New Instrument for WIYN: NEID



Detailed Description 

Spectrograph Characteristics

System Characteristics

Data Products

Queue Policies

How To Propose

What To Propose


Target List

GTO (Guaranteed Time Observer) Programs


The NN-EXPLORE Program is seeking proposals to use NEID, a new cutting edge high-precision spectrograph at WIYN designed for radial velocity measurements of exoplanet host stars. NEID is designed with a goal of achieving 27 cm/s precision per data point, providing the exoplanet community with high-precision radial velocity measurements appropriate for studying Earth and super-Earth mass planets orbiting bright host stars over a wide range of spectral types. NEID will help fulfill needs foreseen at the time of the 2010 Decadal Survey and be a timely resource to support follow-up observations in the era of NASA’s TESS Mission.  The NOIRLab will operate NEID in a queue-scheduled mode and NExScI will employ pipeline data reduction on all observations to provide PIs with high-level data products, including high-precision radial velocities.

Detailed Description

The NN-explore Exoplanet Investigations with Doppler spectroscopy, or NEID (NUH-eed or NOO-id, rhymes with “fluid”), gets its name from the Tohono O’odham word meaning “to see”, is funded by the joint NASA/NSF Exoplanet Exploration Program (or NN-EXPLORE), and is currently being commissioned at WIYN.

Programs using NEID will be scheduled in queue mode with WIYN staff executing the observations. The NASA Exoplanet Science Institute (NExScI) runs the data reduction pipeline and provides high-level data products including extremely precise barycentric-corrected radial velocities via the NEID data archive. We anticipate up to 30 nights of NEID time to be scheduled in 2021B. The port adaptor (built at the University of Wisconsin, Washburn Labs) is mounted on the Bent Cassegrain port at WIYN. It is used to acquire and guide on a target star, precisely maintaining the stellar centroid on a science fiber in the focal plane. Other nearby fibers gather simultaneous light from the sky. Calibration light can also be sent to NEID via the port adaptor. The fibers feed light to NEID, situated in a new spectrograph room built by WIYN on the ground floor of the observatory. The room ensures a stable environment for the spectrograph. The NEID spectrograph is built by Penn State University (Suvrath Mahadevan, PI). It is sealed in a vacuum chamber to maintain the optics at a stable temperature (variations <1 mK) and isolated from outside disturbances over the 5-year program baseline.

Spectrograph characteristics

  • Echelle design with prism cross-disperser
  • Continuous broadband wavelength coverage (380-930 nm)
  • 9K x 9K e2v CCD with 10 micron pixels
  • Choice of two science fibers for two resolution modes: One is the high-resolution (HR) mode (R>90,000) for bright targets (V<12). The other, a high-efficiency (HE) mode (R~60,000), is designed for fainter stars or poor observing.
  • Spectrograph throughput is >40% at 500 nm for a mean system throughput of 5.6% over the full bandpass in HR mode.
  • Chromatic exposure meter gathers a time series of low-resolution spectra in parallel to each science spectrum, enabling barycentric corrections to <1 cm/s.
  • Ultra-precise wavelength calibration via multiple sources, including a laser frequency comb
  • Additional simultaneous calibration via the laser frequency comb can be requested (a Fabry-Perot etalon will be used as a backup if the LFC is not available on a given night, but cannot be requested).

System characterics

  • Baseline requirement for single point, long-term radial velocity precision is 50 cm/s
  • Higher-level requirement for the same is 27 cm/s
  • Limiting magnitudes: 3.5 < V < 16
  • Zenith distance range: 3 degrees < ZD < 70 degrees
  • Fiber size on sky is 0.9” for HR and 1.5” for HE mode.
  • Queue designed for radial velocity work on exoplanet host stars with the means to schedule observations relative to periodic ephemerides
  • Queue designed for science-based prioritization as specified by the TAC or a program’s PI. PIs will operate dynamic observing programs with the ability to alter observation requests (e.g., exposure lengths, timing of observations) and targets during the semester.
  • Nighttime calibration data acquired for reduction of data from all programs if needed (charged to the program); standard sets of daytime calibrations taken just before and after the observing night (not charged to the program).
  • Operational over a wide range of seeing and transparency conditions with appropriate choice of target and spectral resolution.
  • Pipeline data reduction, dissemination.

Data Products

All data taken with NEID will be processed through the NEID data reduction pipeline run daily at NExScI. The following data products will be available via the NEID archive at NExScI:

  • Raw 2D echellogram
  • Representative guider camera image
  • Representative coherent fiber bundle flux data stream
  • Extracted, 1D wavelength calibrated spectra and uncertainties for the science, sky, and calibration fiber
  • Representative telluric absorption model
  • Representative sky emission model
  • Cross-correlation functions by order and barycentric corrected RVs
  • Parameterized activity indicators

The metadata (source, observation time, exposure time, release date) for all observations will be available as soon as the data are ingested in the NEID archive. The data products will be available after a proprietary period, the GO proprietary period is 18 months.

