------------------------------------------------------------------------ H2501.tex A&A 2001, in press Content-Type: multipart/mixed; boundary="------------81A2B3FB8E8308781E444406" Content-Length: 46280 This is a multi-part message in MIME format. --------------81A2B3FB8E8308781E444406 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit %astro-ph/0101156 --------------81A2B3FB8E8308781E444406 Content-Type: application/x-tex; name="H2501.tex" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="H2501.tex" \documentclass[a4paper]{aa} \usepackage{psfig,longtable,lscape} \usepackage{epsfig} \def \sax {BeppoSAX} \def \degmark{^\circ} \def \deg{^\circ} \def \nh {N${\rm _H}$} \def \ergsec{\hbox{erg s$^{-1}$}} \def \hcm {\hbox {\ifmmode $ atom cm$^{-2}\else atom cm$^{-2}$\fi}} \def \arcmin {\hbox{$^\prime$}} \def \arcsec {\hbox{$^{\prime\prime}$}} \def \chisq {$\chi ^{2}$} \def \rchisq {$\chi_{\nu} ^{2}$} \def\approxgt{\mathrel{\hbox{\rlap{\lower.55ex \hbox {$\sim$}} \kern-.3em \raise.4ex \hbox{$>$}}}} \def\approxlt{\mathrel{\hbox{\rlap{\lower.55ex \hbox {$\sim$}} \kern-.3em \raise.4ex \hbox{$<$}}}} \newcommand{\mc}{\multicolumn} \newcommand {\Msun}{M_\odot} % \begin{document} %\thesaurus{(04.03.2; 10.03.1; 13.25.3; 13.25.5)} %%catalogs; %Galaxy: center; %x-rays: general %x-rays: stars \title{A catalogue of soft X--ray sources in the galactic center region} \author{L. Sidoli\inst{1}, T. Belloni\inst{2}, S. Mereghetti\inst{3} } \offprints{L. Sidoli (lsidoli@astro.estec.esa.nl)} \institute{ Astrophysics Division, Space Science Department of ESA, ESTEC, Postbus 299, NL--2200 AG Noordwijk, The Netherlands \and Osservatorio Astronomico di Brera, Via Bianchi 46, I--23807 Merate (Lc), Italy \and Istituto di Fisica Cosmica ``G.~Occhialini'', CNR, via Bassini 15, I--20133 Milano, Italy } \date{Received 12 October 2000; Accepted 4 January 2001} \authorrunning{L. Sidoli et al.} \titlerunning{{A catalogue of soft X--ray sources in the GC region}} \abstract{We present a catalogue of 107 point-like X--ray sources derived from a systematic analysis of all the ROSAT PSPC observations of the galactic center region performed in 1992--1993. Besides SgrA*, the massive black hole at the galactic center, 41 X--ray sources have been positionally associated with already classified objects. Twenty are identified with foreground stars and five with known Low Mass X--ray Binaries. The majority of the sources in our catalogue still remains unidentified. They are hard and/or severely absorbed and probably represent a large population of X-ray binaries located in the galactic center region, accreting at low accretion rates, and still largely unknown. \keywords{Catalogues -- Galaxy: center -- X--rays: general -- X--rays: stars}} \maketitle \section{Introduction} \label{sect:intro} The galactic center (hereafter GC) region has always been among the privileged targets of many X--ray missions. The observations made over the years established that a severe crowding of X-ray sources exists towards this part of our Galaxy (see Sidoli et al. (1999) for the results of a \sax\ survey of the GC with its Narrow Field Instruments). Many of the brightest sources are probably Low Mass X--ray Binaries (LMXBs) containing neutron stars or black holes, both with persistent and transient behavior, while the nature of the faintest sources is unknown. Many transient sources have been discovered in the last few years, especially during the monitoring of the galactic center region with the \sax\ Wide Field Camera (Ubertini et al. 1999) and the Rossi-XTE All Sky Monitor (Bradt et al. 2000). The ROSAT Position Sensitive Proportional Counter (PSPC) performed a raster scan of the GC region ($|l|<1.5\deg$)$\times$($|b|<2\deg$) in 1992 and 1993. The region covered is rectangular ($3\deg\times4\deg$) with the major axis oriented perpendicular to the galactic plane. We performed a detailed spatial analysis of these data with the main objective of obtaining a catalogue of X--ray sources in the soft X--ray energy band. All the data analyzed here have been retrieved from the ROSAT public archive in MPE. These datasets have previously been analyzed by Predehl \& Tr\"umper (1994) and by Predehl et al. (1995), but neither of these works was aimed at the production of a full catalogue of sources in the region. \section{Observations and Data Reduction} \label{sect:obs} The PSPC on board the ROSAT satellite (Pfeffermann et al. 1986) covered the energy band 0.1--2.4 keV with a moderate energy resolution (3--4 energy bands can be defined) and an angular resolution of $\sim$20$''$ (FWHM). The detector has a circular field of view of $\sim$2$\deg$ diameter. The radial and circular supports of the entrance window produce some artifacts, whose effects are mitigated by wobbling the satellite during pointing observations. The data consist of 43 pointed observations with exposure times in the range 2000--3000 seconds, aimed at completely covering the central part of our Galaxy with the inner region of the PSPC detector. These observations were performed between 1992 February and 1993 March. We also included in our sample a single deeper pointing (47,000 sec) centered on the Sgr~A* position performed on 1992 March 2. The log of the observations is reported in Table~\ref{rosat_log}. