Grism Spectroscopy with FLITECAM

Erin C. Smith (UCLA)Ian S. McLean (UCLA)

FLITECAM1- 5.5 micron NIR camera

1024x1024 InSb Aladdin III detector

Optics cooled to ~ 80K with LN2

Detector controlled at 30K

SOFIA

8 arcminute circular FOV

.43 arcsec/pixel (SOFIA)

.48 arcsec/pixel (Lick)

Entrance aperture Slit mechanism Collimator

Dual Filter Wheel Re-imaging optics

Detector

Why spectroscopy?

• Water Vapor monitor calibration– Resolve 2.5 micron water line (need R~1000)

• Allows low background, low water vapor spectroscopy in the thermal (3-5.5 micron IR)– No spectral coverage by Spitzer at these wavelengths

Science

PAH features at 3.3 m

Water ices 2.5-4.6 m

Pa-a (1.87 m )

Br- (4.05 m )

Grism Spectroscopy

d

dpupil

Xmm=dpupil/cos AA

i

d

grism normal

T m c= (n –1) sin A

R = 206265 (n – 1) dpupil tan A / Dtel sarc ,

(max/min wavelength) = c +/- [(n – 1) dpix cos A / Fcam m T] *Npix/2,

KRS-5

• N~2.4• Thalium bromo-iodide

• Manufactured by Zeiss-Jena– Can make grisms with T=651/n, up to 40 degrees

Grism T Order OSF c

A 162.75 1 L&M 4.96

A 162.75 2 Klong 2.5 A 162.75 3 Hwide 1.69 B 217 1 L&M 3.73 B 217 2 Hwide 1.86 B 217 3 J 1.28 C 130.2 2 L&M 3.11 C 130.2 3 Kwide 2.11 C 130.2 4 H 1.62

Wavelength coverage

Slit

Lab testing• Neon Argon lamps used to calibrate wavelength solutions

• Slit width found to be slightly larger than designed, narrow slit is 1.3”, wide slit is 2.35” wide

• R ~1700/900

FLITECAM also mounts to the Shane 3 meter telescope at Lick Observatory

Imaging mode commissioned October 2002

Spectroscopy mode was commissioned in June 2004

Difference RAW

C + KwideC + LM

69 Leo

A0V star, for telluric standards

High backgrounds at Lick require differences in thermal IR

1.872

2.346

2.756

3.467

Gl406- (M5.5)

Raw H band spectrum

A-B spectrumHigh-res

position B

High res position A

Data reduction

NGC 7027

Imaging & spectroscopy

• Switching between spectroscopy and imaging takes less than 20 seconds

• Using narrow band filters, we can make maps of spectral features, then use spectroscopy to investigate

Aboard SOFIA