Update portal-intro.rst

data-access-analysis-tools/portal-intro.rst

@@ -16,11 +16,15 @@ How to make a lightcurve of an object with known coordinates
 
 .. This section should provide a brief, top-level description of the page.
 
-.. Most recent update:  November 9 2024
+.. Most recent update:  November 7 2024
 
-Once logged into the Portal aspect of the Rubin Science Platform, it is possbile to extract and plot a light curve of an object with known coordinates.
+The Portal aspect of the Rubin Science Platform lends itself well to extracting and plotting a light curve of an object with known coordinates.
+It can be accessed by clicking on the "Portal" panel on the main landing page st data.lsst.cloud.
 An example here considers a low-redshift SNIa (67.4579, -44.0802).
 
+Plotting of a light curve requires a data table which contains the obervztion time.  
+For the simulated DP0.2 data, such table is the dp02_dc2_catalogs.DiaSource.  
+
 **WARNING:** In this tutorial, the difference-image fluxes are converted to magnitudes in the TAP query.
 This is usually safe to do, because supernovae fluxes should never be negative in a difference image -- unless the supernova also appears in the template image.
 In the case of DP0.2, due to how the template images were built, some of the template images are contaminated with supernova flux, potentially up to 40% of DC2 SNIa.