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At the Telescope
- Internal Use
- 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 and guest observer (GO) programs from the US community submitted through the Call for Proposals. 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 a 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 (may be longer during shared risk time). 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.
- NEID 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 partner 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 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, NOIRLab 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.
- 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.
How to Propose for NEID time
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 the 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. 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 this page 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 300 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, use the following formula:
Time = (# visits to target) * (300s + (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.
- **More information on assigning NEID priority levels can be found in this document.
- 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. 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).
Scheduling Long Sequence Observations on NEID
The current NEID queue is designed with a scheduling system reliant upon each observation having a priority level which the Scheduler uses to select one observation over another, resolving conflicts. Based on anticipated NEID science cases and some experiences relayed to WIYN by HET users, the NEID queue time was distributed with relatively small fractions at the highest priority levels. This scheme was intended to minimize the number of conflicting observations whose epoch of observation was critical because it allowed users or TACs to attach high priority levels to such observations, increasing their chances of being scheduled. These observations would work best at a priority level of P0 and, to a lesser extent, P1.
A review of 2020B observing proposals reveals a significantly higher demand for time-critical observations using NEID than this original plan will easily accommodate. The bulk of the problem lies with a large number of programs seeking to observe host stars using a long sequence of consecutive exposures during planetary transits. Such observations are time critical while their duration requires a large time allocation. Various partner TACs are requesting programs with these types of observations, but were forced to allocate them lower priority time (P2 or lower). In addition to being time critical, such long observations are difficult to schedule without conflicting with other equal or higher priority observations, so merely putting more queue time at high priority level will not solve the problem very well.
The WIYN team has spent some time considering potential solutions that could be used to schedule observations of a specific type: long duration observations that have a stringent requirement in terms of their epochs of observation. One method to deal with these observations would be to modify a current algorithm that identifies and selects them for first-in-line scheduling (before the remaining time is filled in with easier-to-schedule observations). This algorithm had been slated to operate only on observations among the highest priority levels (P0 and maybe P1). However, it could be extended to lower priority levels to accommodate more observations of this type. This would effectively treat such observations in a special, privileged manner that may override some shorter, more easily scheduled observations of higher priority level. Note that "easy-to-schedule" is a property that is relatively straightforward to define on a single night, but not so straightforward to define for the remainder of a semester.
Other methods explored treat these types of observations as "classical" where the program assumes the risk of losing their time allocation due to weather or facility problems. Classical programs and observations would best be declared early on in the semester, ideally by the time the schedule is created. This may limit the type of programs that could use such a mode. NEID standard stars could be observed on classical nights like they are on queue nights, but otherwise would follow normal WIYN protocol. Alternatively, another method would be to define certain well-justified observations as classical, but schedule them in the midst of queue observations at pre-declared times.
Last modified: 18-Jan-2022 10:58:52 MST
- Observing at WIYN