Overviews of EPRV Instruments

The standardized EPRV data format allows the flexibility to incorporate instrument-specific content (e.g. single or multiple spectral traces, ancillary images), pipeline specific corrections (e.g. telluric corrections, barycentric corrections), and/or RV measurements (e.g. different CCF masks, line-by-line, or other custom RV calculations) at each data level. In order to capture key differences, each Instrument Team is encouraged to provide a ReadtheDocs file following the template below. These details are not meant to be exhaustive or to supersede individual instrument documentation, but rather to provide end users with a quick introduction to key instrument design and pipeline algorithm decisions.

ESPRESSO

Instrument Details

  • Instrument Name: ESPRESSO

  • Telescope/Observatory: VLT-Paranal

  • Wavelength Range: 380 - 788 nm

  • Resolution: 70,000 - 190,000 (depending on the mode)

  • Fiber vs. slit: Fiber

Documentation & Data Locations

Instrument era (INSTERA keyword) date ranges

INSTERA

UT_start_date

UT_end_date

Comments

ESPRESSO18

Start

June 27, 2019

/

ESPRESSO19

June 28, 2019

Present

Fiber upgrade

Change log

A list of news about the instrument can be found at https://www.eso.org/sci/facilities/paranal/instruments/espresso/news.html

Instrument-Specific Level 2 Header and Extension Details

  • Fundamental Parameters

    • Trace 1: Science fiber, slice #1

    • Trace 2: Science fiber, slice #2

    • Trace 3: Calibration fiber, slice #1

    • Trace 4: Calibration fiber, slice #2

    • Wavelength Solution: Either using ThAr lamp with Fabry-Perot, or Laser Frequency Comb

    • Extraction Type: Optimal extraction

  • Corrections and Models

    • Barycentric Correction: applied to all orders based on the same BERV value

  • Ancillary Data

    • Exposure Meter: Table of exposure meter measurements.

Useful details or tutorials for working with 1-D data

TBD

EXPRES

Instrument Details

  • Instrument Name: EXPRES (Extreme Precision Spectrograph)

  • Telescope/Observatory: Lowell Discovery Telescope, Lowell Observatory

  • Wavelength Range: 390-780 nm

  • Resolution: 137,000

  • Fiber vs. slit: fiber

Documentation & Data Locations

  • Link to instrument manual: N/A

  • Link to data reduction pipeline manual: https://ui.adsabs.harvard.edu/abs/2020AJ….159..187P/abstract

  • Link to data archive:

  • Person/email for translator maintenance & bug reports: Lily Ling Zhao ()

  • Naming convention for all data standard products:

    • L2 :

    • L3 :

    • L4 :

  • Date of last translator update and current version number:

Instrument era (INSTERA keyword) date ranges

INSTERA

UT_start_date

UT_end_date

Comments

1.1.0

April, 15, 2018

May, 5, 2018

1.2.0

May 23, 2018

June 15, 2018

2.1.0

June 16, 2018

June 28, 2018

2.2.0

June 29, 2018

July 15, 2018

3.1.0

July 16, 2018

November 18, 2018

3.2.0

December 18, 2018

December 31, 2018

4.1.0

February 5, 2019

June 4, 20191

4.2.0

June 5, 2019

July 1, 2019

5.1.0

August 10, 2019

October 4, 2019

5.2.0

October 5, 2019

December 18, 2019

5.3.0

December 23, 2019

June 24, 2020

5.4.0

June 25, 2020

August 14, 2020

5.5.0

August 15, 2020

December 14, 2020

5.6.0

December 15, 2020

April 27, 2021

5.7.0

April 28, 2021

March 2, 2022

5.8.0

March 2, 2022

June 30, 2022

5.9.0

June 30, 2022

July 15, 2023

5.10.0

July 15, 2023

July 30, 2024

5.11.0

July 30, 2024

Present

Change log

TBD

Instrument-Specific Level 2 Header and Extension Details

Useful details or tutorials for working with 1-D data

TBD

G-CLEF

Instrument Details

  • Instrument Name: G-CLEF (Giant Magellan Telescope Consortium Large Earth Finder)

