CASSOWARY

CASSOWARY Gravitational Lenses

C A S S O W A R Y
Cambridge And Sloan Survey Of Wide ARcs in the skY
The Cassowary is the second largest flightless bird on the planet.

Artist impression of the Cosmic Horseshoe lens by Brendon Brewer

The Survey
The aim is to carry out systematic searches for wide separation (>1.5 arcsec) gravitational lens systems, looking for multiple, blue companions around massive ellipticals in the Sloan Digital Sky Survey (SDSS) object catalogue. Typically, the target systems correspond to lensing of z > 0.5 star-forming galaxies by luminous red galaxies and brightest cluster galaxies. The survey started in the summer of 2007 and the first version of the catalogue was published in June 2008.

The Catalogue
The current version (08th November, 2019 ) of the CASSOWARY catalogue contains 45 objects (counting binaries twice).
It is also available for download as an ASCII table. The 14 collumns are: CSWA ID, SDSS ObjID, RA (deg), Dec (deg), SDSS lens magnitudes (not corrected for Galactic extinction) u, g, r, i, z, SDSS SpecObj ID, lens redshift, redshift reference, source redshift, redshift reference. Missing values are indicated by -99.

The ObjIDs of the arc knots (as resolved by the SDSS pipeline) are also available. These are used to generate arc total magnitudes.

