# Cesium Features - By Category¶

Cadence/Error | Description |
---|---|

all_times_nhist_numpeaks | Number of peaks (local maxima) in histogram of all possible delta_t’s. |

all_times_nhist_peak1_bin | Return the (bin) index of the ith largest peak. Peaks is a list of tuples (i, x[i]) of peak indices i and values x[i], sorted in decreasing order by peak value. |

all_times_nhist_peak2_bin | Return the (bin) index of the ith largest peak. Peaks is a list of tuples (i, x[i]) of peak indices i and values x[i], sorted in decreasing order by peak value. |

all_times_nhist_peak3_bin | Return the (bin) index of the ith largest peak. Peaks is a list of tuples (i, x[i]) of peak indices i and values x[i], sorted in decreasing order by peak value. |

all_times_nhist_peak4_bin | |

all_times_nhist_peak_1_to_2 | Compute the ratio of the values of the ith and jth largest peaks. Peaks is a list of tuples (i, x[i]) of peak indices i and values x[i], sorted in decreasing order by peak value. |

all_times_nhist_peak_1_to_3 | Compute the ratio of the values of the ith and jth largest peaks. Peaks is a list of tuples (i, x[i]) of peak indices i and values x[i], sorted in decreasing order by peak value. |

all_times_nhist_peak_1_to_4 | Compute the ratio of the values of the ith and jth largest peaks. Peaks is a list of tuples (i, x[i]) of peak indices i and values x[i], sorted in decreasing order by peak value. |

all_times_nhist_peak_2_to_3 | |

all_times_nhist_peak_2_to_4 | |

all_times_nhist_peak_3_to_4 | |

all_times_nhist_peak_val | Peak value in histogram of all possible delta_t’s. |

avg_double_to_single_step | Mean value of ratios (t[i+2] - t[i]) / (t[i+2] - t[i+1]). |

avg_err | Mean of the error estimates. |

avgt | Mean of the time values. |

cad_probs_1 | Given the observed distribution of time lags cads, compute the probability that the next observation occurs within time minutes of an arbitrary epoch. |

cad_probs_10 | Given the observed distribution of time lags cads, compute the probability that the next observation occurs within time minutes of an arbitrary epoch. |

cad_probs_20 | Given the observed distribution of time lags cads, compute the probability that the next observation occurs within time minutes of an arbitrary epoch. |

cad_probs_30 | |

cad_probs_40 | |

cad_probs_50 | |

cad_probs_100 | |

cad_probs_500 | |

cad_probs_1000 | |

cad_probs_5000 | |

cad_probs_10000 | |

cad_probs_50000 | |

cad_probs_100000 | |

cad_probs_500000 | |

cad_probs_1000000 | |

cad_probs_5000000 | |

cad_probs_10000000 | |

cads_avg | Mean value of cads (discrete difference between times). |

cads_med | Median value of cads (discrete difference between times). |

cads_std | Standard deviation of cads (discrete difference between times). |

mean | Mean of observed values. |

med_double_to_single_step | Median value of ratios (t[i+2] - t[i]) / (t[i+2] - t[i+1]). |

med_err | Median of error estimates. |

n_epochs | Total number of observed values. |

std_double_to_single_step | Standard deviation of ratios (t[i+2] - t[i]) / (t[i+2] - t[i+1]). |

std_err | Standard deviation of the error estimates. |

total_time | Absolute difference between max and min of time values. |

General | Description |
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amplitude | Half the difference between the maximum and minimum magnitude. |

flux_percentile_ratio_mid20 | A ratio of ((50+x) flux percentile - (50-x) flux percentile) / (95 flux percentile - 5 flux percentile), where x = percentile_range/2. |

flux_percentile_ratio_mid35 | A ratio of ((50+x) flux percentile - (50-x) flux percentile) / (95 flux percentile - 5 flux percentile), where x = percentile_range/2. |

flux_percentile_ratio_mid50 | A ratio of ((50+x) flux percentile - (50-x) flux percentile) / (95 flux percentile - 5 flux percentile), where x = percentile_range/2. |

flux_percentile_ratio_mid65 | |

flux_percentile_ratio_mid80 | |

max_slope | Compute the largest rate of change in the observed data. |

maximum | Maximum observed value. |

median | Median of observed values. |

median_absolute_deviation | Median absolute deviation (from the median) of the observed values. |

minimum | Minimum observed value. |

percent_amplitude | Returns the largest distance from the median value, measured as a percentage of the median. |

percent_beyond_1_std | Percentage of values more than 1 std. dev. from the weighted average. |

percent_close_to_median | Percentage of values within window_frac*(max(x)-min(x)) of median. |

