# Presentation: 011223

## Swift X-ray Telescope Status & Observations of the Afterglow of GRB 041223

**Swift X-ray Telescope Status & Observations of the Afterglow of GRB 041223**
- David Burrows - PSU

## The Swift Observatory

- Launched: 20 November 2004
- XRT turned on: 23 November 2004
- XRT First Light: 11 December 2004
- First BAT Burst: 17 December 2004
- First XRT Afterglow: 23 December 2004

**XRT First Light: Cas A**

## XRT

- Thermal
- Tests

- UVOT
- Activation

- Beginning XRT
- Thermal Control

**TEC Power**

- Heating
- CCD

## XRT First Light Observations

- Cas A:
-  (13 ks)

***Focus is perfect!!***

***2% shift in gain***

- M. Goad, UL

- A. Moretti, OAB

- J. Hill, PSU

- Mkn 421:

## Preliminary Crab spectral fit

- NH = 0.35 ± 0.04
- Γ = 2.10 ± 0.01

## GRB 041223

- Offset from optical transient:
- 	2.1 arcseconds

- Discovered by BAT at 14:06:18 on 23 December 2004
- XRT was in midst of thermal tests, taking data in PC mode
- Slewed to GRB 4.6 hrs after burst as ToO
- Observed on 3 consecutive orbits for total of about one hour on-target

- XRT position:
-    RA(J2000) = 06:40:47.5
-    Dec (J2000) = -37:04:22.5
-    SWIFT J064047.5-370423

- Offset from BAT position:
- 	50 arcseconds

## Lightcurve

- X-ray source was uncatalogued.
- X-ray source faded rapidly.
- Data extracted with *ximage* from 20” radius circle.  Background extracted from 47” radius circle.
- Only used times when pointing was stable and background was low.
- 520 counts in 3504 seconds.

## Spectrum

- NH = (1.5 ± 0.5) x 1021
- Γ = 2.02 ± 0.21 (90%)
- χ2  / ν = 15.4 / 22
- Fx = 6.5 x 10-12 (0.5-10 keV)

## Broad-band SED

- (VLT observations from MISTICI collaboration)

- For *F**ν**(t) = t** **-α** ** *and *F(ν) = ν** **-β*

| Band | αν | βν | t – t0 |
| --- | --- | --- | --- |
| J | 1.14 ± 0.08 | 0.40 ± 0.03 | 16 – 87 |
| 0.5-10 keV | 1.72 ± 0.20 | 1.02 ± 0.07 | 4.6 – 7.9 |

- Spectral break suggests that cooling frequency lies between the X-ray and optical bands.

- (68% confidence errors)

## Broad-band SED

- If αx and αNIR are constant, then
- νNIR < νc < νx   and
- ν c  *t* –α,  where α = 1.0 ± 0.2 to fit data

## Conclusions

-  NIR and X-ray data are consistent with the following scenario:
- Jet has two components: narrow component that produces X-rays and broader component that produces optical
- Jet break of narrow component occurs before X-ray observations
- Produces self-consistent model with electron power-law index of about 1.9 – 2.0

-  XRT is working well and producing excellent data in spite of higher operating temperature
- Images are spectacular
- Spectroscopy is better than Chandra at beginning of GTO phase
- Spectroscopy expected to remain better than ASCA over life
- High resolution timing available (up to 140 microseconds)

## Co-Authors

- Penn State:
-     David Burrows
-     Joanne Hill
-     Judith Racusin
-     Shiho Kobayashi
-     Peter Meszaros
-     John Nousek
-     Jamie Kennea
-     David Morris
-     Claudio Pagani

- OAB:
-     Guido Chincarini
-     Gianpiero Tagliaferri
-     Sergio Campana
-     Alberto Moretti
-     Patrizia Romano
-     Daniele Malesani
-     Stefano Covino
-     Paolo D’Avanzo

- UL:
-     Paul O’Brien
-     Alan Wells
-     Julian Osborne
-     Tony Abbey
-     Andy Beardmore
-     Mike Goad
-     Kim Page
-     Dick Willingale

- GSFC:
-     Neil Gehrels
-     Lorella Angelini
- UNLV:
-     Bing Zhang
- OAR (Rome):
-     Luigi Stella
-     Angelo Antonelli
- ASDC:
-     Paolo Giommi
-     Milvia Capalbi

## Centroiding

- Her X-1

- Cyg X-3

- Cyg X-1

- On-board calculation

- Pipeline processing

- 10” x 10” box,
- centered on source position