1. GIFTS Blackbody Subsystem Critical Design Review Blackbody Requirements Flowdown
Fred Best
9 March 2004

2. Topics GIFTS Calibration Scheme Flowdown of requirements
Blackbody Error Contributions to GIFTS Calibration
Overview of Top Level BB Subsystem Specifications

3. GIFTS Radiometric Calibration Concept
Two small reference Blackbodies located behind telescope, combined with Space View.
Blackbody design is scaled from the UW ground-based AERI and NAST / S-HIS aircraft instruments.
Constraints on original S/C prevented traditional external large aperture blackbody configuration.
Advantages compared to large external blackbody: (1) higher emissivity is practical with small size (2) protection from solar forcing.

4. GIFTS Electro-optical Diagram

5. Aperture stop image at blackbody aperture
GIFTS Sensor Module
BENCH
FORE OPTICS BAFFLE
A-FOCAL BAFFLE
AFT OPTICS
BAFFLE
FORE OPTICS
SECONDARY BAFFLE
PMA BAFFLE
BLACKBODIES
Blackbodies
Aperture stop image at blackbody aperture

6. GIFTS Blackbody Absolute Calibration Budget

7. GIFTS Blackbody Reproducibility Calibration Budget

8. GIFTS Blackbody Error Sources-LW
Longwave Band (800 cm-1) Absolute TA=255, TH=290, Ts=240, Tt=280, Tm=250
0.1 K
0.1 K
0.001
0.001
5 K

9. GIFTS Blackbody Error Sources-LW
Longwave Band (800 cm-1) Reproducibility TA=255, TH=290, Ts=240, Tt=280, Tm=250
0.014 K
0.014 K
0.0
0.0
5 K

10. GIFTS Blackbody Error Sources-SW
Shortwave Band (1800 cm-1) Absolute TA=255, TH=290, Ts=240, Tt=280, Tm=250
0.1 K
0.1 K
0.001
0.001
5 K

11. GIFTS Blackbody Error Sources-SW
Shortwave Band (1800 cm-1) Reproducibility TA=255, TH=290, Ts=240, Tt=280, Tm=250
0.014 K
0.014 K
0.0
0.0
5 K

12. Summary of Top Level BB Requirements
Current Best
Estimate
Specification*
Ambient Blackbody Nominal Set Point
255 K
Hot Blackbody Nominal Set Point
290 K
Temperature Measurement Uncertainty
< 0.1 K (3 sigma)
< K (3 sigma)
Ambient Blackbody Emissivity
> 0.996
> 0.998
Hot Blackbody Emissivity
Emissivity Uncertainty
< 0.002
< (3 sigma)
Wavelength
,300 cm-1
*Derived From GIRD Using Radiometric Model

13. Summary of Top Level BB Requirements
Current Best
Estimate
Specification*
Source Aperture
2.54 cm
Source FOV (full angle)
> 10°
Mass (two blackbodies plus controller board)
< 2.4 kg
< 2.1 kg
Power: average/max
< 2.2/5.2 W
Envelope
< 8 x 8 x 15.5 cm
< 8 x 8 x 15.4 cm
*Imposed by GIFTS Sensor Module Design