View according to

		CSWA 1 a.k.a. Cosmic Horseshoe ObjId 587742572151374147 RADec 177.1380745 19.50087261 ugriz L 23.3 20.8 19.0 18.2 17.8 ugriz S 20.2 19.8 19.5 19.5 18.7 No SDSS spectrum Z_L 0.444¹ Z_S 2.379¹			CSWA 2.1 a.k.a. Cheshire Cat ObjId 588013382200131773 RADec 159.68160026 48.8215933 ugriz L 23.0 20.3 18.6 17.9 17.4 ugriz S 21.2 20.4 20.1 19.9 19.3 SpecObj 246515463746486272 Z_L 0.426⁰ Z_S 0.97²
		CSWA 2.2 a.k.a. Cheshire Cat ObjId 588013382200131774 RADec 159.67786606 48.82229409 ugriz L 22.3 20.6 18.8 18.2 17.7 ugriz S 21.2 20.4 20.1 19.9 19.3 No SDSS spectrum Z_L 0.432² Z_S 0.97²			CSWA 3 ObjId 588017605222793376 RADec 190.1345157 45.15079076 ugriz L 21.2 20.0 18.4 17.9 17.6 ugriz S 19.8 19.6 19.7 19.4 19.4 No SDSS spectrum Z_L 0.274² Z_S 0.725²
		CSWA 4 a.k.a. SDSS J090122.37+181432.3 ObjId 588023046402670876 RADec 135.34321049 18.24231627 ugriz L 21.5 19.7 18.0 17.3 17.0 ugriz S 22.5 21.4 21.2 20.8 19.7 SpecObj 642838136396709888 Z_L 0.346⁰ Z_S 2.2586⁷			CSWA 5.1 ObjId 588848901528223970 RADec 191.21400615 1.11193257 ugriz L 22.3 20.6 19.1 18.4 18.0 ugriz S 20.5 20.6 20.7 20.6 20.2 No SDSS spectrum Z_L ? Z_S 1.0686¹⁵
		CSWA 5.2 ObjId 588848901528223971 RADec 191.21257821 1.11222194 ugriz L 22.3 20.4 18.4 17.9 17.7 ugriz S 20.5 20.6 20.7 20.6 20.2 SpecObj 82132249671106560 Z_L 0.388⁰ Z_S 1.0686¹⁵			CSWA 6 a.k.a. The Clone ObjId 588013382206357664 RADec 181.50871224 51.70820438 ugriz L 22.7 20.0 18.4 17.7 17.3 ugriz S 21.2 20.0 19.7 19.4 19.1 SpecObj 248767590678134784 Z_L 0.433⁰ Z_S 2.00⁸
		CSWA 7 a.k.a. SDSS J1137 + 4936 ObjId 588295841784725744 RADec 174.41690253 49.60987175 ugriz L 24.5 21.2 19.4 18.6 18.2 ugriz S 20.6 20.3 20.3 20.1 20.0 SpecObj 272412374034546688 Z_L 0.448⁰ Z_S 1.411⁶			CSWA 8 a.k.a. SDSS J120923.7+264047 ObjId 587741600957333763 RADec 182.34869727 26.6796452 ugriz L 24.9 20.8 19.0 17.9 17.4 ugriz S 21.5 21.8 21.3 20.4 19.8 SpecObj 627638892169789440 Z_L 0.558⁰ Z_S 1.018⁵
		CSWA 9 ObjId 587742902862086260 RADec 186.82808228 17.43107014 ugriz L 22.7 19.9 17.9 17.3 16.8 ugriz S 22.2 21.4 21.1 20.8 19.2 No SDSS spectrum Z_L 0.37^-1 Z_S ?			CSWA 10 ObjId 587730773880078847 RADec 339.63047433 13.33218384 ugriz L 21.3 19.8 17.9 17.2 16.7 ugriz S 21.2 20.7 20.1 19.9 19.2 SpecObj 208235580448833536 Z_L 0.413⁰ Z_S 1.0¹⁸
		CSWA 11 ObjId 587744873710682762 RADec 120.05441848 8.20232396 ugriz L 22.4 19.3 17.7 17.0 16.7 ugriz S 20.3 19.9 19.9 20.0 19.4 No SDSS spectrum Z_L 0.31^-1 Z_S ?			CSWA 12 a.k.a. MACS J1133.2+5008 ObjId 587732484357095512 RADec 173.30488333 50.14447842 ugriz L 20.7 19.4 18.1 17.5 17.0 ugriz S 21.6 21.6 21.0 20.5 20.9 No SDSS spectrum Z_L 0.394⁴ Z_S 1.544⁴
		CSWA 13 ObjId 587731870173298881 RADec 189.40082835 55.56190979 ugriz L 23.4 20.7 18.8 18.1 17.5 ugriz S 19.9 19.7 19.8 19.6 19.5 SpecObj 287330913719681024 Z_L 0.410⁰ Z_S ?			CSWA 14 ObjId 587736980648362708 RADec 260.90067032 34.19946453 ugriz L 22.6 20.1 18.4 17.6 17.3 ugriz S 20.6 20.3 20.4 20.6 19.2 No SDSS spectrum Z_L 0.444¹⁸ Z_S 0.995¹⁸