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \begin{table*}[htbp] \begin{center} \caption{The PSPC observations log.} \label{rosat_log} \begin{tabular}[c]{|l|l|l|l|} \hline %\hline Observation & Pointing Direction & Obs. Start & Obs. End \\ ID & R.A. \& Dec. (J2000) & dd/mm/yy hh:mm & dd/mm/yy hh:mm \\ \hline rp400150n00 & 17 49 16.80 --30 12 00.0 & 04/03/92 03:48 & 04/03/92 04:28 \\ rp400179n00 & 17 47 57.60 --30 01 48.0 & 02/03/92 19:53 & 02/03/92 20:41 \\ rp400180n00 & 17 46 38.40 --29 51 00.0 & 02/03/92 08:49 & 02/03/92 09:25 \\ rp400181n00 & 17 45 19.20 --29 40 48.0 & 02/03/92 01:11 & 02/03/92 03:03 \\ rp400182n00 & 17 44 00.00 --29 30 36.0 & 01/03/92 20:06 & 01/03/92 20:45 \\ rp400183a01 & 17 42 43.20 --29 19 48.0 & 28/03/93 19:56 & 28/03/93 20:38 \\ rp400183n00 & 17 42 43.20 --29 19 48.0 & 02/03/92 11:54 & 02/03/92 12:25 \\ rp400184n00 & 17 41 24.00 --29 09 00.0 & 01/03/92 10:26 & 10/03/92 12:14 \\ rp400185n00 & 17 40 07.20 --28 58 48.0 & 29/02/92 21:38 & 29/02/92 22:26 \\ rp400186n00 & 17 38 50.40 --28 48 00.0 & 29/02/92 15:16 & 29/02/92 19:09 \\ rp400187n00 & 17 50 04.80 --29 54 36.0 & 03/03/92 16:37 & 03/03/92 10:45 \\ rp400188n00 & 17 48 43.20 --29 44 24.0 & 03/03/92 11:52 & 03/03/92 17:08 \\ rp400189n00 & 17 47 26.40 --29 34 12.0 & 02/03/92 21:33 & 02/03/92 22:16 \\ rp400190n00 & 17 46 07.20 --29 24 00.0 & 03/03/92 08:40 & 03/03/92 09:20 \\ rp400191n00 & 17 43 31.20 --29 03 00.0 & 04/03/92 19:49 & 04/03/92 20:30 \\ rp400192n00 & 17 42 12.00 --28 52 12.0 & 01/03/92 12:00 & 01/03/92 17:19 \\ rp400193n00 & 17 40 55.20 --28 42 00.0 & 01/03/92 03:56 & 01/03/92 04:42 \\ rp400194n00 & 17 39 38.40 --28 31 12.0 & 29/02/92 20:04 & 29/02/92 20:51 \\ rp400195n00 & 17 50 50.40 --29 37 48.0 & 03/03/92 19:50 & 03/03/92 20:36 \\ rp400196n00 & 17 49 31.20 --29 27 00.0 & 04/03/92 07:01 & 04/03/92 07:40 \\ rp400197n00 & 17 48 12.00 --29 16 48.0 & 03/03/92 18:13 & 04/03/92 13:50 \\ rp400198n00 & 17 43 00.00 --28 35 24.0 & 02/03/92 10:20 & 03/03/92 15:32 \\ rp400199n00 & 17 41 43.20 --28 24 36.0 & 01/03/92 07:13 & 01/03/92 07:54 \\ rp400200n00 & 17 40 26.40 --28 14 24.0 & 29/02/92 23:15 & 01/03/92 00:02 \\ rp400201n00 & 17 51 38.40 --29 20 24.0 & 03/03/92 23:07 & 03/03/92 23:46 \\ rp400202n00 & 17 50 19.20 --29 10 12.0 & 04/03/92 08:37 & 04/03/92 09:15 \\ rp400203n00 & 17 49 00.00 --29 00 00.0 & 04/03/92 18:09 & 10/03/92 15:04 \\ rp400204n00 & 17 47 40.80 --28 49 48.0 & 04/03/92 11:56 & 07/03/92 10:28 \\ rp400205n00 & 17 46 24.00 --28 39 00.0 & 02/03/92 18:18 & 03/03/92 13:54 \\ rp400206n00 & 17 43 48.00 --28 18 00.0 & 01/03/92 18:21 & 02/03/92 15:36 \\ rp400207n00 & 17 45 55.20 --28 11 24.0 & 01/03/92 13:42 & 02/03/92 13:59 \\ rp400208n00 & 17 41 14.40 --27 57 00.0 & 01/03/92 04:51 & 01/03/92 06:18 \\ rp400209n00 & 17 52 24.00 --29 03 00.0 & 04/03/92 05:23 & 04/03/92 06:03 \\ rp400210n00 & 17 51 04.80 --28 52 48.0 & 04/03/92 02:13 & 04/03/92 02:53 \\ rp400211a01 & 17 49 48.00 --28 42 36.0 & 23/03/93 09:24 & 23/03/93 09:47 \\ rp400211n00 & 17 49 48.00 --28 42 36.0 & 03/03/92 21:56 & 03/03/92 22:11 \\ rp400212n00 & 17 48 28.80 --28 32 24.0 & 16/03/93 21:06 & 16/03/93 21:53 \\ rp400213n00 & 17 47 12.00 --28 22 12.0 & 16/03/93 22:42 & 16/03/93 23:30 \\ rp400214n00 & 17 45 55.20 --28 11 24.0 & 02/03/92 07:06 & 02/03/92 07:49 \\ rp400215n00 & 17 44 36.00 --28 01 12.0 & 01/03/92 21:34 & 01/03/92 22:21 \\ rp400216n00 & 17 43 19.20 --27 51 00.0 & 01/03/92 23:10 & 01/03/92 23:57 \\ rp400217n00 & 17 42 02.40 --27 40 12.0 & 01/03/92 08:48 & 01/03/92 09:30 \\ rp900162n00 & 17 45 40.80 --29 00 00.0 & 02/03/92 03:56 & 09/03/92 05:40 \\ \hline \end{tabular} \end{center} \end{table*} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% The data have been analysed using EXSAS (Extended Scientific Analysis System, version 98APR; Zimmermann et al. 1993) implemented in the ESO--MIDAS version 97NOVpl2.0 on Sun/Solaris. All the analysis described below was performed in four different energy ranges: 0.1--2.4 keV (channels 8--240, total energy band, T), 0.1--0.4 keV (channels 8--40, soft energy band, S), 0.5--0.9 keV (channels 52--90, medium energy band, M) and 0.9--2.4 keV (91--240, hard energy band, H). %---------------------------------------------------------------------- \begin{figure*}[!ht] \centerline{\psfig{figure=H2501f1.ps,height=110mm,bbllx=70mm,bblly=80mm,bburx=140mm,bbury=250mm}} \vspace{1cm} \caption[]{Mosaic