The Roman Background Visualization Tool (RBVT)

The Roman Background Visualization Tool (RBVT)#

Kernel Information and Read-Only Status#

To run this notebook, please select “Roman Research Nexus {VERSION}” kernel at the top right of your window. For example “Roman Research Nexus 2026.2”.

This notebook is read-only. You can run cells and make edits, but you must save changes to a different location. We recommend saving the notebook within your home directory, or to a new folder within your home (e.g. file > save notebook as > my-nbs/nb.ipynb). Note that a directory must exist before you attempt to add a notebook to it.

Introduction#

The Roman Background Visualization Tool (RBVT) is an interactive visualization tool for exploring time-variable background levels across the sky as seen by the Nancy Grace Roman Space Telescope. It provides a fast and intuitive way to assess how background emission at a specific sky position and wavelength evolves throughout the year, using a Bokeh-based graphical user interface similar in style to the Roman Interactive Sensitivity Tool (RIST).

RBVT draws from a pre-computed sky background cache that includes zodiacal light, Galactic ISM, and thermal self-emission. Users can explore these components by adjusting the target’s:

  • RA/Dec (sky position)

  • Wavelength

  • Threshold above minimum background

  • Calendar day

The tool produces an interactive plot showing total background versus calendar day, with optional breakdown into background components. This is useful for optimizing Roman WFI exposure scheduling and minimizing background contamination in faint source observations.

Requirements#

RBVT uses the Roman background model cache and depends on the following packages:

  • numpy

  • scipy

  • healpy

  • bokeh

Import#

The Roman Background Visualization Tool (RBVT) is launched from within a Jupyter notebook using the plot_rbt module.

# Bokeh assumes port 8888. If Jupyter uses another port, uncomment the URL
# below and match your browser's hostname and Jupyter port (no path/token).
NOTEBOOK_URL = None
#NOTEBOOK_URL = "http://localhost:8890"

# Allow Bokeh WebSocket connections from any origin.
# Required for local Jupyter, JupyterLab, and VS Code; harmless on Nexus.
import os
if 'BOKEH_ALLOW_WS_ORIGIN' not in os.environ:
    os.environ['BOKEH_ALLOW_WS_ORIGIN'] = '*'
    print("BOKEH_ALLOW_WS_ORIGIN set to *")

BOKEH_ALLOW_WS_ORIGIN set to *

To begin, run the cell below

from rbt import validate_reference_data
from rbvt import plot_rbt
from bokeh.io import show, output_notebook
from bokeh.application import Application
from bokeh.application.handlers.function import FunctionHandler

# Check reference files before starting the Bokeh server.
validate_reference_data()

output_notebook()
app = Application(FunctionHandler(plot_rbt))

# Nexus needs no local port override. Bokeh uses its configured connection.
# For local use, uncomment NOTEBOOK_URL in the setup cell above.
show_options = {}
if NOTEBOOK_URL is not None:
    show_options["notebook_url"] = NOTEBOOK_URL
show(app, **show_options)
Loading BokehJS ...

Additional Resources#

Help#

For assistance with RBVT, please contact the Roman SOC Help Desk

About this Notebook#

Author: Melissa Shahbandeh & R. Diaz

Last Updated: 2026-10-14

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