  • Telescope/Observatory: Magellan Clay Telescope (2026+) then move to Giant Magellan Telescope (2032+)

  • Wavelength Range (A): 350 - 950 nm

  • Resolution: 108,000 in EPRV mode

  • Fiber vs. slit: multiple fiber traces

Documentation & Data Locations

  • Link to instrument manual: TBD

  • Link to data reduction pipeline manual: TBD

  • Link to data archive: TBD

  • Person/email for translator maintenance & bug reports: Cem Onyuksel (cem.onyuksel@cfa.harvard.edu)

HARPS

Instrument Details

  • Instrument Name: HARPS

  • Telescope/Observatory: 3.6m Telescope-La Silla

  • Wavelength Range: 378 - 691 nm

  • Resolution: 115k

  • Fiber vs. slit: Fiber

Documentation & Data Locations

Instrument era (INSTERA keyword) date ranges

INSTERA

UT_start_date

UT_end_date

Comments

HARPS03

February 2003

June 3, 2015

First light to octagonal fiber upgrade

HARPS15

June 3, 2015

Present

After the octagonal fiber upgrade

Change log

TBD

Instrument-Specific Level 2 Header and Extension Details

  • Fundamental Parameters

    • Trace 1: Science Fiber

    • Trace 2: Calibration Fiber

    • Wavelength Solution:

    • Extraction Type:

  • Corrections and Models

    • Barycentric Correction: Correction applied to all orders based on the same BERV value.

  • Ancillary Data

Useful details or tutorials for working with 1-D data

TBD

HARPS-N

Instrument Details

  • Instrument Name: HARPS-N

  • Telescope/Observatory: Telescopio Nazionale Galileo, Roque de los Muchachos Observatory (La Palma)

  • Wavelength Range: 383 - 690 nm

  • Resolution: 115k

  • Fiber vs. slit: Fiber

Documentation & Data Locations

Instrument era (INSTERA keyword) date ranges

INSTERA

UT_start_date

UT_end_date

Comments

Change log

TBD

Instrument-Specific Level 2 Header and Extension Details

  • Fundamental Parameters

    • Trace 1: Science Fiber

    • Trace 2: Calibration Fiber

    • Wavelength Solution:

    • Extraction Type:

  • Corrections and Models

    • Barycentric Correction: Correction applied to all orders based on the same BERV value

  • Ancillary Data

Useful details or tutorials for working with 1-D data

TBD

HERMES

Instrument Details

  • Instrument Name: HERMES (High Efficiency and Resolution Mercator Echelle Spectrograph)

  • Telescope/Observatory: Mercator Telescope

  • Wavelength Range: 377-900 nm

  • Resolution: 85,000

  • Fiber vs. slit: Fiber

Documentation & Data Locations

Instrument era (INSTERA keyword) date ranges

INSTERA

UT_start_date

UT_end_date

Comments

1.0

2009

July 2018

First generation fiber link

2.0

July 2018

Present

Second generation fiber link

Change log

TBD

Instrument-Specific Level 2 Header and Extension Details

  • Fundamental Parameters

    • Trace 1:

    • Trace 2:

    • Trace 3:

    • Wavelength Solution:

    • Extraction Type:

  • Corrections and Models

    • Barycentric Correction:

  • Ancillary Data

Useful details or tutorials for working with 1-D data

TBD

iLocater

Instrument Details

  • Instrument Name: iLocater

  • Telescope/Observatory: Large Binocular Telescope, Mt. Graham International Observatory

