Alert subscriptions

An alert subscription tells Skynet: "when an external astronomical alert matches these conditions, create this observation automatically." When a matching alert arrives — a gamma-ray burst, a gravitational-wave detection, a survey transient — Skynet builds a pre-configured observation with the event's position filled in and hands it to the scheduler, with no human in the loop.

Skynet maintains the connections to the alert brokers centrally, so you never configure a feed or a credential. You just describe what you care about and what to do about it.

Typical uses:

Time-domain follow-up — image the position of every new transient that passes your filter (a nearby supernova candidate, a kilonova, a bright GRB).
Coordinated campaigns — point an organization's telescopes at the same events as part of a follow-up consortium.
Education — surface high-impact events to a classroom account.

How it fits together

Every subscription has three parts:

A source and a filter — which alert streams to listen to, and which alerts within them are worth acting on.
A response observation — the observation to create when an alert passes the filter. It's a saved observation spec with the target left open; Skynet fills in the alert's position when it fires.
Funding and policies — the observing grants that pay for fired observations, plus rules for how often to fire and what to do when an event is later updated or retracted.

Alert sources

Alerts arrive from two brokers. A subscription can listen to one or several streams at once.

NASA GCN (the Gamma-ray Coordinates Network) delivers rapid positions for high-energy transients:

Swift gamma-ray bursts — burst positions from Swift's BAT/XRT.
Einstein Probe — fast X-ray transients.
Gravitational-wave alerts (LVK) — LIGO/Virgo/KAGRA compact-binary and burst candidates.

Fink delivers classified optical transients from time-domain surveys (such as ZTF), enriched with machine-learning classifiers:

Kilonova candidates and supernova candidates.

Creating a subscription

Open Settings → Alerts on your account (or an organization you manage) and choose New subscription. The editor is organized into a few sections.

Basics

Name — a label for the subscription.
Sources — one or more of the streams above.
Notice types — whether to act on the initial notice for an event, later updates (refined positions), or both. Most subscriptions fire on the initial notice.
Enabled — subscriptions can be toggled on and off without deleting them.

Filters

Filters are how you narrow a firehose of alerts down to the handful you want to chase. Leave a filter blank and it doesn't restrict anything — you opt in to each cut you care about. The filters available depend on the sources you picked.

General (any source):

Localization size — reject events with a poorly-constrained position (a large error region), which are hard to image.
Declination band and galactic-latitude cut — keep events your telescopes can actually reach, or restrict to extragalactic sky.
Moon and Sun separation — skip events too close to the Moon or Sun to observe well.
Event age — ignore stale notices (useful protection against backfilled or replayed streams).
Active months — only fire during part of the year (e.g. your observing season).

Gamma-ray / X-ray bursts (Swift, Einstein Probe):

Instruments — restrict to specific mission instruments.
Minimum significance (SNR) — only bright-enough detections.
Exclude flagged/bogus notices — drop known false-trigger flags.

Gravitational waves (LVK):

Significant only — ignore low-confidence candidates.
False-alarm rate — require a candidate rare enough to be worth following (the canonical electromagnetic-follow-up cut).
Classification — compact-binary vs. burst, and probability thresholds for a neutron star being involved (BNS / NSBH / has-NS / has-remnant).
Distance and sky-area caps — keep events near enough and well-enough localized to tile.

Survey transients (Fink):

Kilonova / supernova score — minimum classifier confidence.
Brightness — a magnitude limit.
Age and number of detections — how new and how well-sampled the object is.

Response observations

Attach one or more response observations. Each is a saved observation spec — the easiest way to make one is to build the observation you'd want in the editor, export its spec, and paste it here. For each response you set:

A name template for the fired observation, with placeholders for the event name, source, and time — e.g. GRB {event_name} follow-up.
An optional start delay after the event time.

When an alert fires, the spec's target is replaced with the alert's position and the observation is created. (If an alert has no position, that fire is skipped.) Attaching several responses lets one alert kick off several observations — say a rapid wide-field image plus a deeper follow-up.

Funding and instruments

Observing grants (required) — fired observations are charged against these, exactly like observations you create by hand. If a grant is later revoked, the subscription disables itself and notifies you rather than firing un-funded.
Instruments (optional) — restrict fired observations to specific instruments.

Lifecycle policies

Events evolve — positions get refined, and some are retracted as false alarms. You choose what happens after the first fire:

On update — update the target of the existing observation to the refined position (the default), retrigger a new observation, or ignore the update.
On retraction — cancel the fired observation (the default), just notify you, or ignore the retraction.

Rate limits

Guards against a noisy stream flooding your night:

Max per night — cap the number of fires in a rolling 24 hours.
Cooldown — a minimum gap between consecutive fires.
Auto-cancel after — automatically cancel a fired observation a set number of hours after the event, so stale follow-ups clean themselves up.
Expires on — an optional date after which the subscription stops matching.

Try it before you commit

Two tools help you trust a subscription before it runs live:

Backtest. Run your draft filters against the alerts Skynet has actually received over the last few months. You'll see how many would have matched and which filter rejected the rest — so you can tune the thresholds before turning the subscription on.
Test fire. Send a synthetic alert at a position you choose and watch the full path execute — funding check, target substitution, and observation creation — without waiting for a real event.

Tracking what fired

Settings → Alerts has three views:

Subscriptions — your subscriptions, each with quick enable/disable, edit, and delete.
Activity — a log of every match decision: what fired, what was skipped (and why — rate-limited, no position, filtered out), and a link to the observation that was created.
Alert stream — the recent alerts Skynet has received across all brokers, so you can see what's flowing in.

A fired observation is a normal observation owned by the same account or organization as the subscription. It shows up in your observation list, runs against your grants, and is yours to edit, watch, or cancel like any other — see Observation detail.