1. The 2-channel focal reducer (FoReRo2): a new observing facility for the 2-meter telescope Tanyu Bonev Institute of Astronomy Bulgarian Academy of Sciences 1.Optical parameters 2.Mechanical design 3.Modes of observations with examples 4.Conclusions

2. 16 m Focal length 5.6 m f/8 f ratio f/2.8 0.31 arcsec/px Scale (1 px = 0.024 mm) 0.88 arcsec/px

4. FoReRo2: Modes of Observations 1. Broadband imaging 2. Narrowband imaging 3. Long slit spectroscopy 4. Fabry-Perot imaging 5. Imaging polarimetry

5. FoReRo2: Broad band imaging and photometry Available Filters: U, B, V, R, I Example: Landolt field PG1633+099, filter V, Exposure = 15 sec

6. FoReRo2: long slit spectrography Blue Channel Red Channel 600 lines/mm300 lines/mm 0.3 nm/px 0.5 nm/px Long slit: Length: covers the full FOV Width: 110 microns = 1.5 arcsec Grating prisms (grisms)

7. 490 nm FoReRo2: long slit spectrography Blue Channel Red Channel

8. FoReRo2: low dispersion spectra 490 nm Blue Channel Red Channel

9. FoReRo2: Fabry-Perot Imaging NameKindUseful range nm Reference wavelength nm Free spectral range mounted Quensgate visual tunable410 - 7006275.8Before beamsplitter Quensgate blue tunable355 – 510374.74.3Before beamsplitter CSIRO visual Fixed airgap 410-7006200.21Before beamsplitter CSIRO redFused silica 450-7006150.26Red arm CSIRO blue Fused silica 350-5304000.17Blue arm

10. FoReRo2: Fabry-Perot Imaging interferogram of [OI] 6300 in comet Q4 (NEAT), obtained on May 23, 2004. Interference filter + 500 micron Fabry- Perot etalon in the red channel. Exposure: 600 sec [OI] 6300 night sky emission

11. FoReRo2: Imaging polarimetry mode Comet Q4 (NEAT) Optical arrangement +45 o 0o0o 90 o -45 o

12. FoReRo2: Narrow band imaging Part of the available interference filters Blue channelRed channel Filters for cometary observations 390 nm - CN 406 nm - C 3 426 nm - CO + 443 nm - Blue Continuum … 590 nm - Na 616 nm - H 2 O + 630 nm – [OI] 642 nm – Red Continuum … Filters of common interest [SIII] 3722 [SII] 4069, 4076 [OIII] 5007 … [OI] - 6300 H alpha - 6563 [SII] 6716, 6731 …

13. Narrow band imaging of comet Q4 (NEAT) On-line, 616 nm, H 2 O + Off-line, 642 nm, Continuum - k *

14. Comet Q4 (NEAT), May 26, 2004 H 2 O + ions in the near nucleus region

15. Comet Q4 (NEAT), May 26, 2004 Dynamics of the H 2 O + ions in the near nucleus region 11 frames x 300 sec exposure Total time of the sequence < 1 h

16. FoReRo2: Conclusions The 2-channel focal reducer increases the power of the 2-meter telescope by: 1.Changing the f ratio from f/8 to f/2.8 2.Allowing simultaneous data acquisition in two spectral ranges The 2-channel focal reducer offers several modes of observations: 1.Broad band imaging 2.Narrow band imaging 3.Long slit spectroscopy 4.Fabry-Perot imaging 5.Imaging polarimetry