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
The open call
Proposals are being accepted for observations between 1 December 2026 – 31 August 2027. The deadline is 23 October 2026, 23:59 KST. The dates, the documents to download and the rules that apply to this particular call are on the call for proposals page. This page is about writing the proposal, and does not change between calls.
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.
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. How a proposal is assigned to a pool and reviewed is set by each call, and is given in its Call for Proposals. This is time on the array outside the three surveys, which otherwise occupy the night.
The current call, its dates and its documents are on the call for proposals page. The observation calculators are available for costing a program. 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.
Any paper, conference contribution, thesis or other public output that uses 7DT data not yet in a 7DS public release must include the core members of the 7DS team as co-authors. They are named in the Call for Proposals, along with the reference to cite and the acknowledgment to include. 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 wider publication policy of the 7DS collaboration — the public release schedule among it — is being finalized, and will be posted under publication policy once ratified.
Guidelines
A request is a program type, an observation mode, a target or an area, the exposures that reach the signal-to-noise the science needs, and the constraints under which the array may take them. 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.
Program type
| ToOTarget of opportunity | Observations triggered by an unpredictable event — a gamma-ray burst, a gravitational-wave counterpart, a newly discovered supernova. The trigger condition is described in prose; the response time is a separate field. |
|---|---|
| TargetPre-selected targets | One or more targets observed on a planned schedule. A custom tiling may be used. Every target has to be listed with its coordinates — a representative subset is not enough, since each is judged on its own visibility and priority. |
| SurveyWide area or many tiles | Systematic coverage of an area. Carried out on the existing 7DS tiling grid, the same one RIS, WTS and IMS use, rather than a tiling of your own. Give the coordinate range and the area in square degrees rather than a tile list. |
Observation mode
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.
Spec
Maximum spectral resolutionThe 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. With the 16 telescopes currently in operation and the default 32-filter set used for Open Time proposals, this takes two sequential exposures, 16 filters at a time.
Deep
Maximum depthA selected subset of filters is used, trading spectral sampling for signal-to-noise. Used when the question is detection rather than characterization.
Color
Broadband, fastBroad-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.
Search
Maximum sky coverageEach 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.
Every unit takes its first filter, then its second: two sets of sixteen, one after the other. From the array's configuration, 20260523/specall.specmode.
Before you write
Four things are worth settling first, because each of them can make a program unnecessary or unworkable, and all four can be checked from this site.
- 01
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, or with the 7DT Visibility Tool
- 02
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, and the 7DT Tile Matcher shows which survey tile covers it.
- 03
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. The 7DT Exposure Time Calculator uses these same measurements to compute the exposure needed for a target SNR, or the SNR for a given exposure.
- 04
Calculate the total observing time
Once the exposure time per filter is set, the 7DT Overhead Calculator adds the per-frame and per-target overheads, such as filter exchange, autofocus, slewing, setup, and readout, to give the total requested hours.
Technical justification
| Field | What to give |
|---|---|
| Total requested hours | The whole request, overheads included — slewing, filter changes, readout — not time on source. The overhead calculator gives the difference. |
| Minimum acceptable hours | The smallest allocation that still meets the core objective. Used when a partial allocation is considered. |
| Program type | ToO, Target or Survey, as above. |
| Observation mode | Spec, Deep, Color or Search. More than one may be listed, with the time allocated to each explained. |
| Proprietary period | None, 12 months or 18 months, counted from the date the data products are delivered rather than from the observation. |
| Observing window | Any constraint on when the observations may happen — a seasonal visibility window, coordination with another facility, a deadline for a fading object. “None” if there is none. The visibility calculator gives the window a target actually has. |
| Moon phase | Dark, gray or bright; more than one if the program tolerates a range. |
| Required response time | ToO programs only: the longest acceptable delay between trigger and the start of observation. |
| Exposure time justification | The exposure per target or tile and how it was derived, the target signal-to-noise and the calculation or calculator used to reach it, the filters and the time on each, and the arithmetic that adds up to the total requested hours. The exposure calculator works in either direction. |
| Target coordinates | Target programs: every target in RA and Dec, J2000. Survey programs: the coordinate range and the area in deg². The tile matcher shows which tiles cover a position, and how they overlap. |
| Duplication with existing 7DS data | Whether the targets or area overlap RIS, IMS or WTS. “None”, or why the existing data are not sufficient — greater depth, a different cadence, a different filter set. What exists on a given tile is on the status page. |
Two limits shape the exposure time before the science does. A single frame should be at least 100 seconds, which is what it takes to reach background-limited conditions, and no more than 180, beyond which tracking accuracy starts to elongate the PSF. Depth comes from taking frames in series, not from lengthening one. Bright targets can use shorter frames at the cost of more overhead, and any frame time other than 100 seconds adds overhead for its own calibration frames. Survey observations use 100 seconds as standard.
Of the observing conditions, only Moon phase can be requested — seeing and cloud cover cannot be specified, though observations are made under nominal conditions wherever possible. A unit may also be out of service on the night, in which case the delivered data lack whatever that telescope was carrying.