  • Wavelength Range: 0.97-1.31 microns

  • Resolution: 190,000

  • Fiber vs. slit: Fiber

Documentation & Data Locations

KPF

Instrument Details

  • Instrument Name: KPF

  • Telescope/Observatory: Keck

  • Wavelength Range: 445 - 870 nm

  • Resolution: 100k

  • Fiber vs. slit: fiber

Documentation & Data Locations

Instrument era (INSTERA keyword) date ranges

INSTERA

UT_start_date

UT_end_date

Comments

0.5

2000-01-01 0:00:00

2022-11-09 0:00:00

Before First Light (engineering)

1

2022-11-09 0:00:01

2024-02-03 0:00:00

First science era: First Light to Service Mission #1

1.5

2024-02-03 0:00:01

2024-02-11 0:00:00

Service Mission #1 (engineering)

2

2024-02-23 12:00:00

2024-11-01 0:00:00

Second science era: After Service Mission #1

2.5

2024-11-01 12:00:00

2025-01-01 0:00:00

Service Mission #2 (engineering) which extended into on-sky science observations because of quasi-fixed pattern noise

2.6

2025-01-01 12:00:00

2025-03-28 23:00:00

After a full Green-side warmup (CCR pressure issue)

2.7

2025-03-28 23:00:01

2025-04-23 0:22:00

Service Mission #3 (engineering) (Red CCR installed; Green CCR misbehaving; quasi-fixed pattern noise)

3

2025-04-23 0:22:01

3000-01-01 0:00:00

After Service Mission #3 (quasi-fixed pattern noise reduced)

Change log

TBD

Instrument-Specific Level 2 Header and Extension Details

  • Fundamental Parameters

    • Trace 1: Calibration fiber

    • Trace 2: Science slice 1

    • Trace 3: Science slice 2

    • Trace 4: Science slice 3

    • Trace 5: Sky fiber

    • Wavelength Solution: 9th order Legendre polynomial fit to LFC data then interpolated between 2 nearest LFC wavelength solutions

    • Extraction Type: optimal extraction

  • Corrections and Models

  • Ancillary Data

    • Exposure Meter: Table of exposure meter measurements. One column per wavelength bin

    • Ancillary Spectrum: Separate spectrograph covering only the CaHK region. Stored in the CA_HK_SCI_WAVE and CA_HK_SCI_FLUX extensions

Useful details or tutorials for working with 1-D data

TBD

MAROON-X

Instrument Details

  • Instrument Name: MAROON-X

  • Telescope/Observatory: Gemini North

  • Wavelength Range: 500 - 920 nm

  • Resolution: 85,000

  • Fiber vs. slit: Fiber

Documentation & Data Locations

  • Link to instrument manual: N/A

  • Link to data reduction pipeline manual: N/A

  • Link to data archive: https://archive.gemini.edu

  • Person/email for translator maintenance & bug reports: Tanya Das (tanyadas@uchicago.edu)

  • Naming convention for all data standard products:

