lisa spectrograph long slit intermediate resolution spectrograph for astronomy performances and...
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LISA spectrographLong slit Intermediate resolution Spectrograph for Astronomy
Performances and application
Christian Buil
Active Spectroscopy in AstronomyEssen – 7 May 2011
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Spectrograph resolution categories ( R)
High resolution Lhires R = 16000
eShel R = 11000
Medium resolution(or intermediate)
LISA R = 500 to 1000
Low resolutionStar Analyser R = 100 to 200
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Spectral resolution (R) and luminosity (L) : a complementary effortR x L = constant
Planetary nebulae NGC 2392 – 15 x 30 seconds
Faint object spectroscopyThe example of Star Analyser : very low resolution, very high luminosity
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But do not mystake luminosity and detectivity !
Faint object spectroscopy
One limitation of slitless spectroscopy : sky background pollution
The symbiotic star V1016 Cyg
Another limitation of SA : optical aberration
Chromatic coma : a source of detectivity degradation (bad capacity to concentrate energy)
Grism improvement
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Faint object spectroscopy
The importance of an entrance slit
Large slit
Narrow slit
The sky background level if proportionnal to the slit wideThe backgroung photon noise is proportionnal to the square root of slit wide
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The LISA concept (1/2)
- Ajustable entrance slit by step (from 15 microns to 100 microns) (capacity to optimise spectral resolution to a specific target)
- Fast input beam : up to f/5 input i.e. high luminosity spectrograph (reduce potential guidance problem because shorter focal length, capture of faint surface objet like galaxies, comets, …
- Optimized spectral dispersion to modern camera (2 A / pixel sampling on a popular KAF8300 CCD ship)
- Balance between power resolution capacity and scientific interest (R = 500 to 1000 typically) – Sodium doublet is just separated with a 23 microns slit
Mg I,2,3 NaDA, D2 Halpha
2D spectrum of moon surface
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- Wide spectral range in one shot : 3950 A – 7200 A (+ IR option)
- Integrated calibration system (neon lamp + tungsten lamp) : easy to use and standard pipeline processing. Possibility to fully automatize acquisition.
- Compact and moderate weigth : adaptable on small refractor and refractor.
- Low cost : large diffusion if possible!
The LISA concept (2/2)
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Optical design
Internal grandissement G = 0,603
For example: if the telescope focal / diameter ratio is 6, the final F/D is 6 x 0,603 = 3,6(LISA is equivalent to a focal reducer).
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Mechanical design
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Mechanical design
Calibration unit Ajustable grating angle
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Pointing and guidance system
High reflectivity slitVery constant edge
High quality slit image on the guidance camera(here M104 galaxy with a Watec 120N)
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LISA on a Celestron 11 telescope
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Calibration module (spectral calibration and flat-field)
Electromagnetic system – 12 V power – Remote operation possible
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Interfaces
Optimal input focal ratio f/5 to f/7A fast Newton telescope is ideal (achromatism)
For SC Telescope : focal reducer(here a Baader Alan Gee - final ratio f/6.8)
Fast adaptation for CCD camera and DSRL
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Example of setup with Atik CCD cameras
Atik 314L for spectra acquistion (1390 x 1040 x 6.45 µm pixel size)Readout noise : 4.5 e-, Camera gain : 0.250 e-/ADU, typical quantum efficiency @ 656 nm : 55%
Atik Titan for pointing and guiding functions(faint object identification capability + rudimentary photometry measure on the targets)
Low cost solution for LISA, low mass on the telescope, high performances
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Amovible entrance slitHigh precision chromium serigraphy
Slit 23 microns – R = 1100W = 2,5 arcsec on C11 f/6.8
Slit 50 microns – R = 600W = 5.4 arcsec on C11 f/6.8
15 – 19 – 23 – 32 microns (option 50 – 75 – 100 microns + 19 microns hole)
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Automatised processingRlhires application
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Automatic spectral calibration by using observed type A, B or G star spectra and internal neon lamp spectrum
Fit dispersion law with a 3e order polynomial function (typical RMS error : 0.3 to 0.4 A) 18Essen - 7 May 2011
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Many tools available : computation of heliocentric velocity, H2O removal, atmopsheric transmission, spectra database, …. French/english interface
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Slit 23 µmR = 1100
Slit 50 µmR = 600
Slit 100 µmR = 290
D = 12.8 cmF/D = 8
12.5 13.1 13.4
