1

WFC3 Science Data Volume

Data Volume Estimates for WFC3 OperationsData Volume Estimates for WFC3 Operations ISR WFC3 2001-02; Lisse, Henry, Knezek, Hanley; 3/27/2001ISR WFC3 2001-02; Lisse, Henry, Knezek, Hanley; 3/27/2001

Data Volume per WFC3 exposureData Volume per WFC3 exposure

UVIS ChannelUVIS ChannelFull frame image Full frame image = 4140 x 4206 pixels (including overscan)= 4140 x 4206 pixels (including overscan)

= 266 Mbits/exposure= 266 Mbits/exposure

IR ChannelIR ChannelFull frame image Full frame image = 1024 x 1024 pixels (including reference = 1024 x 1024 pixels (including reference

pixels)pixels)

= 16 Mbit/image= 16 Mbit/image

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WFC3 Primary Data Volume

Observing time allocation assumptionsObserving time allocation assumptionsOne third of orbits are used for spectroscopy and two thirds for imagingOne third of orbits are used for spectroscopy and two thirds for imagingImaging is divided evenly between WFC3 and ACS (5 orbits/day each)Imaging is divided evenly between WFC3 and ACS (5 orbits/day each)60% of WFC3 primary orbits will use the UVIS channel (3 orbits/day)60% of WFC3 primary orbits will use the UVIS channel (3 orbits/day)40% of WFC3 primary orbits will use the IR channel (2 orbits/day)40% of WFC3 primary orbits will use the IR channel (2 orbits/day)

WFC3 ETC was used to determine the number of exposures per WFC3 ETC was used to determine the number of exposures per orbit for each filter used in 41 DRM proposalsorbit for each filter used in 41 DRM proposals

UVIS exposures assumed CRSPLIT = 2UVIS exposures assumed CRSPLIT = 2Number of exposures per orbit was limited to 10 for UVIS and 17 for IR Number of exposures per orbit was limited to 10 for UVIS and 17 for IR based on the transfer rate out of the WFC3 data buffer and a 60 minute based on the transfer rate out of the WFC3 data buffer and a 60 minute visibility periodvisibility period

3

WFC3 Primary Data Volume

Summary of exposure statisticsSummary of exposure statisticsUVISUVIS IRIR

Total number of exposuresTotal number of exposures 42,36142,361 29,05329,053Total number of orbitsTotal number of orbits 9,7399,739 5,1405,140Average exposures/orbitAverage exposures/orbit 4.44.4 5.75.7

Primary UVIS data volume Primary UVIS data volume 266 Mbits/exp * 4.4 exp/orbit * 3 orbits/day = 3461 Mbits/day266 Mbits/exp * 4.4 exp/orbit * 3 orbits/day = 3461 Mbits/day

Primary IR data volumePrimary IR data volumeAverage number of nondestructive readouts = 10Average number of nondestructive readouts = 10Average data volume per exposure = 16 Mbits/image * 10 images/exp Average data volume per exposure = 16 Mbits/image * 10 images/exp 160 Mbits/exp * 5.7 exp/orbit * 2 orbits/day = 1808 Mbits/day160 Mbits/exp * 5.7 exp/orbit * 2 orbits/day = 1808 Mbits/day

4

WFC3 Parallel Data Volume

Assume WFC3 is in parallel for all non-prime orbitsAssume WFC3 is in parallel for all non-prime orbits30% of WFC3 parallel orbits will use the UVIS channel (3 orbits/day)30% of WFC3 parallel orbits will use the UVIS channel (3 orbits/day)70% of WFC3 primary orbits will use the IR channel (7 orbits/day)70% of WFC3 primary orbits will use the IR channel (7 orbits/day)Assume an average of 2 exposures per parallel orbit for UVIS and IRAssume an average of 2 exposures per parallel orbit for UVIS and IR

Parallel UVIS data volumeParallel UVIS data volume266 Mbits/exp * 2 exp/orbit * 3 orbits/day = 1596 Mbits/day266 Mbits/exp * 2 exp/orbit * 3 orbits/day = 1596 Mbits/day

