utils/convert.py: Add function "JyPerPix_to_K()"

Signed-off-by: Aaron LI <aly@aaronly.me>

1 files changed, 17 insertions, 0 deletions

diff --git a/fg21sim/utils/convert.py b/fg21sim/utils/convert.py
index c36d5fc..d238339 100644
--- a/fg21sim/utils/convert.py
+++ b/fg21sim/utils/convert.py
@@ -137,3 +137,20 @@ def Fnu_to_Tb_fast(Fnu, omega, freq):
     """
     Sb = Fnu / omega  # [Jy/arcsec^2]
     return Sb_to_Tb_fast(Sb, freq)
+
+
+def JyPerPix_to_K(freq, pixelsize):
+    """
+    The factor that converts [Jy/pixel] to [K] (brightness temperature).
+
+    Parameters
+    ----------
+    freq : float
+        The frequency where the flux density measured.
+        Unit: [Jy]
+    pixelsize : float
+        The pixel size.
+        Unit: [arcsec]
+    """
+    factor = Fnu_to_Tb_fast(Fnu=1.0, omega=pixelsize**2, freq=freq)
+    return factor