STATUS REPORT OF FPC

FPC Science MeetingFebruary 11, 2010

Jeong Woong-Seob (KASI)MATSUMOTO, Toshio (SNU)

Current design of FPC-G, S

Field of View 6 arcmin, 0.18 arcsec/pixel

Problems of current design (FPC-G/S and FPC-G)

1. Weight Current estimation amounts to 16 kg

Requirement is < 10 kg2. Space

There is not enough space for FOV of 6 arcmin. (FPC-S) on the focal plane.

3. ScienceWe need science targets that FPC can do better than JWST.

Concept of new design of FPC

• Three channels -> Two separate channels (FPC-G and S) FPC-S has a back up function of FPC-G

FPC-S has a focus diffuser on the filter wheel

• FPC-G and S must have a same FOV and pixel scale.1K x 1K InSb array (25mm pixel) 5 arc-minutes FOV for 1 frame0.3 arc-second FOV for 1 pixel (~diffraction limit at 5mm)

• Wavelength range can be extended to optical wavelength

• Filters for FPC-S is placed in front of detector array, since the size of array is much smaller than that of previous design

• FPC-S and FPC-G are independent instrument.New name should be assigned. cf. FPC-G -> FPG (Focal Plane Guider)FPC-S -> NIC (Near Infrared Camera)

New optical design by Genesiaone more optical elementclear space before the first lens to make integration easy

a little longer than previous design (520 mm)

Spot diagram for white light (0.8-5 mm)

Typical spot size 24 mm Max spot size 31 mm

For monochromatic light2-5mm max spot size ~34 mm0.8-2mm max spot size ~42 mm

Distortion effect can be corrected by interpolation formula. Error of centroid for 4’x4’ field is

average:0.03”, Max 0.06”Error of centroid for 5’x5’ field is

average:0.07”, Max 0.37”

Structure of FPC-S

Weight ~ 10kg (FPC-S + FPC-G)Filter wheel 8 positions (blank, diffuser + 6 filters)

Detector proposed by Raytheon• Format: 1024 x 1024 active (plus two columns of

reference pixels) • Pixel Pitch: 25 μm • Input Circuit: SFD (source follower per detector) • Active Fill Factor: > 98% • Spectral Response: 0.4-5.3 μm • Average Quantum Efficiency: > 70% (1 - 5 μm) • Typical Response Uniformity: ≤ 5% (1σ) • Average Dark Current: ≤ 0.02 e-/sec at 30 K • Read Noise: < 7.5 e- rms with multiple sampling • Power Dissipation: < 1 mW • Well Capacity: 2x105 e- • Frame Time: ≤ 3 sec • Pixel Read Test: ≤ 10 μsec/pixel • Outputs: 4 • Reset Modes Global Reset or reset by Row pair • ROIC operates at <6K• Frame rate ?

Matsumoto will visit Raytheon on March 11

Expected performance of FPC-S

• Assumed parametersTelescope 3-m aperture (7m2)Efficiency 0.5 (Optical + quantum efficiency)Read out noise 20 e- Reset interval 100 sec (read out noise -> 0.2 e-)Spectral resolution, R 5

• 3s sensitivity for I hr integration 9.5 x 10-9 Jy, or 29 mag(AB) for all bandsVega magnitudeJ(1.25mm) H(1.6mm) K(2.2mm) L(3.5mm) M(5.0mm)28.2 27.6 27.2 24.2 23.7

Sensitivity has a dependence, linear to the reset intervalsquare root of number of integration

Science with new FPC-S

Smaller FOV and less angular resolution may cause difficulties in observations previously studied.

However,

Larger throughput and extension to optical band provides new science that can not be done by JWST

New mode: LVF Spectroscopy

• Three sets of LVF (Linear Variable Filter) is installed as one of filters

• LVF has transmission depending on the physical position (scanning direction). Wavelength resolution is ~ 50.

http://www.lwecorp.com/product-literature/lvf_ds_co_ae_042506.pdf

• Slit less spectroscopy at the wavelength range from 0.8 to 5 mm

• Combined with slow scan, surface spectroscopy can be done efficiently for diffuse extended source Scan direction

↓

← 5 arc-minute →

LVF

0.8-1.6 mm

1.4-2.8 mm

2.5-5 mm

Compared with grizm spectroscopy

• No source confusion• Spectroscopy of extended source is possible

Surface spectroscopy!• JWST does not have this capability

• Problem: Ghost!Antireflection coating is possible (Raytheon)Filters should be placed as far as from detector arraya kind of trade with spectral resolution of filter numbers

Expected performance for LVF spectroscopy • Assumed parameters

Telescope 3-m aperture (7m2)Efficiency 0.5 (Optical + quantum efficiency)Read out noise 20 e- Reset interval 100 sec (read out noise -> 0.2 e-), Step scan 1 pixel (0.3”) / 100 sec7 pixels can be co-added due to over samplingSpectral resolution, R 50

• 3s sensitivity for continuum7.2 x 10-8 Jy, or 26.8 mag(AB) for all bandsVega magnitude 6.3 x 10-19 x l-2 W.m-2.mm-1 (l in mm)J(1.25mm) H(1.6mm) K(2.2mm)L(3.5mm) M(5.0mm)26.8 26.2 25.8 22.8 22.3

• 3s sensitivity for line1.29 x 10-20 l-1 W.m-2 (l in mm)

• 3s sensitivity for surface brightness (l.Fl)

300 x l-1 nW.m-2.sr-1 (l in mm)

Science with spectroscopic survey

• Search for Lyman Break galaxies and Lyman Alpher Emitters at high redshift (z>8)

• AGN/ULIRG survey in collaboration with MIR and FIR observations, PAH feature

• Galactic objects, Star forming region, SNR, ?PAH, H2O, H2, CO, SiO2 etc

• Comets and solar system objects H2O, ice, SiO2,　mineral features etc

• Observation of pop.III stars Measurement of absolute brightness and fluctuation of cosmic background

The result of science meeting on Feb.11

• New optical design was approved.• FPC-G must be a simpler optical design dedicated for

the H-band observation. Reduction of weight is expected.

• Surface spectroscopy could be a special feature of FPC/SPICA.

• Number of filters are increased from 8 to 10 Filters: blank, diffuser, LVF1, LVF2, LVF3, I, J, H, K, L