How to propose
Who may ask for time on 7DT, how much of it there is, and what the array can be asked to do with it.
General information
Who may propose
The 7DS team is being formally constituted. Anyone taking part in a 7DS Science Working Group becomes a member of the team automatically, without having to ask — opting out is the action that requires notice, not joining. The working groups follow the seven science themes.
Team membership carries two rights. The first is early access to 7DS data during its proprietary period, before it is released more widely. The second is the right to propose an independent observing program of your own on 7DT, rather than working only from what the surveys happen to collect.
Who Members of the 7DS team. Joining a science working group makes you one.
How much 200 hours for KASI and 200 hours for the Korean Astronomical Society.
When No call has opened yet. It will be announced on this page.
Time available, and when
Two hundred hours of 7DT time are allocated to the Korea Astronomy and Space Science Institute, and a further two hundred hours to the Korean Astronomical Society — four hundred hours in total, held separately and awarded through their own routes. This is time on the array outside the three surveys, which otherwise occupy the night.
No call for proposals has opened against either allocation. The schedule will be announced here when it is fixed, together with a proposal template and an exposure time calculator. Target-of-opportunity requests are handled separately and continuously, and do not wait for a call.
Data rights and authorship
Data taken for the surveys and for approved programs carry a proprietary period during which they are available to the 7DS team before wider release. Team membership is what grants that access, which is the practical reason the working groups matter as much as the allocations do.
Authorship on work using 7DS data is governed by a policy still under discussion. What is settled is that it will include the initial core members of the 7DS team — seven people at present — in the author list of collaborative papers drawing on 7DS data. Anyone intending to publish is asked to contact the principal investigator first, so that authors and acknowledgments are agreed before submission rather than after.
The full policy — proprietary period, terms for sharing data outside the team, the public release schedule and authorship for external collaborators — is being prepared by the collaboration and will be posted under publication policy once ratified.
Decided Team members have proprietary-period access; the seven core members appear on collaborative papers.
Still open How long the proprietary period runs, how data may be shared outside the team, when it becomes public, and authorship for collaborators outside the team.
Meanwhile Contact the PI before submitting, and acknowledge the funders listed on the funding page.
Guidelines
Observing modes
Because each unit carries its own filter complement, the array can be reconfigured between science goals without changing hardware. The full spectral range is covered by assigning different filter combinations to individual units and rotating through them during an observation. Four modes are in routine use; the choice between them trades spectral sampling, depth and sky coverage against one another.
- 01
SpecMaximum spectral resolution
The default mode. Units rotate through every available medium and broad band, covering the full spectral range in as few exposures as the filter distribution allows. This is the mode in which 7DT delivers low-resolution spectroscopy over 1.25 square degrees.
- 02
DeepMaximum depth
A selected subset of filters is used, trading spectral sampling for signal-to-noise. Used when the question is detection rather than characterization.
- 03
ColorBroadband, fast
Broad-band filters only. Used for faint, fast events such as gamma-ray bursts and young supernovae, where early detection on the light curve matters more than spectral detail.
- 04
SearchMaximum sky coverage
Each unit points at a different region of sky. A gravitational-wave counterpart is localized only to a probable region covering a wide area, so covering that area quickly takes priority over observing any single field deeply.
What a request contains
An observation is a mode, a target, a filter set, an exposure and a cadence, plus whatever constraints the science imposes. Positions on the survey tiling are preferred wherever the science allows: data taken on a tile coadd directly with the survey data already there, and difference against the existing reference image without a separate calibration step.
| Parameter | What to give |
|---|---|
| Observing mode | Spec, Deep, Color or Search. The mode decides how the array divides itself between filters and fields. |
| Target | Position in RA and Dec, or a tile identifier. A tile is preferred where the science allows, since the data then coadd and difference against what already exists. |
| Filters | Which of the 35 medium bands and five broad bands, or a wavelength range and a mode that covers it. Each unit carries nine slots, so a wider set costs more units or more nights. |
| Exposure time | Seconds per frame. One hundred is the fiducial exposure the surveys are built from, and the depth every published figure is quoted at. |
| Repetitions | Frames per visit, and visits per target. Depth in the coadd goes as the square root of total time, so four frames buy 0.75 magnitudes over one. |
| Cadence | For a monitoring program: interval between visits and the total span. For a single epoch: the window it has to fall in. |
| Constraints | Airmass limit, moon separation and phase, time window, and anything else that would make a frame useless if violated. |
| Trigger criteria | Target-of-opportunity programs only: what event triggers the observation, which response mode, and how the alert reaches the scheduler. |
Camera gain and binning are set by the observatory rather than chosen per proposal, and are recorded per frame — the pipeline matches calibration masters by camera, gain, binning, unit, night and filter, so a frame always carries the settings it was taken with. If a program requires a specific gain, say so and why; the selectable settings are not published here.
Target of opportunity
When a transient alert arrives — a gamma-ray burst, a gravitational-wave candidate — the scheduler interrupts the observing plan and repoints. Two response modes are available: a regular mode that completes the current exposure block before switching, and a rapid mode that interrupts immediately. Once the follow-up finishes, the array returns to the queue and resumes the interrupted target if it is still observable. Time from alert ingestion to the start of a follow-up exposure is under one minute.
Target-of-opportunity data are processed at elevated priority and the requester is notified when raw data arrive, as each filter set completes, and on completion with a spectral energy distribution plot and magnitude table attached.
178 follow-up campaigns have been carried out since automated target-of-opportunity response entered service, 9 of them on gravitational-wave events.
LVK superevent identifiers as issued in the public alert stream. Target-level details are not published here.
Before you write
Three things are worth settling first, because each of them can make a program unnecessary or unworkable, and all three can be checked from this site.
- 01
Check what already exists
Much of the southern sky already has a medium-band reference image, and the tile under your position may already carry the bands you need. The data access page reports the bands and frame counts held for any position.
- 02
Estimate depth from measurements, not aperture
The measured limiting magnitudes per band, for the fiducial 100-second exposure, are what a coadded depth should be scaled from.
- 03
Check the target is observable
Visibility from El Sauce in the intended window, and the filter response over the wavelengths that matter, can both be computed with
supy.
Requesting observing time
Outside the KASI and KAS allocations described above, observing time is allocated within the collaboration and its partner institutions, and there is no general call for proposals. A proposal template and an exposure time calculator will be published here when a call opens. Until then, and for anything outside the survey program — including target-of-opportunity requests — write to the project directly.
Contact the project