image of the galactic center region in the 0.1-2.4 keV energy range. Only the inner part of the PSPC detector has been used. The image has been corrected for the exposure and for the vignetting } \label{fig:totcor} \end{figure*} %---------------------------------------------------------------------- \begin{figure}[!ht] \vskip 0.5truecm \centerline{\psfig{figure=H2501f2.ps,height=70mm,bbllx=86pt,bblly=283pt,bburx=510pt,bbury=629pt,clip=}} \vskip 0.5truecm \caption{Exposure map appropriate for the PSPC mosaic in the total energy band } \label{fig:expo} \end{figure} %---------------------------------------------------------------------- \subsection{Source Detection} \label{sect:detection} We first merged all the observations to produce mosaic images (with a binsize of 15$''$) in the four energy bands, using only the inner part of the PSPC detector. In fact the pointing directions were appropriately defined to continuosly map the region with the inner part of the detector, that provides the best sensitivity and angular resolution (adding the overlapping outer regions with a different Point Spread Function would degrade the image quality). The corresponding exposure images were also produced in the four energy bands. The final mosaic in the total energy band, corrected both for the different exposure times and for the vignetting, is displayed in Fig.~\ref{fig:totcor}. The corresponding (vignetted) exposure map, used to correct it, is shown in Fig.~\ref{fig:expo}. We then applied, for each energy band, a source detection algorithm based on the following steps: \begin{itemize} \item {\em local--detection algorithm}: consisting of a sliding window technique, where a detection cell of $3\times3$ pixels is shifted across the images. The total counts inside the detection cell are compared with a local background taken from the 16 pixels surrounding the detection cell itself. A 3$\sigma$ detection threshold has been applied. This local detection is used to produce a preliminary list of sources. \item {\em production of a smoothed background image}: the source list produced in the previous step is used to remove from the image circular regions around each source position. The resulting source-free image is fitted by a two--dimensional spline function to fill the holes and to produce a background image. A background image is produced for each energy band. \item {\em map--detection algorithm}: a new sliding window search is performed, this time using the background image to extract information about the local background. In other words, for each detection cell, the corresponding background is extracted, not from a frame surrounding it, but from the background map at that position. A second list of sources is produced, again with a 3$\sigma$ detection threshold. \item {\em merging of the source lists}: the two lists of sources resulting from the two sliding window searches are merged together, removing duplicates in order to have a unique list of sources (in each energy band). Duplicates are removed checking whether the distance between two sources is less than twice the sum of the size of the detection windows or less than the FWHM of the point spread function of the instrument. \item {\em maximum-likelihood method}: a maximum-likelihood method (Cruddace et al. 1987) is then applied to the photon lists, using the merged list of sources as candidates. This method considers the ROSAT PSPC point spread function and the position of the source inside the detector and derives a source position and an existence likelihood. Only a detection likelihood larger than 10 (corresponding to a probability of a chance detection smaller than e$^{-10}$) was considered as a true source. A final list of sources with their positions and positional uncertainties is thus produced. \end{itemize} This process yielded four lists of sources (one for each energy band). The same procedure was also applied on the individual observations, this time also considering the external part of the PSPC detector, resulting in 4$\times$43 lists of sources (4 energy bands and 43 observations). This second search was motivated by the fact that, e.g. due to source variability, some sources might have been missed in the previous global analysis. Finally, all the lists of detected sources were cross correlated in order to clean the catalogue, removing all the sources with a multiple detection. By multiple detection we mean two or more sources whose position is compatible with each other, in which case only the source with higher existence likelihood has been kept. This procedure yielded a final catalogue containing 107 sources. The count rates and upper limits (2$\sigma$) in each energy band have been extracted from the photon events tables at the position of the detected sources. Two softness ratios have been also derived: S/H and M/H, where H, M and S are the net source counts in the hard, medium and soft energy bands defined in Sect.