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The instructions below are mainly aimed at PIs who will request assistance to:
weave_open_time_support@ing.iac.es |
Communication with the PI
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General assistance can be provided at the following email:
weave_open_time_support@ing.iac.es |
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Phase 2: the simple guide
The purpose of the phase 2 is the upload of a FITS catalog containing fiber positions on sky, and observing blocks (OB) written in XML describing the necessary observations to the submission platform WASP, maintained by CASU in Cambrige (IoA). At the beginning of every trimester, the uploaded, validated and selected OBs are ingested into the observing queue at the WHT.
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Below we provide an example of real observations made from a simple OB which consists of 3 exposures 1020s each following a 3-point dithering pattern in LIFU low-resolution mode and arbitrary position angle:
CSV catalog:
TARGID,TARGNAME,GAIA_RA,GAIA_DEC,PROGTEMP,OBSTEMP,IFU_DITHER |
Validated FITS catalog on WASP: WS2022A2-002.fits
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Only the preparation of the CSV catalog is the applicant's responsibility , and while ING can prepare the rest is ING's , unless the PI 's team is familiar with the use of the IFU workflow package.
Regarding any other calibrations:
ING takes biases every night and twilight sky flats regularly. If you need these sets of calibrations when working with your data, please contact ING.
A flux calibration is provided in L1 products. However, if the PI plans to flux calibrate the data him or herself, then we expect the submission of OBs for observing flux standards. Note that we can’t repeat OBs if formerly observed, so if there are 6 targets, for example, then we expect 6 OBs for flux standards submitted.
LIFU mode: catalogue preparation
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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 trimester. See below the allowed RAs for each trimester.
Trimester A1 |
2h (30º) → 20h (300º) Expanded range: |
Trimester A2 |
9h (135º) → 2h (30º) Expanded range: |
Trimester B1 |
|---|
15h (225º) → 9h (135º) Expanded RA range: |
Trimester B2 |
20h (300º) → 16h (240º) Expanded RA range: |
Total requested time
The total length (counted as science exposure time) of all the submitted OBs can't exceed the science time allocation of your proposal (see the time allocations).
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3. Filling in a simplified CSV version of the catalogue template. Below it's an example of this simplified template and 4 catalogue rows that each describe an OB definition:
<filename: WS2023B2-001_target_list.csv> TARGID,TARGNAME,GAIA_RA,GAIA_DEC,PROGTEMP,OBSTEMP,IFU_DITHER |
Filling out the catalogue template with targets
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An example would be LIFU observations of the core of M33. If a user requires 3 OBs, each with different dither positions, then the CPS could not ordinarily stack these data, because they do not share the same Central CNAME (CNAME 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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Above: Three LIFU dither positions centred on a putative target. This information must be encoded in the input FITS catalogue, but grouped by common TARGNAME.
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 exist to create larger mosaics from these data, then they should use the common TARGNAME to group L1 products.
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Above: Example LIFU coverage of an extended source. Each colour here represents an OB. Within each pointing there would be a series of dithers (as per previous Figure). Whilst these pointings might share the same TARGNAME ("M33"), the CPS would recognise these as a mosaic and not stack them into a single LIFU data cube.
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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.
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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 360º. |
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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.
# A custom 3-dither pattern LIFU pointing |
Summary of table columns and examples
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Description and VOT file | LIFU FoV and sky bundles | LIFU FoV |
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Photo of a real view of the LIFU unit using fibre back illumination. |  |  |
No dithering (as seen in Aladin) Download VOT file: |   | |
3-pointing dithering (as seen in Aladin) Download VOT file: |   | |
6-pointing dithering (as seen in Aladin) Download VOT file: |   |   |
Catalogue upload to WASP
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