Harvard Plate Collection Metcalf Telescope

Digital Access to a Sky Century @ Harvard
A New Look at the Temporal Universe

DASCH Lightcurve Access

Enter the J2000 object position or a Simbad-searchable reference in the box below and press Search to obtain the lightcurve query results in a separate window. The search center is currently restricted to released regions, a maximum of ten entries, and a maximum search radius is 60 arcsec. Note that the positions returned by Simbad may not necessarily match the DASCH positions because of discrepancies between catalogs. DASCH positions are corrected by UCAC4 proper motions.
N >= d <= arcsec
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We are currently using the AAVSO Photometry All-Sky Survey (APASS) Release 8 Catalog , the Kepler Input Catalog (KIC), and the GSC2.3.2 Catalog for photometry calibration. The APASS calibration gives the best photometric accuracy over the entire sky. The KIC calibration gives comparable accuracy for the field of the Kepler satellite. Finally, the GSC2.3.2 catalog provides magnitudes for objects outside the 9 to 15 magnitude range of APASS. An overview of DASCH calibration appears in Laycock, S. et. al, Digital Access to a Sky Century at Harvard. II: Initial Photometry and Astrometry and in Sumin Tang et al., Improved Photometry for the DASCH pipeline . An overview of the DASCH pipeline appears in the project photometry page.

Objects in the Kepler field calibrated with the Kepler Catalog (KIC) have g-band magnitudes; objects calibrated with APASS have B-band magnitudes; and objects calibrated with GSC2.3.2 have JpgMag (IIIaJ) magnitudes.

To access photometric data enter object ID's (one per line) in the window above. Valid identifications are: J2000 RA DEC (5.45 -81.5 or 5:26:50 -81:35:12 or 8 41 43.8 +19 43 33.5 where a +declination sign is mandatory in the third case only), GSC2.3.2 ID (for the gsc2.3.2 dataset only; e.g. N2312220195 or N120013341), Kepler Input Catalog ID (for the KIC dataset only; e.g. K3433237), APASS Catalog ID (for the APASS dataset only; e.g. APASS_J115140.7+020334), Simbad-searchable object name (XX Dor), or DASCH object (DASCH_J123349.2-113822), i.e. an object which does not have a matching catalog entry. All stars within d arcsecs from center, having more than N measurements will be listed. Because of astrometry issues inherent in the processing of old photographic plates, measurements of interest may appear in adjacent lightcurves. To obtain object's light curve, click on its listed ID in the query results window. Data tables for all points returned by the query may be obtained by selecting the Download all points in table form. link at the bottom of the query results window. WARNING: The Simbad name resolution service has been intermittently unreliable from this web site. If you experience problems, please retrieve the coordinates directly from the Simbad reflector site.


The DASCH project at Harvard is grateful for partial support from NSF grants AST-0407380, AST-0909073, and AST-1313370; which should be acknowledged in all papers making use of DASCH data.

We acknowledge the one-time gift of the Cornel and Cynthia K. Sarosdy Fund for DASCH, and thank Grzegorz Pojmanski of the ASAS project for providing some of the source code on which the DASCH web-interface is based.

The ongoing AAVSO Photometric All-Sky Survey (APASS) has improved DASCH photometric calibration and is funded by the Robert Martin Ayers Sciences Fund.