From David Le Mignant (LAM) As of early 2016, several PFS spectrograph activities are on-going in parallel in France, led by Laboratoire d’Astrophysique de Marseille (LAM) with the support from the other PFS members. Among them, two major items are: 1) the thermal validation for the Visible Camera Unit: Since last year we have been undertaking this validation process (https://pfs.ipmu.jp/blog/2015/11/p124)…. Read more »
Subaru Telescope, where PFS will be installed, has been used for cutting-edge researches in astronomy and astrophysics since 1999 when it started its science operation. Because we will install a brand-new, state-of-the-art instrument on the more than 15-years old telescope, we sometimes run into difficulties due to “generation gap”. Today we will talk about network connection, one of many such… Read more »
— From David Le Mignant (LAM) We talked about the cooling verification of the cryostat body of the Visible Camera Unit for the Spectrograph at Johns Hopkins University (USA). https://pfs.ipmu.jp/blog/2015/09/p68 After that process, the cryostat body was shipped to Laboratoire d’Astrophysique de Marseille (LAM) in France, where other parts are also delivered from the collaborators and a complete Visible Camera… Read more »
As introduced in the previous post, a various parts for Spectrograph are arriving in France, where we started building up the Spectrograph and verifying its performance. https://pfs.ipmu.jp/blog/2015/08/p17 This time, we are talking about dichroic mirror as one key parts in the spectrograph. PFS delivers spectra covering such a wide range of wavelengths as from visible to near infrared with a… Read more »
One of the unique features of the PFS instrument is its multiplicity: Using 2400 fibers, a number of spectra of stars and galaxies can be obtained simultaneously. The actuator named “Cobra”, which is comprised of two motors, is used for moving each fiber to the position of an astronomical object of interest on the focal plane. The “patrol area”, where each fiber attached to Cobra… Read more »
The cooling experiment of camera modules for spectrograph is going on at Johns Hopkins University, the US. In order to observe faint stars and galaxies, astronomical detectors in visible and near infrared are used under very low temperature (-100 degree Celsius / -148 degree Fahrenheit or less than it) and high vacuum (less than one billion of atmospheric pressure). By this experiment… Read more »
The PFS project has reached a major milestone toward completing the instrument. PFS has four identical spectrograph modules in order to observe about 2400 astronomical objects. Among them, various modules for the first spectrograph are coming to a clean room at Marseille Observatory (LAM) in France from our team over the world. (delivery of modules) Below are the pictures of the modules;… Read more »
We will observe ~2400 objects using four identical spectrograph modules, each of which acquires ~600 spectra of astronomical sources and calibration sources. Each module covers wide wavelength range on visible and near-infrared band (380 — 1260 nm). To achieve this, the module has 3 camera units; visible-blue, visible-red and near-infrared. The light of each band is introduced by using two “dichiroic mirrors”, which split the light at a given wavelength.
PFSでは約2400個の天体を観測しますが、4つの同型の分光器を用いてそれぞれ600本のスペクトルを取得します。各分光器は可視光域から近赤外域までの広い波長範囲 (380 から1260 nm) をカバーする為、「可視光域青用」、「可視光域赤用」、「近赤外域用」の3つのカメラユニットを持っています。3つのカメラには、特定の波長で光を分けることのできるダイクロイックミラーを2つ用いて、光を導入します。
To measure the fibers position on the focal plane, “Metrology Camera System” is attached on the Cassegrain focus of Subaru telescope. Looking up to the prime focus (see this image from HSC blog for clear image), this camera takes a image of back-illuminated fibers. Thanks to a large format of ~50 M pixels CMOS sensor, this camera can acquire all ~2400 fiber spots in a single exposure. The camera system is also designed to execute the process from exposure to measurement of fiber centroids within 5 seconds. Effective measurement of the fibers position enables us to shorten overhead for fiber configuration and execute large statistical survey observation.
The Metrology Camera System will be delivered to Subaru in early 2018.
焦点面上のファイバーの位置を測定する為に、『メトロロジカメラシステム』をすばる望遠鏡のカセグレン焦点に取り付けます。このカメラは焦点面を見上げるようにして後ろ側から照らされたファイバーの画像を取得します(イメージ的にはこちらの画像 (HSCブログより) のような感じです)。メトロロジカメラには50Mピクセルの大判のCMOSセンサが搭載されているため、約2400本のファイバー像をたった一回の露出で得ることができます。また、画像の取得から各ファイバーの位置測定までを5秒以内に行うように設計されています。このようにファイバーの効率よく位置を測定することで、ファイバーの配置など観測準備にかかる時間をなるべく短くし、大規模サーベイ観測を行うことができるのです。
メトロロジカメラシステムは2018年4月にすばる望遠鏡へ搬送されるました。
The Spectrograph Clean Room is a room whose size is 6.7 m wide, 8.6 m long ,and 3.6 m high. Four PFS spectrographs will be accommodated in the clean room. To stabilize the spectrograph performance, the temperature in the room will be controlled at 5 +- 1 degree Celsius. Besides, a crane with capability of 500 kg is installed for assembly and maintenance of the Spectrograph.
分光器設置室は、すばる望遠鏡ドーム棟4階に建設された部屋で、幅6.7m × 奥行8.6m × 高さ 3.6 mの大きさです。 PFSの4台の分光器がこの部屋に設置されます。分光器の安定性を図るために、部屋全体が5±1℃の範囲で温度管理されます。また、分光器の設置やメンテナンス用に室内には耐荷重500kgのクレーンが設置されています。
