- HORuS temporarily unavailable
- HORuS not working
- HORuS ADR version released
- Science operations with HORuS
- HORuS commissioning completed
- HORuS First Light and commissioning
- HORuS integration
- HORuS arrival and integration at GTC
- Kick-off for the HORuS instrument
February 2022
Subject: HORuS temporarily unavailable
HORuS will not be offered for the period March–August 2022, since OSIRIS have been moved from the Nasmyth-B to the Cassegrain focus. The Nasmyth acquisition and guiding (A&G) camera will also be upgraded at this time. Until now, HORuS have been using OSIRIS to facilitate target acquisition, but with these changes the acquisition will carried out with a new A&G camera. Grantecan is evaluating the possibilty of putting HORuS back into operation in the Nasmyth focus in the near future. In any case HORuS will need to solve the problem with the cooling system prior any decision is taken.
November 2020 - December 2021
Subject: HORuS not working
In November 2020 the cryo-cooler of HORuS stopped working properly, resulting in a quasi-periodic temperature variation and a replacement is sent to La Palma. In January the Cabinet B with cryo-cooler is installed but fails to cool down the CCD. One month later the camera head is taken to Tenerife for testing. The cryo components of the camera are replaced with spares available. The camera remained cooled and stable the entire weekend so it is to ship back to GTC immediately. In March 2021 the efforts to fix the cooling system of the CCD have not produced any improvements. The system is taken back to Tenerife for further testing at the IAC. Later 2021, after a series of cleanups and tests, the HORuS team are unable to restore the CCD to regular operation. There are multiple issues such as an elevated dark current and degraded cosmetics that persist. Early 2022 the HORuS team starts to look for funds and planning the acquisition of a new detector and cooling system.
January- September 2020
Subject: HORuS ARP version released
HORuS chain for automated data reduction (ADR) was released early 2020. Late 2020 there were multiple upgrades to the HORuS chain with an improved removal of cosmic rays, and a few format in which orders are combined. The ADR software can be downloaded from here.
March 2019
Subject: Science operations with HORuS
Since March 2019 the cohort of GTC instruments has included the High Optical Resolution Spectrograph, HORuS, which allows spectroscopic observations with a broad spectral coverage (370–680 nm) and high spectral resolution (R = λ/δλ = 25,000).
March 2019
Subject: HORuS commissioning completed
The commissioning of HORuS was completed on March 2019. The observations carried out during commissioning, between November 2018 and March 2019, have recently been made public on the instrument’s web site.
May 2015
Subject: HORuS First Light and commissioning
On May 23rd took place the official first light of the HORuS instrument at GTC. The first stellar object observed by the scientific instrument was Polaris. With the instrument integrated in the telescope, works on commissioning test have already started. Two half nights and one full night were be devoted to undertake the initial set of tests designed and planned by the HORuS team, agreed and approved by the GTC team.
May 2015
Subject: HORuS arrival and integration at GTC
HORS, which weighs just over a ton and a half, left the IAC on Tuesday 19th 2015 in a truck that embarked for La Palma in the port of Los Cristianos, in the south of Tenerife. The day after the instrument was transferred by road to the Roque de los Muchachos Observatory (ORM) and its assembly at GTC took place on Thursday. The instrument integration took only one day at GTC. The first step has been the installation of the optical bench, which occupies a good portion of the Nasmyth B, shared with OSIRIS instrument (blue box on the right).
HORuS team, from IAC, as well as GRANTECAN personnel are working hard together to get this part of HORuS ready to start the commissioning the next night.
February 2015
Subject: Kick-off for the HORuS instrument
On February 12 the kick-off meeting for the HORuS instrument was held, marking the start of the design and construction of a new visitor instrument for the GTC.
HORuS was not built from scratch. Most of the components of the instrument have been at the Roque de los Muchachos Observatory, in La Palma, for 30 years, formerly integrated as the Utrecht Echelle Spectrograph (UES). UES operated on the 4.2 m William Herschel Telescope between 1991 and 2002 and, after decommissioning, the Isaac Newton Group donated the instrument to the Instituto de Astrofísica de Canarias, where it was upgraded with a new CCD and a fresh set of cross-dispersion prisms. The addition of a folding mirror reduced the original footprint substantially, allowing it to fit in the Nasmyth-B platform of the GTC, shared with OSIRIS. An optical fibre link with microlenses on both ends couples HORuS to the GTC.
The HORuS fibre link consists of an arrangement of 3 × 3 circular fibres giving a field-of-view of 2.1'' × 2.1''. The right-hand panel of Fig. 1 corresponds to an observation of the sky at twilight, showing how the solar spectrum is repeated in the nine fibres for each spectral order. The fibre array has too few fibres for meaningful spatially resolved observations, but it gives the instrument the ability to remain effective under mediocre seeing conditions. This is being exploited by multiple ‘filler’ programs on the queue-scheduled GTC that take advantage of observing conditions that cannot be used by other instruments.
Recycling most of the optical components brought about significant savings — the cost of building HORuS was about ten times lower than the price tag for similar instruments. It also reduced the human effort and construction time. The instrument was modified to become simpler, eliminating moving parts and adopting a commercial closed-circuit gas cooling system for the detector, making it essentially maintenance-free. The software packages for data acquisition and data reduction were created in-house, with simplicity as the main driver. The observing graphical interface has a calibration tab that allows the performance of full calibration (flat, bias, and wavelength calibration exposures) or wavelength-calibration-only sequences at the push of a button, illuminating the science fibres with calibration lamps.
Last modified: 16 February 2022
