SUMMARY OF PROPOSAL 42200
DR. JOHN P. HUGHES
SMITHSONIAN INSTITUTION ASTROPHYSICAL OBSERVATORY
MA USA 02138
CAMBRIDGE
60 GARDEN STREET

  E-mail: JPH@CFA.HARVARD.EDU	Tel: 617-495-7142	Fax: 617-495-7356
  Medium: 4GBDAT

Subject: CLUSTERS OF GALAXIES AND SUPERCLUSTERS                      
  Title: ASCA OBSERVATIONS OF SUNYAEV-ZEL'DOVICH CLUSTERS                                


Abstract:
 We propose ASCA observations of three clusters of galaxies which have been recently
 detected in the Sunyaev-Zel'dovich (SZ) effect: A611, A697 and A2261. These clusters
 were chosen so that selection effects that arise in determining the cosmic distance
 scale using SZ effect and X-ray data are tightly controlled. The ASCA data will
 provide the essential information on the temperature of the intracluster hot gas for
 the application and testing of the distance measuring technique. The proposed
 observations represent the first rigorous attempt to measure the selection effect
 biases in the SZ/X-ray distances, which must be understood before the
 distance-measuring techniques (which can, in principle, be applied at large redshifts) can be used with confidence.

 Co-Is:
   1  MARK BIRKINSHAW     	SAO                           USA       
      (No Co-I contact data)
   2  JOHN CARLSTROM      	CAL TECH                      USA       
   3  LAURA GREGO         	CAL TECH                      USA       
   4  MARSHALL JOY        	NASA/MSFC                     USA       


Target Name           PRI RA        Dec        Time TC  Off GIS SIS_Cts  Obs
-------------------   --- --------  --------   ---- --  --- --- -------  ---
          
A2261                  0  260.6125   32.1331    20   N   Y   P  0.59000   1 
          
A611                   0  120.2375   36.0561    62   N   Y   P  0.17000   1