When creating finding charts for observations with the OSIRIS instrument on GTC you need to check the field-of-view (fov). With the Aladin Sky Atlas it is easy to download an image and overplot an instrument footprint (Edit > Load instrument footprint). Although there is a selection of instruments, by default the OSIRIS is not included. It is possible however to “create your footprint” which opens a link to an online editor.
Using this and the information collected from the manual and the web for OSIRIS I created a footprint that displays the fov for the imaging (larger box) along with the fov for the Multi-Object Spectroscopy (inner boxes) which display the two CCDs with the gap in between. Then, it is easy to place the footprint to the exact coordinates you wish in order to include (or exclude) sources of interest, check which parts are outside the fields or in the gap.
You can find the file here: gtc-osiris-v2.vot (better right click on that and save as…)