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).

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

T-T0,  filter, exposure,  OT

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:

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