RESULTS

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Over the years, Citizen ASAS-SN has

• Discovered ~15,000 New Variable Stars: Identified 10,420 stars in DR1 and 4,432 in DR2, including pulsating, rotating, and binary systems.
• Improved the identification of noisy light curves: Labeled 12,000+ "junk" light curves that were used to train a machine learning model with 98% accuracy.
• Proven Human Accuracy: Demonstrated that human volunteers achieve up to 89% precision, matching the reliability of professional variable star catalogs.
• Caught Rare Phenomena: Flagged complex "hybrid" systems and transient eclipses that automated pipelines frequently overlook.
• Large-Scale Impact: Over 9,300 volunteers contributed 2,265,000+ classifications, directly improving the ASAS-SN Variable Star Database (https://asas-sn.osu.edu/variables).

The ASAS-SN project continues to monitor the entire visible sky every night. Follow our latest developments here: https://www.astronomy.ohio-state.edu/asassn

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Citizen ASAS-SN Data Release II

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Citizen ASAS-SN Data Release II: Variable Star Classification Using Citizen Science
O. Kotrach, C. S. Kochanek, C. T. Christy, T. Jayasinghe, K. Z. Stanek, D. M. Rowan, J. L. Prieto, B. J. Shappee

Here, we present the second and final data release from Citizen ASAS-SN.

We present the second results from Citizen ASAS-SN, a citizen science project for the All-Sky Automated Survey for Supernovae (ASAS-SN) hosted on the Zooniverse platform. Citizen ASAS-SN tasks users with classifying variable stars based on their light curves. We started with 94975 new variable candidates and identified 4432 new variable stars. The users classified the new variables as 841 pulsating variables, 2995 rotational variables, 350 eclipsing binaries, and 246 unknown variables. We found 68% user agreement for user-classified pulsating variables, 51% for rotational variables, and 77% for eclipsing binaries. We investigate user statistics and compare new variables to known variables. We present a sample of variables flagged as interesting or unusual.

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The ASAS-SN Catalog of Variable Stars X

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The ASAS-SN Catalog of Variable Stars X: Discovery of 116,000 New Variable Stars Using g-band Photometry
C. T. Christy, T. Jayasinghe, K. Z. Stanek, C. S. Kochanek, T. A. Thompson, B. J. Shappee, T. W.-S. Holoien, J. L. Prieto, Subo Dong, W. Giles

Here, we present the ASAS-SN Catalog of Variable Stars X, where data from Citizen ASAS-SN was used to improve our classification algorithms.

The All-Sky Automated Survey for Supernovae (ASAS-SN) is the first optical survey to monitor the entire sky, currently with a cadence of ≲ hours down to ≲ mag. ASAS-SN has routinely operated since 2013, collecting 2,000 to over 7,500 epochs of and band observations per field to date. This work illustrates the first analysis of ASAS-SN's newer, deeper, higher cadence band data. From an input source list of million isolated sources with ~mag, we identified variable star candidates using a random forest classifier trained on features derived from , 2MASS, and AllWISE. Using ASAS-SN band light curves, and an updated random forest classifier augmented with data from Citizen ASAS-SN, we classified the candidate variables into 8 broad variability types. We present a catalog of new variable stars with high classification probabilities, including periodic variables and irregular variables. We also recovered known variable stars.

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Citizen ASAS-SN Data Release I

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Citizen ASAS-SN Data Release I: Variable Star Classification Using Citizen Science
Christy, C. T.; Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Way, Z.; Prieto, J. L.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, T. A.; Schneider, A.

Here, we present the first results from Citizen ASAS-SN and the associated DR1 catalog of g-band variable stars.

