Las Cumbres Observatory Derived Data Product Collection Data Abstract ============= We obtained images of the NEO (65803) Didymos binary asteroid and supporting calibration data with the Las Cumbres Observatory global telescope (LCOGT) network through several filters. These images were obtained in support of NASA's Double Asteroid Redirection Test (DART) mission. The DART mission was a planetary defense mission designed to test and measure the deflection caused by a kinetic impactor (the spacecraft) on the orbit of Dimorphos asteroid around its primary, Didymos. These ground-based observations were used to obtain light curves of Didymos and time the mutual events of Dimorphos to determine the period change caused by the impact of the DART spacecraft. This collection consists of the Las Cumbres Observatory photometry summary tables, which are a PDS4 derived product. Data Set Overview ================= The photometry of Didymos is measured from the calibrated frames (see date_lcogtcal collection) using the NEOexchange or PHOTOMETRYPIPELINE pipelines. Both perform source detection in the images using SExtractor (Bertin, E and Arnouts, S. 1996. SExtractor: Software for source extraction. A&AS, 117, 393), astrometric fits to the detected sources based on the known positions of Gaia DR2 stars in the field using SCAMP (Bertin, E. 2006. Automatic Astrometric and Photometric Calibration with SCAMP. ASPC, 351,112), photometrically calibrates the zero point of the images based on the measured flux of field stars that have known catalog magnitudes (typically from eithe the PanSTARRS or Gaia-DR2 catalogs), and then using these astrometric and photometric solutions derives a calibrated magnitude for Didymos. The photometry tables included in this collection are the output of these pipelines. The photometry summary table is named according to the following convention: lcogt______photometry.tab where: * is the LCOGT site code as defined in the table below, * is the LCOGT instrument code e.g. ‘fa15’ where the first letter indicates CCD manufacturer (f=Fairchild), second letter indicates controller manufacturer (a=Archon) and the 2 digits indicate serial number, * is the date of the start of data collection for that night, * is the unique LCOGT (integer) identifier assigned to the observation request by the LCOGT Observing Portal * is the asteroid name and number in PDS-compatible identifier format i.e. all lowercase An example would be lcogt_lsc_fa15_20220730_2956963_65803didymos_photometry.tab for a photometry file for (65803) Didymos from the fa15 instrument at Cerro Tololo (site code 'lsc') from 2022-07-30. The LCOGT site codes (which are based on the IATA code of the nearest airport) are defined as follows: LCOGT Site Site code location description --------- ----------------------------------------------------------------- ogg Haleakala, Maui, HI, USA coj Siding Spring Observatory, NSW, Australia lsc Cerro Tololo Inter-American Observatory, Chile cpt South African Astronomical Observatory, Sutherland, South Africa elp McDonald Observatory, Texas, USA tfn Teide Observatory, Tenerife, Canary Islands, Spain ngq Ali Observatory, western Tibet, China sin Meta site for all Sinistro cameras in the network Photometry data are stored as a PDS4 ASCII fixed-width table according to the following format. validity_flag: Flag whether this is a valid photometric datapoint, # indicates probably invalid blended data due to asteroid interference with the star. file: file name of the calibrated image where data were measured julian date: Julian date of the exposure midtime mag: Calibrated PanSTARRS r-band apparent magnitude of Didymos sig: 1-sigma error on the apparent magnitude ZP: Calibrated zero point magnitude in PanSTARRS r-band ZP_sig: 1-sigma error on the zero point magnitude inst_mag: Instrumental magnitude of Didymos inst_sig: 1-sigma error on the instrumental magnitude SExtractor_flag: Flags associated with the Source Extractor photometry measurements, see source_extractor_flags.txt in the documents folder for this archive for more detailed description. aprad: Radius in pixels of the aperture used for the photometry measurement References ========== E. Bertin and S. Arnouts., 1996. SExtractor: Software for source extraction. A&AS, 117:393–404, June 1996. doi:10.1051/aas:1996164. E. Bertin., 2006. Automatic Astrometric and Photometric Calibration with SCAMP. ASPC, 351:112. 2006ASPC..351..112B T. Lister, et al, 2021. NEOExchange - an online portal for NEO and Solar System science. Icarus, 364, 114387. doi:10.1117/12.2314340 Proceedings of the SPIE, 10707, 107070K. doi:10.1117/12.2314340 Mommert, M., 2017. PHOTOMETRYPIPELINE: An automated pipeline for calibrated photometry. Astronomy and Computing, 18, pp.47–53. doi:10.48550/arXiv.1702.00834