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CLASS B1555+375, a quad image gravitational lens

Lens System Summary

CLASS B1555+375 is a quad-image gravitational lens system.

This Lens System

Lens name B1555+375
Survey CLASS
Images 4
B1950.0 coords 15h55m22.030s 37°30'10.942"
J2000.0 coords 15h57m11.940s 37°21'35.965"

Lens System Structure and Labelling

Image labelling for this lens (RA increases to the left, declination increases upwards)

Images labelled as in Marlow et al.

Image/Lens Positions

Image/Lens Relative Position
East (mas) North (mas)
A +0.0 +0.0
B -72.6±1 +48.0±1
C -411.7±1 -28.0±1
D -161.9±6 -368.0±6

Image/Lens Separations

Separation (mas)
Component A B C D
87.0 412.7 402.0
B 87.0
347.5 425.5
C 412.7 347.5
D 402.0 425.5 421.9
Position angle (°)
Component A B C D
123.5 86.1 23.7
B -56.5
77.4 12.1
C -93.9 -102.6
D -156.3 -167.9 143.7

Maps and Images

Click on an image to see a larger JPEG version, or click on the accompanying text to download a gzipped FITS or PostScript file of the map or image. The images and maps are available in one gzipped file here. To see a DSS image of the region around this lens, click here - note that you will have to start the search manually by clicking on the 'Search' button.

Radio images Click to see a larger version
MERLIN 5GHz image

Radio Flux Densities

Component Flux density (mJy)
5 GHz 8.4 GHz 15 GHz
A 17.0
B 9.7
C 8.3 9.6 11.4
D 1.3
Flux errors

Resolution (mas) 50 250 150
Map noise level
0.06 0.14 0.27
Date observed 1997/12/01 1995/08/16 1998/05/15
Reference [1] [1] [1]

Sub-millimetre Flux Densities

Component Flux density (mJy)
850 μm 450 μm
Total <6.8 <39
cal. error
5-10% 5-10%
Date observed 1999-2001 1999-2001
Reference [2] [2]

Optical Imaging

Component Brightness (Magnitudes)
Total ~25 ~19
Instrument LRIS (Keck II) WHT
Integration time 2 exp, 5 min each 5 exp, 20 min total
PSF size (arcsec)

Pixel scale (mas/pixel)
Date observed 1998/08/02 1997/08/24
Reference no. [1] [1]

Lens Models

Click on the model's reference number to go to the relevant paper's abstract on ADS.

Marlow et al. fitted a singular isothermal ellipsoid mass profile without external shear to the lens system.


  1. Currently no redshifts are available for this system.


Click here to see the CASTLES data available for this object, or here to search for references on NED. You can go to a paper's abstract on ADS by clicking its reference number.

[1] CLASS B1555+375: A new four-image gravitational lens, D. R. Marlow et al., Astron. J. 118, pp. 654-658 (1999)

[2] A submillimeter survey of gravitationally lensed quasars, R. Barvainis and R. Ivison, Astrophys. J. 571, pp. 712-720 (2002)

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