Las Cumbres Observatory Raw Data Collection Overview 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 raw images. Data Set Overview ================= This collection consists of raw images of the (65803) Didymos system taken by the Las Cumbres Observatory 1-meter telescope network through several filters (normally a PanSTARRS w broad filter equivalent to g'+r'+i' or one of the Sloan/PanSTARRS g', r', i' filters. Note in the FITS headers, the prime (') is replaced with a ASCII lower case 'p' e.g. observations in a g' filter will appear as 'gp'). 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. The visible-wavelength, direct-imaging CCD instruments for the Las Cumbres Observatory (LCOGT) 1-meter Telescopes are called the Sinistro Imagers. Sinistro imagers contain a Fairchild deep depletion, back-illuminated monolithic CCD with 4096 x 4097 pixels. The instrument is mounted on the straight through port on the LCOGT 1-meter instrument support structure. Sinistro is a 4k x 4k CCD that images a 26.5 arc minute square field of view. The device is back illuminated and has 15-micron pixels. The unbinned detector provides a pixel scale of 0.389 arcsec/pixel. The instrument can also be operated in a central_2k_2x2 mode which reads the central 2048 x 2048 pixels, with 2x2 pixel binning, giving 0.778 arcsec/pixel. The chip is linear up to 65k ADU and the gains of the four individual amplifiers are normalized to 1.0 by the processing pipeline for calibrated images. Read noise is typically 7.5 to 9 electrons depending on the particular CCD and the readout time is 28 seconds for unbinned images, and 9 sec for the central_2k_2x2 mode. The CCD quantum efficiency is 64% for 350 - 400 nm, 72% at 500 nm, rising to 80-90% over 600-800 nm and declining to 24% at 1000 nm. The quantum efficiency falls off very sharply below 350 nm. The Sinistro imagers on the Las Cumbres Observatory 1-meter telescope network acquire data in FITS format. Raw image data includes the science sky frames, bias and dark frames, and flat fields. Bias and dark frames are taken during the local site afternoon before sunset and flat fields are automatically scheduled by the calibration system for those filters that have the oldest master flatfields. Flat fields are obtained by taking dithered images of the twilight sky with the telescope pointed at the point opposite the Sun which minimizes sky curvature. Naming Convention ================= Raw Sinistro images consist of a single FITS file containing a primary header and 4 image extensions corresponding to the individual quadrants and amplifiers of the CCD. They are named according to the following LCOGT-wide convention: ----. where: filename section Description ---------------- -------------------------------------------------------------- LCOGT site code (one from {ogg, coj, lsc, cpt, elp, tfn, ngq}) Size/class of telescope (one from {2m0, 1m0, 0m4}) telescope serial number within size class 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. UTC date of the start of the night (defined to be UTC date at 1600 local time at the site). Does not change if the site observes through UTC midnight. four digit image counter for that instrument, resets at start of new night (defined as above). Counter starts at 0001 Type of file. One of {a=arc, b=bias, d=dark, e=exposure, s=standard, f=sky flat, l=lambert flat, w=lamp flat, x=experimental}) Reduction level from 00-99 with higher numbers indicating higher levels of data processing. In practice, one of {00=raw, 91=BANZAI processed, 92=NEOexchange processed} the file extension. ".fits" for fits file format, ".xml" for the PDS label. e.g. coj1m011-fa12-20210408-0176-e91.fits is a processed expose(sky) data product from the Siding Spring Observatory (coj), from 1-meter telescope #11 and the fa12 Sinistro instrument from the night of 2021-04-08. It is the 176th image taken by that instrument on that night. 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