To make a basic cutout, the user is only required to supply an RA, DEC, cutout size and band (see orange point 1 in the figure below). You can then generate a cutout with these properties by hitting the "Make Cutout" botton (orange point 2 in figure). Note that currrently the RA and DEC must be entered in degrees. VISTA-view will display 4 panels at this stage, but only the top-left panel will be populated (the others are for running ProFound). However, when downloading the cutout (see below) you will only be provided with the top-left image panel.
The user also has the option to display the axes of the cutoutin sexidecimal, degress or pixels using the drop down menu at red point 3.
In addition to this, VISTA-view also also allows the user to resolve the RA and DEC of sources based on a common name. To do this input the name of your source of interest into the "Name" box and click "resolve name". This will automatically populate the RA and DEC field boxes for your source (blue point 4 - GAMA IDs can be called as: GAMAXXXXX, where XXXXX=CATAID). Note that you must click the "resolve name" button for this to work, not just fill in the name. Finally, VISTA-view also has a sample of pre-programmed "pretty" sources. To access these, click on the "Pretty Sources" drop down. This will reveal a list of these source (right figure below). You can then select one of these sources (gold point 5), then the RA, DEC and Width feilds will be correctly populated.
Remember that to generate the cutout, you must click "Make Cutout" following every update to parameters.
In addition to basic cutouts, VISTA-view also allows users to tune key SWARP parameters for the cutout. This governs how the individual paw-prints are combined and sky subtracted. You can change the weighting, combine type and if/how the SWARP background is removed (green point 6 in figure below). If you would like to know more about these paramters, please see the SWARP documentation
Once again, when the SWARP paramaters have been changed, you must click "Make Cutout" to update the current cutout to these parameters.
Once your cutout has been generated, VISTA-view allows you to download the cutout as either FITS or PDF (purple 7 in figure above). The FITS download will provide the SWARP output with associated header information, while the PDF download will provide the image in the top left panel of the VISTA-view display.
Note, that this will always download the currently displayed cutout. If you have changed any parameters, you will need to click "Make Cutout" before downloading.
While VHS and VIKING cover a significant fraction of the southern hemisphere, there are some small gaps in coverage. In addition, the Z, Y, H-band data only covers the VIKING regions. As such, users can find the most up-to-date VISTA coverage here .
Displayed below are the VISTA coverage plots at the time VISTA-view was produced. Green-brown regions show VHS coverage, while red regions show VIKING coverage.
VISTA-view has the functionaily to automatically run ProFound source finding over the cutout region. Full detils of the ProFound code can be found in Robotham et al., 2018
Firstly, in order to run profound users must select the "Run ProFound over Cutout?" option highlighted by green point 8 in the figure below. This will expand the ProFound Paramters options in the side bar displayed in the right panel of the figure below.
Once expanded, users can select the desired ProFound inputs. Note that not all ProFound inputs are avilable here, only select ones which are required to perform robust source segmentation. A very brief overview of each parameter is given in the figure, but for full details of each parametere, see the ProFound documentation and/or examples . To aid in deciding which parameters to use, VISTA-view also provieds a number of suggested starting points for large resolved sources, small resolved sources and point source. To use these simply click on the relavent button (green point 9) and the ProFound parameters will be populated. Note that you still need to click "Make Cutout" before these take effect.
Once ProFound has been run you will then be presented with the full 4-panel output (shown below). This provides the cutout image with central segment overlaid, the segmentation plot showing extracted sources, the sky map produced by ProFound and the sky RMS map. Within the segmentation map, segments are coloured in rainbow colours, red-to-blue based on magnitude. Using these plots it is possible to determine whether or not the photometric measurments from ProFound are robust (i.e. does the sky map look okay, does the segmentation enclose all of the target source and no additional flux from other sources).
Below these figures, you will then also be presentated with a selection of key segmentation statisitics for the ProFound run (see figure below). These define the size and shape of the segments, as well as the mangitudes and surface brightnesses measured by ProFound and rows are sorted by magnitiude. If you require the full table of segmentation statistics, it can be downloaded (see below).
Finally, you can dowload either the full segmentation statisitics table as a .csv file or the full ProFound output an R object (see green point 10 on the top figure of this page). The segmentation statisitics table contains the information provided in the VISTA-view table, as well as further data products derived by ProFound. The full ProFound output provides segmenation, sky and skyRMS maps, the segmentation statistics, and various other ProFound-derived properties (see the ProFound documentation for further details).
The code for this project was written, and is maintained by Luke Davies