Data release for The SARAO MeerKAT 1.3 GHz Galactic Plane Survey, Goedhart et al. (2024) (Paper).
Download Description MFS_cubes The main data cube in FITS format. The âIâ indicates that this is Stokes I (total intensity). This has the following layers. The presence of âFxâ indicates that the time and frequency errors in the earliest data have been fixed; otherwise not. 1: the brightness at 1359.7 MHz derived from a weighted average of the subband image planes. The weighting is proportional to 1/RMS_subband averaged over all mosaics to ensure a consistent effective frequency. The images only include values in pixels in which all subbands could be included. Units are Jy/beam
2: the spectral index, alpha, from a nonlinear power law fit, with brightness B being proportional to nu**alpha, where B is the brightness and nu the frequency. For any pixels where there was less than 500 micro-Jy/beam of broadband emission, the spectral index is blanked. The spectral index is also blanked if the addition of alpha to the fit did not decrease the Chi squared per degree of freedom of the fit. Unitless
3-16: the images in the individual sub-bands. Note that layers 9 and 10 are blanked in all cubes due to radio frequency interference. Units are Jy/beam
fitted_SED FITS cube of the Stokes I image, incorporating a spectral fit across the observed band, with the values in the cube being those for 1359.7 MHz. This cube has the same first two layers as the MFS cubes. The layers are 1: the broadband brightness evaluated at 1359.7 MHz (see description above). The units are Jy/beam
2: the spectral index (see description above), defined so that brightness is proportional to nu**alpha. Unitless
3: the uncertainty of layer 1. For pixels with a fitted spectral index, this is the uncertainty derived from the fit. For the remainder, it is an estimate of the off-source RMS brightness. Units are Jy/beam
4: the uncertainty estimate for the spectral index (blanked for pixels for which the spectral index is blanked). Unitless
5: the Chi squared per degree of freedom of the fit. Unitless
Mom0 The zeroth moment images of the intensity averaged across the observing band. The units are Jy/beam. The zeroth moment is calculated by summing the product of the flux density and usable bandwidth over the fractional bandwidth images, and then dividing by the total usable bandwidth, in other words the bandwidth-weighted mean intensity. The effective frequency for the zeroth moment images is given by the bandwidth-weighted mean frequency. Both the total bandwidth over which this mean is formed, and the corresponding effective frequency vary slightly towards the edges of the cubes, where some of the higher-frequency layers are blanked due to primary beam effects. For each Mom0 image, we provide, in two separate folders, the corresponding effective frequency and the total bandwidth corresponding images. Mom0_eff_nu These show the effective frequency for the "Mom0" image. The units are Hz. Mom0_bandwidth These images show the total bandwidth over which the "Mom0" image was integrated for each pixel. The units are Hz. Mom0_png Quick look pngs rendered from the zeroth moment files. MFS_cubes_full_pol A limited set of partial mosaic cubes for polarization products are included, these have "Q", "U" or "V" in the name. The structure is the same as for Stokes I except that the second plane contains no useful information and the broadband Q and U images are of limited usefulness as they have not been corrected for Faraday rotation. Quick look png files have been included, primarily to show the coverage of the calibrated images.
This data release was issued on 25 March 2024.