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An Introduction to Hyper Suprime-Cam (HSC)

The Hyper Suprime-Cam  (HSC) is the next generation camera on the Subaru Telescope, replacing its’ predecessor  Suprime-cam that had been used for 18 years. The field of view (FOV) has been dramatically increased from 0.16 to 1.5 square degree (10 times!!!). The HSC has not only a large FOV but it is also mounted on one of the biggest telescopes in the world. The camera’s ability and efficiency are the mightiest in the current observatories. HSCs physical extent is larger than three meters. Its focal plane (60 cm in diameter) is paved with 116 CCDs (including focus and tracking chips), operating in -100 degrees centigrade. The diameter of the front lens is 82 cm, the length of the lens barrel is 165 cm. The total weight is 890 kg. Every exposure includes 870 million pixels.

(c) Subaru Telescope, NAOJ

Before the HSC era, most of the cameras with large sky coverage were installed on  medium or small telescopes (48-inch-a few meter telescopes), e.g. GigaPixelCamera on Pan-STARRS 1 (1.8m), MegaCam on the  Canada-France-Hawaii Telescope (3.6m) and Magellan(3.6m), Dark Energy Camera on the Blanco Telescope (4m). Although they can cover a few square degrees, the sensitivity is  25% less than what you can achieve on an 8-meter class telescope. In some astrometry topics, like micro-lensing and large structure in the universe, both large aperture and FOV are vital. The enough sample will lead astrometers to a significant and compact conclusion.


(c) Subaru Telescope, NAOJ

The HSC Subaru Strategic Program (SSP) is most important and largest programs o the  Subaru Telescope in this decade. This survey started in 2014, finishing at 2019. This program will survey 1400 square degrees, using optical to near-infrared filters (g, r, i, z and y), reaching a 26.5 magnitudes in stacked images. The survey regions are fixed on the equator (Dec = 0) and cross with Ecliptic plane where are the locations including a lot of solar system bodies. Hence, beside cosmology science, this survey data is quite valuable for Solar System science. Now with the HSC Survey Search, you can search for cometary activity in asteroids imaged in the HSC survey on Comet Hunters.

The Story of the Subaru Telescope


Subarau Telescope (right) and dome (left). Credit: M.E. Schwamb

The images you see on Comet Hunters come from the public archive images from the Subaru Telescope. Subaru is the first 8.2-meter class telescope in the world, built at 1998. It is equipped with a single mirror (8.2-meters is the largest size that currently is able to ground with precision into an astronomical mirror). The telescope is located on one of the best observing sites in the word,on the big island of Hawaii near the summit of Mauna Kea. Subaru is also the only 8.2-meter class which was constructed by a single government (Japan). The name for the telescope is the Japanese word for the Pleiades star cluster (sometimes referred to as the 7 sisters).

View of the top of Mauna Kea from the Subaru Telescope Catwalk - Credit: M.E. Schwamb

View of the top of Mauna Kea from the Subaru Telescope Catwalk – Credit: M.E. Schwamb

The images we serve on the site come specifically from the Suprime-Cam which is located at prime focus of the telescope. It has a 34′ x 27′ field of view on the sky with a pixel scale of 0.20”. We use are using the publicly available observations for the telescope which you can peruse further on your here.

Although it is 17 year old, Subaru is still one of the most powerful telescopes, by continuing to update its suite of instruments. In 2014, Subaru announced the open-use of Hyper Suprime-Cam (HSC) which is a very wide field camera with 10x field of view of old Suprime-Cam. HSC is at preset the world’s largest field-of-view camera on a 8-10-m class telescope (the largest collecting area optical telescopes we have to date). We are planning to incorporate HSC data into Comet Hunters in the near future.

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