Step 3 — Requests
The requests step asks: what data should we collect?
An observation can have one or more data requests, each describing one kind of acquisition. You add requests, pick the type of each, and tune that type's settings. The editor lets you add, edit, reorder, and remove requests inline.
You need at least one request before you can create the observation.
Adding a request
Click Add request to pick a type. There are three:
| Type | What it does |
|---|---|
| Optical imaging | Capture science frames through an optical imager — filters, exposures, framing, tiling. |
| Radio tracking | Point-and-integrate at the target with a radio dish (spectroscopy and/or continuum). |
| Radio mapping | Raster- or daisy-scan a region with a radio dish to build a map. |
(Calibration frames — bias, dark, and flat — aren't added here. The telescope's scheduler produces the calibrations your data needs automatically.)
You can add several requests to one observation, and they don't all have to be the same type. Drag a request to reorder it — the order is the order they're scheduled.
Two places to set things
Each request type has settings in two places:
- On the request row — the per-request basics, set inline on each request.
- In the configuration dialog (the gear icon on the row) — the type's constraints and parameters. These apply to all requests of that type on the observation, so you set them once.
The split matters: you might add two optical-imaging requests with different filters and exposures (row settings), but they share one set of field-of-view, tiling, and sky-condition constraints (dialog settings).
Optical imaging
On the request row
- Iterations — how many times to repeat this request.
- Filter(s) — the filter or named filter group to shoot through; list several to loop through them in order.
- Exposure mode — how each exposure is sized:
- Time — an explicit exposure duration you set.
- SNR — aim for a target signal-to-noise; the scheduler computes the exposure from the target's brightness.
- Well-depth — fill the detector to a chosen fraction of full well, capping exposure so bright targets don't saturate.
- Coadding allowed — let the scheduler stack several shorter exposures to reach the target instead of one long one.
- Binning allowed — let the scheduler bin pixels for sensitivity or smaller downloads.
- Active — park a request without deleting it.
In the configuration dialog (gear icon)
The optical-imaging dialog groups its settings into three tabs.
Observing Constraints — when the target may be observed:
- Target elevation — minimum (and optional maximum) altitude above the horizon.
- Sun elevation — how far the Sun must be below the horizon (darkness requirement).
- Moon — minimum separation from the Moon, a maximum Moon phase, and which side of the lunar cycle (waxing/waning) is acceptable.
Imaging Constraints — framing, tiling, pointing, and dithering:
- Field of view — minimum FOV in X and Y, position angle, and optional pixel-scale limits. If the area you want is larger than one frame, this drives tiling.
- Tiling — the maximum number of tiles allowed to cover the area and the overlap between adjacent tiles (a mosaic).
- Tracking — sidereal (track the stars) or target tracking (follow a moving solar-system object), plus a re-centering threshold and timing offsets.
- Dithering — shift the pointing slightly between exposures to beat down hot pixels and artifacts; choose a pattern (grid, snake, spiral, cross, jitter), the number of steps, and the step size.
Brightness — exposure-sizing models:
- Brightness model — the target's reference magnitude, used to size exposures in SNR and well-depth modes.
- Saturation model — the brightest source you expect in the frame, used to cap exposure so it doesn't bloom.
Radio tracking
A point-and-integrate observation: the dish stays on the target (or alternates on- and off-source) and integrates.
On the request row: iterations, the total duration, the spectroscopy windows to record (each a center frequency and bandwidth), an optional polarization requirement, a minimum spectral resolution, and a maximum integration time. You can also require simultaneous continuum output.
Configuration dialog tabs:
- Observing Constraints — minimum target elevation, how far the Sun must be down, and minimum separation from the Sun.
- Tracking — the on/off strategy (on-source only, on/off, or off/on for background subtraction) and the offset to the off-source position, in degrees or beamwidths.
Radio mapping
A sweep that samples many pointings to build a map of a region.
On the request row: iterations, the spectroscopy windows, optional polarization, and minimum spectral resolution.
Configuration dialog tabs:
- Observing Constraints — same elevation and Sun constraints as radio tracking.
- Mapping — the sweep pattern (raster grid or daisy spiral), its size (raster extent, or daisy diameter), the sampling density along and between sweeps, and whether depth is set by a per-point integration time or a continuous slew speed. Coordinates can be given in degrees or beamwidths, in the frame you choose (equatorial, galactic, horizontal, …).
How many requests is enough?
Common patterns:
- One imaging request, multi-filter — most optical workflows: a single request looping through B/V/R/I (or g/r/i) at the desired SNR.
- Multiple imaging requests — different filter sets or exposure strategies on the same target without splitting into separate observations.
- One radio tracking + one radio mapping — an on/off integration for continuum context, plus a sweep for spatial structure.