The LSST Camera (LSSTCam)#

Citation: SLAC National Accelerator Laboratory & NSF-DOE Vera C. Rubin Observatory, The LSST Camera (LSSTCam) (2025) DOI Logo https://doi.org/10.71929/rubin/2571927 [BibTeX]

The LSST Camera (LSSTCam) was mounted on the Simonyi Survey Telescope in March 2025. LSSTCam will be used to take data for the Legacy Survey of Space and Time [Ivezić et al., 2019]. It has 3.2 Gigapixels over a 9.6 square degree field of view and six optical filters.

The camera mounted on the Simonyi Survey Telescope

Focal plane#

The LSST Camera focal plane is composed of 189 individual science charge-coupled devices (CCDs), arranged into 21 “rafts,” along with 8 wavefront and 8 guider CCDs located in 4 additional corner rafts. Each pixel is 0.2 arcseconds on the sky, and so each CCD of approximately 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 [Plazas Malagón et al., 2025] by the LSST Science Pipelines [Rubin Observatory Science Pipelines Developers, 2025].

A visualization of the LSSTCam focal plane.

Figure 1: A depiction of the focal plane of the LSST Camera.#

Key numbers#

Except for the gap sizes, these numbers come from Table 6 of [Roodman et al., 2024].

  • Inter-raft gap size (x, y) [mm]: 0.50, 0.50

  • Inter-sensor gap size, (x, y) [mm]: 0.28, 0.25 (e2v); 0.27, 0.27 (ITL)

  • Serial charge transfer inefficiency [%]: 7.3 e-6 (e2v); 1.5 e-4 (ITL)

  • Parallel charge transfer inefficiency [%]: 1.1 e-5 (e2v); 1.2 e-6 (ITL)

  • Dark current [e-/pix/s]: 0.023 (e2v); 0.021 (ITL)

  • Photon Transfer Curve (PTC) turnoff [e-]: 103000 (e2v); 129000 (ITL)

  • Read noise [e-]: 5.40 (e2v); 6.21 (ITL)

  • Gain [e-/ADU]: 1.51 (e2v); 1.68 (ITL)

Components#

Exploded view of camera view of the shutter

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.

filter change mechanism

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.).

For each filter, the effective wavelength – defined as the mean wavelength by the system response in energy units – and the full width at have maximum (FWHM) – defined as the wavelength interval between the points where the system throughput drops to 50% of its peak value – are shown in the following table.

Band

eff_wavelen (nm)

fwhm (nm)

u

372.4

46.3

g

480.7

148.5

r

622.1

139.9

i

755.9

128.6

z

868.0

104.0

y

975.3

86.2

The data for this table can be found in the throughputs package.

Lsst filters

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

Citing LSSTCam#

Use of the correct formal citation strings and keywords ensures that all uses of data from LSSTCam can be found using community tools.

  • DOI: https://doi.org/10.71929/rubin/2571927 (refers to this document)

    • Use this DOI when referring to the instrument specifically; otherwise a dataset DOI may be more appropriate (see the documentation for the specific data release you are using) or a technical reference such as Roodman et al. (2024) given below.

  • IVOA ObsCore keywords: facility_name = Rubin:Simonyi, instrument_name = LSSTCam

  • AAS facility keyword: Rubin:Simonyi or, for specificity, Rubin:Simonyi (LSSTCam)

  • Minor Planet Center observatory code: X05

Technical Documentation#

References#

[1]

Aaron Roodman, Yousuke Utsumi, and Sean MacBride. LSST Camera Electro-Optical Test Results. Commissioning Technical Note SITCOMTN-148, NSF-DOE Vera C. Rubin Observatory, December 2024. URL: https://sitcomtn-148.lsst.io/, doi:10.71929/rubin/2583999.

[2]

Željko Ivezić, Steven M. Kahn, J. Anthony Tyson, and others. LSST: From Science Drivers to Reference Design and Anticipated Data Products. ApJ, 873(2):111, March 2019. arXiv:0805.2366, doi:10.3847/1538-4357/ab042c.

[3]

Andrés. A. Plazas Malagón, Chris Waters, Alex Broughton, Eli Rykoff, Agnès. Ferté, Merlin Fisher-Levine, and Robert Lupton. Instrument signature removal and calibration products for the Rubin Legacy Survey of Space and Time. Journal of Astronomical Telescopes, Instruments, and Systems, 11:011209, January 2025. arXiv:2404.14516, doi:10.1117/1.JATIS.11.1.011209.

[4]

Rubin Observatory Science Pipelines Developers. The LSST Science Pipelines Software: Optical Survey Pipeline Reduction and Analysis Environment. Project Science Technical Note PSTN-019, NSF-DOE Vera C. Rubin Observatory, August 2025. URL: https://pstn-019.lsst.io/, doi:10.71929/rubin/2570545.