6244					(tm5510k2095)
CKS91	CKS91	LPV	-	12.37	J132948-631227	P>60	12.56
13264-6256					(tm5510n4312)
CKS91	CKS91	M	-	12.65	J133222-632339	P>60	12.65
13289-6308					(tm5513k12129)

The period and coordinates we report are compatible with the ones given by the GENERAL CATALOGUE OF VARIABLE STARS (GCVS) (Kholopov 1985) (see Table 6). It seems that an error occurred when the coordinates of this particular star were filled in the SIMBAD. The light curve of this object is shown in Fig. 6.

We have performed several cross-identifications of our catalogue with those previously available, namely the IRAS POINT SOURCE CATALOG (Beichman et al. 1998), the MSX5C INFRARED ASTROMETRIC CATALOG (Egan et al. 1996), the TWO MICRON ALL SKY SURVEY (2MASS) (Skrutskie et al. 1997), the CKS91 catalogue (Caldwell et al. 1991) and the GENERAL CATALOGUE OF VARIABLE STARS (GCVS) (Kholopov 1985). A total of 38 IRAS sources and 220 MSX5C objects have been thus retrieved. The overlap with the available 2MASS catalogue exists only for the EROS field gn459, representing 255 stars. A total of 233 2MASS objects have been thus retrieved among them 37 objects classified as Semi-Regular variables.

An overlap exists with the CKS91 catalogue (Caldwell et al. 1991). These authors have searched for bright Cepheids and other variable stars with I < 14, towards Crux and Centaurus, during 42 days with less than 10 measurements per star. A small overlap exists between this survey and the GSA fields tm550 and tm551. Unfortunately this overlap involves our CCD #2 which was not operational at the time of the observations. Therefore the comparison can only be carried out on 0.7 square degree. Furthermore, as pointed above, this comparison is restricted to stars with magnitude $I_{\rm C} < 14$. A total of 118 EROS objects, 6 GCVS and 23 CKS91 objects lie in this region. Three objects are common to the GCVS and CKS91 catalogues one. The overlap between the three catalogues represents only 19 objects. Among them one finds the most interesting ones, such as Cepheids OO CEN and V881 CEN (see Table 7). Some objects show a large difference between the two magnitude determinations. These are long period variables for which the mean magnitude is measured on only a part of the whole period, and thus ill determined in both surveys. Only 7 known variable stars are not recovered by our analysis (see Table 8). Conversely, 99 objects of our catalogue are not listed by CKS91. All of them are labelled Long Period Variable stars (LPV).

Figure 10: Finding chart of the star OO Cen - J132630-630945(tm5504m12359). The position given by the SIMBAD database is shown by the square which is 10$\arcsec$ wide, while the EROS position is shown by the circle.

 

 

Table 8: Previously known variable stars not recovered by this survey. For each of them we give (where possible) their type of variability, their period and the reason for their absence in the catalogue.

Object	Type	P(days)	catalogue	comment
HQ Nor	EB	90.9	GCVS	too long period
HY Nor	Mira	236	GCVS	close to
				the CCDs gap
UW Nor	EA	8.4860	GCVS	fails cut 6
13214-6256	LPV		CKS91	fails cut 6
13218-6254	LPV		CKS91	fails cut 6
13248-6249	LPV		CKS91	fails cut 6
13232-6249	LPV		CKS91	fails cut 6