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Science exposures with less than 30 counts are not easily reduced with the pipeline.
The default Flower number is 16 and this should be used whenever possible.
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Recommended exposure times - approximate, typical seeing is 0.8":
| Kmag | itime (sec) Seeing~0.6" | itime (sec) Seeing~0.8" | itime (sec) Seeing~1" | itime (sec) Seeing~1.2" | itime (sec) Seeing~1.6" | itime (sec) Seeing~2.0" |
|---|---|---|---|---|---|---|
| 4 | <10 | <15 | <20 | <25 | < 30 | 30 |
| 5 | 15 | 30 | 30 | 45 | 45 | 60 |
| 6 | 30 | 45 | 60 | 60 | 90 | 120 |
| 7 | 60 | 90 | 120 | 160 | 180 | 200 |
| 8 | 90 | 120 | 180 | 220 | 260 | 300 |
| 9 | 180 | 300 | 300 | 480 | 600 | 600 |
| 10 | 300 | 480 | 600 | 600 | 900 | 900 |
| 11 | 600 | 900 | 1200 | infinity | infinity | infinity |
| 12 | 900 | 1200 | infinity | infinity | infinity | infinity |
| >13 | 1200 | infinity | infinity | infinity | infinity | infinity |
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DCT SNR Estimation:
Estimate your SNR with this equation:
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SNR=(273*sqrt(600*4)*10^(-0.2*(10-1))) /(1.66*ln(1.0)+1.9) ~ 110
Empirical SNR estimates based on the peak counts in the continuum:
| Peak counts in single frame continuum: | ABBA SNR (per resolution element) | ABBA(x2) |
50 | 55 | 80 |
| 150 | 100 | 140 |
| 300 | 140 | 200 |
| 600 | 200 | 280 |
| 1000 | 250 | 360 |