Posts Tagged ‘GRB’

Observation of optical transients now and in real time

NASA

This week at our observatory a program of automatic observations of optical transients began. Receiving notice of a gamma ray burst, the telescope automatically goes to the object and takes a series of images. This way, any ongoing observation program comes to a halt with the interruption of the exposure.

The first observation of a gamma ray burst in full automatic mode took place October 29. Our telescope began observations of the event just 77 seconds after receiving an urgent message about the gamma ray burst (alert). Unfortunately, this time it was not possible to detect the afterglow, but the best is still ahead!

In addition, in automatic mode we were able to conduct automatic observations of optical transients posted on the Transient Objects Confirmation Page – TOCP. At the moment two supernovas have already been confirmed.

Bright and continuous afterglow from GRB 100901A

September 2, 4, 5, and 6, at the observatory, observations were made of yet another interesting gamma ray burster – GRB 100901A. Notice about it arrived when it was already morning at the observatory, and we were able to begin observing it just over 20 hours after the recording of the burst.The optical afterglow was easily visible on the images, with a brightness of mag. 17.82. This is the brightest of such objects observed at our observatory. Its uniqueness is that GRB 100901A has preserved its brightness at such a high level longer than all the other known gamma ray bursters. In the picture at left, you can see how the brightness of the afterglow faded over the next three days. The last estimate of the brightness was received at the Maidanak Observatory (Volnova et al., GCN 11266). After 6.2977 days, the brightness of the object had faded to mag. 22.05.

As with the previous unusual gamma ray burster GRB 100814A, a sufficiently rare occurrence was recorded – radio afterglow. The EVLA radio telescope (Expanded Very Large Array) recorded an afterglow at frequencies of 4.5 and 7.9 gHz.

TITLE:   GCN CIRCULAR

NUMBER:  11234

SUBJECT: GRB 100901A: ISON-NM optical observations

DATE:    10/09/06 17:30:05 GMT

FROM:    Leonid Elenin at ISON

L. Elenin, I. Molotov (ISON) and A. Pozanenko (IKI) report on behalf of

larger GRB  follow-up collaboration:

We continue observation of the Swift GRB 100901A (Immler et al. GCN Circ.

11159) with 0.45-m telescope of ISON-NM observatory on Sep. 04 (UT) 09:04:35 –

10:06:19, Sep. 05 (UT) 08:45:52 – 09:50:20 and Sep. 06 (UT) 09:36:57 – 11:14:22.

The afterglow (Immler et al., GCN 11159; Guidorzi et al., GCN 11160; Ivanov

et al., GCN 11161; Klunko et al., GCN 11162) is well detected on stacked images

for three epochs.

Preliminary photometry of unfiltered image against USNO-B1.0 1127-0027229,

assuming R=16.16  is following:

T-T0      filter   exposure   mag.  mag. error

————————————————————–

2.8336    W      12×300   19.78    +/- 0.25

3.8206    W      12×300   20.38    +/- 0.20

4.8700    W      20×300   20.97    +/- 0.22

————————————————————–

The images of GRB100901A is available at:

http://www.spaceobs.org/images/GRB1000901A-3epochs.jpg

Further observing of GRB100814A

August 20th and 21st we continued our observations of the unusual gamma ray burster GRB100814A. After a lengthy “plateau” at magnitude 19.5-20, the object began to decrease in brightness. On August 20th it had reached mag. 21.66, and within a day was at mag. 22.5. Today’s observations were probably our final ones of this enigmatic object. Tomorrow its brightness may reach mag. 23.5-24 which is not reachable by our telescope. It is also interesting that GRB100814A is the first gamma ray burster whose afterglow was observed over a period of three nights at the observatory ISON-NM! At the moment scientists have not yet put forth a hypothesis about the nature of this long-duration gamma ray burster. Most probably it is not an explosion of a very distant so-called “hypernova”. The duration of the explosions may be connected to repeat episodes of activity or to geometric effects – we are seeing a jet from a substantial angle.

It is interesting that GRB100814A on August 18th with the aid of the high sensitivity radio telescope EVLA (Expanded Very Large Array) was also found to have an radio afterglow at wavelengths of 4.5 and 7.9 gigahertz. Radio components of gamma ray bursters with distances exceeding z=0.5 are seldom observed . I remind the reader that the distance to GRB100814A is calculated to be z=1.44 (9.3 billion light years).

TITLE:   GCN CIRCULAR
NUMBER:  11133
SUBJECT: GRB 100814A: ISON-NM optical observations
DATE:    10/08/22 07:30:05 GMT
FROM:    Leonid Elenin at ISON

L. Elenin, I. Molotov (ISON), A. Volnova (SAI MSU), A. Pozanenko (IKI)
report on behalf of larger
GRB  follow-up collaboration:

We continue observation of the Swift GRB 100814A (Beardmore et al. GCN
11087) with 0.45-m telescope of ISON-NM observatory on Aug. 20 (UT)
08:42:06 – 09:33:14 and Aug. 21 (UT) 09:45:22 – 11:04:41.

The afterglow (Schaefer et al. GCN  11086; Beardmore et al. GCN  11087)  is
well detected on stacked images for both epochs. Preliminary photometry of
unfiltered image against USNO-B1.0 star 0720-0016107, assuming R=19.73  is
following:

T-T0,  filter, exposure,  OT
(day)

6.2205    W     300×10    21.66  +/- 0.23
7.2734    W     300×15    22.50  +/- 0.30

The photometry errors are statistical only.

The images of GRB100814A is available at:

http://spaceobs.org/images/GRB1000814A-3epoch.jpg

Observing of “anomalous” gamma-ray burst

The results of GRB100728B photometry

July 2017
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