ELFT HÍRADÓ

[ilka AT konkoly.hu (Kalman Belane)]

                                 Meghivoó
                az MTA KTM Csillagászati Kutatóintézete
                              szeminariumara


Elõadó: Mike Bessell (Research School of Astronomy and Astrophysics
                      Australian National University) 

Cím: "Problems in Realisation of the Stromgren Photometric System
           and the new SKYMAPPER survey of the southern skies."

Absrtract:
In the 1950s much stellar work involved qualitative photographic 
spectral-types and often imprecise broad-band UBV photometry based on 
poorly defined historical wave bands.
In the 1950s Stromgren introduced a 6 filter system to measure two 
parameters, H beta and the Balmer Jump in B, A and F stars. He later 
extended this to the uvby beta system using one glass filter and 6 
interference filters and a 1P21 photomultiplier tube.
The system has since been extended by others to include white dwarfs, K 
giants and dwarfs and FGK super-giants but severe and often little 
understood problems have occurred in the standardization owing to 
differences in passbands (especially the v filter) and to the restricted 
color and spectral type range of the original standards. Ironically, a 
narrow band system devised to overcome perceived limitations in the 
precision of broad-band photometric systems has resulted in poorly 
standardized photometry due to the great sensitivity of uvby photometry to 
the exact position of the passbands. 
The best current system is that of Olsen, Schuster and coworkers who use 
spectrometer defined bands. I will discuss this system compared to the 
original filter system and the complications and uncertainties associated 
with trying to realize the passbands of the Standard System in order to 
compute synthetic photometry.

Finally, I will outline the new SKYMAPPER project, 
(http://www.mso.anu.edu.au/skymapper/index.php) which is a 1.35m telescope 
with an 8-sq degree field of view located at Siding Spring Observatory. It 
will have an integrated 16kx16k CCD mosaic with 0.5" pixels covering 
5.7-sq degrees and will be fully automated. It will conduct a multi-colour 
(6), multi-epoch (6) survey of the southern hemisphere known as the 
Stromlo Southern Sky Survey and commence in mid-2007. It should take 5 
years to complete. It will reach to 22 mag and have a precision of 
0.02-0.03 mag. Its photometric system will use the Stromgren u and the 
DDO38 violet band together with the SDSS griz bands. These bands are very 
well suited for stellar work being capable of providing precise 
temperatures, gravities and abundances for a wide range of stars.  We 
anticipate being able to identify halo stars with metallicities below -3.5 
dex and will use the Munari, Sordo, Castelli and Zwitter fluxes and 
Cassisi isochrones for calibration. 

A szeminárium idõpontja: 2006. szeptember 7, csütörtök 14 óra
Helye: MTA Konkoly Thege Miklós Csillagászati Kutatóintézete
           1121 Budapest, Konkoly Thege Miklós út 13-17
    
Patkós László s.k.