Parallel IR data volumeParallel IR data volumeAverage number of nondestructive readouts = 16Average number of nondestructive readouts = 16Average data volume per exposure = 16 Mbits/image * 16 images/exp Average data volume per exposure = 16 Mbits/image * 16 images/exp 256 Mbits/exp * 2 exp/orbit * 7 orbits/day = 3584 Mbits/day256 Mbits/exp * 2 exp/orbit * 7 orbits/day = 3584 Mbits/day

5

WFC3 Calibration Data Volume

Routine calibration exposures performed during occultationsRoutine calibration exposures performed during occultations

UVISUVIS IR IR

Internal FlatsInternal Flats 693 693 303303Earth FlatsEarth Flats 300 300 300300Dark FramesDark Frames 208 208 208208Bias FramesBias Frames 104104Total per cycleTotal per cycle 1305 1305 811811

Exposures/dayExposures/day 3.6 3.6 2.22.2

Calibration UVIS data volumeCalibration UVIS data volume266 Mbits/exp * 3.6 exp/day = 950 Mbits/day266 Mbits/exp * 3.6 exp/day = 950 Mbits/day

Parallel IR data volumeParallel IR data volume256 Mbits/exp * 2.2 exp/day = 568 Mbits/day256 Mbits/exp * 2.2 exp/day = 568 Mbits/day

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WFC3 Average Data Volume

UVISUVIS IRIR

Exp/dayExp/day Mbits/dayMbits/day Exp/dayExp/day Mbits/dayMbits/day

PrimaryPrimary 1313 34713471 11.311.3 18081808

ParallelParallel 66 15961596 1414 35843584

CalibrationCalibration 3.63.6 950950 2.22.2 568568

TotalTotal 22.622.6 60176017 27.527.5 59605960

Combined WFC3:Combined WFC3: 50 Exp/day 50 Exp/day 11.7 Gbits/day11.7 Gbits/day

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Post SM4 Average Data Volume

PrimaryPrimary ParallelParallel CalibrationCalibration TotalTotal

WFC3WFC3 5.25.2 5.15.1 1.51.5 11.7 11.7

ACSACS 3.83.8 5.15.1 1.01.0 9.9 9.9

COSCOS 0.40.4 0 0 0.20.2 0.6 0.6

STISSTIS 0.20.2 0.10.1 0.10.1 0.4 0.4

TotalTotal 9.69.6 10.310.3 2.82.8 22.6 22.6

Average daily data volume in Gbits without overheadsAverage daily data volume in Gbits without overheads

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Average Data Volume Trend (Gbit)

PrimePrime ParPar CalCal DailyDaily Weekly Weekly (w (w overheads)overheads)

SM2SM2 2.12.1 1.81.8 1.51.5 5.3 5.3 48 48

SM3SM3 5.05.0 8.38.3 3.23.2 16.5 16.5 150150

SM4SM4 9.69.6 10.310.3 2.82.8 22.6 22.6 190190

190 Gbit/week is 80% of the 245 Gbit maximum using one transmitter190 Gbit/week is 80% of the 245 Gbit maximum using one transmitter

Test SMSs with 150 Gbit of science data have shown the feasibility of Test SMSs with 150 Gbit of science data have shown the feasibility of scheduling at 60% of TDRSS capacity using both HST SSRs to buffer data scheduling at 60% of TDRSS capacity using both HST SSRs to buffer data (High data Volume SMSs and TDRS Contact Usage, Patterson et al, 5/18/200)(High data Volume SMSs and TDRS Contact Usage, Patterson et al, 5/18/200)

Using two HST transmitters raises maximum weekly downlink to 440 Gbit Using two HST transmitters raises maximum weekly downlink to 440 Gbit but transmitter lifetime concerns make operating in this mode undesirable.but transmitter lifetime concerns make operating in this mode undesirable.