ELFT HÍRADÓ

[ilka AT konkoly.hu (Kalman Belane)]

                              Meghivó

      az MTA Konkoly Thege Miklós Csillagászati Kutatóintézete
                          szemináriumára

Elõadó: Piotr Popowski
        Max Planck Institut für Astrophysik, Garching b. München   

Cim: "Non-microlensing applications of microlensing surveys: Galactic 
     extinction"

Abstract:
Microlensing surveys are massive photometric searches covering tens of 
square degrees on the sky. As a result, they find many applications that 
go far beyond their original purpose. I will illustrate this point with a 
few examples. Then I will concentrate on a single issue of Galactic 
extinction and present a (V-R)-based reddening map of about 43 square 
degrees of the Galactic bulge/bar. The map was constructed using template 
image photometry from the MACHO microlensing survey. I will discuss our 
new method of reddening estimate that is based on (V-R)-color averages of 
the entire color-magnitude diagrams (CMDs). The conversion from the 
observed color to the reddening follows from an assumption that CMDs of 
all bulge fields would look similar in the absence of extinction. 
Consequently, the difference in observed color between various fields 
originates from varying contribution of the disk extinction summed along 
different lines of sight. Our (V-R)-colors correlate very well with 
extinction maps based on other methods and allow us to identify several 
low-extinction windows. I will argue that a dusty disk obeying a cosec|b| 
extinction law well describes gross properties of the extinction toward 
the bulge/bar fields. Finally, I will discuss briefly the physical model 
of dust distribution that is implied by observations.

A szeminárium idöpontja: 2003. szeptember 04, csütörtök, 14 óra
Helyszine: MTA Konkoly Thege Miklós Csillagászati Kutatóintézete
                  1121 Budapest Konkoly Thege M. ut 13-17.  


                                      Patkós László s.k.