NEID obtains a standard calibration sequence every night and morning, which includes bias, flats and wavelength calibrators. Spectrophotometric and telluric standards will not be taken as standard products; proposers should request these (and account for them in their time request) if they are desired.

NEID also observes a small set of RV standard stars every night, and the raw and reduced data products will be available to the community with zero proprietary period. From the following standard star list, 1-3 will be observed every night NEID operates.

Standard star list:
HD 4628
HD 3651
HD 9407
HD 10700 (τ Ceti)
HD 89269
HD 127334
GJ 699 (Barnard’s Star)
HD 185144 (σ Draconis)
HD 221354

Queue Policies

  • The NEID queue will be shared by multiple partners. Time at WIYN used by the NN-EXPLORE Program will be divided into a guaranteed time observer (GTO) program for the Penn State instrument team (15 nights in 2021B) and guest observer (GO) programs from the community submitted through this call. The WIYN university partners may also devote some of their timeshare to the queue for the equivalent amount of queue allocation.
  • No target stars are considered to be restricted; that is, no targets will be rejected programmatically because they are planned to be observed by another team. The NN-EXPLORE TAC, however, has the discretion to consider duplication of science in its proposal ranking.
  • GO targets must be approved, either by the TAC at proposal review time or the WIYN NEID team, if submitted later.
  • Basic target information (e.g., PI, target ID and position) are made public for all programs using the queue, once the program is accepted.
  • Basic observation information (e.g., target ID, instrument mode and SNR) is published for all programs using the queue within ~1 day of the observation. All target IDs will be informative (no target codenames will be allowed).
  • NEID data taken as part of GO programs can be assigned up to an 18-month proprietary period.

NN-EXPLORE time is awarded to a successful proposal in hours in one or more “priority” levels. There are 5 priority levels, each consisting of a certain percentage of the total NN-EXPLORE time for the semester: Priority 0 (8%), Priority 1 (17%), Priority 2 (25%), Priority 3 (25%) and Priority 4 (50%). More information on selecting priorities can be found here:


How to Propose

NEID observations can address a variety of problems. The high radial-velocity precision planned for NEID is its most unique aspect, but NEID proposals are reviewed with the same guidance as NN-EXPLORE proposals to use other instruments at WIYN.

Because of queue scheduling, proposers should consider that observations are taken under a wide variety of conditions and consider the option of proposing projects that can take advantage of relatively poor seeing, transparency or sky brightness. It is likely that competition for observing time will be lessened under such conditions and projects planned with this in mind could be among the most successful. The high efficiency (HE) spectral resolution mode may be useful for certain programs expecting to acquire data under suboptimal conditions.  Upon receiving proposals for the NEID queue, NOIRLab staff will inspect the proposals for technical feasibility.  This information will be passed to the TAC so that the telescope time can be allocated efficiently.

During Phase 2 and 3, proposers will specify the limiting, poorest conditions under which their observations can be taken and will be able to specify relaxed constraints for observations that can take advantage of poor conditions.

For instance:

  • Rossiter-McLaughlin measurements that must be made on a particular night might have relaxed observational constraints for seeing and guiding performance because otherwise they may not be executed at all.
  • Observations that do not require the full precision of NEID and are granted priority 3 or 4 time might be entered with relaxed observational constraints to improve their completion fraction.
  • Observations that push the limits of NEID’s RV precision or require good spectrophotometry but are not time sensitive could specify only the best observing conditions to maximize the scientific return.

Additional information

Supplemental information on NEID can be found within the slides from the January 2019 AAS splinter session at

Additional questions can be emailed to

What to Propose

Proposals for NEID queue time are done in 3 phases. The first of these, Phase 1, includes the ordinary NOIRLab proposal process completed by all proposers (due by the proposal deadline in this Call). The second, Phase 2, will be required for all successful proposals and its purpose is to fill in target and observation details to complete the needed information to schedule observations before the semester starts (due in July 2021 for 2021B programs). Phase 3 of an observing program describes changes or requests for new targets made during the observing semester.

Instructions for Phase 1 are given here. Instructions for completing the next phases of the proposal process will be provided in the future.

Proposers to use NEID should fill out the standard NOIRLab proposal forms for 2021B. This is one part of Phase 1. In addition to the standard text descriptions, more details are needed during Phase 1 that describe a program’s targets and observation requests.

