Status
What the array can observe at the moment, and what data already exist. Start here before planning an observation or a data request.
What is on sky tonight
16 of 20 telescopes are in routine operation. Units not listed as online are either awaiting installation or out of service for maintenance. Each operational unit carries a nine-slot filter wheel holding Sloan broad bands and a share of the medium-band set, so the number of distinct bands available on a given night depends on how many units are observing.
What a night produces
Over 769 observing nights since Oct 10, 2023, the array has recorded 2,230,565 science frames in 49,485 hours of open shutter. A typical night covers 36 tiles in 2,595 exposures and writes 374 GB of raw data, calibration frames included.
Medians rather than means: target-of-opportunity nights run to 24,570 exposures and would otherwise dominate the figure. Progress of each survey is on its own page — RIS, WTS and IMS.
Bands available
The filter set is what distinguishes 7DT from other survey arrays. Twenty medium bands of 25 nm width are spaced regularly at 25 nm from 400 to 875 nm. Fifteen further filters, installed in late 2025, fall between them with central wavelengths from 375 to 832 nm and bandwidths of 14 to 41 nm. Sloan g, r and i are carried by every unit; u is carried by one and z by three.
The original twenty are the calibrated set in operational use. Spectrophotometric calibration of the fifteen added filters is in preparation, and their central wavelengths are not aligned to a regular grid — check which bands a given tile actually carries on the data access page, which reports the medium bands observed on any tile.
| Original set (25 nm spacing) | 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, 700, 725, 750, 775, 800, 825, 850, 875 |
|---|---|
| Added 2025 (irregular) | 375, 386, 412, 438, 462, 483, 512, 534, 561, 586, 615, 640, 661, 769, 832 |
| Broad bands | u, g, r, i, z |
How much sky each band has reached
A band is only useful where it has been taken. Because each unit carries nine slots out of the 37 bands in use, the array works through the set over many nights, and coverage runs well ahead in some bands and behind in others. The count below is tiles with at least one science frame in that band.
| Band | Central λ | Tiles in the grid | Of the grid | Frames |
|---|---|---|---|---|
| m375w | 375 nm | 7 | 0.0% | 21 |
| m386 | 386 nm | 200 | 0.8% | 716 |
| m400 | 400 nm | 14,526 | 57.0% | 59,083 |
| m425 | 425 nm | 14,521 | 57.0% | 58,642 |
| m438 | 438 nm | 3,451 | 13.5% | 14,553 |
| m450 | 450 nm | 14,869 | 58.4% | 60,479 |
| m475 | 475 nm | 14,578 | 57.2% | 58,899 |
| g | 477 nm | 9,000 | 35.3% | 45,651 |
| m483 | 483 nm | 3,451 | 13.5% | 14,614 |
| m500 | 500 nm | 14,881 | 58.4% | 61,230 |
| m512 | 512 nm | 1,418 | 5.6% | 5,714 |
| m525 | 525 nm | 14,897 | 58.5% | 60,429 |
| m534 | 534 nm | 3,451 | 13.5% | 14,613 |
| m550 | 550 nm | 15,129 | 59.4% | 61,633 |
| m561 | 561 nm | 3,045 | 12.0% | 12,365 |
| m575 | 575 nm | 15,073 | 59.2% | 60,141 |
| m586 | 586 nm | 3,250 | 12.8% | 13,515 |
| m600 | 600 nm | 15,003 | 58.9% | 61,107 |
| m615 | 615 nm | 893 | 3.5% | 3,364 |
| r | 623 nm | 11,318 | 44.4% | 52,958 |
| m625 | 625 nm | 14,722 | 57.8% | 59,792 |
| m640 | 640 nm | 3,421 | 13.4% | 14,502 |
| m650 | 650 nm | 14,958 | 58.7% | 59,584 |
| m661 | 661 nm | 3,435 | 13.5% | 14,561 |
| m675 | 675 nm | 14,939 | 58.6% | 60,995 |
| m700 | 700 nm | 13,545 | 53.2% | 54,175 |
| m725 | 725 nm | 13,944 | 54.7% | 57,175 |
| m750 | 750 nm | 14,503 | 56.9% | 69,132 |
| i | 762 nm | 5,597 | 22.0% | 29,661 |
| m769w | 769 nm | 2,980 | 11.7% | 11,684 |
| m775 | 775 nm | 12,586 | 49.4% | 49,817 |
| m800 | 800 nm | 15,194 | 59.6% | 87,308 |
| m825 | 825 nm | 14,813 | 58.2% | 84,146 |
| m832w | 832 nm | 3,420 | 13.4% | 14,489 |
| m850 | 850 nm | 14,634 | 57.5% | 77,779 |
| m875 | 875 nm | 12,541 | 49.2% | 79,487 |
| z | 913 nm | 367 | 1.4% | 1,351 |
Counted over the original reference grid, so the percentages are comparable with the 61.4% figure above. Broad bands are listed at their effective wavelength. Which bands a particular tile carries is reported on the data access page.
Filter response curves
Curves are read from the reference data shipped with supy, which is also what its simulator module uses, so a response computed there matches this figure exactly.
What has been observed
61.4 percent of the reference tiling has been observed at least once: 15,646 of 25,472 tiles, or 15,712 of 28,520 counting the northern extension. A tile with data has calibrated images and a source catalog.
The reference grid is the survey as designed — every tile the array intends to reach — reconstructed from the tiling rule rather than published as a list, and checked against every observed tile. WTS has not begun and has no footprint to draw yet. Target-of-opportunity observations are made across the whole grid, and the portal publishes their counts but not their positions, so they cannot be drawn as a layer; the 202 follow-up campaigns to date are summarized under how to propose.
Is this position observed?
Try , , . Right ascension is read as hours when written with colons or spaces, and as degrees when written as a single number.
Enter a position to see whether it has been observed and what exists for it.
Processing status
Data are reduced the same day they are taken. Raw frames are transferred from Chile overnight and a typical night clears the pipeline in about five hours of wall-clock time after transfer completes, so survey data are normally available the following day. Target-of-opportunity data skip compression and the wait for sunrise, which brings latency down to tens of minutes. What the pipeline produces, and the quality metrics attached to each product, are described under using the data.