Contents

General Information

The proposal submission was closed on 14 October 2022.

An integral part of the commissioning of a new instrument at the VLT is the Science Verification phase. SV programmes include a set of typical scientific observations that should verify and demonstrate to the community the capabilities of the new instrument in the operational framework of the VLT Observatory. In accordance with its SV Policy and Procedures  ESO encourages the community to submit also highly challenging or risky science observations that will push ERIS to its limits in order to better understand the instrument and mode performance parameter spaces and their envelopes.  

The Enhanced Resolution Imager and Spectrograph (ERIS) is a 1-5 μm instrument for the Cassegrain focus of UT4 at the VLT. It combines an imager (NIX) and an integral-field spectrograph (SPIFFIER).  

ERIS is now offered to the community for Science Verification (SV) for 4 nights in December 2022. All astronomers are invited to participate in this opportunity to obtain unique science with ERIS and thus to demonstrate its scientific capabilities. The community is invited to submit proposals for the ERIS science verification using the Phase 1 web interface. The proposal cycle "ERIS SV" should be used for the proposal submission. Only modes offered in P111 will be accepted for SV observations (see the ERIS User Manual for modes offered in P111). Proposals must not request protected ERIS GTO targets. Please follow the dual-anonymous guidelines applicable since P108.

The deadline for proposal submission was 14 October 2022, 12:00 CEST.

Proposals have been reviewed by an internal panel and allocated time on the basis of scientific merit and feasibility, as well as the demonstrated ability of the Principle Investigators to deliver results on a timely basis. The titles of the selected proposals are listed below.

The observations will be conducted in Service Mode by a dedicated team of ESO astronomers. The ERIS SV team will be able to assist the successful PI’s in the preparation and optimisation of the OBs. The ERIS Exposure Time Calculator has been updated, but may still change as the commissioning is still ongoing.

Proposers are reminded that all SV data are made public worldwide immediately after passing the usual quality control checks.

Short description of ERIS

The Enhanced Resolution Imager and Spectrograph (ERIS) is a near-infrared instrument at the Cassegrain focus of UT4. ERIS has two science arms, SPIFFIER and NIX. SPIFFIER (IFS) is a medium-resolution integral field spectrograph covering J to K band. NIX is capable of imaging between J and M band. ERIS is designed to be used in conjunction with UT4's deformable secondary mirror. The atmospheric turbulence can be sensed with either a natural guide star, or a single artificial star generated with the Adaptive Optics Facility (AOF). ERIS replaces many of the functionalities provided by both NaCo and SINFONI within a single instrument.

ERIS consists of three main instrumental modules:

• The adaptive optics (AO) module, which uses the AOF Deformable Secondary Mirror (DSM), and one AOF laser, providing natural guide star (NGS) and laser guide star (LGS) visible wavefront sensing with real-time computing capabilities. The AO module allows for single-conjugate adaptive optics (SCAO) operations. Both infrared science instruments, the imager (NIX) and integral-field spectrograph (SPIFFIER), are fed by a dichroic beamsplitter which reflects the visible light to the AO module. The AO module is capable of correcting using guide stars between 1^st-11^th Gaia RP magnitude (NGS) and 7^th-17^th Gaia RP magnitude (LGS). AO guide stars must have Gaia BP < 19^th magnitude. Observations without the AO module are also supported in some observing modes.
  
• The NIX imager, which is designed to provide diffraction limited imaging and low-resolution (R~900) L-band long-slit spectroscopy. The imager has two pixel scales, 13 mas/px and 27 mas/px, providing a field of view of ~26”x26” and 55”x55”, respectively. Currently, only the imaging and pupil plane coronagraphy observing modes are offered.
  
• The SPIFFIER integral-field spectrograph (IFS), which is a refurbished version of SPIFFI, the 1-2.5 μm integral field unit formerly on-board SINFONI. This module offers diffraction limited integral field spectroscopy over a user-selectable 0.8” to 8.0” arcsecond field of view, with spatial sampling between 25 and 250 mas/spaxel. There are nine grating configurations; three low-resolution gratings (R~5,000) that span each of the JHK bands and one high-resolution grating (R~10,000).

For a complete list of the available observing modes, capabilities and limitations of the instrument consult the ERIS web page and the user manual.

Phase 2 preparation

The PIs (or their Phase 2 delegates) of accepted proposals must prepare and submit the Phase 2 material using P2. We foresee a deadline of

25 November 2022, 12:00 Central European Time (CET)

to ensure that all observing material can be verified and is ready for the observations during the SV run.

The service mode guidelines for preparing the SV observations are the same as those for regular ERIS observations, available at
https://www.eso.org/sci/observing/phase2/SMGuidelines.html.

Approved programmes

A total of 23 proposals have been allocated SV time. The observations were performed in Service Mode by a dedicated team and the collected data are available to the whole user community through the ESO Archive. See VLT SV Policy and Procedures for more details.

ERIS Data Products available

Data of all ERIS/NIX and ERIS/SPIFFIER Science Verification proposals listed as 'Completed' or 'Partially' completed' have been processed and are available through the ESO archive as Internal Data Products. These advanced data products can be retrieved using these links:
https://archive.eso.org/scienceportal/home?data_collection=ERIS-NIX
and
https://archive.eso.org/scienceportal/home?data_collection=ERIS-SPIFFIER.

The NIX data products include the combined/stacked image (IMG_OBS_COMBINED) and the source extraction catalogue (IMG_OBS_CATALOGUE). The fully prociessed individual science exposures (CAL_PHOT_OBJECT_JITTER) are also available.
For SPIFFIER the following data products are available: re-constructed 3D combined cube (OBJECT_CUBE_COADD_FLUXCAL), processed individual 3D cubes (OBJECT_CUBE), white light image (OBJECT_CUBE_COADD_FLUXCAL_MEAN), sky exposure cubes (SKY_CUBE), and exposure map (EXPOSURE_MAP).

A more detailed description of the data products available can be found in:
https://www.eso.org/rm/api/v1/public/releaseDescriptions/216. (ERIS/NIX)
https://www.eso.org/rm/api/v1/public/releaseDescriptions/217. (ERIS/SPIFFIER)

ERIS pipeline information

The latest versions of the ERIS data reduction pipelines are available for installation for the reduction of your science verification data.  It is important to note that these pipelines are still being developed, do not yet have their full complement of features, have not yet been verified to be fully “science ready”, and may still contain bugs. Therefore, in the spirit of science verification, this pipeline distribution is on a shared risk basis. The pipeline versions are delivered without user manuals or any guarantee of scientific veracity.

Both pipelines have been tested on the ERIS commissioning data and produce advanced science level products. For each science exposure, the ERIS/NIX pipeline removes the instrumental signature from the data (dark-correction, flat-fielding, and linearity correction) and when possible corrects the astrometric plate solution using field GAIA stars and a photometric solution based on field 2MASS stars. Multiple exposures of the same field are combined into a final image stack and a source detection catalogue is created.
For each science exposure, the ERIS/SPIFFIER pipeline removes the instrumental signature from the data (dark-correction, and flat-fielding), calibrates a wavelength solution from
associated arc lamps, applies a field distortion mapping, computes a simple sky subtraction, and generates a resampled 3d data cube and a simple source spectral extraction.   
Both pipelines exist within a Reflex workflow having interactive actors to display intermediate processing results and allow the user to modify pipeline parameters.

Pipeline

For installing the ERIS pipelines please follow the instructions on the pipeline release page.  

Useful links

• ERIS instrument pages
• VLT Science Verification pages
• http://www.eso.org/sci/software/pipelines/