Information on Service 'Magellanic Clouds Extinction Values'

Further access options are discussed below

For a list of all services and tables belonging to this service's resource, see Information on resource 'Reddening and Extinction maps of the Magellanic Clouds'

Service Documentation

The Optical Gravitational Microlensing Experiment (OGLE III) has monitored both Magellanic Clouds in the V and I band. Using the public stellar photometry database of OGLE III in order to derive spatially resolved reddening maps, we subdivide the OGLE III observations of the Large Magellanic Cloud (LMC) in 3174 subfields. The size of the fields varies from 4.5 x 4.5 square arcmin to 36 x 36 square arcmin in order to ensure that each field contains at least 300 stars and no more than 4800 stars. I.e., in dense regions our reddening resolution is higher.

In each of these subfields the mean (V-I) colour of the red clump is determined. A theoretical colour of (V-I):sub:0 = 0.92 mag is adopted for the LMC and subtracted from the measured value. The difference is defined as reddening E(V-I). To provide you directly useable data we calculated the reddening for different filters by adopting Schlegels list of conversion factors (Table 6 in Schlegel et al. 1998, AJ, 500, 525). To use this table the extinction has to be recalculated from E(B-V) to E(V-I). For this purpose we adopted E(V-I) = 1.38 × E(B-V) (Tammann et al. 2003, A&A, 404, 423).

For the Small Magellanic Cloud (SMC) the same procedure is used. The OGLE III data are subdivided into 693 contiguous subfields. The reddening of each subfield is determined adopting a theoretical colour of (V-I)₀ = 0.89 mag.

The following table (containing values taken from 1998ApJ...500..525S) shows the laws adopted to compute extinction values in the various bands:

SELECT ev_i, mine.* FROM
        mcextinct.exts AS exts
        JOIN tap_upload.t1 AS mine
        ON (1=CONTAINS(POINT('ICRS', mine.raj2000, mine.dej2000),exts.bbox))

SELECT ev_i*3.74 as A_sloan_u, ev_i*1.07 as A_sloan_z, mine.* FROM
        mcextinct.exts AS exts
        JOIN tap_upload.t1 AS mine
        ON (1=CONTAINS(POINT('ICRS', mine.raj2000, mine.dej2000),exts.bbox))

#!/bin/sh
cp $1 $1.bak
tapsh <<EOF
server ivo://org.gavo.dc/__system__/tap/run
SELECT ev_i, mine.* FROM                mcextinct.exts AS exts          JOIN tap_upload.mytable AS mine                 ON (1=CONTAINS(POINT('ICRS', mine.raj2000, mine.dej2000),exts.bbox))
upload "$1" as mytable
run
save "$1"
EOF

Overview

You can access this service using:

• scs.xml -- a standard SCS interface as defined by the IVOA to access catalog-type data; SCS clients use https://dc.g-vo.org/mcextinct/q/cone/scs.xml? to access the service
• form -- an interface for web browsers through an HTML form

Coverage

1.23956 3.75739 eV

Copyright, License, Acknowledgements

If you use this data, please cite Haschke, R., Grebel, E., Duffau, S., 2011: "New Optical Reddening Maps of the Large and Small Magellanic Clouds", AJ 141, 158, 2011AJ....141..158H

The photometric data of the red clump is provided by the OGLE collaboration.

Part of this research was supported by SFB 881 "The Milky Way System".

Citation Info

VOResource XML (that's something exclusively for VO nerds)