January 4, 2026 9 am – 5 pm AAS 247 Room TBD

Registration

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Workshop/AAS 247 Registration

You can register for this workshop when you register for the AAS 247 Meeting. Select “Roman Galactic Bulge Time Domain Survey Data Challenge” from the list of offered workshops.

Description

The RMDC25 AAS Workshop is a hands-on, full-day session designed to get participants—from newcomers to seasoned microlensers—set up and productive with the Roman Research Nexus and the core open-source tools used in the Roman Microlensing Data Challenge. We’ll walk through Nexus access and environment setup, introduce essential microlensing concepts and modeling workflows, explore single- and binary-lens fitting (including grid searches and practical strategies for degeneracies and higher-order effects), and show how to organize, validate, and package results for submission using microlens-submit. Bring a laptop and a willingness to experiment; light Python experience is helpful but not required. The day closes with an information session and Q&A covering timelines, tiers, data access, evaluation, and how to get help throughout the challenge.

Requirements

  • A laptop with a functioning web browser (optionally, VS Code and Slack installed).
  • Ideally, some Python experience.
  • An intention to participate in the Roman Microlensing Data Challenge 2025 or be on an already signed-up team. You can sign up here.
  • Microlensing-specific knowledge or experience is not necessary.

Itinerary

Morning

9:00–10:30 Nexus help
10:30–11:00 Break
11:00–12:30 Single lenses and pipelines
12:30–1:30 Lunch

Afternoon

1:30–3:00 Binary lenses
3:00–3:30 Break
3:30–onward Data Challenge Q&A

Session Outlines

1. Introduction to the Nexus

For discussion, information, troubleshooting, and updates about the Nexus, see the #nexus channel and the channel canvas. In this session we will be covering:

  • Creating Nexus accounts
  • How to access the Nexus
  • Nexus notebook content:
    • Creating Teams
    • Microlensing open source software
    • Accessing data and creating data challenge submissions
  • Installing packages and other technical help
  • Using the Nexus with VSCode

2. Single Lenses and Pipelines

In this session, we will learn about basic microlensing parameterization and terminology and test that knowledge on a mini modeling Data Challenge. Topics covered:

  • An introduction to microlensing
  • Helpful microlensing resources
  • Alternate data access, for those not using the Nexus
  • Hack-session where we will learn about:
    • Single lens fitting
    • Priors
    • Parallelization
    • L2 observer
    • Anomaly finding

3. Binary Lenses

We will begin this session with a more complicated binary-lens model and exercises to demonstrate the challenges of binary-lens fitting and common approaches to addressing them. We will fit that same event using three different methods:

  1. Start a fit from an uninformed guess
  2. Start with a grid search
  3. Start from an informed guess

Some of these methods are computationally expensive, so we will parallelize our efforts and discuss common challenges in microlensing binary-lens modeling, e.g., degeneracies, stochastic likelihood space, and higher-order effects.

4. Information Session and Q&A

Ask the demonstrators anything you would like to know about microlensing and/or the Data Challenge. They will also provide details on:

  • The RGES-PIT website
  • The Slack channel
  • Sign-up
  • Tiers
  • Data insights
  • Submission rules and guidelines
  • Evaluation process and rubric
  • Publication plans
  • Important dates
  • Contact