MCELS is a survey of two of our nearest neighboring galaxies, the Large and Small Magellanic Clouds. We are doing the survey in the bright emission of Hydrogen (Halpha 6563), Sulfur ([S II] 6724), and Oxygen ([O III] 5007) from the interstellar gas of these two galaxies to study the properties, kinematics, and dynamics of the "violent" int erstellar medium.
These optical emission-line images were taken on the UM/CTIO Curtis Schmidt telescope at Cerro Tololo Inter-American Observatory (CTIO) as part of the Magellanic Cloud Emission Line Survey (MCELS). The detector was a thinned, back-side illuminated Tek 2048 x 2048 CCD with 24 micron pixels, giving a 1.3 degree x 1.3 degree field-of-view with a scale of 2.3 arcsec per pixel and a resulting angular resolution of approximately 4.6 arcsec. The narrow band images were taken with filters centered on the [O III] (5007A, FWHM 40A), H-alpha (6563A, FWHM 30A), and [S II] (6724A, FWHM 50A) emission lines. Two slightly offset images were obatined through each filter to allow for cosmic ray rejection and bad pixel replacement. The total integration times were 1200 sec in the [O III] and [S II] images and 600 sec in the H-alpha images per field.
The data were reduced using a modified version of the Essence/SuperMaCHO pipeline for overscan correction, bias subtraction, and flat-field correction. The images were then normalized to have 1 sec exposures. Final astrometric solutions were derived using the IRAF software ``ccfind'' and ``ccmap'' using the UCAC catalog. At this time, the images were re-sampled to have 2'' x 2'' pixels with an rms error of approximately 0.1 pixel (0.2''). The individual frames for each field were then aligned using the astrometric solutions and multiple exposures in each filter were combined using a median filter. The final mosaics for the 30 Dor region in each filter were created by casting the individual fields onto a larger canvas and combined.
The data are available via anonymous FTP at
ftp://ftp.ctio.noao.edu/pub/mcels/prelimdr/
The data are in FITS format. The lmc*.fits files are individual exposures, while the 30dor*.fits files are mosaics in each of the three emission line bands.
The MCELS project has been supported in part by NSF grants AST-9540747 and AST-0307613, and through the generous support of the Dean B. McLaughlin Fund at the University of Michigan, a bequest from the family of Dr. Dean B. McLaughlin in memory of his lasting impact on Astronomy. The National Optical Astronomy Observatory is operated by the Association of Universities for Research in Astronomy Inc. (AURA), under a cooperative agreement with the National Science Foundation.
This Web page is maintained by Chris Smith and Roger Leiton at Cerro Tololo Inter-American Observatory. Please send comments, suggestions, or reports of any problems to csmith@ctio.noao.edu.
Last update: January 9, 2006 by RCS