Las Campanas Swope Derived Data Product Collection Overview

Data Abstract
=============
We obtained images of the (65803) Didymos system and supporting calibration 
images with the Swope 4K CCD on the Swope 1m Telescope at the Las Campanas 
Observatory (LCO). These images were taken in order to determine the orbit 
period of Dimorphos, the satellite of Didymos. This collection consists of 
photometry summary tables, which are a PDS4 derived product, detailing the 
results of photometric processing performed on collected images.

Data Set Overview
=================
Instrumental aperture photometry is measured in every image on the asteroid's 
and on the selected stars' positions for a set of apertures from 3 to 20 
pixels radius using the python package SEP (Barbary, K. 2016) for the initial 
detection of the brightest non-saturated stars and the subsequent background 
subtraction across the entire image, in order to measure the flux in the 
different apertures and transform directly into instrumental magnitudes.
A 7 pixel radius was used for Swope.

In order to estimate the photometry zero points of the individual images, 
different python packages are used: astroquery (Ginsburg et al. 2019) to 
query Vizier and Horizon databases in order to identify GAIA stars in the 
set of selected stars inside a 2 arcsecs tolerance radius, and to obtain the 
coordinates of the asteroid for the given date of the images; and gaiaxpy 
python package (De Angeli et al. 2023), to request and download synthetic 
photometry of GAIA stars (Gaia Collaboration et al. 2023) in Sloan-r band 
when available. Final photometry of the Didymos-Dimorphos system is estimated 
adding the zero points to measured instrumental magnitude in the corresponding 
images. All data are taken with Sloan_r' and magnitudes are calculated for 
Sloan_r' primarily with reference to GAIA.

The photometry summary tables are named according to the following convention: 

photometry_<instrument>_<yymmdd>.tab

where:
<instrument> is either imacs or swope (always swope for this collection)

<yymmdd> is the UTC year, month, day of observation

Photometry data are stored as a PDS4 ASCII fixed-width table according to the 
following format:

Julian date: Julian date at middle of exposure
Magnitude: Calibrated magnitude estimate, unitless
Uncertainty: Instrumental magnitude uncertainty, unitless
Flag: Binary flag to mark discrepant data. 0 = discrepant, 1 = non-discrepant
Filename: File name of the calibrated image where data were measured

References
==========
Barbary, K., “SEP: Source Extractor as a library”, The Journal of Open Source 
    Software, vol. 1, no. 6, 2016. doi:10.21105/joss.00058.
De Angeli, F. et al, “Gaia Data Release 3. Processing and validation of BP/RP low-
    resolution spectral data”, Astronomy and Astrophysics, vol. 674, 2023. 
    doi:10.1051/0004-6361/202243680.
Gaia Collaboration et al., “Gaia Data Release 3. The Galaxy in your preferred 
    colours: Synthetic photometry from Gaia low-resolution spectra”, Astronomy 
    and Astrophysics, vol. 674, 2023. doi:10.1051/0004-6361/202243709.
Ginsburg, A. et al, “Astroquery: An Astronomical Web-querying Package in Python”, 
    The Astronomical Journal, vol. 157, no. 3, 2019. doi:10.3847/1538-3881/aafc33.