Surveys · 1 of 6

ASAS-SNSky Patrol v2

Ground-based, bands g, V. Detections from 2011-11-26 to 2024-05-31.

https://asas-sn.osu.edu/

epochs held

4.53 billion

3.59 billion of them detections

stars with a light curve

2,994,897

2,994,412 with ≥ 1 detection

median epochs per star

1,343

all bands

sky with light curves

100.0%

HEALPix order-6 cells, as mapped

Where its stars are

Footprint

Brightness is stars per cell with a light curve from ASAS-SN (HEALPix order 6, log scale), over the whole archive in gray. Galactic Mollweide, Galactic center in the middle, east left, 30° graticule. It shows where the archive holds light curves, not the survey's full footprint.

native → BJD_TDB

Time system

native column: jd
time scale: UTC
reference frame: geocentric
origin: JD
reference position: not applicable
archive time axis: BJD_TDB (bjd_tdb)

Converted to BJD_TDB by applying the barycentric correction. The native jd is also served.

Bands

band	λ_eff	saturation	collection	stars with a light curve	epochs	detections	era
ASAS-SN gasassn:g	477 nm	11.375 mag	curves_live	2,994,881	3,492,404,130	2,738,485,024	2017-09-04 → 2024-05-31
ASAS-SN Vasassn:V	551 nm	11 mag	curves_static	2,905,361	1,036,063,274	847,300,919	2011-11-26 → 2018-11-29

V and g overlap for about 15 months; they stay separate.

quality rules

Epoch selection

good epochs: quality flag G
detections: detected when mag < limit
non-detections: reported; the rule above marks them

Alias frequencies

|f ± k·f_sid| (k=1,2), |f ± 1/365.25|, window at 365.25 / 182.63 / 29.53 d

linking

Crossmatch to VSX

Linked by identifier.

Sky Patrol light curves carry no positions of their own, so no separation or radius is stored.

ID column: asas_sn_id
catalog epoch: J2015.5

ASAS-SN IDs are permanent.

Caveats

V is archival and will not change; g is live, and a refresh replaces a star's whole g light curve.
6,609 V light curves have one isolated commissioning-era epoch (median 1,116 days early). It is kept, but inflates their baseline 1.77×.
g epochs after 2024-05-31 carry a limiting magnitude only (no magnitude, no quality flag) and count as non-detections.
Camera zero points differ by up to ~0.3 mag. Statistics and periodograms use camera-corrected magnitudes; served magnitudes are raw.

LSDB

Bulk access

Light curves are in the nested lc_asassn column of two collections, split by band.

PythonASAS-SN light curves around a position

# read the release directly over HTTPS
import json, lsdb
from upath import UPath

root = UPath("https://data.varchive.app")
ptr = json.loads((root / "catalogs/latest.json").read_text())
RA, DEC = 0.0, 0.0   # your field center, degrees

# curves_static: ASAS-SN V
static = lsdb.read_hats(root / ptr["collections"]["curves_static"]["path"],
                        columns=["varchive_id", "ra", "dec", "lc_asassn"])
df = static.cone_search(RA, DEC, 600).compute()   # radius in arcsec
lc = df["lc_asassn"].iloc[0]   # band, bjd_tdb, mag, mag_err, detected, jd, limit, camera, quality, fwhm, image_id
v = lc[lc["band"] == "V"]   # one band at a time

# curves_live: ASAS-SN g
live = lsdb.read_hats(root / ptr["collections"]["curves_live"]["path"],
                      columns=["varchive_id", "ra", "dec", "lc_asassn"])
df = live.cone_search(RA, DEC, 600).compute()   # radius in arcsec
lc = df["lc_asassn"].iloc[0]   # band, bjd_tdb, mag, mag_err, detected, jd, limit, camera, quality, fwhm, image_id
g = lc[lc["band"] == "g"]   # one band at a time

# never concatenate across bands or surveys; bjd_tdb is the time axis for science

Citation

Shappee et al. 2014, ApJ 788, 48 The Man behind the Curtain: X-Rays Drive the UV through NIR Variability in the 2013 Active Galactic Nucleus Outburst in NGC 2617
Kochanek et al. 2017, PASP 129, 104502 The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
Jayasinghe et al. 2018, MNRAS 477, 3145 The ASAS-SN catalogue of variable stars I: The Serendipitous Survey
Jayasinghe et al. 2019, MNRAS 486, 1907 The ASAS-SN catalogue of variable stars - II. Uniform classification of 412 000 known variables
Hart et al. 2023, arXiv:2304.03791 ASAS-SN Sky Patrol V2.0

This work made use of data from the All-Sky Automated Survey for Supernovae (ASAS-SN), served through Sky Patrol v2.

