WEAVE Open-Time Phase 2: The Short Guide

The purpose of the phase 2 of the WEAVE Open Time programme is the preparation of a FITS catalogue containing fibre positions on sky, and observing blocks (OB) written in XML describing the necessary observations. The FITS catalogue and the XML OBs are uploaded and validated on 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. Below you will find a short phase-2 guide. We also provide a more extensive phase-2 guide.

Phase 2 in a few steps

WEAVE Open Time submissions follow this calendar. At the beginning of phase 2, the PI will receive a couple of emails with the credentials to log on WASP, and some other instructions. Then you will receive some emails about the building of a catalogue template on WASP. For LIFU observations, you can skip this step (a standard catalogue template is automatically generated on WASP for your programme when the deadline is passed).

Next it is the preparation of the FITS catalogue and the XML OBs. This process is very simple: we expect that the PI emails a CSV catalog containing some basic information to:

along with the WASP credentials, so ING can proceed with the preparation, upload and validation of the FITS catalogue and the XML OBs on behalf of the PI. Every trimester we can accept up to 100 OBs  per programme.

Note that we recommend that all the OBs are submitted in the first trimester window of the observing period. In certain cases, however, the PIs may prefer submitting some of the OBs in the second trimester window, or in any subsequent windows, in the case of Band A proposals.

Instructions on how to prepare the CSV catalog

Below we provide an example of a CSV catalogue. It describes a simple OB which consists of 3 exposures of 1020s each, following a 3-point dithering pattern in LIFU low-resolution mode and arbitrary position angle: 

CSV catalog:

TARGID, TARGNAME: these are identifiers of your observations. TARGNAME is used to stack exposures, read more on TARGID, TARGNAME.

GAIA_RA,GAIA_DEC: RA and DEC of your target. Please note that certain restrictions apply.

PROGTEMP, OBSTEMP: use the OBSTEMP and the PROGTEMP builders. For custom dithering and/or exposure times, please contact:

IFU_DITHER: it is set to 0 if not specified (no dithering). Standard dithering patterns for 3, 4, 5 and 6 points are available for selection (read more information on IFU_DITHER).

POSITION ANGLE: the position angle (PA, as measured from North to East) is automatically set to 180º, for declinations North to 28.7º, and to 0º, for declinations South to 28.7º. Note that these PAs could be slightly different to allow for finding a suitable acquisition and guiding star. If you request a specific PA, please read the information on requested PA. Please note that not all values of PA are possible given the rotator limits, and similarly to the above, it could also change automatically for finding a suitable acquisition and guiding star.

CALIBRATIONS:

Lamp flats and arcs are automatically added to every OB. Regarding other calibrations:

1. 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.

2. A flux calibration is provided in L1 products. However, if the PI plans to flux calibrate the data, then we expect the submission of OBs for observing any flux standards. Note that we can’t repeat OBs that have been observed previously so provide enough OBs (for instance, if you have 6 targets, then we expect 6 OBs for flux standards submitted).

Please contact for more information on the above extra calibrations:

The FITS catalogue and the XML OBs

Just for your information, and following the example above, we provide here the FITS catalogue generated by ING using the IFU workflow software package and validated on WASP:

Validated FITS catalog on WASP:  WS2022A2-002.fits

The XML OB file contains the instructions on how 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. Next is the XML OB generated for the example above, and validated on WASP:

Validated XML OB on WASP and ready for ingestion into the observing queue: 1713807920_1.xml

The XML OBs are ingested into the observing queue of the WHT at the beginning of the observing period. Below it is the log entries of the execution of the example OB. Note that the target coordinates correspond to the center of the field of view, not the centre of the LIFU array.

Open

Phase 3: data reduction and calibration

Every observed OB is automatically reduced and calibrated using the automatic pipelines at CASU (IoA, Cambridge). The data is made available in a few days after the observations on the WEAVE operational repository platform.