~\ref{sect:obs}. %----------------------------------------------------------------------- \begin{figure*}[!ht] \vskip -0.5truecm \centerline{\psfig{figure=H2501f3.ps,height=120mm}} \vskip -1.0truecm \caption{Distribution of the ROSAT sources detected in the galactic center region} \label{fig:sources} \end{figure*} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \section{The catalogue of galactic center sources} The spatial distribution of the sources detected in the surveyed region is displayed in Fig.~\ref{fig:sources}. The remarkable symmetry of this distribution, and in particular the rather uniform source density as a function of galactic latitude, probably indicates that many sources are at a distance much closer than that of the galactic center. The final catalogue is reported in Table~\ref{catrosat}, where for each source the identification number, coordinates (J2000), count rate in the total energy band (0.1--2.4 keV), softness ratios S/H and M/H and possible identifications are reported. It is possible that a source has an upper limit in the total energy band, but is detected in one of the single energy bands. This is due to the energy-dependent background: faint sources detected, for example, in the hard energy range, could have been missed in the total energy band due to a higher background level. For these sources, the count rate in the energy band where a detection has been found is shown (and marked). On the other side, a few sources have been detected in the total energy band, but have only upper limits in all the other energy ranges; in this case the softness ratios are missing from Table~\ref{catrosat}. In Figs.~\ref{fig:hr1} and \ref{fig:hr2} the two softness ratios versus the count rate in the total energy band are shown. A ROSAT PSPC count rate of 0.01 counts s$^{-1}$ corresponds to about 5$\times10^{-11}$ ergs~cm$^{-2}$~s$^{-1}$ (unabsorbed flux), assuming a 5 keV bremsstrahlung spectrum and a column density of 6$\times10^{22}$~cm$^{-2}$. %---------------------------------------------------------------------- \begin{figure*} \centerline{\psfig{figure=H2501f4.ps,height=150mm,angle=-270}} \vspace{0cm} \caption[]{Softness ratio S/H as a function of the source count rate in the total energy band (0.1-2.4 keV). The upper limits on the total count rate refer to the sources that were detected only in the Soft or in the Hard energy bands. All the error bars are at 1$\sigma$ and the upper/lower limits at 2$\sigma$. The square symbols mark the sources possibly identified with stars } \label{fig:hr1} \end{figure*} %---------------------------------------------------------------------- %---------------------------------------------------------------------- \begin{figure*} \centerline{\psfig{figure=H2501f5.ps,height=150mm,angle=-270}} \vspace{0cm} \caption[]{Softness ratio M/H as a function of the source count rate in the total energy band (0.1-2.4 keV). The upper limits on the total count rate refer to the sources that were detected only in the Medium or in the Hard energy bands. All the error bars are at 1$\sigma$ and the upper/lower limits at 2$\sigma$. The square symbols mark the sources possibly identified with stars } \label{fig:hr2} \end{figure*} %---------------------------------------------------------------------- \section{Discussion} \label{sect:discussion} The application of the maximum--likelihood method to 43 pointings of the GC region performed with the ROSAT PSPC instrument in 1992--1993 has led to a new catalogue of soft X--ray sources. Our catalogue contains 107 detections, down to a count rate of $\sim$0.001 counts s$^{-1}$ in the energy range 0.1--2.4 keV. A correlation with the SIMBAD database resulted in probable identifications based on positional coincidence. The most plausible identifications (objects falling inside the PSPC error circle) are reported in Table~\ref{catrosat}. Other candidate counterparts (IRAS sources, for example) whose positions fall outside the PSPC error are also listed, when their large error boxes overlap with the ROSAT error box. For the possible counterparts listed in column (8) we give in parenthesis the distance between the optical and X--ray positions, the spectral type and magnitudes for stars, and other relevant informations as described in the notes to Table~\ref{catrosat}. \vspace{0cm} \begin{table}[!ht] \begin{center} \caption{X--ray sources not detected} \label{xrb} \begin{tabular}[c]{ll} \hline Source & Reference \\ \hline 1E 1743.1--2843 & Cremonesi et al. 1999 \\ XTE~J1748--288 & In 't Zand et al. 1998 \\ KS~1741--293 & In 't Zand et al. 1990 \\ GX+1.1--1.0 & Proctor et al. 1978 \\ GX+0.2--1.2 & Proctor et al. 1978 \\ GRS~1741.9--2853 & Sunyaev et al. 