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About
Variable Star Plotter (VSP), developed by the American Association of Variable Star Observers (AAVSO), is a specialized web-based tool designed to assist astronomers in planning and conducting variable star observations. It enables users to generate high-quality finder charts and photometry comparison tables for virtually any variable star in the sky. Users can search for a target star by name, AAVSO designation, AUID, or by entering equatorial coordinates (RA/Dec). Charts can be customized across a wide range of parameters: predefined scales from A (900 arcmin) to G (7.5 arcmin), custom field-of-view settings up to 1200 arcminutes, magnitude limits, resolution in DPI, chart orientation (North/East preferences), and CCD vs. visual mode. An optional Digital Sky Survey (DSS) overlay can be retrieved for enhanced field recognition. The photometry mode provides tabulated comparison star data across multiple photometric filters including U, B, V, Rc, Ic, J, H, K, and Sloan bands. Users can also mark other variable stars in the field, display magnitude label lines, and generate binocular or standard field specialty charts. Chart IDs allow exact reproduction of previously generated charts, supporting long-term observing programs and citizen science collaboration. VSP integrates with the broader AAVSO ecosystem, including VPhot for photometric reduction, the Light Curve Generator, and the Variable Star Index (VSX). It is free to use and is an indispensable tool for variable star observers, astronomy students, and researchers worldwide.
Key Features
- Flexible Star Search: Locate any variable star by name, AAVSO designation, AUID, or equatorial coordinates (RA/Dec).
- Customizable Chart Scales & Orientation: Choose from 7 predefined scales (A–G, 7.5–900 arcmin) or set a custom field of view, and configure North/South and East/West orientations.
- Multi-Filter Photometry Tables: Display comparison star magnitudes across standard photometric bands including U, B, V, Rc, Ic, J, H, K, and Sloan filters.
- Digital Sky Survey (DSS) Overlay: Optionally retrieve and overlay real DSS imagery on your finder chart for precise field recognition during observation.
- Chart ID Reproducibility: Save and reproduce exact charts using a unique Chart ID, ensuring consistency across long-term observing programs and collaborative projects.
Use Cases
- Amateur astronomers planning nightly variable star observing sessions with correctly scaled and oriented finder charts.
- Citizen scientists participating in AAVSO observing campaigns who need standardized comparison star photometry for consistent magnitude estimates.
- Students and educators in astronomy courses using photometry tables to learn about stellar brightness and filter-band measurements.
- Professional researchers requiring reproducible chart references (via Chart ID) for long-term monitoring programs of specific variable star fields.
- CCD and DSLR astrophotographers selecting precise comparison stars within a chosen field of view for differential photometry reductions.
Pros
- Completely Free: Provided at no cost by the non-profit AAVSO, making it accessible to amateur and professional astronomers alike.
- Highly Customizable Output: Extensive options for scale, orientation, magnitude limit, filter selection, and DSS imaging give observers full control over their charts.
- Integrated AAVSO Ecosystem: Seamlessly connects with VSX, VPhot, Light Curve Generator, and AAVSO's observing campaign infrastructure for end-to-end variable star science.
- Reproducible Charts: Chart IDs allow exact chart reproduction, supporting rigorous long-term scientific programs and peer collaboration.
Cons
- Astronomy-Specific Use Case: VSP is purpose-built for variable star observation and has no utility outside of astronomical research and observation planning.
- No Mobile App: The tool is web-only with no dedicated iOS or Android app, which can limit usability at a dark-sky observing site.
- Learning Curve for New Observers: The range of photometric filters, chart scales, and AAVSO-specific identifiers can be overwhelming for beginners unfamiliar with variable star terminology.
Frequently Asked Questions
What is the Variable Star Plotter (VSP)?
VSP is a free web tool by the AAVSO that generates customizable finder charts and comparison star photometry tables to help astronomers observe variable stars.
How do I search for a star in VSP?
You can search by the star's common name, AAVSO designation, AUID, or by entering its Right Ascension and Declination coordinates directly.
What photometric filters are supported?
VSP supports U, B, V (always shown), Rc, Ic, J, H, K, P, Z, SG, SU, SR, SI, Y, and also displays B-V color index. You can select which bands to include in photometry-mode output.
What is a Chart ID and why is it useful?
A Chart ID is a unique identifier for a previously generated chart. Entering it reproduces that exact chart, ensuring consistency when making repeated observations or sharing charts with collaborators.
Is VSP free to use?
Yes. VSP is provided free of charge by the American Association of Variable Star Observers (AAVSO), a non-profit organization supporting global variable star science.
