Exposure Time Calculator – pre-launch configuration

DISCLAIMER Following the In-Orbit Commissioning results, changes to the exposure times are required compared to the pre-launch estimates. This implies updates for this ETC taking into account all findings from commissioning. This is work in progress and this website will be updated once the new ETC is available.
In the meantime, and in order for the user to be able to calculate the exposure time for CHEOPS observations, we have generated an Excel sheet that, given the ‘Gaia Magnitude’ and the ‘Effective Temperature’ of the target star, returns the suggested exposure time for individual CHEOPS images. The excel sheet contains a Helper Sheet that explains how it should be used.
 
Click here to download the Excel sheet ‘ImageETCv1.5’.
 
The Excel sheet ImageETCv1.5 does not, however, compute the achieved precision in observations of a specified duration. For this purpose we continue to provide the original pre-launch ETC on this page. The predicted precisions are reasonably accurate if the exposure time is calculated by using the Excel sheet ImageETCv1.5.

Input Parameters

Additional Parameters
Calculation Results
Precision for uninterrupted observations
with flicker
without flicker

Precision when accounting for interruptions
with flicker
without flicker

Comment on exported PDF
Exposure time guidelines
Minimum suggested exposure time: PSF peak at 10% of full well capacity
Maximum suggested exposure time: PSF peak at 98% of full well capacity, or the limit exposure time of 60s
Note: We recommend to use an exposure time close to the maximum exposure times in the tables below.
F0V star
mag V Minimum exposure time [s] Maximum exposure time [s]
6 0.06 0.54
6.5 0.09 0.86
7 0.14 1.36
7.5 0.22 2.15
8 0.35 3.41
8.5 0.55 5.41
9 0.87 8.57
9.5 1.39 13.58
10 2.20 21.52
10.5 3.48 34.81
11 5.52 54.06
11.5 8.74 60.00
12 13.86 60.00
12.5 21.96 60.00
13 34.81 60.00
G0V star
mag V Minimum exposure time [s] Maximum exposure time [s]
6 0.05 0.51
6.5 0.08 0.81
7 0.13 1.28
7.5 0.21 2.04
8 0.33 3.23
8.5 0.52 5.11
9 0.83 8.11
9.5 1.31 12.85
10 2.08 20.36
10.5 3.29 32.27
11 5.22 51.14
11.5 8.27 60.00
12 13.11 60.00
12.5 20.78 60.00
13 32.93 60.00
K0V star
mag V Minimum exposure time [s] Maximum exposure time [s]
6 0.05 0.49
6.5 0.08 0.77
7 0.12 1.22
7.5 0.20 1.94
8 0.31 3.07
8.5 0.50 4.86
9 0.79 7.71
9.5 1.25 12.22
10 1.98 19.36
10.5 3.13 30.69
11 4.96 48.64
11.5 7.87 60.00
12 12.47 60.00
12.5 19.76 60.00
13 31.31 60.00
M0V star
mag V Minimum exposure time [s] Maximum exposure time [s]
6 0.04 0.38
6.5 0.07 0.60
7 0.10 0.96
7.5 0.15 1.52
8 0.25 2.40
8.5 0.39 3.81
9 0.62 6.04
9.5 0.98 9.57
10 1.55 15.16
10.5 2.45 24.03
11 3.89 38.09
11.5 6.16 60.00
12 9.76 60.00
12.5 15.47 60.00
13 24.52 60.00

Cheops ETC V 1.3
Copyright ©2018-2019 Space Research Institute, Austrian Academy of Sciences
Monika Lendl, Harald Ottacher

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