D = 28 cmF/D = 6.8
13.6 14.6 15.0
D = 35 cmF/D = 6.8
13.9 14.9 15.4
D = 50 cmF/D = 6.0
14.4 15.5 16.2
D = 100 cmF/D = 6.0
15.2 16.3 17.2
Slit 23 µmR = 1100
Slit 50 µmR = 600
Slit 100 µmR = 290
D = 12.8 cmF/D = 8
13.1 13.6 13.9
D = 28 cmF/D = 6.8
14.5 15.2 15.6
D = 35 cmF/D = 6.8
14.8 15.6 16.1
D = 50 cmF/D = 6.0
15.3 16.3 16.9
D = 100 cmF/D = 6.0
16.1 17.3 18.2
Integration time : 1 hour (6 x 600 sec)Signal to noise ratio = 10 (@ Halpha)
Type A0V star – Seeing = 3 arcsecCCD KAF-8300 (Binning 1 x1)
Limit magnitude
Altitude 0 m - Suburban Altitude 3000 m – Dark sky
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Slit 50 µmR = 600
Slit 100 µmR = 280
D = 12.8 cmF/D = 8
13.7 14.0
D = 28 cmF/D = 6.8
15.4 15.8
D = 35 cmF/D = 6.8
15.8 16.2
D = 50 cmF/D = 6.0
16.4 17.0
D = 100 cmF/D = 6.0
17.4 18.3
Slit 50 µmR = 600
Slit 100 µmR = 280
D = 12.8 cmF/D = 8
14.2 14.5
D = 28 cmF/D = 6.8
15.8 16.2
D = 35 cmF/D = 6.8
16.2 16.7
D = 50 cmF/D = 6.0
16.9 17.5
D = 100 cmF/D = 6.0
17.8 18.7
Integration time : 1 hour (6 x 600 sec)Signal to noise ratio = 10 (@ Halpha)
Type A0V star – Seeing = 3 arcsecAltitude 3000 m – Dark sky
Limit magnitude (function of detector type)
CCD KAF-8300 (Binning 2 x2) CCD KAF-3200 (Binning 2 x2)
3 hours integration (18 x 600 sec) – Slit 50 µm – D = 28 cm F/D = 6.8 M = 16.1 (KAF-8300)M = 16.5 (KAF-3200)M = 16.6 (ICX424AL)
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Slit 50 µmR = 600
Slit 100 µmR = 280
D = 12.8 cmF/D = 8
14.3 14.7
D = 28 cmF/D = 6.8
16.0 16.3
D = 35 cmF/D = 6.8
16.4 16.8
D = 50 cmF/D = 6.0
17.1 17.6
D = 100 cmF/D = 6.0
18.1 19.0
CCD ICX285AL (Binning 2 x2)
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Observation with LISA spectrograph
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Star Analyser
Typical aspect of LISA 2D spectraSymbiotic star V1016 Cyg
2D spectrum before sky removal (23 µm slit)
2D spectrum after sky substraction
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Symbiotic star V1016 Cyg (V = 11.2) : lines identification
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First step : observation of normal stars (1/2)
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First step : observation of normal stars (2/2)
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Survey of know Be Star + and detection of new Be star
Beta Lyrae (Shelyak) – 15 x 30 s
Rapid scan of B and A star for Halpha emission signature (5-10 minutes exposure)(list of nearly 1000 stars – magnitude < 10)
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Faint Be stars observation (BeSS)
V = 6.09 – 9 x 120 s V = 4.74 – 8 x 60 s
V = 8.62 – 6 x 300 s (new BeSS entry) V = 8.63 – 7 x 300 s (new BeSS entry) 28Essen - 7 May 2011
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Survey of cataclysmic(novae like)
SS Cyg outburst (V = 8.7) – April 4.1, 2011
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List of cataclysmic star (François Teyssier)
…
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Outburst of cataclysmic V694 MonHigh velocity wind – Fast evolution
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V694 Mon – Visible + IR capacity of LISA spectrograph
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Recurent nova T Pyxidis : day to day monitoring of profile evolution
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T Pyxidis 2D spectrum
6 arcsec refractionat 12 degree elevation
Paralactic angle
Observation at very low angular elevation : associated problemT Pyxidis declinaison = -32 degrees
Horizon
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Nova Sagittarii 2011 #2 (V5588 Sgr)V = 13.2
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Eruption of Herbig Ae/Be star Z CMa
Vis + IR spectrum
Detail of IR spectrum
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MIRA starR Leo at V = 8.5
Wide band spectrum
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HD 56925 in NGC 2359 nebula
Wolf-Rayet star HD 56925WR 7 – V = 11.7
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R Mon in NGC 2261 nebula3 x 600 s @ R = 1000
Messier 1 (Crab nebulae) - 5 x 600 s @ R = 600
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SUPERNOVASN 2011ae in MCG-3-30-19
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SUPERNOVASN 2011by in NGC 3979
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Messier 104Sombrero galaxy
Audela autoguiding
2D spectrum
Na rest = 5892.9 A - Na observed = 5916.9 A – z = (5916.9 – 5892.9) / 5892.9 = 0.0041 (17 Mpc)
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NGC 4151
NGC 4051
Active galaxies (Seyfert)
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McDonald 2,1 mK. Thompson AJ, 395, 404,417, 1992
Quasar 3C273
Observed Halpha at 7584 Az = (7584 - 6563)/6563 = 0.155(official z = 0.158)
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LISA infrared version
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Quasar Mrk 205 observation(V = 15.5)
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Observed z = 0.0710 (official value z = 0.0705)
Quasar Mrk 2057 x 600 sec. – 50 µm slit
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Thank you
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