Lasair allows you to make a filter on the millions of alerts per day that come in from the Rubin Observatory alert streram. You can select alerts from a specific set of points in the sky (watchlist of cones) or a specific region of the sky (watchmap, also known as a MOC file). You can select alerts based on the lightcurve, requiring for example fast risers or high effective temperature. You can select alerts with a host galaxy using the Sherlock intelligent crossmatch.
In order to create a Lasair filter, you sign in with your Lasair account. Getting an account is simple and immediate, requiring only that you have a valid email address. You select watchlists etc and type in snippets of SQL. You can also start with one of the public filters made by others, or one of the “commmunity resources”, then duplicate into your own account, then modify.
You can click on “Run Filter” to see the results of running your filter on existing (past) objects in the Lasair database. For each object in the resulting table, you can click on the object ID to get a full description, images, and lightcurve. You can also run filters through the Lasair client.
When you duplicate or save a filter, a dialogue asks for Name and Desciption, if you want it public or not, as well as “Streaming”. For this, the choices are “muted”, “email stream”, or “kafka stream”. These last two are flavours of “active” filter, meaning that it runs in real time as the alerts come in, and anything that passes your filter is immediately sent, either as email or machine-readable kafka protocol. If you have chosen email and there are a lot, alerts are bundled you will only get at most one per day. For more information in streaming filters see here.
Making an example filter is discussed in detail at the Quick Start page.
One last thing to note: these active resources – filters, watchlists, and watchmaps – add work to Lasair’s real-time ingestion pipeline, and we don’t want to use computing resources if nobody is interested in the results. Therefore there is an expiry date for an active resource, usually 6 months in yhe future. Emails are sent out in advance and the owner of the resource must click “save” on the website for it to continue being active.