BibTeX · 5 entries from NASA ADS

@ARTICLE{2014ApJ...788...48S,
       author = {{Shappee}, B.~J. and {Prieto}, J.~L. and {Grupe}, D. and {Kochanek}, C.~S. and {Stanek}, K.~Z. and {De Rosa}, G. and {Mathur}, S. and {Zu}, Y. and {Peterson}, B.~M. and {Pogge}, R.~W. and {Komossa}, S. and {Im}, M. and {Jencson}, J. and {Holoien}, T.~W.-S. and {Basu}, U. and {Beacom}, J.~F. and {Szczygie{\l}}, D.~M. and {Brimacombe}, J. and {Adams}, S. and {Campillay}, A. and {Choi}, C. and {Contreras}, C. and {Dietrich}, M. and {Dubberley}, M. and {Elphick}, M. and {Foale}, S. and {Giustini}, M. and {Gonzalez}, C. and {Hawkins}, E. and {Howell}, D.~A. and {Hsiao}, E.~Y. and {Koss}, M. and {Leighly}, K.~M. and {Morrell}, N. and {Mudd}, D. and {Mullins}, D. and {Nugent}, J.~M. and {Parrent}, J. and {Phillips}, M.~M. and {Pojmanski}, G. and {Rosing}, W. and {Ross}, R. and {Sand}, D. and {Terndrup}, D.~M. and {Valenti}, S. and {Walker}, Z. and {Yoon}, Y.},
        title = "{The Man behind the Curtain: X-Rays Drive the UV through NIR Variability in the 2013 Active Galactic Nucleus Outburst in NGC 2617}",
      journal = {\apj},
     keywords = {galaxies: active, galaxies: nuclei, galaxies: Seyfert, line: formation, line: profiles, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics},
         year = 2014,
        month = jun,
       volume = {788},
       number = {1},
          eid = {48},
        pages = {48},
          doi = {10.1088/0004-637X/788/1/48},
archivePrefix = {arXiv},
       eprint = {1310.2241},
 primaryClass = {astro-ph.HE},
       adsurl = {https://ui.adsabs.harvard.edu/abs/2014ApJ...788...48S},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

@ARTICLE{2017PASP..129j4502K,
       author = {{Kochanek}, C.~S. and {Shappee}, B.~J. and {Stanek}, K.~Z. and {Holoien}, T.~W.-S. and {Thompson}, Todd A. and {Prieto}, J.~L. and {Dong}, Subo and {Shields}, J.~V. and {Will}, D. and {Britt}, C. and {Perzanowski}, D. and {Pojma{\'n}ski}, G.},
        title = "{The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0}",
      journal = {\pasp},
     keywords = {Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics},
         year = 2017,
        month = oct,
       volume = {129},
       number = {980},
        pages = {104502},
          doi = {10.1088/1538-3873/aa80d9},
archivePrefix = {arXiv},
       eprint = {1706.07060},
 primaryClass = {astro-ph.SR},
       adsurl = {https://ui.adsabs.harvard.edu/abs/2017PASP..129j4502K},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

@ARTICLE{2018MNRAS.477.3145J,
       author = {{Jayasinghe}, T. and {Kochanek}, C.~S. and {Stanek}, K.~Z. and {Shappee}, B.~J. and {Holoien}, T.~W.-S. and {Thompson}, Todd A. and {Prieto}, J.~L. and {Dong}, Subo and {Pawlak}, M. and {Shields}, J.~V. and {Pojmanski}, G. and {Otero}, S. and {Britt}, C.~A. and {Will}, D.},
        title = "{The ASAS-SN catalogue of variable stars I: The Serendipitous Survey}",
      journal = {\mnras},
     keywords = {catalogues, surveys, binaries: eclipsing, stars: variables: general, Astrophysics - Solar and Stellar Astrophysics},
         year = 2018,
        month = jul,
       volume = {477},
       number = {3},
        pages = {3145-3163},
          doi = {10.1093/mnras/sty838},
archivePrefix = {arXiv},
       eprint = {1803.01001},
 primaryClass = {astro-ph.SR},
       adsurl = {https://ui.adsabs.harvard.edu/abs/2018MNRAS.477.3145J},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

@ARTICLE{2019MNRAS.486.1907J,
       author = {{Jayasinghe}, T. and {Stanek}, K.~Z. and {Kochanek}, C.~S. and {Shappee}, B.~J. and {Holoien}, T.~W.-S. and {Thompson}, Todd A. and {Prieto}, J.~L. and {Dong}, Subo and {Pawlak}, M. and {Pejcha}, O. and {Shields}, J.~V. and {Pojmanski}, G. and {Otero}, S. and {Britt}, C.~A. and {Will}, D.},
        title = "{The ASAS-SN catalogue of variable stars - II. Uniform classification of 412 000 known variables}",
      journal = {\mnras},
     keywords = {catalogues, surveys, binaries: eclipsing, stars: variables: general, Astrophysics - Solar and Stellar Astrophysics},
         year = 2019,
        month = jun,
       volume = {486},
       number = {2},
        pages = {1907-1943},
          doi = {10.1093/mnras/stz844},
archivePrefix = {arXiv},
       eprint = {1809.07329},
 primaryClass = {astro-ph.SR},
       adsurl = {https://ui.adsabs.harvard.edu/abs/2019MNRAS.486.1907J},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

@ARTICLE{2023arXiv230403791H,
       author = {{Hart}, K. and {Shappee}, B.~J. and {Hey}, D. and {Kochanek}, C.~S. and {Stanek}, K.~Z. and {Lim}, L. and {Dobbs}, S. and {Tucker}, M. and {Jayasinghe}, T. and {Beacom}, J.~F. and {Boright}, T. and {Holoien}, T. and {Ong}, J.~M. Joel and {Prieto}, J.~L. and {Thompson}, T.~A. and {Will}, D.},
        title = "{ASAS-SN Sky Patrol V2.0}",
      journal = {arXiv e-prints},
     keywords = {Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena},
         year = 2023,
        month = apr,
          eid = {arXiv:2304.03791},
        pages = {arXiv:2304.03791},
          doi = {10.48550/arXiv.2304.03791},
archivePrefix = {arXiv},
       eprint = {2304.03791},
 primaryClass = {astro-ph.IM},
       adsurl = {https://ui.adsabs.harvard.edu/abs/2023arXiv230403791H},
      adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

Also cite AAVSO VSX and Gaia.

license: public, no registration required (ASAS-SN Sky Patrol)
data: https://asas-sn.osu.edu/
release: Sky Patrol v2