Gammaglimt og deres synlige efterglød .

Gamma ray burst GRB080319B and its afterglow.


Om gammaglimt (Danish)


GRB080319B seen at #5 at 01.51 UT  mag 19.8 CR compared to star #2 with mag(r)= 15.11 (SDSS)
Afterglow of GRB080319B seen inside circle 5 at mag 19.8 CR at 01.51 UT (2008/03/20.077)
Image composed of 70 stacked 1 minute exposures between 01.14 UT and 02.29 UT on 2008/03/20,
i.e. 19,634 hours after the burst. The image above is a 200% zoomed part of the stacked image.
Telescope: Modified 11" f/4.5 Celestron Starhopper Newton without coma corrector on Vixen New Atlux mount.
CCD: Starlight Xpress MX916 camera in high resolution progressive mode, unfiltered.
Moon: Close to full
Photometry: Aperture photometry, raw data (ADU counts) obtained from AstroArt4.
Differential photometry using SDSS data for star#2 (RA:217.91529, DEC:36.31496)SDSS mag(r) = 15.11.

The afterglow of this GRB was optically unusually bright reaching mag 5.76 about 60s after the gamma ray burst was detected.
More info on AAVSO's site and the AAVSO Alert Notice #372


SDSS chart with reference star #2 used for differential photometry
Sloan Digital Sky Survey chart of the region showing photometric and positional data of the reference star 2.


SDSS image of an extended object, probably the parent galaxy of the GRB
SDSS image of an extended object of mag(r)=21.49, probably the parent galaxy of the GRB.


Photometric data for the long lasting afterglow of GRB080319B
Photometric data for the long lasting afterglow of GRB080319B
based on preliminary data collected from GNC
Circulars found here and my measurement, which fits the general thrend neatly.


Light curve of the afterglow of GRB080319G
Light curve of the afterglow of GRB080319G showing the very long lasting afterglow.


The short term optical afterglow of GRB080319B
The peak optical afterglow was detected less than 10s after the gammaburst and the optical brightness reached above mag 6 for a few seconds.
The automated "Pi of the Sky" telescope at Las Campanas Observatory in Chile caught the early optical flash, which can be seen
live at this link: http://grb.fuw.edu.pl/pi/ot/grb080319b/normal.html


Some key facts about GRB080319B

The total energy output of this GRB can be estimated by integrating the power received outside the earth's atmosphere. We need to know the distance of the GRB which can be derived from its redshift, which was measured by Paul Wreeswijk et al. (NGC circular #7451) to be z=0,937. This corresponds to a present distance of 7.5 billion light years, and means that our Universe has expanded by nearly a factor of 2 while the light was traveling towards us.
Total energy release assuming isotrophy:
E(total) = 1.3 x 10^47 J
Maximum power or luminosity:
L(max) = 9.7 x 10^45 W (L(sun) = 3.826 x 10^26 W)
Data is from the Konus-Wind group, see GNC circular #7482


Other links

SWIFT home
Dark Cosmology Centre, Copenhagen
More on this GRB in Danish
NASA's official announcement of GRB080319B
Astronomy Picture of the Day 28 March, 2008