Telescopes in AO Belogradchik:
  1. Kassegrain 60cm - Zeiss.
  2. Schmidt-Kassegrain 14inch - Celestron.
  3. Kassegrain 15cm - Zeiss.
  4. A few small binocular intruments.
Photo receiving instruments:
  1. Photometer with EMI-9789.
  2. New photometer still in test phase.
  3. CCD camera SBIG ST-8.
  4. CCD camera Star-1.
  5. Planetary and stellar photocameras.
Filter sets:
  1. BVRcIc Johnson-Cousins standard filters
  2. Comet photometry filter set

The 60cm telescope

The 60cm Kassegrain telescope was mounted in August 1969 in the 6m dome of the observatory. Its focal length is 7500mm. Currently, it is being worked on its automation. It is equipped with a electrophotometer working in photon counting regime with UBV filter system, and a CCD camera ST-8. There is also a new photometer still in test phase. The picture to the left shows the telescope with the ST-8 CCD camera.

The 14inch telescope

The 14inch Celestron telescope is mounted in the 4m dome in 1994. It is equipped with a Star-1 CCD camera. This telescope is fully automated and has a database of 8000 deepsky and stellar objects.

The 15cm telescope

The 15cm Zeiss Kassegrain telescope is the first instrument at the AO Belogradchik. It had been mounted in the 6m dome till 1969, when the 60cm one arrived. Now it is used for demonstrations. It is equipped with a planetary and stellar photocamera, and a big set of eyepieces.

The electrophotometer

This photometer was built in 1985. The core of this photometer is the EMI-9789 photomultiplier. In 1997 the HF amplifier was changed with a new one built in Ukraine.

The new photometer

It is still in test phase. Hopefully it will soon be fully operative. The optical and machanical parts were made in the Bulgarian Academy of Sciences, and the electronic part - in Ukraine.

The ST-8 CCD camera

This camera has been in the observatory since 1997. The core of SBIG ST-8 is a Kodak KAF1600 CCD with a resolution of 1530x1020 pixels, and a 16 bit ADC. The linear dimensions of the active area are 13.8x9.2 mm (9x9 micron pixel). CCD spectral sensitivity reaches maximum at 6750 A, and half-drops at approximately 4500 and 7500 A. The field in the main focus of the 60cm telescope is 6.4'x4.2'. Basically BVRcIc Johnson-Cousins standard filters are used. Another filter set for comet photometry is available.

The Star-1 CCD camera

Star-1 is a 12 bit CCD camera with a good cooling system which achieves -42deg Celsius.

BVRcIc Johnson-Cousins standard filters

The comet photometry filters


filter Center FWHM Transparency
1 3860 60 40%
2 4050 90 50%
3 4430 50 70%
4 5120 120 80%
5 6630 30 80%
6 6840 100 85% 
 

Rumen G.Bogdanovski
(c)1999