  • PIs should provide the Target Name, RA, Dec, and optical magnitude for each star they plan to observe. For proposals that contain different types of observations or targets (e.g., a set of bright stars distributed across the sky, each requiring a single spectrum at any time during the semester and another set of fainter stars, each requiring multiple spectra taken at specific phases of a planetary orbit), the target list should be sorted into labelled sections for each set. See the target list information at the bottom for the proper format of this file.
  • The total time you need to request for your program can be estimated based on a calculation for the exposure time of each observation plus an additional 180 seconds for each time a target is visited. Multiple exposures may be taken during a single visit to a target. Allow 30s for CCD readout between consecutive exposures of the same target. A set of exposure time calculators has been provided by the instrument team and should be used to estimate exposure times. Follow the link below and select from among the four input/output options:

·       To account for the overhead, which you must include in the total time you request in your proposal, account for the number of visits to your target (V), the exposure time in seconds (T) and the number of exposures per visit (N) along with the acquisition overhead time of 300s and readout time of 30s.  A formula for the required telescope time is:

Time (sec) = V * (300 + T*N + 30*(N - 1))

  • Time will be awarded in units of hours (fractional hours are permitted). Proposers may request any amount of time appropriate to their science, and should not attempt to make their science fit into an integer number of “nights”.
  • In the event that you propose to observe targets that are anticipated, but not yet known at the time of Phase 1 (e.g., planets turned up by TESS or due for your own vetting prior to NEID observations), create example target descriptions to simulate the number of targets you ultimately plan to observe, their position in the sky, brightness etc. These example targets must be truly representative of the proposed science and sufficient to guide scheduling, justify the amount and priority of the time requested, and allow for a technical review of the proposal.
  • For anticipated targets, like those noted above, proposers should describe the specific quantitative rubric or procedure they will use to select targets to observe, sufficient for the TAC to determine how the proposed science and ultimate target list will overlap with other proposals. For instance: “We will select the five brightest dwarf stars in our effective temperature range with transiting planets with radii between 1.5 and 2 times that of Jupiter and orbital periods less than 10 days.” Proposals with vaguely described selection criteria will not allow the TAC to evaluate the chances of duplicative science, and so could be penalized with respect to more specific proposals.
  • A description of the observation should be detailed for each type of target you wish to include in your program: choice of HR/HE mode, total number of exposures per visit, total number of observations in the semester and priority level (see below). Describe also the range of exposure times for your targets.
  • Proposers should specify the observational priority(-ies) they are requesting for their observations, and justify this priority. A rough guide to priority justifications would be:
    • P0: Overrides all other observations. Appropriate for extremely time sensitive observations such as Rossiter-McLaughlin measurements or similarly transient phenomena.
    • P1: Appropriate for moderately time sensitive observations, such as RV measurements at quadrature, periastron, or a small number of observations evenly spaced in orbital phase.
    • P2: The lowest priority for science requiring a very high completion percentage under good conditions, such as a proposal requiring a large number of observations spread over many nights.
    • P3: Appropriate for programs that can tolerate suboptimal observing conditions, are not time sensitive, and can tolerate some incompleteness.
    • P4: Similar to P3. Also good for proposals to observe an arbitrary subset of a large number of targets spread around the sky, such as single spectra of any of a large number of TIC stars.
  • Proposers should request an amount of time at each priority appropriate to their science, and may request a mix of priorities. For instance, one might propose for observations that can be placed into two groups, one requiring 3.5h of P1 time and the other 2.5h of P2 time. The priority levels proposed for each group should be indicated in the list of targets. Justifications for these priorities should include a description of each group that can be relatively easily understood by a TAC (e.g., bright stars needing one observation at any time; faint stars needing 8-12 exposures, each distributed throughout a short orbital period). More information on selecting priorities can be found here (
  • The TAC will very likely have to award some proposers time at lower (worse) priorities than requested, so proposers should explain the consequences of receiving lower priority time and specify the worst priorities their science can tolerate, to help guide the TAC in this decision. In general, the TAC should strive to award the highest-ranked proposals time at the requested priorities, provided it is well justified; lower-ranked proposals will likely receive worse priorities than they requested. While priority level is the principal means by which an observation is weighted in the queue scheduling decisions, low priority observations can be expected at times when the number of eligible targets in the overall queue dwindles (e.g., under poor seeing and transparency, when telescope azimuth is restricted due to strong wind, or possibly in bright conditions).
  • To guide these requests: A star that needs one observation on any night during the semester is generally easy to schedule. This is especially the case if it is bright and may be observed under poor conditions and bright skies. Such an observation shouldn’t require high priority time. A star that is relatively far south for WIYN and that you wish to observe at specific times (e.g., observing twice at times of both quadratures relative to a planetary transit) is likely to require somewhat high priority time. A star that you wish to sample 12 times over a planet’s orbital period may have a mixture of easily scheduled observations (starting out) and more difficult ones (later on to fill in missing orbital phases).
  • Finally, you have the option of specifying certain nights on the calendar that would be most advantageous to observe your proposed targets in the same way that you may specify the minimally acceptable observing conditions. These requests from accepted proposals will be used to guide the WIYN instrument schedule. Specific nights are probably relevant to a few science programs, but the schedule can only be partially flexible to meet a request for specific nights. A justification for requesting specific nights could be that you need to observe specific events in a planetary ephemeris that occur only rarely during the semester. The nominal scheduling plan for the queue is to switch often between queue nights and non-queue nights. Most of the time there will be a maximum of three “off” nights between queue nights, but longer periods will be scheduled occasionally. Many periodic events would then recur frequently throughout the semester (e.g., a particular phase of a planet with a short orbital period).


