A description of the mechanical and optical design and details on the on-sky commissioning runs made on both telescopes (1-m Zeiss SAO RAS and 2.5-m KGO SAI MSU) are provided in Moiseev et al, 2020

Main parameters of MaNGaL at the SAO RAS and SAI MSU telescopes

 1-m SAO RAS
(Cassegrain, F/13)
2.5-m SAI MSU
(Nasmyth-2, F/8)
Total focal ratio: F/5.26 F/3.25
IFP: ET-50 IC Optical Systems Ltd
Reducer: 1:2.2
Field of view: 11.8′ 5.6′
Pixel scale: 0.90′′ 0.33′′
Spectral range: 460–750 nm
Spectral resolution: 1.0–1.5 nm
CCD: TK1024
24×24 μm
Andor iKon-M 934
13×13 μm
Medium-band filters: Edmund optics, FWHM = 10 - 25 nm, peak transmission ~ 95%

Basic idea

Tunable filter (TF) imaging systems based on low-order scanning Fabry-Perot interferometers (FPIs) have a long history of astronomical applications related to the study of extended emission-line targets: galactic and extragalactic nebulae, solar system objects. The main idea of observations are illustrated in the next Figure. If the gap between FPI plates is small and corresponds to the interference orders n = 10−30, then it is easy to attain the FWHM of the instrumental profile δλ = 1−2 nm. Since the distance between neighbouring interference orders (interfringe) δλ = λ/n, we can cut the desired transmission peaks by the medium-band filter with a typical bandwidth of about 15–30 nm. The peak transmission central wavelength (CWL) can be switched between the desired emission line and neighboring continuum using a piezoelectrically-tuned and servo-stabilized FPI; the redshift/systemic velocity of the studied objects can be taken into account.

Tunable filter operating principle. The regions filled with various tones of orange show the transmission profiles of the FPI tuned for observations in the Hα (1) and [N II]λ6583 (2) emission lines and in the continuum (3). The blue dashed line shows the transmission curve of the medium-band filter which isolates only one transmission peak of the interferometer. The parameters of FPI and medium-band filter are similar to those used in the MaNGaL; the integrated spectrum of the NGC 4460 starburst galaxy was taken from R.Bacon+, 2014.

Optical scheme

The instrument optical scheme consists of a two-component achromatic field lens and a six-component anastigmatic photographic lens ‘Helios-44M-7’ (F/2). In contrast to the ‘classical’ optical layout having a TF in the collimated beam, MaNGaL is an afocal reducer with the FPI in the convergent beam as was proposed by Courtes. This arrangement provides a significantly larger size of a central monochromatic regions that is crucial in studying the extended targets.

MaNGaL optomechanical layout and photo of the device in the Nasmyth-2 focus at the 2.5-m SAI MSU telescope. (1) – the calibration unit; (2) – the diagonal mirror; (3) – the scanning FPI; (4) – the medium-band filters wheel; (5) – the field lens; (6) – the photo lens; (7) – the CCD camera; (8) – the control computer.


We use hard coated bandpass filters also produced by Edmund Optics. The main set of the filters with the 25-nm bandwidth is similar to that described in Dodonov et al., 2017. These filters uniformly cover the 460–750-nm wavelength interval, their trans- mission curve has an almost rectangular shape with a maximum throughput of ~ 95%. Also, we use several filters with the 10-nm bandwidth which cover the spectral regions between the 25-nm filter profiles.

The transmission curves of the filters were measured in the SAO RAS laboratory.

Pictures of filters will be here

Papers based on MaNGaL observations

  1. Star formation in the elliptical (?) galaxy NGC5173
    Sil'chenko O. K., Proshina I. S., Moiseev A. V., Oparin D. V.
    2022AstBu..77...40S; Russian PDF
  2. The TELPERION survey for distant [O III] clouds around luminous and hibernating AGN
    Keel W.C., Moiseev A., Kozlova D.V., Ikhsanova A.I., Oparin D.V., Uklein R.I., Smirnova A.A., Eselevich M. V.
  3. Medium-band photometric reverberation mapping of AGNs at 0.1 < z < 0.8. Techniques and sample
    Malygin, E.; Uklein, R.; Shablovinskaya, E.; Grokhovskaya, A.; Perepelitsyn, A.
  4. Extended gaseous disk in S0 galaxy NGC 4143
    Sil'chenko O.K., Moiseev A.V., Oparin D.V.
  5. Ionized gas in the galaxy NGC 3077
    Oparin D.V., Egorov O.V., Moiseev A.V.
    2020AstBu..75..361O; Russian PDF
  6. Measurement of the supermassive black hole masses in two active galactic nuclei by the photometric reverberation mapping method
    Malygin, E. A.; Shablovinskaya, E. S.; Uklein, R. I.; Grokhovskaya, A. A.
  7. 3D structure of the H II region Sh2-235 from tunable-filter optical observations
    Kirsanova, M. S.; Boley, P. A.; Moiseev, A. V.; Wiebe, D. S.; Uklein, R. I.
  8. Mapper of Narrow Galaxy Lines (MaNGaL): new tunable filter imager for Caucasian telescopes
    Moiseev, A. V.; Perepelitsyn, A. E.; Oparin, D. V.
  9. Photometric Reverberation Mapping of AGNs at 0.1 < z < 0.8. I. Observational Technique
    Uklein, R. I.; Malygin, E. A.; Shablovinskaya, E. S.; Perepelitsyn, A. E.; Grokhovskaya, A. A.
  10. AGN photoionization of gas in companion galaxies as a probe of AGN radiation in time and direction
    Keel, William C.; Bennert, Vardha N.; Pancoast, Anna; Harris, Chelsea E.; Nierenberg, Anna; Chojnowski, S. Drew;
    Moiseev, Alexei V.; Oparin, Dmitry V.; Lintott, Chris J.; Schawinski, Kevin; Mitchell, Graham; Cornen, Claude

Confernce posters

  1. "Kinematics and ionization properties of gas outflows in nearby galaxies viewed with Fabry-Perot interferometry."
    Alexei Moiseev, Dmitry Oparin, Aleksander Perepelitsin & William C. Keel
    15th Potsdam Thinkshop
    “The role of feedback in galaxy formation from small-scale winds to large-scale outflows”, Potsdam, Germany.
    The poster in pdf format