# Presentation: 871985

## The Astro-E2 Mission

- Richard L. Kelley
*for the joint US and Japan Astro-E2 Teams*
- NASA/Goddard Space Flight Center

## Astro-E2

- 1700 kg

## A short history of the XRS and the Astro-E programs

- The XRS initially selected in 1985 as one of the focal plane instruments
- for AXAF.
- 1992	AXAF split into the AXAF-I and AXAF-S programs, with the XRS comprising the AXAF-S
- 1993	AXAF-S/XRS moved to the Japanese Astro-E mission
- 2000	Astro-E launched but failed to reach orbit
- 		   *  “XRS” proposed as a Small Explorer mission (named *“Joule”)*
- 	   *  Astro-E2 mission approved in Japan
- 2001	*“Joule”* converted to a Mission of Opportunity on Astro-E2.
- 	   *  US participation in Astro-E2 approved by NASA
- Rebuild of XRS and XRT (and XIS) confirmed by NASA
- 2004	All XRS and XRT hardware delivered to Japan and integrated

## Astro-E2 Instruments

## X-Ray Optics

- Reduces stray x-ray light from off-axis sources

## X-ray Imaging Spectrometer (XIS)

- MIT, Osaka Univ., Kyoto Univ., ISAS

- Pixel Size	25 x 25 m
- Format		1024 x 1024
- dE @ 6keV	120 eV
- Temperature	-90 C
- (Lincoln Lab. CCD chips)

**X-ray Imaging Spectrometer (XIS)**

## XIS Effective Areas

- Actually...
*3 Front Illuminated*
*1 Back Illuminated*

## Hard X-Ray Detector (HXD)

- GSO	6 x 6 cm
- BGO	32 cm depth well.
- 	guard detector
- Format	4 x 4 units
- FOV	4.6 x 4.6 degrees
- Si	2 mm thick
- 	21.5 x 21.5 mm
- FOV	0.56 x 0.56 deg

- Univ. of Tokyo, ISAS

## High Resolution X-Ray Spectrometer

- 			(XRS)

- X-ray -calorimeter array

## XRS Spectral Resolution and Spectral Redistribution

## Determination of Energy Scale

## XRS Background

*Expected incident* particle flux of  0.1 - 0.5 cps/cm2  in LEO.
- Scaling from ASCA, we expect ~ 7 x 10-4 cps/array
*(Measured* residual BG rate in lab: ~ 10 x 10-4 cps/array)
- Cosmic rays will also deposit heat in the frame of the array at a rate of a few cps, and these will be sensed by *multiple* pixels.  These events can be eliminated from telemetry (adjustable threshold) and they can be removed in data analysis.

## Slide 13

## XRS Event Grades

## Filter Wheelfor attenuation and calibration

| Open | -- |
| --- | --- |
| Open | 55Fe & 41Ca
(default at least during the Earth occultation) |
| Be 300 m | -- |
| Be 300 m | 55Fe |
| ND 10% | -- |
| ND 10% | 55Fe |

- 55Fe
- 0.1c/s/pix

- 41Ca 0.2c/s/XRS

- Be filter

## XRS Effective Area

## Slide 17

## Energy Resolution Comparison for Point Sources

## Simulation of spectra of the merging cluster A2256 from two pointings

- Chandra contours

- A2256

- XRS FOV

- He-like triplet

- z = 0.058, 50 ksec

- z = 0.055, 100 ksec

## Determination of Line Energy

## Measured at 6.4 keV

## Determination of Line Width

- 1 eV increase to FWHM

## Non-ideal effects:

- Very low-level thermal cross-talk between pixels creates additional “noise” term that scales with flux.

- Calorimeter housing is not completely light-tight for long wavelength radiation, so pulse height gain depends on *He* and *Ne* temperatures.  Sensitivity not the same for all pixels.

## Point Source Continuum Sensitivity

## Diffuse Source Continuum Sensitivity

## Status of Astro-E2

- Launch was delayed from late January 2005 to summer 2005.
- This is at the direction of JAXA in order to devote full resources to the launch of a weather satellite on an **H2-A** (presently scheduled for February 24.)
- Launch of Astro-E2 could be as early as latter part of May; June said to be most likely)
- Projected XRS lifetime is 3 years.
- AO-1 completed.  Selected first year of joint US/Japan GO program for the period following 6 month SWG segment.

## Data Sharing Agreement

- _Observing Time Allocation_:

- _Archival Data_:  All data (US and Japan) go into archive after one year and are available to everyone.

- US allocated 50% of observing time and all of the data after one year.

- http://astroe2.gsfc.nasa.gov

## Slide 28

## Energy Resolution

- Red: 6 keV
- Blue: < 1 keV

## Slide 30

## Internal 55Fe Calibration Source

- Cal
- pixel

- 13 mm