  To understand the potential for observing forming planets and their
circumplanetary disks (CPDs) with JWST and ELT, we created mock observations
from 3D radiative hydrodynamic simulations and radiative transfer
post-processing for planets with 10, 5, 1 Jupiter and 1 Saturn masses with
orbital separation of 50 and 30 AU in 0$^{\circ}$, 30$^{\circ}$ and
60$^{\circ}$ inclinations. Instrumental effects were then simulated with Mirage
for JWST/NIRCam and NIRISS, MIRISim for JWST/MIRI and SimCADO & SimMETIS for
ELT/MICADO and METIS. We found that the longer wavelengths (mid-IR and beyond)
are the best to detect CPDs. Longer is the wavelength, the smaller mass
planet's CPD could be detected. MIRI on JWST and METIS on ELT offers the best
possibility on these telescopes. Specifically, below 3 $\mu$m, only 10
$M_{\mathrm{Jup}}$ planets with their CPDs are detectable with NIRCam and
MICADO. 5 $M_{\mathrm{Jup}}$ planets are only detectable if at 30 AU (i.e.
closer) orbital separation. Planets above 5 $M_{\mathrm{Jup}}$ with their CPDs
are detectable between 3-5 $\mu$m with NIRCam and METIS L/M band, or above 10
$\mu$m with MIRI and METIS N band. For $\leq$ 1 $M_{\mathrm{Jup}}$ planets > 15
$\mu$m are needed, where MIRI uniquely offers imaging capability. We present
magnitudes and spectral energy distributions for separate components of the
planet+CPD+CSD system, to differentiate the extinction rates of CPDs and CSDs
and to provide predictions for observational proposals. Because the CPD turns
out to be the main absorber of the planet's emission, especially <10 $\mu$m,
this makes the detection of forming planets quite challenging.