		CSWA 15.1 ObjId 587742014344265970 RADec 152.2490633 19.62151556 ugriz L 21.3 19.0 17.4 16.7 16.5 ugriz S 23.3 22.0 22.0 22.5 20.6 SpecObj 667889578840948736 Z_L 0.306⁰ Z_S ?			CSWA 15.2 ObjId 587742014344265969 RADec 152.24695521 19.62092953 ugriz L 21.8 19.3 17.6 16.8 16.4 ugriz S 23.3 22.0 22.0 22.5 20.6 SpecObj 668171053188513792 Z_L 0.465⁰ Z_S ?
		CSWA 16.1 ObjId 587731868557115670 RADec 167.76534454 53.14858718 ugriz L 22.1 20.2 18.7 18.0 17.6 ugriz S 21.8 20.7 20.7 20.5 19.8 No SDSS spectrum Z_L 0.33^-1 Z_S ?			CSWA 16.2 ObjId 587731868557115671 RADec 167.76378766 53.14774276 ugriz L 24.5 20.7 19.0 18.2 17.8 ugriz S 21.8 20.7 20.7 20.5 19.8 No SDSS spectrum Z_L 0.46^-1 Z_S ?
		CSWA 17 ObjId 587741709956546742 RADec 174.53730655 27.9085314 ugriz L 21.6 20.4 18.7 18.1 17.8 ugriz S 24.1 22.0 21.6 21.4 20.8 No SDSS spectrum Z_L 0.33^-1 Z_S ?			CSWA 18 ObjId 587742191511273514 RADec 173.52808224 25.55977002 ugriz L 17.3 15.3 14.4 14.0 13.7 ugriz S 20.3 19.4 19.3 19.1 18.9 SpecObj 587742191511273514 Z_L 0.07⁰ Z_S ?
		CSWA 19 ObjId 587741421640024462 RADec 135.01101894 22.56801561 ugriz L 24.1 21.1 19.1 18.2 17.9 ugriz S 20.3 19.9 19.8 19.8 19.3 SpecObj 643119522567421952 Z_L 0.489⁰ Z_S 2.0325¹³			CSWA 20 ObjId 587742611340001632 RADec 220.4548069 14.68904854 ugriz L 24.6 25.1 22.7 20.7 20.2 ugriz S 20.1 20.1 19.9 19.9 19.7 No SDSS spectrum Z_L 0.741⁹ Z_S 1.433⁹
		CSWA 21 a.k.a. 8 O'Clock Arc ObjId 588290880028999911 RADec 5.67049154 14.51956525 ugriz L 22.1 20.1 18.4 17.8 17.3 ugriz S 23.0 20.0 19.8 19.7 19.5 SpecObj 212174997320368128 Z_L 0.38¹⁰ Z_S 2.73¹⁰			CSWA 22 a.k.a. Hall's Arc ObjId 587727230523080836 RADec 26.73337065 -9.49791496 ugriz L 21.6 20.3 18.5 17.8 17.6 ugriz S 21.0 20.4 19.9 19.2 19.5 SpecObj 187123470625144832 Z_L 0.44¹¹ Z_S 1.944¹⁸
		CSWA 23 a.k.a. SDSS J082728.70+223256.4 ObjId 587739115775197598 RADec 126.87013375 22.54831707 ugriz L 24.9 20.5 18.8 18.2 17.8 ugriz S 20.0 19.9 20.2 19.4 19.2 No SDSS spectrum Z_L 0.349¹² Z_S 0.766¹²			CSWA 24 a.k.a. SDSS J151118.73+471340.3 ObjId 587733412060987606 RADec 227.82806483 47.22787249 ugriz L 24.4 20.1 18.4 17.6 17.1 ugriz S 22.9 22.3 23.1 22.2 22.2 SpecObj 295775162215694336 Z_L 0.452⁶ Z_S 0.98⁶
		CSWA 25 a.k.a. SDSS J104943.14+442035.6 ObjId 588297863115047025 RADec 162.42975402 44.34322791 ugriz L 21.3 18.6 17.0 16.5 16.2 ugriz S 21.4 20.8 20.3 19.9 19.4 SpecObj 403862977867939840 Z_L 0.230⁶ Z_S 0.4⁶			CSWA 26 a.k.a. SDSS J111310.64+235639.5 ObjId 587741829121638526 RADec 168.294359 23.94431091 ugriz L 21.0 18.2 16.5 15.8 15.5 ugriz S 23.7 21.7 20.8 20.6 19.9 SpecObj 701949540034412544 Z_L 0.336⁶ Z_S 0.77⁶