1991 \\ GRS~1734--29 & Sunyaev et al. 1991b \\ GRS~1743--290 & Cordier et al. 1993 \\ GRS~1747--312 & Pavlinski et al. 1994 \\ GRS~1747--341 & Cordier et al. 1993 \\ 1E~1742.5--2845 & Watson et al. 1981 \\ 1E~1742.7--2902 & Watson et al. 1981 \\ 1E~1742.9--2849 & Watson et al. 1981 \\ 1E~1743.1--2852 & Watson et al. 1981 \\ 1E~1741.2--2859 & Mitsuda et al. 1990 \\ GC~X--2 & Cruddace et al. 1978 \\ GC~X--4 & Cruddace et al. 1978 \\ XTE~J1755--324 & Remillard et al. 1997 \\ GRO~J1744--28 & Lewin et al. 1996 \\ SAX~J1750.8--2900 & Bazzano et al. 1997 \\ 1E~1740.7--2942 & Mirabel et al. 1992 \\ SAX~J1747.0--2853 = GX~0.2--0.2 & In 't Zand et al. 1998b \\ XTE~J1739--285 & Markwardt et al. 1999 \\ GRS~1739--278 & Paul et al. 1996 \\ \hline \end{tabular} \end{center} % \end{table} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \subsection{X--ray binaries} Our discovery of ROSAT counterparts to a few previously known X--ray sources, allows us to significantly improve their positions. This is the case of the recently discovered 729~sec X--ray pulsar AXJ 1740.2--2848 (Sakano \& Koyama 2000, later named AX~J1740.1--2847 by Sakano et al. 2000) and of the other two ASCA sources AX~J1744.3--2940 (Sakano et al. 1999a) and AX~J1740.3-2904 (Sakano et al. 1999b). We also inspected the error boxes of the X--ray binaries indicated in Table~\ref{xrb}, without finding any ROSAT counterparts in our catalogue, within a radius of 1$'$ of their position. \subsection{Foreground Stars} \label{sec:stars} A number of ROSAT sources have stellar counterparts in their error circles (see Table~\ref{catrosat}). To test these associations, we computed the log(f$_{\rm X}$/f$_{\rm opt}$) as in Voges et al. (1999), using a constant conversion factor of 1.48$\times10^{-11}$ ergs~cm$^{-2}$~cts$^{-1}$, appropriate for stellar sources (Fleming et al. 1995). The derived optical to X--ray flux ratios are displayed in Fig.~\ref{fig:stars} as a function of the count rate in the total energy band. Stars usually have log(f$_{\rm X}$/f$_{\rm opt}$) values in the range [$-$6,$-$1], depending on the spectral type. Therefore, on the basis of the ratio between their X-ray to optical flux, all these sources could indeed be stellar X--ray sources. From Figs.~\ref{fig:hr1} and \ref{fig:hr2} it can be seen that the sources tentatively identified with stars have relatively softer (or less absorbed) spectra. %---------------------------------------------------------------------- \begin{figure} \centerline{\psfig{figure=H2501f6.ps,height=70mm,angle=0}} \vspace{0cm} \caption[]{Log(f$_{\rm X}$ / f$_{\rm opt}$) as a function of the source count rate in the total energy band (0.1-2.4 keV) for the sources identified with stars } \label{fig:stars} \end{figure} %---------------------------------------------------------------------- \subsection{Supernova Remnants} \label{snr} We searched for the possible association of ROSAT sources with galactic supernova remnants. The inspection of the Green catalogue of all the SNRs (Green 1998) located in the region shows that no ROSAT point sources in our catalogue fall inside the region covered by the following supernova remnants: G0.3+0.0, G0.9+0.1, G1.0--0.1 and G359.1--0.5. Two ROSAT sources (n~81 and n~71) fall on or nearby the northern part of the radio shell of G359.0--0.9 (23$'$ size). Source n~3 is located at the center of the shell like SNR 359.1+0.9 (11$'$$\times$12$'$ size). This source can also be associated with the star HD316072 (see Sect.~\ref{sec:stars}). Diffuse X--ray emission has been recently detected with ASCA from the G359.0--0.9 shell and, marginally, from 359.1+0.9 (Sakano et al. 1999). \section{Conclusions} The spatial analysis, using a maximum-likelihood method, applied to public ROSAT PSPC data of the GC region led to the detection of 107 point-like sources, down to a PSPC count rate of 0.001 counts s$^{-1}$ in the 0.1--2.4 keV energy range. Using the SIMBAD database, 42 sources have been associated with objects at other wavelengths; 20 are probably stars and 5 have been identified with previously known LMXBs. Other sources have been already classified as X--ray objects, but their nature is still uncertain. Two sources in our catalogue could be associated with shells of supernova remnants and one with a molecular cloud or a maser source (n~72). An error circle of 1$'$ radius centered on the positions of 25 LMXBs known to lie inside the region surveyed with PSPC has been inspected, leading to negative results. All the sources brighter than 0.060 counts s$^{-1}$ have been positionally associated with known objects. The majority of our sources still remains unidentified. They are mostly undetected in the soft and medium PSPC energy ranges, they are quite hard and/or severely absorbed. Their average count rate in the total energy band (0.01~counts~s$^{-1}$) translates into a luminosity in the range $10^{35}$--$10^{36}$~erg~s$^{-1}$ (assuming a distance of 8.5 kpc) which is suggestive of mass-transfer from a companion star onto a compact object in a binary system. We propose that these still unidentified sources belong to a large population of X-ray binaries located in the GC region, accreting at low accretion rates, and still largely unknown. The transient sources recently discovered with ASM--XTE and WFC--BeppoSAX would be only the high luminosity tail of this population of LMXBs. \begin{acknowledgements} We have made use of the ROSAT Data Archive of the Max Planck Institut f\"ur extraterrestrische Physik at Garching; and of the SIMBAD database operated at Centre de Donn\'ees astronomiques in Strasbourg. We thank A.~Parmar for reading this manuscript and providing helpful comments. L.Sidoli acknowledges an ESA Fellowship. \end{acknowledgements} \begin{thebibliography}{} \bibitem{} Bazzano A., Heise J., Ubertini P., et al., 1997, IAU Circ. 6597 \bibitem{} Bradt H., Levine A.M., Remillard R.A., Smith D.A., 2000, In ``X--ray Astronomy 1999; Stellar Endpoints, AGN and the Diffuse Background", Bologna, Sep. 1999, Eds. G.Malaguti, G.Palumbo and N.White, pub. Gordon and Breach, in press (astr-ph/0003438) \bibitem{} Cordier B., et al., 1993, In ``The Second Compton Symposium", AIP 304, Eds. C.E.Fichtel, N.Gehrels and J.P.Norris (New York), 446 \bibitem{} Cremonesi D.I., Mereghetti S., Sidoli L., Israel G.L., 1999, A\&A 345, 826 \bibitem{} Cruddace R.G., Hasinger G.R., Schmitt J.H.M.M. 1987, In ``Astronomy from Large Databases", Murtaugh F., Heck A. 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Column n.8 reports the probable identifications based on the cross-correlation with SIMBAD database; in parenthesis we indicate the offset, spectral type, B and V magnitude for stars. The meaning of the other symbols is: Al*=Eclipsing Binary of Algol type; V*=variable star; bL*=Eclipsing Binary of beta Lyr type; *i*= star in double system; Em*=emission line star; IR=infrared source } \label{catrosat} \begin{tabular}[c]{|l|l|l|c|c|c|c|l|} \hline %\hline Source & R.A. & Dec. & Error & cts ks$^{-1}$ & Log(S/H) & Log(M/H) & Notes \\ ID & (J2000) & (J2000) & ($''$) & (0.1--2.4 keV) & & & \\ \hline 1 & 17 38 26.3 & $-$29 01 47.2 &6.2 & 79 $\pm{6.93}$ & $-0.111\pm{0.228}$ & $-0.0287\pm{0.203}$ & RXJ1738.4--2901 \\ 2 & 17 39 08.6 & $-$28 20 32.5 &14.9 & 11.1 $\pm{2.27} $ & $-$ & $-$ & \\ 3 & 17 39 31.1 & $-$29 09 50.3 &8.9 & 61.9 $\pm{5.86}$ & $< -0.840 $ & $-0.291\pm{0.206}$ & HD316072 (3$''$; K0;B=11.2;V=9.97); at the center of G359.1+0.9 \\ 4 & 17 39 40.9 & $-$28 51 11.3 &10.0 & 6.61 $\pm{1.36}$ & $< -0.416 $ & $< -0.229 $ & V846 Oph (1$''$; (Al* V*) A2; B=10.32; V=9.90) \\ 5 & 17 40 09.2 & $-$28 47 23 &11.4 & 5.06 $\pm{1.17}$ & $< -0.713 $ & $< -0.386$ & AXJ 1740.2--2848 (pulsar ) \\ 6 & 17 40 15.9 & $-$29 03 32.1 &10.0 & 19.2 $\pm{2.54}$ & $< -0.519 $ & $< -0.597 $ & AXJ1740.3-2904 \\ 7 & 17 40 19.9 & $-$29 00 4.90 &9.8 & 4.34 $\pm{1.30}$ & $< -0.334 $ & $< -0.863 $ & \\ 8 & 17 40 23.2 & $-$29 03 58.2 &20.9 & 5.73 $\pm{1.52}$ & $< 0.451 $ & $< -0.00757 $ & \\ 9 & 17 40 24.0 & $-$28 56 50.5 &3.6 & 55.4 $\pm{3.23}$ & $ 0.425\pm{0.147}$ & $0.0601\pm{0.169}$ & 1RXSJ174024.6--285700 (18$''$) \\ 10 & 17 40 41.2 & $-$28 08 50.0 &16.0 & 3.73 $\pm{1.2}$ & $-$ & $>$ 0.0988 & \\ 11 & 17 40 42.7 & $-$28 18 13.4 &1.4 & 251 $\pm{6.75}$ & $< -1.97 $ & $-1.59\pm{0.180}$ & RXJ1740.7--2818 (11$''$); 1E1737.5--2817 (47$''$) \\ 12 & 17 40 45.6 & $-$29 16 31.3 &11.9 & 10.2 $\pm{2.15}$ & $< 0.2067 $ & $< -0.796 $ & \\ 13 & 17 40 46.7 & $-$28 38 48.1 &9.8 & 9.24 $\pm{1.73} $ & $< 0.395 $ & $0.124\pm{0.422}$ & \\ 14 & 17 40 51.4 & $-$28 18 56.0 &14.8 & 4.26 $\pm{1.32}$ & $< -0.0684 $ & $<$ 0.404 & \\ 15 & 17 41 04.4 & $-$28 15 4.3 & 5.0 & 22.3 $\pm{2.14}$ & 0.0140$\pm{0.236}$ & $-0.141\pm{0.232}$ & \\ 16 & 17 41 23.7 & $-$28 47 43.0 &9.1 & 8.92 $\pm{1.60} $ & $0.247\pm{0.402}$ & $-0.169\pm{0.484}$ & \\ 17 & 17 41 33.8 & $-$28 40 35.0 &5.9 & 20.3 $\pm{1.92} $ & $< -1.107 $ & $-0.441\pm{0.209}$ & \\ 18 & 17 41 36.7 & $-$29 25 30.6 &22.5 & 4.32 $\pm{1.22}$ & $< -0.345 $ & $<$ 0.202 & \\ 19 & 17 41 41.8 & $-$28 33 22.1 &6.4 & 22.4 $\pm{2.08} $ & $0.271\pm{0.208}$ & $-0.177\pm{0.256}$ & \\ 20 & 17 41 58.0 & $-$29 05 34.5 &5.0 & 21.5 $\pm{1.97}$ & $0.15\pm{0.24}$ & $0.150\pm{0.231}$ & HD160572 (2$''$; F3V ;B=9.59;V=9.16) \\ 21 & 17 42 06.5 & $-$27 54 12.5 &18.7 & 3.07 $\pm{0.9} $ & $-$ & $-$ & \\ 22 & 17 42 15.2 & $-$29 14 59.2 &3.2 & 54.70 $\pm{3.43}$ & $0.387\pm{0.16}$ & $0.0245\pm{0.187}$ & \\ 23 & 17 42 16.9 & $-$28 37 1.2 & 16.9 & 3.99 $\pm{1.00}$ & $< -0.203 $ & $<$ $-0.897 $ & \\ 24 & 17 42 17.5 & $-$28 56 47.6 &11.6 & 3.98 $\pm{1.11}$ & $< -0.099 $ & $< -0.499 $ & \\ 25 & 17 42 27.8 & $-$28 14 55.9 &13.0 & 2.1 $\pm{0.7}^{(H)}$ & $< -0.342 $ & $<$ $-0.421$ & \\ 26 & 17 42 30.3 & $-$28 44 56.3 &1.8 & 212 $\pm{6.65} $ & $0.203\pm{0.077}$ & $0.0280\pm{0.0836}$ & V2384 Oph (1$''$; (bL* V*) G3/G5V; B=9.75; V=9.02) \\ 27 & 17 42 41.3 & $-$29 02 13.6 &8.7 & 11.6 $\pm{1.45}$ & $< -0.599 $ & $< -0.760 $ & \\ 28 & 17 43 19.5 & $-$29 14 1.10 &15.7 & 5.40 $\pm{1.14}$ & $< -0.688 $ & $< -0.579 $ & \\ 29 & 17 43 21.0 & $-$29 08 29.9 &19.2 & 3.1 $\pm{0.99}$ & $< -0.0307 $ & $< -0.462 $ & \\ 30 & 17 43 32.7 & $-$28 07 25.0 &5.5 & 23.5 $\pm{1.9}$ & $0.544\pm{0.220}$ & $0.0348\pm{0.267}$ & HD316199 (2$''$; K5; B=10.6) \\ 31 & 17 43 40.2 & $-$28 22 27.7 &52.0 & 1.9 $\pm{0.7}^{(H)}$ & $< -0.302 $ & $<$ 0.0246 & HD316212 (47$''$; K5; B=11.3; V=9.9) \\ 32 & 17 43 51.1 & $-$28 46 43.7 &11.6 & 11.0 $\pm{1.94}$ & $< -0.934 $ & $-0.420\pm{0.377}$ & \\ 33 & 17 43 53.8 & $-$29 06 21.9 &15.1 & 2.7 $\pm{1.0}^{(H)}$ & $< -0.308 $ & $< -0.571$ & IRAS17407--2904 (44$''$) \\ 34 & 17 43 55.6 & $-$28 29 57.9 &14.1 & 4.09 $\pm{1.23}$ & $< -0.402 $ & $<$ $-0.192$ & IR [OF84] 18 (37$''$); IRAS 17407--2829 (49$''$) \\ 35 & 17 44 03.1 & $-$28 30 1.5 & 15.3 & 5.33 $\pm{1.4}$ & $-$ & $>$ $-0.295$ & \\ 36 & 17 44 17.6 & $-$29 39 48.0 &6.6 & 14.9 $\pm{1.79}$ & $< -0.748 $ & $-0.553\pm{0.298}$ & AXJ1744.3--2940 (19$''$) \\ \hline \end{tabular} \end{center} \begin{small} \end{small} \end{table*} %................................................. \clearpage \addtocounter{table}{-1} \begin{table*}[htbp] \begin{center} \caption{Continued} \label{catrosat} \begin{tabular}[c]{|l|l|l|c|c|c|c|l|} \hline %\hline Source & R.A. & Dec. & Error & cts ks$^{-1}$ & Log(S/H) & Log(M/H) & Notes \\ ID & (J2000) & (J2000) & ($''$) & (0.1--2.4 keV) & & & \\ \hline 37 & 17 44 27.4 & $-$29 03 29.7 &8.4 & 2.9 $\pm{0.356} $ & $< 0.00717 $ & 0.0489$\pm{0.256}$ & \\ 38 & 17 44 46.2 & $-$27 47 27.3 &17.4 & 5.3 $\pm{2.0} $ & $-$ & $> -0.161 $ & \\ 39 & 17 44 47.0 & $-$28 49 28.3 &17.3 & 1.27 $\pm{0.316}$ & $-$ & $-$ & \\ 40 & 17 44 47.3 & $-$29 07 27.9 &13.9 & 2.3 $\pm{0.355}$ & $- $ & $> -0.198$ & \\ 41 & 17 44 53.3 & $-$28 51 39.3 &10.0 & 2.8 $\pm{0.4}^{(H)}$ & $< -0.404 $ & $< -1.494$ & IR MGM 1--3 (6$''$) \\ 42 (4) & 17 45 00.1 & $-$28 51 24.9 &15.0 & 3.9 $\pm{0.436} $ & $< -0.495 $ & $< -0.934 $ & 1E 1741.7--2850 (56$''$) \\ 43 & 17 45 03.8 & $-$29 10 47.8 &16.2 & 1.2 $\pm{0.279}$ & $-$ & $-$ & IR GCS13 (18$''$) \\ 44 (13) & 17 45 18.1 & $-$29 06 21.4 &10.5 & 1.3 $\pm{0.243} $ & $< -0.522 $ & $< -1.036 $ & \\ 45 & 17 45 22.5 & $-$28 17 32.5 &15.1 & 3.62 $\pm{1.24}$ & $<$$-0.273 $ & $< -0.126 $ & \\ 46 & 17 45 26.1 & $-$28 56 32.6 &10.9 & 0.38 $\pm{0.10}^{(M)}$ & $-$ & $>$ 0.0986 & CSI-28-17423 (7$''$; B; B=11.5;V=11.2); HD316223 (7$''$; G;B=1.3) \\ 47 & 17 45 28.0 & $-$29 12 4.5 & 26.2 & 1.2 $\pm{0.3}^{(H)}$ & $< -0.462 $ & $< -1.103 $ & IRAS 17422--2911 (51$''$) \\ 48 & 17 45 29.0 & $-$28 09 25.1 &10.3 & 8.37 $\pm{1.60}$ & $<$$-0.866$ & $< -0.648 $ & \\ 49 (12) & 17 45 30.3 & $-$29 07 06.8 &2.3 & 9.6 $\pm{0.499} $ & $< -0.753 $ & $0.0989\pm{0.108}$ & \\ 50 (8) & 17 45 32.5 & $-$28 59 47.6 &25.6 & $<$0.30 & $-$ & $-$ & \\ 51 & 17 45 32.6 & $-$28 47 17.3 &11.4 & 1.4 $\pm{0.275} $ & $< -0.147 $ & $-0.0456\pm{0.371}$ & \\ 52 (11) & 17 45 33.1 & $-$29 05 50.0 &8.0 & 1.0 $\pm{0.220}$ & $< -0.2446$ & $<$$-0.536$ & \\ 53 & 17 45 39.4 & $-$29 17 33.6 &16.4 & 0.9 $\pm{0.2}^{(H)}$ & $< -0.3189 $ & $<-0.642 $ & \\ 54 (7) & 17 45 40.7 & $-$29 00 29.4 &13.7 & 2.46 $\pm{0.48}$ & $< -1.145 $ & $< -1.316 $ & SgrA* (9$''$) \\ 55 & 17 45 41.7 & $-$29 08 52.7 &17.4 & 0.33 $\pm{0.10}^{(M)}$ & $-$ & $>$ 0.367 & \\ 56 & 17 45 43.1 & $-$28 59 36.7 &18.7 & 5.5 $\pm{0.5}$ & $< -1.297 $ & $< -0.684 $ & \\ 57 (14) & 17 45 44.0 & $-$29 13 22.9 &11.2 & 1.6 $\pm{0.289}$ & $< -0.427 $ & $-0.0802\pm{0.315}$ & HD316232 (6$''$; O+...; B=11.1 , V=10.4 ) \\ 58 (9) & 17 45 44.1 & $-$29 04 59.4 &5.5 & 2.2 $\pm{0.287} $ & $< -0.1869 $ & 0.0329$\pm{0.257}$ & \\ 59 (6) & 17 45 45.6 & $-$28 58 29.2 &4.8 & 2.4 $\pm{0.286}$ & $< -1.39 $ & $-0.765\pm{0.191}$ & \\ 60 (3) & 17 45 50.7 & $-$28 52 43.7 &5.9 & 2.1 $\pm{0.275} $ & $< -0.786 $ & $-0.209\pm{0.259}$ & \\ 61 (10) & 17 45 52.5 & $-$29 07 49.4 &6.6 & 1.8 $\pm{0.266}$ & $< -0.0979 $ & $-0.0926\pm{0.306}$ & \\ 62 & 17 46 01.8 & $-$28 29 16.7 &16.4 & 8.64 $\pm{1.5} $ & $>$ 0.556 & $>$ 0.199 & HD316297 (11$''$; K7; B=11.4; V=10.0) \\ 63 & 17 46 05.5 & $-$29 30 54.8 &3.2 & 121 $\pm{4.37}$ & $< -2.091$ & $<$ -2.446 & A1742--294 (13'') \\ 64 & 17 46 06.2 & $-$29 40 9.40 &13.0 & 3.27 $\pm{0.80}$ & $< -0.272$ & $< -0.0168 $ & V734 Sgr (4$''$; (Al* V*?); B=13.00) \\ 65 (5) & 17 46 07.3 & $-$28 59 50.2 &5.7 & 1.9 $\pm{0.271}$ & $< -0.713 $ & $< -0.558 $ & \\ 66 & 17 46 08.2 & $-$28 17 56.4 &12.5 & 5.12 $\pm{1.27}$ & $-$ & $-$ & \\ 67 (2) & 17 46 14.1 & $-$28 51 44.9 &18.2 & 4.1 $\pm{0.623} $ & $< -1.53 $ & $< -1.26 $ & 1E 1742.9--2849 (30$''$) \\ 