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

On Sunday, Sept. 5, NASA’s EPOXI  spacecraft (formerly Deep Impact) was obtained the first of more than 64,000 images it’s expected to take of comet 103P/Hartley 2. This first image of comet Hartley 2 taken by Deep Impact was taken by the spacecraft’s Medium Resolution Imager when the spacecraft was 60 million kilometers (37.2 million miles) away from the comet. The rendezvous with 103P scheduled on Nov. 4, 2010.

September 8, 2010, a small asteroid with the designation 2010 RF12 will fly by the Earth. The diameter of the celestial body is estimated to be 7-14 meters. The object was discovered Sept. 5th by the American Mt. Lemmon Sky Survey. The minimum distance from our planet will be 84,000 km., which is a little over twice the distance of the orbit of geostationary satellites.

2010 RF12 belongs to the Aten family. The semi-major axis of the orbits of this family is less than 1 a.u. Practically all Atens have a large eccentricity; for some members of the family, it is larger than 0.9! In connection with this, several asteroids cross the orbit of Mercury and approach within 0.1 a.u. of the Sun. Today at our observatory we acquired position measurements of this cosmic newcomer. You can see its picture on the left.

Today is the first day of Fall. The influence of the monsoons is lessening, and the nights are getting longer. During this season we plan to increase the productivity of the observatory, improving the automation of routine processes. This full moon we installed a new observatory guiding complex – RTS2. At the moment it is going through checkout, after which we will begin testing under real conditions.

We are changing our strategy on “deep” surveys, with the goal of detecting super-slow and distant objects. This way we can detect objects to mag. 21.5, at a distance of tens of astronomical units. Additionally, the work continues on alert observations of the optical afterglow of gamma ray bursters, and also photometry of near-earth asteroids (NEAs). And when the moon lights up the dark skies above our observatory, we can rest a little and independently occupy ourselves with problems of Potentially Hazardous Objects.