Citizen ASAS-SN utilizes the newer, deeper, higher cadence ASAS-SN g-band data and tasks volunteers to classify periodic variable star candidates based on their phased light curves. We started our project with 40,640 new variable candidates from an input list of ∼7.4 million stars with δ < −60∘. In addition to recovering ~18,000 known variables, our volunteers were able to make 10,420 new variable star discoveries, consisting of 4,234 pulsating variables, 3,132 rotational variables, 2,923 eclipsing binaries, and 131 variables flagged as Unknown. Our citizen scientists classified known variable stars with an accuracy of 89% for pulsating variables, 81% for eclipsing binaries, and 49% for rotational variables. We examine our volunteers' performance, agreement between volunteers, and compare the citizen science classifications with our machine learning classifier updated for the g-band light curves. In general, user activity correlates with higher classification accuracy. We used the Citizen ASAS-SN DR1 "Junk" classifications to develop an effective machine learning classifier to separate real from false variables, and there is a clear path for using this "Junk" training set to significantly improve our primary machine learning classifier and our variable star candidate selection process. We also illustrate the value of Citizen ASAS-SN for identifying unusual variables with several examples.

AAS Presentation: Citizen ASAS-SN: Citizen Science with The All-Sky Automated Survey for SuperNovae (ASAS-SN)

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Citizen ASAS-SN: Citizen Science with The All-Sky Automated Survey for SuperNovae (ASAS-SN)
Christy, C. T.; Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.

Citizen science projects aim to engage everyday people from our communities and allow them to get involved in ongoing scientific research. In the search for unusual variable stars, the All Sky Automated Survey for SuperNovae (ASAS-SN,Shappee et al. 2014; Kochanek et al. 2017) has developed a citizen science project under the name “Citizen ASAS-SN”, hosted on the Zooniverse platform. This project will allow volunteers to identify periodic variable star candidates using g-band data from ASAS-SN. The classification workflow enables volunteers to classify these sources into major variability groups, while also allowing for the identification of unique variable stars for additional follow-up. This process will aid in the classification of millions of stars in the ASAS-SN time-series data along with identifying both anomalous and classical variable stars.

Download catalog and light curves
Usernames of volunteers who contributed to DR1

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Citizen ASAS-SN Research Note

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Citizen ASAS-SN: Citizen Science with The All-Sky Automated Survey for SuperNovae (ASAS-SN)
Christy, C. T.; Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Way, Z.; Prieto, J. L.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, T. A.

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The ASAS-SN Catalog of Variable Stars

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The ASAS-SN Catalog of Variable Stars I: The Serendipitous Survey
Jayasinghe, T.; Kochanek, C. S.; Stanek, K. Z.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, Todd A.; Prieto, J. L.; Dong, Subo; Pawlak, M.; Pejcha, O.; Pojmanski, G.; Otero, S.; Hurst, N.; Will, D., 2018, MNRAS, 477, 3145

The ASAS-SN Catalog of Variable Stars II: Uniform Classification of 412,000 Known Variables
Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, Todd A.; Prieto, J. L.; Dong, Subo; Pawlak, M.; Pejcha, O.; Shields, J. V.; Pojmanski, G.; Otero, S.; Britt, C. A.; Will, D., 2019, MNRAS, 486, 1907

The ASAS-SN Catalog of Variable Stars III: Variables in the Southern TESS Continuous Viewing Zone
Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, Todd A.; Prieto, J. L.; Dong, Subo; Pawlak, M.; Pejcha, O.; Shields, J. V.; Pojmanski, G.; Otero, S.; Hurst, N.; Britt, C. A.; Will, D., 2019, MNRAS, 485, 961

The ASAS-SN Catalog of Variable Stars IV. Periodic variables in the APOGEE survey
Pawlak, Michał; Pejcha, O.; Jakubčík, P.; Jayasinghe, T.; Kochanek, C. S.; Stanek, K. Z.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, Todd A.; Prieto, J. L.; Dong, S.; Shields, J. V.; Pojmanski, G.; Britt, C. A.; Will, D., 2019, MNRAS, 487, 5932

The ASAS-SN Catalog of Variable Stars V: Variables in the Southern Hemisphere
Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, T. A.; Prieto, J. L.; Dong, S.; Pawlak, M.; Pejcha, O.; Shields, J. V.; Pojmanski, G.; Otero, S.; Hurst, N.; Britt, C. A.; Will, D., 2020, MNRAS, 491, 13

The ASAS-SN Catalog of Variable Stars VI: An All-Sky Catalog of δ Scuti stars
Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Vallely, P. J.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, Todd A.; Prieto, J. L.; Pejcha, O.; Fausnaugh, M.; Otero, S.; Hurst, N.; Will, D., 2020, MNRAS, 493, 4186