    • L2 : maroonxblue_SL2_YYYYMMDDTHHMMSS.fits/ maroonxred_SL2_YYYYMMDDTHHMMSS.fits

    • L3 : maroonxblue_SL3_YYYYMMDDTHHMMSS.fits/ maroonxred_SL3_YYYYMMDDTHHMMSS.fits

    • L4 : maroonxblue_SL4_YYYYMMDDTHHMMSS.fits/ maroonxred_SL4_YYYYMMDDTHHMMSS.fits

  • Date of last translator update and current version number: 06-10-2026; v1.0.0

Instrument era (INSTERA keyword) date ranges

INSTERA

UT_start_date

UT_end_date

Comments

1.0.0

September 1, 2020

September 14, 2020

2.0.0

November 27, 2020

November 30, 2020

3.0.0

February 17, 2021

March 3, 2021

4.0.0

April 15, 2021

April 29, 2021

5.0.0

May 20, 2021

June 3, 2021

6.0.0

August 10, 2021

August 22, 2021

7.0.0

October 26, 2021

November 22, 2021

8.0.0

March 23, 2022

April 26, 2022

9.0.0

May 23, 2022

June 1, 2022

10.0.0

July 7, 2022

August 14, 2022

11.0.0

June 20, 2023

July 10, 2023

12.0.0

October 9, 2023

October 27, 2023

13.0.0

November 20, 2023

November 28, 2023

14.0.0

December 4, 2023

January 2, 2024

15.0.1

February 22, 2024

April 23, 2024

15.0.2

May 3, 2024

June 12, 2024

15.0.3

June 18, 2024

September 1, 2024

15.0.4

September 12, 2024

October 13, 2024

15.0.5

November 13, 2024

March 31, 2025

15.1.6

April 3, 2025

September 14, 2025

15.1.7

September 15, 2025

January 7, 2026

15.1.8

January 8, 2026

Present

Change log

TBD

Instrument-Specific Level 2 Header and Extension Details

  • Fundamental Parameters

    • Trace 1: Sky fiber 1 (currently empty)

    • Trace 2: Science fiber 2.

    • Trace 3: Science fiber 3.

    • Trace 4: Science fiber 4.

    • Trace 5: Simultaneous calibration fiber 5 with etalon.

    • Trace 6: Virtual fiber. Created by resampling fiber 2 and 4 onto the wavelength grid of fiber 3, then applying outlier rejection and proper weighting to combine the 3 fibers into a virtual one.

    • Wavelength Solution: Non-parametric

    • Extraction Type: Fibers 2-4 uses flat optimal extraction. Fiber 5 uses box (sum) extraction.

  • Corrections and Models

    • Barycentric Correction: Flux-weighting is based on exposuremeter data and barycentric velocity is calculated using barycorrpy. The correction is not applied but stored in the header for use by SERVAL. BJD_TDB value produced is calculated at flux weighted midpoint.

    • Drift Correction: The drift correction is calculated per extracted pixel using an offset derived from the master calibration frames taken every night.

  • Ancillary Data

    • Exposure Meter: N/A

Useful details or tutorials for working with 1-D data

Specific flat files are required to create MAROON-X standard level2 fits file. Please contact Tanya Das (tanyadas@uchicago.edu) to request for the translator compatible flat files, with the following information: Target name and the date, month and year of the observations.

MARVEL

Instrument Details

  • Instrument Name: MARVEL (Mercator Array for Radial VELocity observations)

  • Telescope/Observatory: 4-telescope MARVEL array at Mercator Observatory

  • Wavelength Range: 380 - 950 nm

  • Resolution: 90,000 or 135,000

  • Fiber vs. slit: fiber (4 input fibers, 1 per telescope)

Documentation & Data Locations

Instrument era (INSTERA keyword) date ranges

INSTERA

UT_start_date

UT_end_date

Comments

Change log

TBD

Instrument-Specific Level 2 Header and Extension Details

  • Fundamental Parameters

    • Trace 1:

    • Trace 2:

    • Trace 3:

    • Wavelength Solution:

    • Extraction Type:

  • Corrections and Models

    • Barycentric Correction:

  • Ancillary Data

Useful details or tutorials for working with 1-D data

TBD

NEID

Instrument Details

  • Instrument Name: NEID

  • Telescope/Observatory: WIYN 3.5 m Telescope/Kitt Peak National Observatory

  • Wavelength Range: 380-930 nm

  • Resolution: R~110,000 (High Resolution Mode); R~70,000 (High Efficiency Mode)

  • Fiber vs. slit: fiber-fed

Documentation & Data Locations

  • Link to instrument manual:

  • Link to data reduction pipeline manual: https://neid.ipac.caltech.edu/docs/NEID-DRP/

  • Link to data archive: https://neid.ipac.caltech.edu

  • Person/email for translator maintenance & bug reports: Chad Bender (cbender@arizona.edu)

  • Naming convention for all data standard products:

