Instruments | Rubin Observatory

LSST Science Camera (LSSTCam)

The LSST Science Camera is the world's largest digital camera. It has 3.2 Gigapixels over a 9.6 square degree field of view and six optical filters.

Go to SLAC's webpage for LSSTCam.

Focal plane

The LSST Science Camera is composed of 189 individual charge-coupled devices (CCDs) arranged into 21 "rafts". Each pixel is 0.2 arcseconds on the sky, and so each CCD of 4,000 by 4,000 pixels covers 13.3 by 13.3 arcminutes (0.22 by 0.22 degrees). Every CCD has 16 amplifiers, each reading 1 million pixels, enabling the full focal plane of of 3.2 Gigapixels to be read out in 2 seconds.

The CCDs were supplied by two vendors, ITL and e2v. All nine detectors in a given raft are from the same vendor. Differences between sensors are accounted for during the Instrument Signature Removal (ISR) stage of image processing by the LSST Science Pipelines.

Key numbers

Inter-raft gap size (x, y): 0.50, 0.50 mm
Inter-sensor gap size, (x, y): 0.27, 0.27 mm (ITL); 0.28, 0.25 mm (e2v)
Charge transfer inefficiency: TBC
Dark current: TBC
Non-linearity: TBC
Read noise: TBC
Gain: TBC

Above, a graphic depicting the focal plane of the LSST Science Camera.

References

LSST camera electro-optical test results, LSST Camera group (2025; SITCOMTN-148)
LSST camera verification testing and characterization, Roodman et al. (2024; SPIE)
Integrating the LSST camera, Lange et al. (2024; SPIE)
LSST camera focal plane optimization, Utsumi et al. (2024; SPIE)

Components

The LSST Science Camera is about 1.65 meters across and 3 meters long, and contains lenses, filters, shutter, sensors, cryostats and electronics.

Above, an exploded view of the camera's internal components.

The shutter's two sides slide back and forth to expose and then cover the focal plane. The nominal shutter open/close time is 1 second.

The filter changer mechanism - which holds 5 of the 6 LSST filters at a time - moves a filter in and out of the light path. The nominal filter change time is 2 minutes.

Filters

The LSST's six filters are u, g, r, i, z, and y. At any given time, five will be loaded into the camera's filter carousel, with a sixth filter swapped in every couple of weeks (depending on moon illumination, survey strategy, etc.).

Visit GitHub to download the filter throughputs shown below.

Above, the filter transmission curves for the LSST Science Camera's six filters: u, g, r, i, z, and y. These throughputs include atmospheric transmission (assuming an airmass of 1.2, dotted line), optics, and the detector sensitivity.

Commissioning Camera (ComCam)

ComCam was mounted on the telescope for seven weeks in late 2024. It is the same as the LSST Science Camera but contains only the central raft of 9 CCDs.

References