The ASAS-SN Catalog of Variable Stars VII: Contact Binaries are Different Above and Below the Kraft Break
Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Pinsonneault, M. H.; Holoien, T. W. -S.; Thompson, Todd A.; Prieto, J. L.; Pawlak, M.; Pejcha, O.; Pojmanski, G.; Otero, S.; Hurst, N.; Will, D., 2020, MNRAS, 493, 4045

The ASAS-SN Catalog of Variable Stars VIII: 'Dipper' stars in the Lupus star-forming region
Bredall, J. W.; Shappee, B. J.; Gaidos, E.; Jayasinghe, T.; Vallely, P.; Stanek, K. Z.; Kochanek, C. S.; Gagné, J.; Hart, K.; Holoien, T. W. -S.; Prieto, J. L.; Van Saders, J., 2020, MNRAS, 496, 3257

The ASAS-SN Catalog of Variable Stars IX: The Spectroscopic Properties of Galactic Variable Stars
Jayasinghe, T.; Kochanek, C. S.; Stanek, K. Z.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, Todd A.; Prieto, J. L.; Dong, Subo; Pawlak, M.; Pejcha, O.; Pojmanski, G.; Otero, S.; Hurst, N.; Will, D., 2020, MNRAS, in review

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Selected work on unusual variable stars

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An Extreme Amplitude, Massive Heartbeat System in the LMC Characterized Using ASAS-SN and TESS
Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Thompson, Todd A.; Shappee, B. J.; Fausnaugh, M., 2019, MNRAS, 489, 4705

A noninteracting low-mass black hole─giant star binary system
Thompson, Todd A.; Kochanek, Christopher S.; Stanek, Krzysztof Z.; Badenes, Carles; Post, Richard S.; Jayasinghe, Tharindu; Latham, David W.; Bieryla, Allyson; Esquerdo, Gilbert A.; Berlind, Perry; Calkins, Michael L.; Tayar, Jamie; Lindegren, Lennart; Johnson, Jennifer A.; Holoien, Thomas W. -S.; Auchettl, Katie; Covey, Kevin, 2019, Sci, 366, 637

An all-sky search for R Coronae Borealis stars in ASAS-SN
Shields, J. V.; Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, Todd A.; Prieto, J. L.; Dong, Subo, 2019, MNRAS, 483, 4470

ASAS-SN Identification of a Detached Eclipsing Binary System with a ~7.3 Year Period
Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Holoien, T. W. -S.; Thompson, T. A.; Prieto, J. L.; Dong, Subo; Stevens, D. J., RNAAS, 2, 125

ASAS-SN Discovery of an Unusual, Deep Dimming Episode of a Previously Non-Variable Star
Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Vallely, P.; Shields, J. V.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W. -S.; Prieto, J. L.; Dong, Subo; Stritzinger, M., 2019, ATel, 12836

ASAS-SN Discovery of an Unusual Stellar System with Deep Dimming Episodes
Way, Z.; Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Vallely, P.; Basinger, C.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W. -S.; Prieto, J. L.; Dong, Subo; Stritzinger, M., 2019, ATel, 13106

ASAS-SN Discovery of an Unusual, Rapidly Fading Star
Way, Z.; Stanek, K. Z.; Kochanek, C. S.; Jayasinghe, T.; Vallely, P.; Basinger, C.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W. -S.; Prieto, J. L.; Dong, Subo; Stritzinger, M., 2019, ATel, 13346

ASAS-SN Discovery of a Heavily Reddened Eclipsed Giant Star in a 750 day Orbit
Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Way, Z.; Vallely, P.; Basinger, C.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W. -S.; Prieto, J. L.; Dong, Subo, 2020, ATel, 13745

ASAS-SN Discovery of an Unusually Luminous Cataclysmic Variable Candidate Undergoing a Dimming Episode
Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Way, Z.; Vallely, P.; Basinger, C.; Thompson, T. A.; Shappee, B. J.; Holoien, T. W. -S.; Prieto, J. L.; Dong, Subo, 2020, ATel, 13824