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Target declination and right ascension limits
The current target declination limit is -25º. Objects with a declination lower than that cannot be observed.
WASP sets limits to allowed target RA and Dec, and it will not validate your OB if your target coordinates lie outside the limits for that the trimester. See below the allowed RAs RA ranges for each trimester.
Allowed RA range - Trimester A1 |
2h (30º) → 20h (300º) Expanded range: |
Allowed RA range - Trimester A2 |
9h (135º) → 2h (30º) Expanded range: |
Allowed RA range - Trimester B1 |
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15h (225º) → 9h (135º) Expanded RA range: |
Allowed RA range - Trimester B2 |
20h (300º) → 16h (240º) Expanded RA range: |
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TARGPROG is an optional column, to be filled out at the discretion of the catalogue creator.
TARGNAME and TARGID
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TARGNAME
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This parameter is used to group IFU observations of the same target, in cases where stacks are required. This helps the Core Processing System (CPS) responsible for obtaining the data, to identify cases where the same astrophysical target is observed but the OBs executed were not related (via for example the "chained" directive).
An example would be LIFU observations of the core of M33. If a user requires 3 OBs, each one with different dither positionsdithering, then the CPS could not ordinarily stack these data, because they do not share the same Central CNAME Name (or CNAME, which is the WEAVE object name from coordinates). In the input FITS catalogue, these observations are represented by 5,427 rows: 603 fibres, dithered 3 times for 3 OBs. Each of these rows must be tied together by a common TARGNAME, e.g. "M33 bulge". This indicates to the CPS that these observations should be evaluated for stacking.
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It is not always true that IFU observations with common TARGNAME will be stacked. Only common TARGNAMEs with sufficient overlap will be stacked by the CPS. However, if Contributed Data Products CPS data products exist to create larger mosaics from these data, then they should use the common TARGNAME to group L1 products.
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Please use this exposure time calculator for your signal-to-noise calculations: https://a.ing.iac.es/signalWEAVE/. There is more information, including a downloadable version, at /wiki/spaces/WEAV/pages/13239474WEAVE Exposure Time Calculator .
Instrument configuration
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IFU_PA_REQUEST allows the catalogue provider to specify a rotation angle (position angle) of the LIFU, if this is required. Any dithering requested for the field is applied to the rotated LIFU frame. If a specific PA value is not 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 the requested IFU_PA could be changed by the IFU workflow software if a suitable guiding star 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 (from the requested PA marked as a blue cross to the final PA marked as a black cross).
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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 |
180º so if requesting PA=300º, then enter -60º. |
The table below shows the allowed values for the PA depending on minimum elevation requested in the OB and the target’s declination. Following are plots showing two cases, for better understanding of the PA ranges in the table.
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For custom dither patterns, constraints on the dither step size are imposed by the WASP to ensure that the guide star remains within the guiding camera field of view. From the perspective of IFU users, careful consideration of the dithering options should be made. Below it's an example of custom dithering. Note that pointings are provided for each dither, rather than the dither pointings from an initial position. The three pointings provided in the example below would be executed as part of one only OB.
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Note that TARGID must be equal to TARGNAME in every row. The maximum allowed distance between (consecutive, for instance, exposure order 4 and 5) dither points is 4 arcsec while the maximum overall dither distance across all dithers can exceed the maximum permitted dither 10 arcsec. Minimum distance is ~0.3 arcsec. Dither point positions cannot be repeated within an OB.
# A custom 3-dither pattern LIFU pointing |
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Aladin overlays of the LIFU footprints
Aladin overlays can be useful for preparing your observations. To use the Aladin overlays below, follow these instructions:
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IFU workflow package: https://ingbitbucket.ing.iac.es/projects/WVSWG/repos/ifu/browse/workflow
Configure software (used by the IFU workflow): https://weave-project.atlassian.net/wiki/spaces/WEAVE/pages/126615564/configure+for+Open+Time+users