		CSWA 27 a.k.a. SDSS J162954.56+352839.4 ObjId 587733441053065699 RADec 247.47734696 35.47763614 ugriz L 20.1 18.2 16.9 16.4 16.0 ugriz S 19.3 19.8 19.1 18.8 18.7 No SDSS spectrum Z_L 0.17⁶ Z_S 0.85⁶			CSWA 28 a.k.a. SDSS J134332.85+415503.4 ObjId 588017625088393410 RADec 205.88688803 41.91763425 ugriz L 23.3 20.2 18.3 17.6 17.2 ugriz S 21.2 20.8 20.4 20.1 19.6 SpecObj 378810679156539392 Z_L 0.418¹³ Z_S 2.093¹³
		CSWA 29 ObjId 587745403607319063 RADec 130.08769754 10.8701825 ugriz L 21.4 19.9 18.4 17.9 17.6 ugriz S 21.8 21.3 21.4 21.5 20.8 No SDSS spectrum Z_L 0.22^-1 Z_S ?			CSWA 30 ObjId 587732483269198209 RADec 132.8604223 35.97049854 ugriz L 21.1 18.7 17.1 16.6 16.2 ugriz S 22.8 22.9 23.4 24.1 21.1 SpecObj 263123855206252544 Z_L 0.272⁰ Z_S 0.919¹⁸
		CSWA 31 ObjId 588023239671939597 RADec 140.3572627 18.17148017 ugriz L 27.4 22.1 19.8 18.4 17.9 ugriz S 20.6 20.3 19.7 19.8 18.6 SpecObj 686748518408257536 Z_L 0.683⁰ Z_S ?			CSWA 32 ObjId 587729386608722049 RADec 153.77402666 55.50505929 ugriz L 20.7 18.7 17.4 16.9 16.5 ugriz S 20.5 20.1 19.6 19.5 18.9 No SDSS spectrum Z_L 0.205¹⁸ Z_S 0.276¹⁸
		CSWA 33 ObjId 587738617559843056 RADec 162.34745045 35.74471377 ugriz L 21.0 19.4 17.8 17.1 16.8 ugriz S 23.2 23.2 22.3 20.7 19.4 SpecObj 588512323841294336 Z_L 0.322⁰ Z_S 1.028¹⁸			CSWA 34 ObjId 587727226228834771 RADec 4.25642966 -10.15308799 ugriz L 24.9 22.5 20.6 19.7 19.3 ugriz S 22.0 21.1 20.5 20.1 20.1 No SDSS spectrum Z_L 0.5^-1 Z_S ?
		CSWA 35 a.k.a. SDSS J095739.1+05093 ObjId 587732701250519458 RADec 149.41329988 5.15886783 ugriz L 21.3 20.5 18.9 18.1 17.6 ugriz S 21.3 20.5 20.0 19.7 19.6 No SDSS spectrum Z_L 0.44^-1 Z_S 1.823¹⁹			CSWA 36 a.k.a. maxBCG J120735.9+525459 ObjId 588013383817101501 RADec 181.89964171 52.91645343 ugriz L 21.9 19.0 17.5 16.9 16.7 ugriz S 22.5 20.8 20.4 19.9 19.4 No SDSS spectrum Z_L 0.27^-1 Z_S 1.9257¹⁹
		CSWA 37 a.k.a. SDSS J131811.5+394226 ObjId 588017979434795493 RADec 199.54796061 39.70748791 ugriz L 21.7 20.5 18.8 18.0 17.5 ugriz S 26.3 21.0 20.6 20.2 21.0 SpecObj 556705703943733248 Z_L 0.475⁰ Z_S 2.9437¹⁹			CSWA 38 a.k.a. NSCS J122648.0+215157 ObjId 587742013284679929 RADec 186.71535583 21.87373676 ugriz L 22.6 20.8 19.1 18.4 17.9 ugriz S 25.1 20.4 19.9 19.8 19.8 No SDSS spectrum Z_L 0.42^-1 Z_S 2.9233¹⁷
		CSWA 39 a.k.a. SGAS J122651.3+215220 ObjId 587736542562419006 RADec 231.93759592 6.87607048 ugriz L 23.4 20.7 18.9 18.2 17.7 ugriz S 24.8 20.9 20.7 20.9 21.1 SpecObj 512237232292102144 Z_L 0.39¹⁶ Z_S 2.7593¹⁷			CSWA 40 a.k.a. SDSS J0952+3434 ObjId 587738948281499819 RADec 148.16760451 34.5794650 ugriz L 24.3 20.6 18.9 18.2 17.8 ugriz S 22.7 21.5 21.1 21.0 20.5 No SDSS spectrum Z_L 0.349¹⁹ Z_S 2.1896¹⁹
		CSWA 41 a.k.a. SDSS J1450+3908 ObjId 588017605770477796 RADec 222.62769859 39.1386469 ugriz L 21.1 19.1 17.6 17.0 16.7 ugriz S 21.3 21.5 22.0 22.1 22.5 SpecObj 380217935211266048 Z_L 0.289⁰ Z_S 0.8613¹⁹

