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IFU_PA_REQUEST allows the catalogue provider to specify a rotation angle (position angle) of the LIFU, if required (default value is zero)this is required. Any dithering requested for the field is applied to the rotated LIFU frame. If a specific PA value is resquestednot requested, then the following defaults are applied: IFU_PA=0° (for declinations lower than 28.7°) and IFU_PA=180° (for declinations higher than 28.7°). Note that these the requested IFU_PAs can PA could be changed a little by the IFU workflow software if a suitable guiding star can cannot be found at the requested PA. Below it's a plot which shows how the PA is changed to find a suitable guiding star.
| IMPORTANT: During the IFU observation preparation using the IFU workflow software, an analysis is performed on putative LIFU pointings to determine if a rotation is required and provides the optimal value IFU_PA should take. Rotation is generally used in cases where the default or requested PA results in no viable guide stars falling within the autoguider field of view, or when the rotation during an exposure is likely to exceed the angular limits of the rotator. This means that it's not always possible that the IFU workflow software can provide the IFU_PA_REQUEST value in the catalogue. The table below shows the allowed IFU_PA_REQUEST (=PA in the table) ranges PIs can safely apply for. Maximum value of PA is 360º. |
h_min=50. |
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28 (X=1.3) | h_min=45. |
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| 58 (X=1.4) OBSTEMP: __B__ | h_min=41. |
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| 81 (X=1.5) OBSTEMP: __C__ | h_min=38. |
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| 68 (X=1.6) OBSTEMP: __D__ | h_min=33. |
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| 75 (X=1.8) OBSTEMP: __E__ | h_min=25. |
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| 00 (X=2.4) OBSTEMP: __F__ | ||||||||||||
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| Dec (°) | PA range (°) | PA range (°) | PA range (°) | PA range (°) | PA range (°) | PA range (°) | ||||||
| -25 | 225<PA<135 | -135 → 0 → +135 | 245<PA<115 | -115 → 0 → +115 | ||||||||
| -10 | 220<PA<140 | -140 → 0 → +140 | 235<PA<125 | -125 → 0 → +125 | 245<PA<115 | -115 → 0 → +115 | 245<PA<115 | -115 → 0 → +115 | 250<PA<110 | -110 → 0 → +110 | 260<PA<100 | -100 → 0 → +100 |
| 0 | 250<PA<110 | -110 → 0 → +110 | 255<PA<105 | -105 → 0 → +105 | 255<PA<105 | |||||||
| -105 → 0 → +105 | 260<PA<100 |
| -100 → 0 → +100 | 260<PA<100 | -100 → 0 → +100 | 270<PA<90 | -90 → 0 → +90 | ||||||||
| +15 | 270<PA<90 | -90 → 0 → +90 | 270<PA<90 | -90 → 0 → +90 | 270<PA<90 | -90 → 0 → +90 | 270<PA<90 | -90 → 0 → +90 | 275<PA<85 | -85 → 0 → +85 | 275<PA<85 | -85 → 0 → +85 |
| +28.70 | 295<PA<65 | -65 → 0 → +65 | 295<PA<65 | -65 → 0 → +65 | 295<PA<65 | -65 → 0 → +65 | 295<PA<65 | -65 → 0 → +65 | 295<PA<65 | -65 → 0 → +65 | 295<PA<65 | -65 → 0 → +65 |
| +30 | 130<PA<230 | -130→ 180 → +130 | 130<PA<230 | -130 → 180 → +130 | 130<PA<230 | -130 → 180 → +130 | 130<PA<230 | -130 → 180 → +130 | 135<PA<225 | -135 → 180 → +135 | 135<PA<225 | -135 → 180 → +135 |
| +40 | 115<PA<245 | -115 → 180 → +115 | 120<PA<240 | -120 → 180 → +120 | 120<PA<240 | -125 → 180 → +125 | 120<PA<240 | -125 → 180 → +125 | 130<PA<230 | -130 → 180 → +130 | 135<PA<225 | -135 → 180 → +135 |
| +50 | 105<PA<255 | -105 → 180 → +105 | 100<PA<260 | -100 → 180 → +100 | 115<PA<245 | -115 → 180 → +115 | 120<PA<240 | -120 → 180 → +120 | 120<PA<240 | -125 → 180 → +125 | 135<PA<225 | -135 → 180 → +135 |
| +60 | 80<PA<280 | -80 → 180 → +80 | 95<PA<265 | -95 → 180 → +95 | 105<PA<255 | -105 → 180 → +105 | 110<PA<250 | -110 → 180 → +110 | 120<PA<240 | -120 → 180 → +120 | 130<PA<230 | -130 → 180 → +130 |
| +70 | 65<PA<295 | -65 → 180 → +65 | 85<PA<275 | -85 → 180 → +85 | 95<PA<265 | -95 → 180 → +95 | 110<PA<250 | -110 → 180 → +110 | 120<PA<240 | -125 → 180 → +125 | ||
| +80 | 35<PA<325 | -35 → 180 → +35 | 90<PA<270 | -90 → 180 → +90 | 140<PA<220 | -140 → 180 → +140 |
IFU_DITHER
IFU_DITHER allows the PI to specify the dithering strategy for their observations, but may alternatively request not to dither their observations, with the understanding that this will not provide full spatial coverage of their requested field. PIs may request the preset -3, 3, 4, 5 and 6-dither patterns. The LIFU preset patterns will be properly rotated according to the position angle of the observation.
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