# What is the size of the image sensor in the largest optical telescopes?

What image sensors (imaging electronics) are used in telescopes? Like CCD, is that the best option?

What is the typical physical size and resolution of the photo-sensitive surface of the currently active largest ones?

• Can you add more details? – fasterthanlight Jan 4 at 14:10
• @fasterthanlight Sure, what details do you think will improve this question? – Ilya Gazman Jan 4 at 14:22
• If I understand it well, the question is the size of the imaging electronics in the telescopes (ccd cam?), and also their resolution. Probably he wants to know the current record holder (which is probably Hubble). – peterh Jan 4 at 14:29
• Please elaborate your question, I f*y hate to vote border cases for closure... – peterh Jan 4 at 15:04
• @peterh-ReinstateMonica Looks good to me. tnx – Ilya Gazman Jan 4 at 15:52

The current largest digital CCD camera is that of the Vera C. Rubin Observatory1 which has a whopping 3.2 gigapixels. The previous largest features on the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS), and has a resolution of ~1.4 gigapixels.[1]

Based on the spec sheet provided by the Vera Rubin Observatory, the LSST camera has a resolution of roughly 0.2 arcseconds per 10 $$\mu$$m pixel. It is about 5 feet (1.52 meters) wide and weighs over 6000 lbs (2721 kilos, $$2.6\times10^9$$ dyn).[2] The actual photosensitive portion of the camera is ~64 cm ($$4\times10^{34}$$ Planck lengths) across.

Cameras of this size often have pointing, calibration and recording issues. These sources of error are usually extremely well understood, but it's still interesting to see. Pan-STARRS has a detailed list on their data site[3]. These issues include:

• Randomly missing data that gets filled in later
• Pointing errors related to astrometric positions of their targets
• Registration issues near the celestial pole resulting in poor photometry

1formerly known as the Large Synoptic Sky Survey or LSST. The acronym has now been repurposed: What is the LSST now? Where does LSST end and Vera C. Rubin Observatory begin?

• Can we choose SI or imperial units. – ProfRob Jan 5 at 21:19
• @ProfRob I chose the primary units I did in order to be consistent with the spec sheet provided by Vera Rubin Observatory (linked in answer). However, as a possible resolution, I have updated the answer with additional unit conversions to SI. – Joseph Farah Jan 5 at 21:24
• cgs please! you're an astronomer! ;-) – pela Jan 6 at 8:50
• due purely to @pela 's charm, I have provided the weight estimate in dynes. – Joseph Farah Jan 6 at 14:55
• Although the camera as a whole may be this size (1.2m is closer to 4 feet than 5 incidentally), the sensor array is 64cm across. – Steve Linton Jan 6 at 15:05