The Follow-up
We have obtained follow-up for some of these systems on a number of telescopes including

BTA@SAO
3.5m@CAHA
INT@ING
WHT@ING

However, most of the candidates still require spectroscopic confirmation and/or deeper imaging. We welcome the community worldwide to join on the effort of studying these spectacular systems.

References
-1. SDSS photometric redshift, -99, -99
0. SDSS spectroscopic redshift, -99, -99
1. "The Cosmic Horseshoe: Discovery of an Einstein Ring around a Giant Luminous Red Galaxy", Belokurov et al., 2007
2. "Models of the Cosmic Horseshoe Gravitational Lens", Dye et al., 2008
3. "Two New Large Separation Gravitational Lenses from SDSS", Belokurov et al., 2008
4. "A Systematic Search for Gravitationally Lensed Arcs in the Hubble Space Telescope WFPC2 Archive", Sand et al., 2005
5. "SDSS J120923.7+264047: A new massive galaxy cluster with a bright giant arc", Ofek et al., 2008
6. "The Sloan Bright Arcs Survey: Six Strongly Lensed Galaxies at z = 0.4-1.4", Kubo et al., 2009
7. "Rest-Frame Optical Spectra of Three Strongly Lensed Galaxies at z~2", Hainline et al., 2009
8. "Discovery of A Very Bright Strongly-Lensed z=2 Galaxy in the SDSS DR5", Lin et al., 2008
9. "CASSOWARY 20: a Wide Separation Einstein Cross Identified with the X-shooter Spectrograph", Pettini et al., 2009
10. "The 8 O'Clock Arc: A Serendipitous Discovery of a Strongly Lensed Lyman Break Galaxy", Allam et al., 2007
11. "A Systematic Search for High Surface Brightness Giant Arcs in a Sloan Digital Sky Survey Cluster Sample", Estrada et al., 2007
12. "The Sloan Digital Sky Survey Discovery of a Strongly Lensed Post-Starburst Galaxy at z = 0.766", Shin et al., 2008
13. "The Sloan Bright Arcs Survey: Four Strongly Lensed Galaxies with Redshift > 2", Diehl et al., 2009
14. "Discovery of four gravitational lensing systems by clusters in the SDSS DR6", Wen et al., 2009
15. "X-shooter observations of the gravitational lens system CASSOWARY 5", Christensen et al., 2010
16. "A New Survey for Giant Arcs", Hennawi et al., 2008
17. "Two Lensed z~3 Lyman Break Galaxies Discovered in the SDSS Giant Arcs Survey", Koester et al., 2010
18. "CASSOWARY Data Release 1", -99, -99
19. "The Sloan Bright Arcs Survey: Discovery of Seven New Strongly Lensed Galaxies from z = 0.66-2.94", Kubo et al., 2011

The People
@IoA: Vasily Belokurov, Wyn Evans, Paul Hewett, Lindsay King, Richard McMahon, Lukasz Wyrzykowski, Max Pettini, Martin Smith, Mike Irwin
@SAO: Alexei Moiseev
@Sydney: Geraint Lewis
@UCSB: Brendon Brewer
@MPIA: Sergey Koposov
@Nottingham: Simon Dye
@Imperial: Stephen Warren

Credits
The catalogue is distributed freely. The candidate selection procedure is described in our latest paper.

As most of the information presented here is based on the SDSS data, one might want to consider using standard SDSS acknowledgement as well.