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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
The WEAVE Automated Submission Platform (WASP) automatically emails the principal investigators (PIs) with submission deadlines, validation acknowledgements and any other important information concerning the preparation of phase 2. The first two emails contain the following (the subject line is provided):
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emails contains the credentials to log onto WASP. Subject line is:
Subject: [WEAVE] Account created for WEAVE observation preparation
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General assistance can be provided at the following emailemailing:
weave_open_time_support@ing.iac.es |
Phase 2: the
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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.
The kick off of phase 2 is a simple catalog of targets in CSV format prepared by the PI following the instructions provided on this page. ING can provide assistance with the preparation of the aforementioned catalog, and afterwards ING can also process it to make the FITS catalog and the XML OBs, and eventually upload to and validate on WASP on behalf of the PI.
An XML OB contains the instructions to execute the observations: instrument setup, telescope pointing, guiding star, dithering, exposure times, observing constraints and calibrations (one lamp flat and two arcs, before and after the science exposures). The following is an example of the XML code of an OB with comments for users: WC_2023A1-lifu_01-tgcs.xml.
Every observed OB is reduced and calibrated using automatic pipelines at CASU (IoA, Cambridge). Data is flux calibrated using a standard sens functions. However, applicant scan submit their own OBs for observing flux standards along with the science OBs. Every trimester we accept a maximum of 100 OBs per programme.
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:
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TARGID,TARGNAME,GAIA_RA,GAIA_DEC,PROGTEMP,OBSTEMP,IFU_DITHER
NGC3158,NGC3158,153.460497,38.764898,41331,NBCEB,3
Validated FITS catalog on WASP: WS2022A2-002.fits
Validated XML OB on WASP and ready for ingestion into the observing queue: 1713807920_1.xml
Log entry as a result fo the execution of the above OB. Note that the target coordinates correspond to the center of the field of view, not the centre of the LIFU array.
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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.
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short guide
LIFU mode: catalogue preparation
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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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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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 WEAVE Exposure Time Calculator .
Instrument configuration
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It defines how the time within the OB that you wish to observe the target is divided up, by specifying the number of exposures and exposure time within the stipulated OB length. The listed options of exposure time splits correspond to science open-shutter times (note that every exposure incur a 3-minute overhead).
IMPORTANT: It is not recommended unlocking the arms. Note that different exposure splits (unlocking the arms) in the red and the blue arms will have two consequences: firstly, no dithering will be possible, and secondly, OB length will increase as the observing system cannot execute different exposure splits simultaneously but one only exposure in both arms at a time. For example, requesting one exposure in red, and 12 in blue would cause a significant mismatch in overheads between the two arms. |
Binning in the spectral direction
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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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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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PA range (°) | ||||||||||||||||||||||||
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Dec (°) | h_min=50. | 28 28º(X=1.3) | h_min=45. | 58 58º(X=1.4) | h_min=41. | 81 81º(X=1.5) | h_min=38. | 68 68º(X=1.6) | h_min=33. | 75 75º(X=1.8) | h_min=25. | 00 00º(X=2. | 4) Dec (°) | PA range (°) | PA range (°) | PA range (°) | PA range (°) | PA range (°) | PA range (°)4) | |||||
-25 | 225<PA<135 | 245<PA<115 | ||||||||||||||||||||||
-10 | 220<PA<140 | 235<PA<125 | 245<PA<115 | 245<PA<115 | 250<PA<110 | 260<PA<100 | ||||||||||||||||||
0 | 250<PA<110 | 255<PA<105 | 255<PA<105 | 260<PA<100 | 260<PA<100 | 270<PA<90 | ||||||||||||||||||
+15 | 270<PA<90 | 270<PA<90 | 270<PA<90 | 270<PA<90 | 275<PA<85 | 275<PA<85 | ||||||||||||||||||
+28.70 | 295<PA<65 | 295<PA<65 | 295<PA<65 | 295<PA<65 | 295<PA<65 | 295<PA<65 | ||||||||||||||||||
+30 | 130<PA<230 | 130<PA<230 | 130<PA<230 | 130<PA<230 | 135<PA<225 | 135<PA<225 | ||||||||||||||||||
+40 | 115<PA<245 | 120<PA<240 | 120<PA<240 | 120<PA<240 | 130<PA<230 | 135<PA<225 | ||||||||||||||||||
+50 | 105<PA<255 | 100<PA<260 | 115<PA<245 | 120<PA<240 | 120<PA<240 | 135<PA<225 | ||||||||||||||||||
+60 | 80<PA<280 | 95<PA<265 | 105<PA<255 | 110<PA<250 | 120<PA<240 | 130<PA<230 | ||||||||||||||||||
+70 | 65<PA<295 | 85<PA<275 | 95<PA<265 | 110<PA<250 | 120<PA<240 | |||||||||||||||||||
+80 | 35<PA<325 | 90<PA<270 | 140<PA<220 | |||||||||||||||||||||
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.
