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Henden A.,AAVSO | Munari U.,National institute for astrophysics
Contributions of the Astronomical Observatory Skalnate Pleso | Year: 2014

The APASS photometric survey covers the whole sky, from Pole to Pole, and has measured in Landolt B, V and Sloan g',r',i' bands all stars in the range 10.0≤V ≤17.0 over about four distinct epochs between 2009 and 2013. The photometry is accurate to 0.02 mag and the astrometry to 0.17 arcsec. At the time of writing 8 incremental Data Releases have been issued covering ≥50 million stars. The final survey products will be ready by the end of 2014 and will include 100 million stars. Extension to brighter stars (7.5≤V ≤10.0) and additional bands (u', z' and Y) is underway. Source

Zacharias N.,U.S. Naval Observatory | Finch C.T.,U.S. Naval Observatory | Girard T.M.,Yale University | Henden A.,AAVSO | And 3 more authors.
Astronomical Journal | Year: 2013

The fourth United States Naval Observatory (USNO) CCD Astrograph Catalog, UCAC4, was released in 2012 August (double-sided DVD and CDS data center Vizier catalog I/322). It is the final release in this series and contains over 113 million objects; over 105 million of them with proper motions (PMs). UCAC4 is an updated version of UCAC3 with about the same number of stars also covering all-sky. Bugs were fixed, Schmidt plate survey data were avoided, and precise five-band photometry was added for about half the stars. Astrograph observations have been supplemented for bright stars by FK6, Hipparcos, and Tycho-2 data to compile a UCAC4 star catalog complete from the brightest stars to about magnitude R = 16. Epoch 1998-2004 positions are obtained from observations with the 20 cm aperture USNO Astrograph's "red lens," equipped with a 4k by 4k CCD. Mean positions and PMs are derived by combining these observations with over 140 ground- and space-based catalogs, including Hipparcos/Tycho and the AC2000.2, as well as unpublished measures of over 5000 plates from other astrographs. For most of the faint stars in the southern hemisphere, the first epoch plates from the Southern Proper Motion program form the basis for PMs, while the Northern Proper Motion first epoch plates serve the same purpose for the rest of the sky. These data are supplemented by 2MASS near-IR photometry for about 110 million stars and five-band (B, V, g, r, i) APASS data for over 51 million stars. Thus the published UCAC4, as were UCAC3 and UCAC2, is a compiled catalog with the UCAC observational program being a major component. The positional accuracy of stars in UCAC4 at mean epoch is about 15-100 mas per coordinate, depending on magnitude, while the formal errors in PMs range from about 1 to 10 mas yr-1 depending on magnitude and observing history. Systematic errors in PMs are estimated to be about 1-4 mas yr-1. © 2013. The American Astronomical Society. All rights reserved. Source

Henden A.A.,AAVSO
Proceedings of the International Astronomical Union | Year: 2011

The AAVSO is initiating a new survey of the sky. It will cover the entire visible sky, both north and south, on a daily basis, in two colours, and with a limiting magnitude of V = 17. This will be a perfect complement to LSST, but will be available years earlier and will continue into the indefinite future. The photometry will be publicly available within 24 hours through our website. Some details of the hardware and operations are described. © 2012 International Astronomical Union. Source

Henden A.A.,AAVSO
Proceedings of the International Astronomical Union | Year: 2011

Citizen Science is the act of collecting or analyzing data by enlisting the help of volunteers who may have no specific scientific training. The workshop discussed how Citizen Science fits into time-domain astronomy, what the roles of such volunteers might be, and how amateur astronomers can help in the new era of surveys. © 2012 International Astronomical Union. Source

Munari U.,National institute for astrophysics | Henden A.,AAVSO | Belligoli R.,ANS Collaboration | Castellani F.,ANS Collaboration | And 3 more authors.
New Astronomy | Year: 2013

Accurate and densely populated BVRCIC lightcurves of supernovae SN 2011fe in M101, SN 2012aw in M95 and SN 2012cg in NGC 4424 are presented and discussed. The SN 2011fe lightcurves span a total range of 342 days, from 17 days pre- to 325 days post-maximum. The observations of both SN 2012aw and SN 2012cg were stopped by solar conjunction, when the objects were still bright. The lightcurve for SN 2012aw covers 92 days, that of SN 2012cg spans 44 days. Time and brightness of maxima are measured, and from the lightcurve shapes and decline rates the absolute magnitudes are obtained, and the derived distances are compared to that of the parent galaxies. The color evolution and the bolometric lightcurves are evaluated in comparison with those of other well observed supernovae, showing no significant deviations. © 2012 Elsevier B.V. All rights reserved. Source

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