You can give a value to one (or more) of the following searches criterium cluster name, RA, DEC, Radius, Flux, Luminosity, Temperature, Bibliography.

Note that the system will search for clusters and/or references which correspond to  ALL the criteria you give.
Criteria can be physical (cluster name, RA, DEC, Radius, Flux, Luminosity, Temperature) or bibliographic (a list of keywords )

          Query by file  :

          If you want to querry BAX for many clusters or arround  many possitions, you have the possibility to  browse a file containing a list, which name is free but should have the extension .txt  (like myquerry.txt)

           For the query By Name, the file should contain one cluster name per line 


           For the query By Position, the file should contain one position and size  per line  with a  semicolon (;) as a separator :


          12h59mn48.7s ;27d58mn50s;10


    Cluster name

    The name should be given following the NED format.

    Examples of cluster name input:

    For Abell clusters: ABELL0085, ABELL 0085, A85, A 85, a85, a 85, abell 0085, abell0085

    Using wildcard '*" character will cause a template search (all clusters contained in BAX). If the wildcard character is used in front of a near cluster name, the list of synonyms for the specified cluster name are given (Ex: RX* will return all cluster name begining with RX). The '*' is not allowed within a word.

    Some examples for non-Abell clusters:

    Zwicky clusters : ZwCl 1021.0+0426

    Clusters name with CL is used instead of the nomencalture ClG, CLG.


    Right ascension in hh mn ss  or degree (xxx.xx). from NED.


    Declination in hh mn ss or degree (xxx.xx). The coordinates are retrieved from NED database when available.

    System and Equinox

    Coordinates are entered in J2000 system. BAX gives to the user the possibility of converting its coordinates in any given
    system to J2000. In the second panel coordinates are in the Galactic system.


    Longitude is in degree (xxx.xx).


    Latitude in degrees (xxx.xx).


    Is retrieved from NED and the reference therein . It can happen that the redshift is not available in NED  database, in this case we search for it in the literature.


    Radius around the coordinate of the object in arcmin. Default value is 100.  arcmin

    Flux : Fx

    Fluxes are by default in the 0.1-2.4 keV ROSAT band in unit of 10 -12 ergs s -1 cm -1. If the flux is given in an otherenergy band it is automatically converted in the ROSAT band using a Raymond Smith type spectrum with a global metal abundance of 0.33 of the solar value. Note that when the user asks for all measurement, the flux and luminosities are given in their original band. When the flux is not published, it is derived from the luminosity Lx measurement when available. It can happen that for a given cluster for which a flux has been measured, no conversion is possible (neither in the ROSAT band nor in luminosity) because of the lack of redshift. The user can retrieve the flux as published by selecting the all measurements button.

    Luminosity: Lx

      [0.1-2.4 keV] rest-frame luminosity in unit of 10 44 ergs s-1. For the sake of homogeneity, Lx is derived from the Flux measurement using a simple conversion code based on a Raymond Smith type spectrum assuming a metallicity 0.33 times the solar value. The luminosity-temperature relation is used to estimate the temperature.

    Temperature : Tx

        In keV. The errors bars are quoted at 1 sigma confidence level.

    BASIC DATA   :  Only canonical values of Fx, Lx and Tx are given. These canonical values are choosen among the most precise one and/or the latest published measurements.

    all measurements   :  gives all the measurements published in the literature. Note that Fx is given as originally quoted in the reference.

Note that the Hubble constant is set to H_o= 50km <s/Mpc and the cosmological matter density Omega_M = 1.0


    BAX searches in the bibliographic database by keywords. BAX returns the bibliographic references associated with at least one of the selected keyword.
    The keywords are divided into 4 main categories :

    The keywords can be selected from the Observatory list AND/OR from the 3 checkboxes listes: Observational techniques, Physical data, Physical state

    Note In the "By parameters" query menu, the relation between the keywords from the scrolling menu ( Observatory) is an OR relation. Inside the same checkbox list, the relation is AND. The relation between the 4 lists (srolling menu and 3 checkboxes lists) is AND.
    The definition of each keyword is given in the following table.
    Observatory Ariel V, ASCA, BeppoSAX, Chandra, Einstein, EXOSAT, Ginga HEAO-1, ROSAT, Tenma, Uhuru, XMM
    Observational Techniques X-Rays photometry, X-Rays spectroscopy, X-Rays imaging,
    Spatially resolved spectroscopy, Optical, Lensing, UV, SZ, Radio

      Physical data Meaning
      Fx unabsorbed X-ray flux in ROSAT band 0.1-2.4 keV in units 10 -12 ergs s -1cm-2
      Lbol X-ray bolometric luminosity in units of 1044ergs s -1
      Lx X-ray luminosity in the ROSAT band (0.1-2.4 keV) in 1044 ergs s -1
      M_gas Gas mass in a radius r 
      M_tot Total mass in a radius r
      Tx X-ray gas temperature in keV
      Temperature profile Radial profile of the X-ray gas temperature 
      Temperature map X-ray temperature map
      Abundance metallicity 
      Abundance profile Radial profile of the metallicity
      Beta is the slope of the gas density profile derived from the b-model fitting
      Relative abundances ex: [O/Fe], [Mg/Fe]....
      Count rate  Counts rate in cps/s 
      R_c Core radius 
      M_gas  Gas mass inside a given radius
      M_tot  Total gravitating mass inside a given radius
      M_dot The mass deposited in the cluster center due to cooling flows
      Sx profile Surface brightness profile expresses in units of cts s-1 arcmin-2
      ne_o Central gas density
      Velocity dispersion  Velocity dispersion derived from radial velocities measurement
      L_opt Total optical luminosity
      R_E Einstein ring radius in lensing image
      Shear defines the lensing effect
      Shocks presence of shocks
      Physical state Meaning
      Mergers physical state of a cluster which is either in process of merging with a subcluster or which has experienced a merger (collision)
      Morphology defines the shape of a cluster (elongated, spherical, smooth, regular, irregular, etc...)
      Cooling flows  presence of cooling flow
      Ellipticity  defines the geometry of a cluster e=0 if a cluster is not elongated (spherical case)
      X-Rays image  X-rays image obtained from the analysis of fits tables 
      Optical image  image obtained from optical observations
      Substructure inhomegeneities or presence of clumps in clusters

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