68 & 17 46 31.6 & $-$28 10 29.0 &13.5 & 3.90 $\pm{1.15}$ & $<$$-0.374 $ & $< -0.713 $ & \\ 69 (1) & 17 46 39.2 & $-$28 53 52.4 &1.8 & 29.5 $\pm{0.864}$ & $< -1.00 $ & $-0.181\pm{0.060}$ & HD316314 (0$''$; F0; B=9.94; V=9.51); 1E1743.4--2852 (2$''$) \\ 70 & 17 47 00.4 & $-$29 13 1.90 &8.2 & 18.2 $\pm{1.42}$ & $< -1.102 $ & $-0.355\pm{0.167}$ & \\ 71 & 17 47 00.8 & $-$30 11 27.1 &25.6 & 8.8 $\pm{2.54}$ & $-$ & $-$ & inside the shell of the SNR G359.0--0.9 \\ 72 & 17 47 03.7 & $-$29 41 2.70 &17.1 & 3.27 $\pm{1.05}$ & $-$ & $>$ $-0.0539$ & OH359.5--0.7(13$''$; Molecular Cloud); [TVH89]203(15$''$; Maser) \\ \hline \end{tabular} \end{center} \end{table*} %................................................. \clearpage \addtocounter{table}{-1} \begin{table*}[htbp] \begin{center} \caption{Continued} \label{catrosat} \begin{tabular}[c]{|l|l|l|c|c|c|c|l|} \hline %\hline Source & R.A. & Dec. & Error & cts ks$^{-1}$ & Log(S/H) & Log(M/H) & Notes \\ ID & (J2000) & (J2000) & ($''$) & (0.1--2.4 keV) & & & \\ \hline 73 & 17 47 05.3 & $-$28 08 54.8 &6.4 & 27.0 $\pm{2.81}$ & $< -0.941 $ & $-0.147\pm{0.208}$ & BN Sgr (5$''$; (Al* V*) F3V; B=9.60; V=9.28) \\ 74 & 17 47 14.9 & $-$30 01 57.5 &17.7 & 3.6 $\pm{1.2}$ & $<-0.697 $ & $< -0.378 $ & \\ 75 & 17 47 15.5 & $-$29 58 04.3 & 8.0 & 20 $\pm{2.48 }$ & $< -1.450 $ & $<$ $ -1.62$ & G359.23--0.92 (The Mouse) \\ 76 & 17 47 23.5 & $-$30 00 39.3 &22.4 & 36.2 $\pm{3.61}$ & $< -1.189 $ & $<$ $-1.649$ & \\ 77 & 17 47 25.4 & $-$30 02 40.7 &3.6 & 126 $\pm{6.0}$ & $< -2.046 $ & $< -2.12 $ & SLX1744--300 (27$''$) \\ 78 & 17 47 25.9 & $-$29 59 57.8 &2.7 & 197.2 $\pm{7.30}$ & $< -2.258 $ & $-1.88\pm{0.337}$ & SLX1744--299 (15$''$) \\ 79 & 17 47 29.9 & $-$29 58 57.7 &17.3 & 11.0 $\pm{2.09}$ & $< -0.567 $ & $<$ $-1.348 $ & \\ 80 & 17 47 31.0 & $-$28 13 46.8 &5.5 & 31.4 $\pm{3.64}$ & $-0.446\pm{0.353}$ & $-0.138\pm{0.258}$ & \\ 81 & 17 47 37.3 & $-$30 10 23.9 &27.6 & 12.6 $\pm{3.12}$ & $< -0.8195 $ & $< -0.758 $ & near the shell of the SNR G359.0--0.9 \\ 82 & 17 47 54.2 & $-$29 59 8.4 & 15.3 & 4.1 $\pm{1.25}$ & $-$ & $-$ & \\ 83 & 17 48 07.8 & $-$29 07 58.8 &13.9 & 4.82 $\pm{1.13}$ & $< -0.279 $ & $<$ $-0.673$ & CD--29 14004 (7$''$; B+...; B=11.83; V=11.05) \\ 84 & 17 48 25.1 & $-$28 44 24.5 &15.7 & 3.19 $\pm{0.84} $ & $< -0.200 $ & $< -0.452$ & \\ 85 & 17 48 28.7 & $-$29 00 33.0 &12.8 & 3.81 $\pm{0.96}$ & $< -0.319 $ & $< 0.00770 $ & \\ 86 & 17 48 35.3 & $-$29 57 23.3 &10.7 & 8.11 $\pm{1.36}$ & $< -0.681$ & $<-0.717 $ & HD316341 (6$''$; (Em*) O+...;B=9.54;V=9.06) \\ 87 & 17 48 49.4 & $-$30 01 03.9 &10.7 & 5.1 $\pm{1.02}$ & $< 0.0156 $ & $< -0.420 $ & \\ 88 & 17 48 53.4 & $-$29 08 6.70 &7.5 & 8.19 $\pm{1.27}$ & $< -0.363 $ & $-0.259\pm{0.353}$ & \\ 89 & 17 48 54.4 & $-$28 59 39.2 &11.0 & 6.55 $\pm{1.31}$ & $< -0.0571 $ & $-0.343\pm{0.480}$ & HD316308 (9$''$; K0; V=9.0) \\ 90 & 17 49 25.8 & $-$29 01 57.2 &16.7 & 1.9 $\pm{0.7}^{(H)}$ & $< -0.189 $ & $< -0.494 $ & \\ 91 & 17 49 28.6 & $-$29 18 58.8 &4.10 & 41.0 $\pm{2.7} $ & $0.404\pm{0.169}$ & $0.0645\pm{0.191}$ & HD161907 (6$''$; (*i*); B=8.33;V=8.05); \\ & & & & & & & CD--29 14038B (9$''$; (*i*);V=13.0) \\ 92 & 17 49 37.8 & $-$29 03 24.1 &10.5 & 9.35 $\pm{1.54}$ & $< -0.754 $ & $<$ $-0.386$ & \\ 93 & 17 49 41.4 & $-$29 17 12.7 &17.3 & 3.5 $\pm{1.02}$ & $-$ & $-$ & HD316418 (16$''$; F0; B=9.94; V=9.46) \\ 94 & 17 50 04.9 & $-$30 08 29.3 &16.4 & 7.33 $\pm{1.61}$ & $< -0.480 $ & $0.0434\pm{0.428}$ & \\ 95 & 17 50 07.3 & $-$30 01 55.2 &14.1 & 3.73 $\pm{1.17}$ & $< -0.139 $ & $< -0.378 $ & \\ 96 & 17 50 24.9 & $-$29 34 53.5 &16.4 & 1.5 $\pm{0.50}^{(M)}$ & $-$ & $>$ 0.0794 & \\ 97 & 17 50 29.4 & $-$29 00 7.2 & 10.3 & 5.93 $\pm{1.22}$ & $< -0.717 $ & $<$ $-1.123$ & 1RXPJ175029.8--285957 (10$''$) \\ 98 & 17 50 33.8 & $-$29 21 11.4 &15.3 & 2.6 $\pm{0.8} $ & $-$ & $-$ & \\ 99 & 17 50 41.3 & $-$29 16 44.5 &7.5 & 9.35 $\pm{1.38}$ & $< -0.388 $ & $0.0536\pm{0.304}$ & HD162120 (3$''$; (*i*) A2V; B=8.51; V=8.33) \\ 100 & 17 50 58.0 & $-$29 39 00.1 &13.3 & 3.24 $\pm{1.05}$ & $-$ & $-$ & \\ 101 & 17 51 11.1 & $-$29 35 41.9 &9.8 & 3.41 $\pm{0.99}$ & $< -0.570 $ & $< -0.589 $ & \\ 102 & 17 51 25.9 & $-$29 37 44.4 &11.0 & 4.56 $\pm{1.17}$ & $< -0.924 $ & $< -0.457 $ & \\ 103 & 17 51 36.7 & $-$29 05 31.8 &17.1 & 3.02 $\pm{0.86}$ & $-$ & $>$ 0.0793 & \\ 104 & 17 51 38.5 & $-$29 50 26.3 &14.8 & 6.69 $\pm{1.93}$ & $< -0.563 $ & $<$ $-0.857$ & \\ 105 & 17 51 41.4 & $-$29 18 49.5 &12.6 & 4.35 $\pm{1.28}$ & $< -0.252 $ & $<$ $-0.356$ & \\ 106 & 17 51 42.2 & $-$29 45 47.4 &31.0 & 3.5 $\pm{1.1}^{(S)}$ & $>$ 0.293 & $-$ & \\ 107 & 17 52 21.2 & $-$29 04 32.2 &10.9 & 3.9 $\pm{1.12}$ & $< -0.608 $ & $<$ $-0.0804$ & \\ \hline \end{tabular} \end{center} \begin{small} \end{small} \end{table*} \end{landscape} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \clearpage \end{document} --------------81A2B3FB8E8308781E444406--