Image of M8, taken by the AEOS Burst Camera

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Heather Swan

Physics Department

University of Michigan

Carl Akerlof, Timothy McKay, Eli Rykoff, Donald Smith, U of Michigan

Mark Skinner, Andrew Alday, Kevin Moore, Boeing LTS

Outline

• Why?

• What is the AEOS and ABC?

• GRB response

• Data and simulations

GRB 030418 was dimmer than expected at early times

Optical lightcurve

First image ~76s after -rays

Circum-burst absorbsoptical light

if we could see the spectrum, we would expect to see

red -> blue

GRB 990123 was brighter than expected at early times

-rays were still emitting for first few images

Optical lightcurve

Relativistic fireball – example of a reverse shock

if we could see the spectrum, we would expect to see

blue -> red

Swift’s BAT error box is the perfect size for the ABC

90% will be localized to a 3 arc minute radius

(Can see them with the ABC)

50% will be localized within 12 seconds

(Can see them promptly)

(From Fenimore, et al)

The AEOS telescope is a large optical telescope used by the Air Force

Advanced Electro-Optical Systems Telescope (AEOS)

Largest ground based AF optical telescope (3.67m)

Designed to track satellites, can quickly (~20 sec) slew to coordinates

Located in Haleakala, Hawaii, at 10,000 ftABC

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The AEOS Burst Camera (ABC) is attached to the AEOS

• Optics designed by Carl Akerlof

• Package designed by Alan Schier

• Camera built by Astronomical Research Cameras

Field of view 6' x 6'

Focal length of 15.5m

9 ToO observations / year Limiting Mag ~22nd for 10 sec exposure

Burst Filter

Fax::::::::::::::

GCN

SwiftGRB

User Interface

ABC Computers(Modified ROTSE

Software)

CD

The ABC will try to observe GRBs within minutes after they are localized

No prompt response yet…

• GRB needs to be < 1 hour old and visible in Maui

• The few that have been attempted– Bad weather– Bad pointing

• Several test bursts have been sent– Responses between 1 and 10

minutes

• One was caught during testing (030329)– Images taken several days after

the event

GRB 030329

A diffraction grating was recently installed on the ABC

• Low resolving power (8)• Installed Jan ’05

A light bulb viewed through the grating, and a star….

Simulations of the grating are similar to what is seen

Pixels

Inte

nsi

ty 0th

1st

2nd

higher orders

The blaze angle was chosen so most of the light would be in the 1st order

Blackbody, sun’s temp

Image from ABC of a star

Simulations of different temperature blackbodies

We can differentiate between blue and red stars

Hotter temps

Cooler temps

We can differentiate between different types of objects

Star

Quasar

Symbioticbinary

In summary, the ABC is up and running, we’re just waiting for a GRB

• The ABC can quickly and deeply observe GRBs– First image within minutes of GRB detection

– Small 6’ x 6’ field of view

– Deep (22nd mag) images with 10s exposures

• The ABC has a diffraction grating– Will get early spectral information for GRBs

Questions?