IMPORTANT: Exposure options for which fixed dither patterns are available in IFU modes are 3x, 4x |
, 5x, 6x. In other words, the number of exposures in an OB must be the same as the number of points in the dither pattern. |
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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 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. 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 |
Summary of table columns and examples
Column | Description | Format | Length | Value(s) | Units | Example |
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TARGPRO | Optional description of programme | ASCII | ≤40 | WS2023B2-010_001 | ||
TARGNAME | The target name | ASCII | ≤30 | M33 | ||
TARGID | The identifier of the target assigned for this programme | ASCII | ≤30 | M33_NE | ||
PROGTEMP | Observing Programme Template | ASCII | 8 (fixed) |
41331.3+ | |||
OBSTEMP | Observing Constraints Template | ASCII | 5 (fixed) |
FAACA | ||||||
GAIA_ID | GAIA Source Identifier | ASCII | 19 | 1463976195968535680 | ||
GAIA_DR | GAIA Data Release version | I1 | 2, 3 | 3 | ||
GAIA_RA | Gaia RA of target | F11.7 | 0...360 | degrees | 178.221875 | |
GAIA_DEC | Gaia Dec of target | F11.7 | -90...90 | degrees | 44.123919 | |
GAIA_EPOCH | Gaia Epoch of target | F6.1 | 2015.5 (DR2), 2016.0 (DR3) | Julian year | 2016.0 | |
GAIA_PMRA | Gaia Proper Motion of target in RA | F11.3 | mas/yr | 12.1 | ||
GAIA_PMDEC | Gaia Proper Motion of target in Dec | F11.3 | mas/yr | 0.01 | ||
GAIA_PARAL | Gaia Parallax of target | F10.3 | mas | 0.002 | ||
IFU_PA_REQUEST | Position Angle of IFU bundle | F11.7 | -180...180 | degrees | 106.701 | |
IFU_DITHER | IFU dither pattern code | I2 | -3, -1, 0, 3, 4, 5, 6 | 3 |
Aladin overlays of the LIFU footprints
Aladin overlays can be useful for preparing your observations. To use the Aladin overlays below, follow these instructions:
Download the vot files linked below.
Open Aladin and enter an object name in the command field, ex. 'M51'.
File → Load instrument FoV.
In the emerging window, click on 'File' and browse for a suitable vot file.
Click to submit. The vot file will load as a layer with a given colour.
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
The edited catalogue must go through the IFU workflow, a set of scripts which will make a version of the FITS catalogue suitable for uploading to WASP (http://wasp.ast.cam.ac.uk/catsubmit/upload) for validation. First log on using the provided credentials (the ones emailed from WASP), note that you need to register your IP at http://wasp.ast.cam.ac.uk/ipsubmit/upload first. See below the tab used for uploading the catalogue.
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At ING, we can provide assistance in guiding you through the different stages of the IFU workflow package, or we can even process your catalogue provided in any of the formats described above, on your behalf. In this latter case, simply email your catalogue to the contact below:
weave_open_time_support@ing.iac.es |
LIFU mode: OB preparation
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At ING, we can provide assistance in generating the OBs from the CNAMEd catalogue, please contact:
weave_open_time_support@ing.iac.es |
OB upload to WASP
The processed OBs can be then uploaded, as a tar file if many, to http://wasp.ast.cam.ac.uk/xmlsubmit/upload (see below). Remember to log on first.
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In the figure below we show an example of 6 OBs uploaded whose validation failed (the generated report will tell you why). The "Submission Management" button gives access you to all the catalogue and OB uploads made by the user. Note that if you have requested OB repetitions (for instance, PROGTEMP=41331.5, or 5 OB copies), then only one OB is validated on WASP (not 5 OBs following the example). The OB copies are actually made at the time they are ingested into the observing queue according to the information encoded in PROGTEMP.
IMPORTANT: Don't forget to select the right OBs in the submission maganement! Otherwise, they won't be queued. |
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Observations and follow up
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