A set of frequently asked questions is available below. An additional set of FAQs is hosted on a separate Penn State site by the NEID instrument team. More details on instrument capabilities and operational modes are available there: Note that the FAQs may be updated in the future to include new questions. You may wish to consult the latest FAQs while preparing your proposal.

  1. Who can I contact if I have unanswered questions about NEID and proposals for using NEID?

You may send email to Inquiries will be directed to someone who can answer your questions. Additionally, detailed information from the January 2019 AAS splinter session can be found within the NN-Explore NEID pages at

  1. Since NEID will only be scheduled on about 50% of nights at WIYN, can you provide me with a semester schedule so that I can plan my program?

The WIYN schedule is determined only after lists of approved programs are returned from all telescope shareholders. It will be published as soon as possible Proposers who anticipate needing a restrictive set of nights to complete their programs should provide a list of requested nights with a description justifying the need.

  1. How will a proposal submitted in response to this call be handled if it is intended as the start of a multi-semester NEID observing program at WIYN?

The importance of long-term observations with NEID is recognized. It is reasonable to envision long-term plans for your NEID science programs, but 2021B NEID proposals are for one semester only and will generally need to be re-proposed to continue in future semesters. The NEID queue will attempt to make semester boundaries as seamless as possible for renewed programs.

  1. If my program is awarded time, how will I be able to control how my allocated time is used once the observing semester is underway?

During Phase 3 you may set targets to be active or inactive (ie. eligible to be observed or not), assign a specific priority to an observation from priority levels of time you are awarded, alter exposure times, and change the timing constraints for when your observations may be scheduled. You may request adding new targets during the semester. There is a long lead time before a requested target may be added (nominally 10 days).

Target List

The file should list each target as a row with the target name, RA, Dec and magnitude. Targets should have unique, easily-recognized names. Any targets that are time critical, requiring specific dates, should be indicated here, noting date requirements.

Example target list follows below:

Generic TESS exoplanet targets to be identified before Phase 2. Will be observed between 2 and 10 times each at different phases of a periodic ephemeris with periods ranging from 3 and 21 days. Magnitudes are V.
Priority level 1.

Star10,175, -15.12

Stars requiring one spectrum each at any time.
Magnitudes are all V.
Priority level 3

HD 25082,03 58 48.2,-11 34 42,9.71
HD 33785,05 14 40.6,+42 25 06,8.41
HD 36286,05 30 12.4,-08 37 09,9.42
HD 43685,06 17 36.2,+01 46 30,7.67
HD 47590,06 40 46.9,+33 01 32,7.73
HD 53392,07 04 46.0,-01 49 10,8.49
HD 55922,07 15 15.0,+05 49 06,7.40

Stars requiring a series of spectra during transit to measure
the Rossiter-McLaughlin effect. V-band magnitude.
Priority level 0


Nights requested for Rossiter-McLaughlin observations.

2019-12-16 UT (K2-136c)

GTO (Guaranteed Time Observer) Programs

Time at WIYN used by the NN-EXPLORE Program will be divided into a guaranteed time observer (GTO) program for the Penn State instrument team (15 nights in 2021B) and guest observer (GO) programs from the community submitted through this call.

The primary objective of the NEID GTO survey ( is to obtain high-cadence radial velocity (RV) observations of bright, magnetically quiet nearby dwarf stars. The purpose of these observations is to discover low-mass exoplanets that previous surveys lacked the Doppler measurement precision to discover.

80 percent of the NEID instrument team’s GTO allocation (30 queue nights per year total) will be dedicated to this high-cadence survey. The targets of this program will be drawn from the list provided here. Because NEID is not yet commissioned, we cannot be sure at this time which of these stars will be best suited to the GTO survey. As final details of the instrument’s performance become available, the instrument team will revise and reduce this list.

The remaining 20 percent of the GTO allocation will be dedicated to opportunistic RV science, including but not limited to mass measurements of GK dwarfs with V<12 and M dwarfs with V<16 identified by TESS, after the 2021B proposal call, to potentially host transiting planets. The GTO team will avoid observing any targets not currently on the GTO list that it knows, prior to the beginning of the 2021B semester, are being targeted for similar science by successful NOIRLab GO programs, for instance because they are named in the publicly posted titles or abstracts of successful proposals.



Last updated or reviewed March 30, 2021.