percent_difference_flux_percentile | Difference between the 95th and 5th percentiles of the data, expressed as a percentage of the median value. See Eyer (2005) arXiv:astro-ph/0511458v1, Evans & Belokurov (2005) (there the 98th and 2nd percentiles are used). |

period_fast | Fits a simple sinuosidal model |

qso_log_chi2_qsonu | Natural log of goodness of fit of qso-model given fixed parameters. |

qso_log_chi2nuNULL_chi2nu | Natural log of expected chi2/nu for non-qso variable. |

skew | Skewness of a dataset. Approximately 0 for Gaussian data. |

std | Standard deviation of observed values. |

stetson_j | Robust covariance statistic between pairs of observations x,y whose uncertainties are dx,dy. If y is not given, calculates a robust variance for x. |

stetson_k | A robust kurtosis statistic. |

weighted_average | Arithmetic mean of observed values, weighted by measurement errors. |

Lomb-Scargle (Periodic) | Description |
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fold2P_slope_10percentile | Get alphath percentile of slopes of period-folded model. |

fold2P_slope_90percentile | Get alphath percentile of slopes of period-folded model. |

freq1_amplitude1 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq1_amplitude2 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq1_amplitude3 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq1_amplitude4 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq1_freq | Get the ith frequency from a fitted Lomb-Scargle model. |

freq1_lambda | Get the regularization parameter of a fitted Lomb-Scargle model. |

freq1_rel_phase2 | Get the relative phase of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq1_rel_phase3 | Get the relative phase of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq1_rel_phase4 | Get the relative phase of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq1_signif | Get the significance (in sigmas) of the first frequency from a fitted Lomb-Scargle model. |

freq2_amplitude1 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq2_amplitude2 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq2_amplitude3 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq2_amplitude4 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq2_freq | Get the ith frequency from a fitted Lomb-Scargle model. |

freq2_rel_phase2 | Get the relative phase of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq2_rel_phase3 | Get the relative phase of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq2_rel_phase4 | Get the relative phase of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq3_amplitude1 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq3_amplitude2 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq3_amplitude3 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq3_amplitude4 | Get the amplitude of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq3_freq | Get the ith frequency from a fitted Lomb-Scargle model. |

freq3_rel_phase2 | Get the relative phase of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq3_rel_phase3 | Get the relative phase of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq3_rel_phase4 | Get the relative phase of the jth harmonic of the ith frequency from a fitted Lomb-Scargle model. |

freq_amplitude_ratio_21 | Get the ratio of the amplitudes of the first harmonic for the ith and first frequencies from a fitted Lomb-Scargle model. |

freq_amplitude_ratio_31 | Get the ratio of the amplitudes of the first harmonic for the ith and first frequencies from a fitted Lomb-Scargle model. |

freq_frequency_ratio_21 | Get the ratio of the ith and first frequencies from a fitted Lomb-Scargle model. |

freq_frequency_ratio_31 | Get the ratio of the ith and first frequencies from a fitted Lomb-Scargle model. |

freq_model_max_delta_mags | Largest value minus second largest value of fitted Lomb Scargle model. |

freq_model_min_delta_mags | Second smallest value minus smallest value of fitted Lomb Scargle model. |

freq_model_phi1_phi2 | Ratio of distances between the second minimum and first maximum, and the second minimum and second maximum, of the fitted Lomb-Scargle model. |

freq_n_alias | Here we check for “1-day” aliases in ASAS / Deboss sources. |

freq_signif_ratio_21 | Get the ratio of the significances (in sigmas) of the ith and first frequencies from a fitted Lomb-Scargle model. |

freq_signif_ratio_31 | Get the ratio of the significances (in sigmas) of the ith and first frequencies from a fitted Lomb-Scargle model. |

freq_varrat | Get the fraction of the variance explained by the first frequency of a fitted Lomb-Scargle model. |

freq_y_offset | Get the y-intercept of a fitted Lomb-Scargle model. |

linear_trend | Get the linear trend of a fitted Lomb-Scargle model. |

medperc90_2p_p | Get ratio of 90th percentiles of residuals for data folded by twice the estimated period and the estimated period, respectively. |

p2p_scatter_2praw | Get ratio of variability (sum of squared differences of consecutive values) of folded and unfolded models. |

p2p_scatter_over_mad | Get ratio of variability of folded and unfolded models. |

p2p_scatter_pfold_over_mad | Get ratio of median of period-folded data over median absolute deviation of observed values. |

p2p_ssqr_diff_over_var | Get sum of squared differences of consecutive values as a fraction of the variance of the data. |

scatter_res_raw | From arXiv 1101_2406v1 Dubath 20110112 paper. |