# Presentation: 716901

## Solar-B X-ray Telescope (XRT)

**Solar-B **X-ray Telescope (XRT)

- R. Kano (NAOJ) and XRT Team

- STEREO/Solar-B Workshop

- 2005/11/15

## Solar-B Science

- http://sxt4.mtk.nao.ac.jp/xrt/photo/optio/20040915/IMGP1817.JPG

**2004/09/15**

- XRT

- SOT

- EIS

- “Coronal Heating”
- How are coronal structures heated?

- STEREO/Solar-B Workshop

- 2005/11/15

## Targets of XRT Observations

**Photosphere/Corona Coupling**
- Can a direct connection be established between coronal and photospheric events?
**Coronal Heating**
- How do coronal structures brighten?
**Flare Energetics**
- What are the relations to the photospheric magnetic fields?
**CMEs, Jets and other coronal dynamical events**

- Coronal Loop Structures
- &
- Coronal Loop Heating

- STEREO/Solar-B Workshop

- 2005/11/15

## SXT Loops vs. EIT/TRACE Loops

- Aschwanden et al. (1999 &2000, ApJ)

**SXT** Loops vs. **EIT**/**TRACE** Loops

- Kano & Tsuneta (1996, PASJ)

- SXT loops in active regions

**highest T**

- highest T

- EIT Image

- Density est. from EM

- Temperature

**Isothermal**

**Are they really different?**
**Are they heated in a different way?**
- We would like to observe **all of the coronal ****plasma** with a single telescope.
- However, we would like to distinguish between**SXT** loops and **EIT/TRACE** loops.(Importance of **temperature diagnostics**.)

- STEREO/Solar-B Workshop

- 2005/11/15

## SXT Loops vs. EIT/TRACE Loops

- Aschwanden et al. (1999 &2000, ApJ)

**SXT** Loops vs. **EIT**/**TRACE** Loops

- Kano & Tsuneta (1996, PASJ)

- SXT loops in active regions

**highest EM**

- highest T

- EIT Image

- Density est. from EM

- Temperature

**Hydrostatic**

**Do SXT loops have a dense plasma****at the top?**
**Is it an apparent feature in a loop**
**	****(by change of filling factor)?**
- EIS can derive **the coronal density **with density-sensitive line pairs.(Importance of the **coordinated observation** between EIS and XRT.)

- STEREO/Solar-B Workshop

- 2005/11/15

## Solar-B/XRT vs. Yohkoh/SXT

|   | Solar-B/XRT | Yohkoh/SXT |
| --- | --- | --- |
| Type of Optics | Grazing Incidence | Grazing Incidence |
| FOV | 34 arcmin | 42 arcmin |
| Pixel Size | 1 arcsec | 2.5 arcsec |
| PSF FWHM | <1 arcsec @ center | ~ 3 arcsec |
| Bandpass | 3 ~ 200Å | 3 ~ 45Å |
| Temp. Coverage | 1MK  ~ 30MK | 3MK  ~ 30MK |
| Time Cadence |  |  |
|   Full Frame, Full-res. | min 9.5sec | 256sec (Half Frame) |
|   Full Frame, Half-res. | min 5.0sec
avg. 102sec | 128sec |
|   Partial Frame, Full-res.
  (FOV = 300”~400”) | min 2.0sec
avg. 15sec |   8 sec in flare mode
32 sec in Quiet mode |
| Other New Items | Pre-flare Buffer
Focus Mechanism | ---- |

- STEREO/Solar-B Workshop

- 2005/11/15

## XRT characteristics

**Temperature Response**
- TRACE-like image and SXT-like image
**Field-of-View and Spatial Resolution**
- Focus Mechanism
**Observation control by MDP**
- Table Observation
- Image Compression
- Time Cadences
- Preflare Buffer

- STEREO/Solar-B Workshop

- 2005/11/15

## X-ray Analysis Filters

- XRT has 9 X-ray analysis filters and a G-Band filter.

| Name | Metal | Metal
Thickness | Substrate | Substrate
Thickness |
| --- | --- | --- | --- | --- |
| Thin-Al/Mesh | Al | 1600 Å | Mesh |  |
| Thin-Al/Poly | Al | 1250 Å | Polyimide | 2500 Å |
| C/Poly | C | 6000 Å | Polyimide | 2500 Å |
| Ti/Poly | Ti | 3000 Å | Polyimide | 2300 Å |
| Thin-Be | Be | 9 μm | Mesh |  |
| Med-Al | Al | 12.5 μm |  |  |
| Med-Be | Be | 30 μm |  |  |
| Thick-Al | Al | 25 μm |  |  |
| Thick-Be | Be | 300 μm |  |  |

- STEREO/Solar-B Workshop

- 2005/11/15

## XRT Temperature Response

- STEREO/Solar-B Workshop

- 2005/11/15

## To point SOT at a certain target on the solar disk, we have to change Solar-B pointing. Therefore, XRT will not always observe the full solar disk.

