Calibration solutions, light curve and dedispersion data for Murchison Widefield Array rapid-response observations of the short GRB 180805A

This repository includes the final datasets derived from Murchison Widefield Array (MWA) rapid-response observations of gamma-ray burst (GRB) 180805A used for analysis in the paper "Murchison Widefield Array rapid-response observations of the short GRB 1808085A". All raw MWA data for this observation can be obtained from the Murchison Widefield Array All-sky Virtual Observatory (https://asvo.mwatelescope.org/), and include observation identification (ObsID) numbers 1217495184, 1217495304, 1217495424, 1217495544, 1217495664, 1217495784, 1217495904, 1217496024, 1217496144, 1217496264, 1217496384, 1217496504, 1217496624, 1217496744, 1217496864 under project code D0009. These 15 observations are referred to as snapshots in the following. The files attached files to this repository are described below. Calibration solutions (1217495544_infield_solutions.bin): The calibration solutions applied to all ObsIDs, which were derived from an infield calibration of ObsID 1217495544 using the GLEAM model (Hurley-Walker et al. 2017). Light curves (GRB180805A_2m_lc.csv, GRB180805A_30s_lc.csv, GRB180805A_5s_lc.csv, GRB180805A_05s_lc.csv): All observations were imaged on 2 minutes, 30 seconds, 5 seconds, and 0.5 seconds timescales. Priorized fitting was performed at the position of the GRB to obtain monitoring light curves. These csv files list the resulting flux density as a function of time for these four different timescales. Dynamic spectrum: This is the dynamic spectrum created at the pixel position of GRB 180805A by splitting the full 30-minute MWA integration (15 snapshot observations) into the 0.5-second coarse channel (1.28 MHz frequency resolution) images. The first 4s and last 5.5s of each individual snapshot observation are flagged due to instrumental reasons. The axes are Frequency (MHz) vs Time post-GRB (seconds) with the greyscale showing Jy/beam. This dynamic spectrum was used to create a dedispersed time series, for which we search from prompt, dispersed signals. Dedispersed time series: The mean flux density (Jy/beam) for the path swept across the dynamic spectrum (see above) for every dispersion measure (DM) trial ranging from 100-3000 pc cm-3 at 1.0 pc cm-3 intervals for all time steps at a resolution of 0.1s following the GRB detection. This dedispersed time series was searched for evidence of prompt signals but there were no significant signals (above signal-to-noise ratio of 6) for DM > 200 pc cm-3, which is the lowest DM that we expect short GRBs to be detected (corresponding to a minimum redshift of z~0.1).本仓库包含用于论文《"Murchison Widefield Array rapid-response observations of the short GRB 1808085A"》分析的、源自默奇森宽场阵列（Murchison Widefield Array, MWA）对伽马射线暴（gamma-ray burst, GRB）180805A的快速响应观测最终数据集。本次观测的所有原始MWA数据可从默奇森宽场阵列全天体虚拟天文台（https://asvo.mwatelescope.org/）获取，对应的观测标识（Observation Identification, ObsID）编号为项目代码D0009下的1217495184、1217495304、1217495424、1217495544、1217495664、1217495784、1217495904、1217496024、1217496144、1217496264、1217496384、1217496504、1217496624、1217496744、1217496864，下文将这15次观测统称为快照。本仓库附带的文件详述如下：定标解文件（1217495544_infield_solutions.bin）：应用于所有ObsID的定标解，其通过使用GLEAM模型（Hurley-Walker等人，2017）对ObsID 1217495544开展现场定标得到。光变曲线文件（GRB180805A_2m_lc.csv、GRB180805A_30s_lc.csv、GRB180805A_5s_lc.csv、GRB180805A_05s_lc.csv）：所有观测分别以2分钟、30秒、5秒及0.5秒的时间尺度完成成像。针对该伽马射线暴的位置执行优先拟合，以获取监测用光变曲线。上述CSV文件列出了四种不同时间尺度下得到的、随时间变化的流量密度结果。动态频谱：该频谱通过将完整的30分钟MWA积分数据（15次快照观测）拆分为0.5秒粗通道（频率分辨率为1.28 MHz）的图像，在GRB 180805A的像素位置生成。因仪器原因，每次快照观测的前4秒及最后5.5秒将被标记为无效数据段。频谱坐标轴为频率（单位：MHz）与暴后时间（单位：秒），灰度值代表流量密度，单位为Jy/beam。本动态频谱被用于生成去色散时间序列，以此搜寻瞬时色散信号。去色散时间序列：在伽马射线暴被探测后，以0.1秒的时间分辨率对所有时间步长，在100~3000 pc·cm⁻³的范围内以1.0 pc·cm⁻³为步长遍历每一个色散量（dispersion measure, DM）试验值，计算扫过动态频谱路径的平均流量密度（单位：Jy/beam）。本去色散时间序列被用于搜寻瞬时信号证据，但对于DM>200 pc·cm⁻³的情况，未发现信噪比高于6的显著信号——该色散量是我们预期可探测到短伽马射线暴的最低阈值（对应最小红移z~0.1）。