New Instrument for WIYN: NEID

Summary description

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 US 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 type.  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.  NOAO will operate NEID in a queue scheduled mode and NExScI will employ pipeline data reductions 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 scheduled to begin commissioning at WIYN in October 2019.
 
Programs using NEID will be scheduled in queue mode with WIYN staff taking the observations and NExScI providing data reduction, high-level data products, and extremely precise barycentric-corrected radial velocities via the NEID data archive. We anticipate up to 15 nights of NEID time to be scheduled starting in late 2019B, no earlier than November, and will be considered a "shared risk" program at that time. Beginning the NEID queue as a shared risk program is necessitated by the current uncertainties in its starting time, the possibility of nights lost due to schedule slippage toward the end of the semester and instrument and observatory performance.
 
NEID commissioning is slated to begin at WIYN after this call and the system must meet baseline requirements before 2019B observations can begin. “Shared risk” here means that many details of the instrument performance described in this call should be considered preliminary estimates and are expected to be updated as the system is tested and refined. The results returned to PIs during this shared risk period may not meet the expectations described here and there are likely to be issues encountered as WIYN adopts queue operations. The benefits to proposers running NEID programs during 2019B include an opportunity to learn about the system, provide NOAO with experience meeting community needs with NEID, perhaps contribute with some suggestions for improvement, and gather some data during an exciting time for exoplanet astronomy.
 
NEID consists of two principal parts. The port adaptor (provided by the University of Wisconsin) will be 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 their light to 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 NEID's 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 conditions and will be available only in an experimental mode during 2019B (it is not expected to be extensively tested).
  • 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 in 2019B (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 characteristics

  • 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: 5 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. The goal is that 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 will obtain a standard calibration sequence every night and morning, which includes bias, flats, 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 will also observe 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. The standard star list will include ~8-10 targets, of which 2-3 will be observed every night NEID operates.

Queue Policies

  • The NEID queue will be shared by multiple holders. 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 (TBD for this first Call period) and guest observer (GO) programs from the US community submitted through this call. The WIYN university partners may also devote some of their time share 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 director, 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 (may be longer for this shared risk call). All target IDs will be informative (no target codenames will be allowed).
  • NEID data taken as part of GO programs have 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%). These priority levels are a ranking where 0 through 4 spans from highest to lowest priority.  Priority level is the principal weight for selecting one target over another at any given moment. Secondary weights may be applied by the queue software in real time based on timeliness and other factors for efficient scheduling. The oversubscription of time is essential to ensure an efficient queue.

 

One use of priority levels is to reflect the timeliness of observations, allowing extremely time sensitive observations (such as Rossiter-McLaughlin measurements) to take priority over other observations. Because the queue is oversubscribed, observations granted priority 3 and priority 4 time are less likely to be executed. It is the intention of the queue design that a high percentage of observations done with priority 0 through priority 2 time will be completed.

 

What 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. Under particularly windy conditions, WIYN may only observe at certain azimuths, so targets located in other parts of the sky will be inaccessible.  For example, if many queue proposals prefer southern targets (e.g., K2 or south TESS fields), a program having targets north of 32 degrees declination would be in favor whenever the telescope must point north.  For this reason, proposers will be asked to supply some extra details on the targets for their programs during Phase 1.  Upon receiving proposals for the NEID queue, NOAO staff will inspect the proposals to categorize the requests into subsets  appropriate for the range of observing conditions expected.  This information will be passed to the TAC so that the telescope time can be efficiently allocated.  

 

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 https://exoplanets.nasa.gov/internal_resources/1101/
 
Questions can be e-mailed to neid_info@noao.edu .

 

How to Propose

 

Proposals for NEID queue time are done in 3 phases. The first of these, Phase 1, includes the ordinary NOAO 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 Fall of 2019). 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 NOAO proposal forms for 2019B.  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:

    http://neid-etc.tuc.noao.edu/calc_shell/calculate_rv 

  • To account for the overhead, which you must include in the total time you request in your proposal, use the following formula:

    Time = (# visits to target) * (180s + (Exposure time in s) * (# exposures per visit) + 30s * (# exposures per visit - 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 described 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 3.5 h 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).
  • 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 low-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. The 2019B NEID queue will nominally begin in November and run through UT 1 February.  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 two “off” nights between queue nights, but longer shutdown 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).

 

FAQs

--------

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 available there: https://neid.psu.edu/observers-and-proposers-faq/  .  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 neid_info@noao.edu.  Inquiries will be directed to someone who can answer your questions.  Also consider the March 14, 2019 teleconference described in this call.

 

  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.  The start date for the 2019B queue is only approximate at this time and there is risk that it will be difficult to plan some NEID programs with such uncertainty.  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 2019B 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.

 

We are developing a “rollover” strategy.  For 2019B we will target rolling over a few programs based on ranking, completion and queue priorities.  A rollover strategy will be set in later semesters. 

 

  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.  The state of observation requests is frozen prior to the beginning of an observing night.  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

--------

 

Targets are separated into groups, if applicable. The groups correspond to targets that you wish to observe in different manners.  You might require different priority levels for these groups.  If applicable, the same target could be placed into more than one group.  Begin each group with a short description.  The purpose of this file is to help queue organizers understand the scheduling demands for your program, not to explain your scientific rationale and other details that should go into your proposal form.  Don't assume that the TAC will read this file.

 

The file should list each target as a row of comma-separated values (CSV) with this format:

 

TargetName,RA,Dec,magnitude

 

TargetName should be a unique, standard, easily-recognized name.

 

RA should be either decimal degrees of right ascension or a sexagesimal value in hours, minutes and seconds of right ascension.

 

Dec should be either decimal degrees or sexagesimal degrees, minutes and seconds.

 

Magnitude should normally be a standard, optical broadband magnitude such as V.  Red stars may be described better with a redder filter like SDSS i, or G$_{RP}$.  State the filter being used.

 

Sexagesimal fields may be separated by either a space or colon (e.g., "DD MM SS.S" or "DD:MM:SS.S"), but be consistent.

-------------------------------------------------

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.

 

Star1,355,20,11

Star2,15,-10,12

Star3,35,0,13

Star4,55,0,10

Star5,75,0,11

Star6,95,0,12

Star7,115,0,13

Star8,135,-5,10

Star9,155,-10,11

Star10,175, -15.12

Star11,195,-20,13

 

 

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

 

K2-136,67.412460,22.882720,11.2

 

 

 

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 2020A) 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 attached below. 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 2020A 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 2020A semester, are being targeted for similar science by successful NOAO GO programs, for instance because they are named in the publicly posted titles or abstracts of successful proposals. 
 

NEID-GTO-Targets.pdf

Last updated or reviewed September 19, 2019.