instruments

the enclosure

The telescope building (8m x 4m, height 2.5m) was designed by VERIMO SL (Malaga, Spain) and built by ACONDIMA SL (Malaga, Spain), 20m from to the main OSN building hosting the 1.5 and 0.9 diameter telescopes. The interior is divided into the small control room housing the telescope electronics and computers, and the technical room directly below the dome containing the liquid N2 tank, and the telescope pillar (1m diameter, 2.5m height). The pillar is anchored in a separate 1.5m x 1.5m x 1.5m foundation.

A 3.6m diameter fibre-glass clamshell-dome provided by AstroHaven (Langley, Canada) was installed in summer 2003 in order to assure inmediate access to any part of the sky. An inner 3.4m diameter canvas clamshell-dome provided by Toldoe La Nueva Granada (Granada, Spain) was installed as well, since the outer dome has proven not to be totally sealed against snow or rain during the severe winter conditions in Sierra Nevada. The 3.6m fiber-glass dome has been replaced by 4.0m diameter dome in Summer 2006.

the telescope

The telescope was designed by ASTELLCO GmBH (Munich, Germany) and delivered in November 2004. It is a 0.6 Ritchey-Cretien working at f/8. It is direct drives allow it to slew of 10° per second, being capable of pointing any part of sky within 20 seconds, with the typical slew time of 5 seconds. It has two Nasmyth foci, on of which is ocuppied by both the nIR and optical cameras. Initially the second Nasmyth will be idle, although future instrumentation is foreseen.

the nIR camera

The BOOTES-IR camera, also dubbed BIRCAM, was designed by LT Calcodi SAS (Merate, Italy), in collaboration with optical designers of Observatorio Astronomico di Breta (Merate, Italy), following the requirements of the BOOTES-IR Team, under a very fruiful collaboration. BIRCAM is placed at the Nasmyth focal station of the 60cm telescope. It has high transmission optics and it is equipped with a high readout speed controller, The philosophy of design is compactness and light weight.

the dichroic

An interface dubbed "Dadone" is mounted on the flange with the function of linking the visual and nIR cameras. Both the dithering wedge and the dichronic lie within this interface.

A 45° dichroic placed before the entrance of BIRCAM has been purchased from OptoPL (San Petersburg, Russia) with the coating performed by Gestione SILO (Firenze, Italy). The incoming light is divided, with visible light at...

the dithering wedge

Since there are two instruments observing simultaneously, it is not practical to use a chopping secondary, or to nod the telescope in order to substract the sky background. The solution is a motor-driven rotating dithering wedge, placed after the dichroic, slanted in our case at the angle of 20°, that allows a point source to be positioned on a circle 60 pixels in diameter.

the dewar

The detector is cryogenically cooled to a working temperature of 77 K by a change (8 litres) of liquid N2, half-filling an annular tank inside the vacuum dewar. The system is manufactured by RIAL Vaccum (Parma, Italy) and operates equally well in all rotations about the cameras long axis, as required by the position of the camera on the telescope de-rotator.

the optics

The BIRCAM optics have been designed in Observatorio Astronomico di Breta (Merate, Italy) and purchased from OptoTL (San Petersburg, Russia) and Ottica Colombo (Rovagnate, Italy). The optical train is composed of two types of glass: CaF2 and SFTM-16 (from the O'Hara calalogue). The infrared beam leaving the dichronic and dither-wedge beam leaving the Nasmyth passes though a dichronic (CaF2) that divides the light between nIR and visible. The visible path is reflected 90°, while the nIR one goes along the axis. After the dichroic is placed a dithering wedge, slant by a angle of 20°. After that, the light enters into the dewar through a CaF2 window, a collimator (three lenses: two SFTM-16, one CaF2), a filter wheel, and the collimated beam is refocused onto the detector through a camera composed of a further three lenses (two CaF2 plus one SFTM-16). The field of view is 12'.7 x 12'.7 with a scale of 0.74"/pix.

the filter set

The filter wheel has 8 x 25mm filters, and is driven by a stepper motor outside the dewar, via a low conductivity shaft. The filter set contains five broad band filters (zYJJHK) plus two narrow band filters (H and B). The JHK filters are similat to those operating in REM and were ordered from Barr Asociates, Inc. in 2001.

the detector

We are making use of a HAWAII-1 1024 x 1024 HgDdTe detector produced by Rockwell. It has a high-resolution 18.5 microns pixel pitch and comprises four independent quadrants with direct bus outputs, and low dark current bellow 78K. These science-grade detectors are well suited for Astronomical research and have been used in several astronomical instruments already.

last results

last publications