Editing BeppoSAX (section)

== Instrumentation ==
BeppoSAX contained five science instruments:
* Low Energy Concentrator Spectrometer (LECS)
* Medium Energy Concentrator Spectrometer (MECS)
* High Pressure Gas Scintillation Proportional Counter (HPGSPC)
* Phoswich Detector System (PDS)
* Wide Field Camera (WFC)

The first four instruments (often called Narrow Field Instruments or NFI) point to the same direction, and allow observations of an object in a broad energy band of 0.1 to 300 keV (16 to 48,000 [[Joule|attojoule]]s (aJ)).

The WFC contained two [[coded aperture]] cameras operating in the 2 to 30 keV (320 to 4,800 aJ) range and each covering a region of 40 x 40 degrees (20 by 20 degrees full width at half maximum) on the sky. The WFC was complemented by the shielding of PDS which had a (nearly) all-sky view in the 100 to 600 keV (16,000 to 96,000 aJ) band, ideal for detecting [[gamma-ray burst]]s (GRB).<ref>{{cite journal|first=R.|last=Jager|title=The Wide Field Cameras onboard the BeppoSAX X-ray Astronomy Satellite
|url=https://aas.aanda.org/articles/aas/full/1997/15/h0320/h0320.html|volume=125|pages=557–572|date=October 1997|journal=Astronomy and Astrophysics Supplement Series|issue=3 |doi=10.1051/aas:1997243 |bibcode=1997A&AS..125..557J |access-date=October 13, 2022|doi-access=free}}</ref>

The PDS shielding has poor angular resolution. In theory, after a GRB was seen in the PDS, the position was refined first with the WFC. However, due to the many spikes in the PDS, in practice a GRB was found using the WFC, often corroborated by a [[BATSE]]-signal. The position up to [[arcminute]] precision - depending on the signal to noise ratio of the burst - was found using the deconvoluted WFC-image. The coordinates were speedily sent out as an [[International Astronomical Union]] (IAU) and Gamma-ray burst Coordinate Network Circular. After this, immediate follow-up observations with the NFI and optical observatories around the world allowed accurate positioning of the GRB and detailed observations of the X-ray, optical and radio afterglow.

The MECS contained three identical [[X-ray astronomy detector|gas scintillation proportional counter]]s operating in the 1.3 to 10 keV (208 to 1602 aJ) range.<ref>{{cite web|title=The medium-energy concentrator spectrometer on board the BeppoSAX X-ray astronomy satellite|url=https://hera.gsfc.nasa.gov/docs/sax/instruments/new_mecs.html|access-date=October 12, 2022|publisher=nasa.gov|archive-date=October 13, 2022|archive-url=https://web.archive.org/web/20221013043818/https://hera.gsfc.nasa.gov/docs/sax/instruments/new_mecs.html|url-status=dead}}</ref> On 6 May 1997 one of the three identical MECS units was lost when a fault developed in the High Voltage power supply.<ref name=saxstat>{{cite web|title=BeppoSAX Status|url=https://hera.gsfc.nasa.gov/docs/sax/email/sax_status.html#17dec1996|access-date=October 13, 2022|publisher=nasa.gov|archive-date=October 14, 2022|archive-url=https://web.archive.org/web/20221014020724/https://hera.gsfc.nasa.gov/docs/sax/email/sax_status.html#17dec1996|url-status=dead}}</ref>

The LECS was similar to the MECS units, expect that it had a thinner window that allows photons with lower energies down to 0.1 keV (16 aJ) to pass through and operated in a "driftless" mode which is necessary to detect the lowest energy X-rays as these would be lost in the low field regime near the entrance window of a conventional GSPC. The LECS data above 4 keV (641 aJ) is not usable due to calibration issues probably caused by the driftless design. The LECS and MECS had imaging capability, whereas the high-energy narrow field instruments were non-imaging.<ref>{{cite news|title=The low-energy concentrator spectrometer on-board the SAX X-ray astronomy satellite|url=https://hera.gsfc.nasa.gov/docs/sax/instruments/parmar_etal_AaAS.html|access-date=October 13, 2022|publisher=nasa.gov|archive-date=October 14, 2022|archive-url=https://web.archive.org/web/20221014002621/https://hera.gsfc.nasa.gov/docs/sax/instruments/parmar_etal_AaAS.html|url-status=dead}}</ref>

The HPGSPC was also a gas scintillation proportional counter, operating at a high (5 atmospheres) pressure. High pressure equals high density, and dense photon-stopping material allowed detection of photons up to 120 keV (19,000 aJ).<ref>{{cite web|title=The High Pressure Gas Scintillation Proportional Counter on-board the BeppoSAX X-ray Astronomy Satellite|url=https://hera.gsfc.nasa.gov/docs/sax/instruments/hp.html|access-date=October 13, 2022|publisher=nasa.gov|archive-date=October 14, 2022|archive-url=https://web.archive.org/web/20221014002607/https://hera.gsfc.nasa.gov/docs/sax/instruments/hp.html|url-status=dead}}</ref>

The PDS was a crystal ([[sodium iodide]] / [[caesium iodide]]) scintillator detector capable of absorbing photons up to 300 keV (48,000 aJ). The spectral resolution of the PDS was rather modest when compared to the gas detectors, but the low background counting rate resulting from the low inclination BeppoSAX orbit and good background rejection capabilities meant that the PDS remains one of the most sensitive high-energy instruments flown.<ref>{{cite web|title=The high energy instrument PDS on-board the SAX X-ray astronomy satellite|url=https://hera.gsfc.nasa.gov/docs/sax/instruments/pds.html|access-date=October 13, 2022|publisher=nasa.gov|archive-date=October 14, 2022|archive-url=https://web.archive.org/web/20221014002603/https://hera.gsfc.nasa.gov/docs/sax/instruments/pds.html|url-status=dead}}</ref>