Enter an RBS catalogue number, identifier, coordinate:
As an identifier please enter one of the following:

  
the RBS sequence number (e.g. #1 - #2072)
  
the entry in the 1RXS-catalogue (e.g. 1RXS J000312.3-355541)
  
an alternate name (e.g. Abell 2717)
  
the coordinates in the format: ra(hrs) ra(min) ra(sec) +/-dec(hrs) dec(min) dec(sec) 
(e.g. 00 03 15.3 -35 57 18)

Define a radius:
Enter either the radius (deg) of objects around the target to be displayed or the number (next#) of 
following ROSAT Bright Survey Catalogue objects.

Class of objects:
Choose either all classes of objects to be displayed in the output (default) or select a 
single class.

Sort for:
Choose the order of the query output by sorting for one of the following:

  
Ra(2000): The optical right ascension for euqinox J2000
  
Dec(2000): The optical declination for equinox J2000
  
Distance: The distance between the optical and the X-ray coordinate in arcsec
  
Err: The X-ray positional uncertainty
  
0.1-2.4 keV countrate
  
0.5-2.0 keV countrate
  
HR1: The hardness ratio HR1=(H+S)/(H-S), with H and S being the counts in the hard 
(0.5-2.0 keV) and the soft (0.1-0.4 keV) spectral bands, respectively.
  
HR2: The hardness ratio HR2=(H+S)/(H-S), with H and S being the counts in the hard 
(0.9-2.0 keV) and the soft (0.52-0.9 keV) spectral bands, respectively.
  
NH: The hydrogen column density towards the X-ray source in 1020 cm-2 
  
Redshift: The redshift of the X-ray source
  
Optical Mag: The optical magnitude of the X-ray source
  
X-ray flux: The X-ray flux  in the 0.5-2.0 keV
  
log(Fxo): log FX/Fo, where FX is the flux in the 0.5-2.0 keV band and Fo the optical flux.
  
X-ray luminosity: The log of the X-ray luminosity  


up/down:
Choose the sorting order.

# of hits to display:
Choose the number of objects to be displayed.

#:
The RBS sequence number

IMG:
Click on the marked RBS sequence number for finding charts and spectra.

1RXS J...:
The entry in the 1RXS-catalogue (X-ray coordinates for equinox J2000)

RASS:
Click on the 1RXS-catalogue entry of a source links to the ROSAT Source Browser entry of the 
given object.

RA(2000):
The optical right ascension for euqinox J2000

SIMBAD:
Click on the optical right ascension of a source links to the SIMBAD Astronomical Database entry 
of the given object.

DEC(2000):
The optical declination for the X-ray source for equinox J2000

NED:
Click on the optical declination of a source links to the NASA/IPAC Extragalactic Database entry 
of the given object.

SDSS:
Click on the countrate a source links to the SDSS-DR12 entry of the given object.

DIST:
The distance between the optical and the X-ray coordinate in arcsec

ERR:
The X-ray positional uncertainty (1 sigma) in arcsec as given in the 1RXS-catalogue. The 90% 
confidence error radius is r90 = 1.65 sigma.

CR:
The RASS countrate in the total ROSAT window 0.1-2.4 keV

CRH:
The Rass countrate in the hard ROSAT window 0.5-2.0 keV

HR1:
The hardness ratio HR1=(H+S)/(H-S), with H and S being the counts in the hard (0.5-2.0 keV) and 
the soft (0.1-0.4 keV) spectral bands, respectively.

HR2:
The hardness ratio HR2=(H+S)/(H-S), with H and S being the counts in the hard 
(0.9-2.0 keV) and the soft (0.52-0.9 keV) spectral bands, respectively.

NH:
The hydrogen column density towards the source in 1020 cm-2

Name:
An alternate name of the source (for sources with catalogue entries others than RBS), truncated 
to 15 characters 

Class and Type:
The class and the type of the X-ray source with the following abbreviations (a colon indicates 
an uncertain identification): 

Plausible identifications based on NED or SIMBAD correlation entered the table without checking 
the original literature. If class or type of a specific source seemed questionable for its 
specific properties (e.g. unusual high X-ray flux or X-ray extent), it entered our spectroscopic 
identification program.


z:
The redshift of the X-ray source (if extragalactic), a colon indicates an uncertain value

Mag:
An optical magnitude of the X-ray source, a colon indicates an uncertain value. The character 
behind the value identifies the source of information: C - CDS/SIMBAD (V-band), D - CDS/SIMBAD 
(B-Band), N - NED (a magnitude in the optical range), R - APM/ROE scan of POSS/ESO/SERC red (E) 
plate, B - APM/ROE scan of POSS/ESO/SERC blue (O) plate, S - below slit magnitude determined by 
folding a low-resolution spectrum with the sensitivity curve of a V-filter, G - SDSS 12 (G-band, 468.6 nm).

Flux:
The X-ray flux  in the 0.5-2.0 keV range in units of 10-14 erg cm-2 s-1. Assuming a power law 
spectrum with photon index 2 a count-to-energy conversion factor ECF for the ROSAT PSPC was 
computed for given column density towards the X_ray source (galactic NH assumed). The flux was 
then computed using the countrate in the hard band (column 8) via fx = CRH/ECF. This approach 
yields unreliable and inconsistent results for sources with HR1 smaller than -0.4, even an 
unabsorbed power law cannot be softer than this limit.

log(Fxo):
The log of FX/Fo, where FX is the flux in the 0.5-2.0 keV band and Fo the optical flux.

Lx:
The log of the X-ray luminosity in ergs/s computed as Lx = 4 pifx(cz/H0)2, with H0=50 km s-1 Mpc-1.

Note:
The "Y" indicates a note or comment to the source somtimes using shortcuts which are explained in the table below.