Equipment for observations

 

Observatory

                        The observations are performed using the telescopes and instruments of the Wise Observatory of the Tel-Aviv University. The observatory (code: 097) is located on a high plateau in the central part of the Negev desert (E 34:45:47, N 30:35:46 altitude 875 m, time zone is -2 hours relative to Universal Time). The site is about 5 km west of the town of Mitzpe Ramon and 170 km south of Tel-Aviv. The observatory is equipped with two refractors: A 1-m Ritchey-Chrétien telescope; and a 0.46-m Centurion telescope.

 

Telescopes

The 1-m telescope:

The Boller and Chivens telescope is a wide-field Ritchey-Chrétien reflector mounted on a rigid, off-axis equatorial mount. The optics are a Mount Wilson/Palomar Observatories design, consisting of a 1-meter (40-inch) diameter clear aperture f/4 primary mirror, a 20.1-inch diameter f/7 Ritchey-Chrétien secondary mirror, and a quartz corrector lens located 4 inches below the surface of the primary mirror, providing a flat focal field of up to 2.5 degrees in diameter with a plate scale of 30 arcsec mm-1. Excluding some local opening and calibrating procedures, the 1-m telescope can be operated remotely through an internet excess.

 

The 0.46-m telescope:

            The 18'' Centurion telescope (referred to as C18; see Brosch et al. 2008 for a description of the telescope and its performance) is a small and modern telescope manufactured by AstroWorks, USA. The 18'' (0.46-m) mirror is assembled on a fork mount, while the focal plane is maintained at the proper distance from the primary mirror by a carbon-reinforced epoxy plastic truss tube structure. The CCD is set at the f/2.8 prime focus.

            The C18 can be fully operational from remote via the internet and can automatically switch exposures and targets. Some additional abilities were added at the Wise Observatory such as automatic reaction to weather conditions, robotic cover control and remote operation settings. Most of the observing nights reported in this work, were performed remotely from many places but the Wise Observatory (like Tel-Aviv, Be'er-Sheva, Ra'anana, Ramot-Meir in Israel and even Pasadena, CA, and Cairo, Egypt). The availability of the C18 made it a powerful tool for photometric time-series observations of many different objects.

 

CCDs

During the last years, photometry of asteroids at the Wise Observatory were performed using 3 cryogenically-cooled CCDs on the 1-m telescope and two CCDs on the 0.46-m. The characterizations of these CCDs are presented at the following table:

CCD

PI

SITe

Tek

SBIG STL-6303E

SBIG ST-10XME

Mounted on telescope

1-m

1-m

1-m

0.46-m

0.46-m

CCD size [pixels]

1340 x 1300

4096 x 2048

1024 x 1024

3072 x 2048

2184 x 1472

Field of View [arcsec]

13' x 13'

34' x 17'

12' x 12'

75' x 55'

40.5' x 27.3'

Pixel size [mm]

 

15

24

 

6.8

Arcsec to pixel

0.58''

0.872'' (binning 2x2)

0.697''

1.47''

1.1''

Read noise [per pixel]

2.87

12

6/5

15

10

Gain [per ADU]

2.1

5

8.42

1.38

1.37

Reading out time [sec]

 

100

32

 

15

Filters on wheel

8

4

8

5

None

 

The C18 telescope. The mirror is at the telescope's bottom, while the CCD it's at the top.

 

The RC40 telescope. The CCD is at the telescope bottom part.

 

Cleaning the prime mirror (1 meter) of the RC40 telescope.

The light beams transverse through the hole in the middle to the CCD

(and in between reflects from the secondary mirror).

 

The SITe CCD. The golden jar holds the liquid nitrogen for cooling.

 

 

The ST-10XME is mounted on the upper side of the C18 telescope.