Case 3: HabEx 4C, metric C2
The HabEx 4C coronagraphonly architecture uses the same observation scenario as the LUVOIR B scenario. EXOSIMS and AYO evaluated HabEx 4C with metric C2 for 2.5 years of observation time as part of the HabEx Architecture trade comparison of the hybrid, starshadeonly, and coronagraphonly architectures (in the HabEx Final Report).
Going from metric A to C2 requires increasingly long integration times because metric A uses a single 20% BW, while to metric C2 requires 4x 20% BW subspectra in sequence. The EXOSIMS implementation performed characterization observations only on targets for which the characterization would be successful in all the subspectra; partial subspectra were avoided. The total integration time of all the subspectra was required to be less than the mission policy of integration cutoff at 60 days. This integration time limit applied to the total of the subspectra significantly reduces the pool of available targets, as seen in the omniscient upper bound yields. The total integration time to acquire a broad spectrum via a sequence of subspectra was longer than the integration time to acquire the same broad spectrum in one continuous starshade observation.
Dynamic Detection and Characterization Plots
These plots show several quantities relating to detection and characterization in distance/luminosity coordinates. Each star in the target list is represented by one dot in the plot, shaded according to the selected quantity. Some stars in the target list are not observable by the instrument due to SNR limitations, and they are shown in gray.
Hovering over the dot drills down to the target name with exact numerical values and uncertainties. All quantities shown by shading are averages across the runs in the ensemble, and the indicated standard deviation is the standard deviation across the ensemble. This standard deviation captures the inherent variability of the quantity due to the random simulated universe and observational scheduling, if applicable. For instance, the number of exoearths per star is approximately 0.24, and thus the variance of the underlying Poisson count of exoearths is also 0.24, for a typical standard deviation of 0.49. The popup also shows the standard error of the given average, which is the above standard deviation divided by the square root of the ensemble size. This “standard error of the mean” is the error in the given average due to Monte Carlo sampling.
Interactive Detection Plot Widget
Interactive Characterization Plot Widget
PNG static plots

A histogram showing the average, across the ensemble, of the number of exoearths successfully characterized. The bars sum to one.

A timebased plot showing the observing timeline – detections, taking of spectra, slews, and other nonexoplanet observations – from a single representative mission. Slews are shown in narrow gray bars along with taking of spectra. In all timelines, alternating dark and light colors are a visual aid to separate events which are sometimes closely spaced. Integration windows shorter than one day have been enlarged to one day to ensure they are visible in the plot. more

Histogram of the average number of events related to observations: detections, characterizations, and detections resulting in target promotion. The values for each sum to one when added across the event count on the abscissa.

Time spent in different modes (detection, characterization, slew), cumulatively as a function of mission elapsed time. Detection time can overlap slew time. Standard deviation across the ensemble is illustrated by the plot bars.

The average number of exoearths characterized versus time, as a cumulative total up to the given time. One value is plotted for each month of mission elapsed time. The error bars are at plus and minus one standard deviation, again computed across the ensemble. The line for all characterizations is the sum of unique characterizations and revisits.

The average number of exoearths detected versus time, as a cumulative total up to the given time. One value is plotted for each month of mission elapsed time. The error bars are at plus and minus one standard deviation, again computed across the ensemble. The line for all detections is the sum of unique detections and revisits.

The average across the ensemble of the characterization SNR for successful characterizations, separated by 15 mutually exclusive planet types plus exoearths (16 categories total). The measure of variability given by the bars is the 25% and 75% quantiles of observed SNR across the ensemble. All distributions of SNR are truncated below because of the minimum SNR required for characterization. The planet types are as defined in the STDT report following Kopparapu et al., ApJ, 2018. more
Full sized PNGs
Histogram of earths characterized back to list
Observation timeline back to list
Event count, dets and chars back to list
Cumulative mission obs back to list
Cumulative Earth chars back to list
Cumulative det earths back to list
SNR demographic back to list