    • L2 : neid_SL2_YYYYMMDDThhmmss.fits

    • L3 : neid_SL3_YYYYMMDDThhmmss.fits

    • L4 : neid_SL4_YYYYMMDDThhmmss.fits

  • Date of last translator update and current version number: 2026-05-14, v0.3.2

Instrument era (INSTERA keyword) date ranges

INSTERA

Start Date

End Date

Comments

1.0

November 6, 2019

November 30, 2019

Commissioning Run 1

2.0

November 30, 2019

February 27, 2020

Commissioning Run 2

3.0

February 27, 2020

March 31, 2020

Commissioning Run 3

4.0

October 26, 2020

June 16, 2022

Science Run 1 (Until Contreras Fire interruption)

5.0

October 18, 2022

August 19, 2024

Science Run 2 (Post-Contreras Fire restart)

6.0

August 24, 2024

December 8, 2025

Science Run 3 (due to significant upgrade in LFC hardware)

7.0

December 9, 2025

Present

Science Run 4 (due to thermal instability event in December 2025)

Note: these are not in the default NEID data product headers, but are added in the translator

Change log

  • 2026/06/24: NEID translator is ready for first release, and has all functionality for compliance with the standard.

Instrument-Specific Level 2 Header and Extension Details

  • Fundamental Parameters

    • Trace 1: Science fiber (HR and HE modes)

    • Trace 2: Sky fiber (HR and HE modes)

    • Trace 3: Calibration fiber (only for HR mode)

    • Wavelength Solution: polynomial

    • Extraction Type: Flat relative extraction is used (optimal for continuum sources)

  • Corrections and Models

    • Barycentric Correction: Barycorrpy is used to calculate a per-order barycentric correction at the per-order flux weighted midpoint as measured by the chromatic exposure meter. The relevant extensions include array data of length 122, with a value for each echelle order.

    • Drift Correction: The provided drift extension is a single value in km/s that represents the drift relative to the calibration session at the start of the observing window (evening calibrations for nighttime, morning calibrations for solar).

    • Telluric Model: a line and continuum absorption telluric model. The model is only applicable for zero-indexed orders 55 through 110. The rest of the orders have the model values set to 1. The model includes water and molecular oxygen.

  • Ancillary Data

    • Exposure Meter: This extension includes processed chromatic exposure meter data in table format. Rows are temporal sampling and columns are wavelength sampling. The first column are the timestamps for each exposure meter frame. The rest of the columns are labeled with the wavelength corresponding to that spectral bin.

Useful details or tutorials for working with 1-D data

See the NEID Tutorial that provides a guide to working with standardized NEID data at all levels, including appliying telluric corrections and inspecting radial velocities by order.

NIRPS

Instrument Details

  • Instrument Name: NIRPS

  • Telescope/Observatory: La Silla 3.6m

  • Wavelength Range: 0.95 to 1.8 microns

  • Resolution: HE: 90000, HA: 100000

  • Fiber vs. slit: Fiber

Documentation & Data Locations

Instrument era (INSTERA keyword) date ranges

INSTERA

UT_start_date

UT_end_date

Comments

Change log

TBD

Instrument-Specific Level 2 Header and Extension Details

  • Fundamental Parameters

    • Trace 1:

    • Trace 2:

    • Trace 3:

    • Wavelength Solution:

    • Extraction Type:

  • Corrections and Models

    • Barycentric Correction:

  • Ancillary Data

Useful details or tutorials for working with 1-D data

TBD

SPIRou

Instrument Details

  • Instrument Name: SPIRou

  • Telescope/Observatory: CFHT

  • Wavelength Range: 0.9245 to 2.4 microns

  • Resolution: 80,000

  • Fiber vs. slit: Fiber

Documentation & Data Locations

Instrument era (INSTERA keyword) date ranges

INSTERA

UT_start_date

UT_end_date

Comments

Change log

TBD

Instrument-Specific Level 2 Header and Extension Details

  • Fundamental Parameters

    • Trace 1:

    • Trace 2:

    • Trace 3:

    • Wavelength Solution:

    • Extraction Type:

  • Corrections and Models

    • Barycentric Correction:

  • Ancillary Data

Useful details or tutorials for working with 1-D data

TBD