Many varieties of FOV size are available.

Especially, for high-res.- observation, we recommend FOV= 1024”x1024” around CCD center.

- To point SOT at a certain target on the solar disk, we have to change Solar-B pointing. Therefore, XRT will not always observe the full solar disk.
- Many varieties of FOV size are available.
- Especially, for high-res.- observation, we recommend FOV= 1024”x1024” around CCD center.

- XRT

**2048”x2048”**

- Field of View (FOV)

- STEREO/Solar-B Workshop

- 2005/11/15

## Importance of Wide FOV

- Moreton waves tend to propagate along the global magnetic fields.
- X-ray waves also propagate with Moreton waves.

- STEREO/Solar-B Workshop

- 2005/11/15

## Field of View (FOV)

- Many varieties of FOV size are available.
- Especially, for high-res.- observation, we recommend FOV= 1024”x1024” around CCD center.

- XRT

**1024”x1024”**

**2048”x2048”**

- STEREO/Solar-B Workshop

- 2005/11/15

## Aberration at Different Focus Pos.

- φ512”

- φ1024”

- RMS=φ1”

- Distance from the Center

- (Only Geometrical Optics)

- STEREO/Solar-B Workshop

- 2005/11/15

## Observation of XRT

- Mission Data Processor

- Data Recorder

- Image
- Compression

- Pre-Flare
- Buffer

- Autonomous Functions

- Exposure Control

- Region Selection

- Flare Detection

- XRT

- SOT

- EIS

- STEREO/Solar-B Workshop

- 2005/11/15

## Image Compression

- MDP can compress the image data.Observer selects the following options.
- No compression
- DPCM (lossless) compression
- JPEG (lossy) compression
- Q-factor = 98, 90, ... , 65.

- STEREO/Solar-B Workshop

- 2005/11/15

## Typical Time Cadences

- typical data rate for XRT ~ 600 k pixel / min
- ex.1: Continuous Observation for AR
- AR FOV = 384”×384”, 1”-res.
- ex.2: High-Speed Observation for AR
- AR FOV = 384”×384”, 1”-res.
- ex.3: Combination of Narrow and Wide FOV
- Narrow FOV =  384”×384”   , 1”-res.
- Wide FOV     =2048”×2048”, 4”-res.
- .

## Pre-flare Observation

- Shimojo (ASJ 1999 autumn)

**FOV = 256”x256”, 1”-res.**
**Time Cadence = 10 ~ 20 sec for a filter pair**

- STEREO/Solar-B Workshop

- 2005/11/15

## Flare Observation

- XRT
- Detect a flare.
- Report the location to all telescope.

- XRT Intensity

- XRT
- Switch the current observation to Flare one.
- Lock the Pre-Flare Buffer.
- (There is a option not to switch to Flare obsevation.)

- SOT
- Switch the current observation to Flare one,if the flare location is in SOT-FOV.
- (There is a option not to switch to Flare obsevation.)

- EIS
- Switch the current observation to Flare one,if the flare location is in EIS-FOV.
- (There is a option not to switch to Flare obsevation.)

- STEREO/Solar-B Workshop

- 2005/11/15

## Solar-B/XRT vs. STEREO/EUVI

|   | Solar-B/XRT | STEREO/EUVI |
| --- | --- | --- |
| Type of Optics | Grazing Incidence | Normal Incidence |
| FOV | 34 arcmin | 55 arcmin |
| Pixel Size | 1 arcsec | 1.6 arcsec |
| PSF FWHM | <1 arcsec @ center | <1.6 arcsec @ center |
| Bandpass | 3 ~ 200Å | He II     304Å
Fe IX    171Å (1MK) |
| Temp. Coverage | 1MK  ~ 30MK | Fe XII   195Å (1.5MK)
Fe XIV  211Å (2MK) |
| Time Cadence |  |  |
|   Full Frame, Full-res. | min 9.5sec | min 11sec in Fe IX
avg. 20min |
|   Full Frame, Half-res. | min 5.0sec
avg. 102sec | min 4.75sec
avg. 2.5min |
|   Partial Frame, Full-res.
  (FOV = 300”~400”) | min 2.0sec
avg. 15sec | (No Option?) |

- STEREO/Solar-B Workshop

- 2005/11/15

## Summary

- XRT has high sensitivity for **low (1MK) temperature plasma**, as well as high temperature plasma.
- XRT has the highest spatial resolution as GI imager.
**Pixel Size = 1 arcsec**
-  **Observation Tables** respond to various observations.
-  **Autonomous functions** support XRT automatic operation.
- Observers can select types of **Image Compression**.
-  **Built-in visible light optic** allows us to align XRT images with SOT images with sub-arcsec accuracy.

- STEREO/Solar-B Workshop

- 2005/11/15