Friday, November 27, 2009

NOVA ERIDANI 2009 - Update

According to the Cbets 2053 & 2055 the transient in Eridanus has been spectroscopically confirmed as a nova.

Spectra obtained on Nov. 26 by H. Maehara (Kyoto University) and by M. Fujii (Okayama) shows that the object seems likely to be an He/N-class nova

Moreover another spectrum obtained by NASA researchers using the Aerospace Near-Infrared Imaging Spectrograph on the 3-m Shane reflector of Lick Observatory shows very strong, broad emission lines and confirm this object as a nova.

In the meantime prediscovery measurements of Nova Eridani 2009 have been reported on VSNET mailing list by "Pi of the Sky” team.

According to their measurement the nova reached the magnitude 5.60 (R-filter) on Nov. 15:

20091113.301 7.10 R "Pi of the Sky"
20091114.304 5.71 R "Pi of the Sky"
20091115.308 5.60 R "Pi of the Sky"
20091116.302 5.92 R "Pi of the Sky"
20091117.297 6.09 R "Pi of the Sky"

Their light curve and a nice animation showing the first days after the outburst:

http://grb.fuw.edu.pl/pi/var/catac/nova_eri.htm


ASAS-3 system (Pojmanski 2002, Acta. Astron. 52, 397) also detected this object at the following V magnitudes:

Nov. 10.236 UT, [14.0:
Nov. 19.241, 7.34;
Nov. 22.179, 7.98;
Nov. 24.269, 8.12.

by Ernesto Guido

Thursday, November 26, 2009

POSSIBLE NOVA IN ERIDANUS

Following the posting on the Central Bureau's unconfirmed-objects webpage & Cbet No. 2050 about the discovery by K. Itagaki (Yamagata, Japan) of a possible Nova in Eri we performed some follow-up of this object remotely through a 0.25-m, f/3,4 reflector +CCD, from GRAS Observatory (near Mayhill, NM).

On our images taken on November 26.36 we can confirm the presence of an optical counterpart with unfiltered CCD magnitude about 8.2 (UCAC2 Catalogue reference stars) at coordinates:

R.A. = 04 47 54.12, Decl.= -10 10 43.1
(equinox 2000.0; UCAC2 catalogue reference stars).

Our image:
http://bit.ly/5oZj01

A comparison with a DSS red plate (limiting magnitude about 20), obtained on 1990, Nov. 23, shows the proximity of a 15th-mag star to the position of the possible nova in Eri.

This is an animation showing our image and the DSS plate:

http://bit.ly/8N32kV

On the Cbet Yamaoka (Kyushu University) suggests that it might be the brightening of the 15th-mag blue star noting "that the amplitude of seven magnitudes is rather large for a dwarf nova, but somewhat small for a rapid classical nova".

Spectroscopic and time-resolved photometric observations are required to understand the real nature of this transient.

UPDATE

For an update about this object please see our Nov. 27, 2009 post:

http://remanzacco.blogspot.com/2009/11/nova-eridani-2009-update.html

by Ernesto Guido and Giovanni Sostero

Friday, November 20, 2009

Utah Fireball - 18 November 2009

On Nov. 18, just after midnight local time (MST) a great fireball was seen over parts of the western United States

According to Spaceweather website witness in Utah, Wyoming and Idaho saw "remarkable midnight fireball that turned night into day. It was not a Leonid. Infrasound measurements suggest a sporadic asteroid not associated with the Leonid debris stream. The space rock exploded in the atmosphere with an energy equivalent to 0.5 - 1 kilotons of TNT"

Many surveillance cameras have recorded the midnight-landscape illuminated by the fireball:

utah fireball,fireball

(click to enlarge)


Here you can find other videos of the fireball uploaded on youtube:

http://bit.ly/5pqVuW

http://bit.ly/4ZMSAY

http://bit.ly/7p2vpw

http://bit.ly/55ZRDa

http://bit.ly/80dBnS


Few hours after the fireball, strange clouds appeared in the dawn sky. These clouds are strikingly similar to the debris left in the sky after the 2008 TC3 event in Sudan on Oct. 7, 2008.


by Ernesto Guido

References:

http://www.spaceweather.com/

http://www.ksl.com/?nid=148&sid=8714738

Wednesday, November 18, 2009

Leonids 2009

According to preliminary counts from the International Meteor Organization (IMO) the Leonids meteors reached a ZHR(max) ~ 120/130 around 22UT of Nov. 17, as predicted by forecasters.



The ZHR surge, witnessed by observers in Asia, occurred when Earth passed through the debris left from Comet 55P/Tempel-Tuttle in 1466 AD and 1533 AD. When Earth exit these streams, the ZHR count fall to the value ~30/40.

Our meteorcam starting to image at 23:30 UT of Nov. 17. In 5 hours of imaging, our camera detected 35 meteors, of which 26 were leonids.

This is a composite of the brightest meteors (mostly leonids) imaged by the meteorcam from 23:30 UT of Nov.17 to 04:30 UT of Nov. 18 (because the images were collected over several hours, the radiant of the shower is spread out):


While checking online all-sky cameras around the web, I found this nice fireball imaged by the Sbig All-Sky camera on Nov. 17 at 02:20am local time:



Here you can see the video sequence showing the fireball and its trail:

Monday, November 9, 2009

NOVA SCUTI 2009

Following the posting on the Central Bureau's unconfirmed-objects webpage about a possible nova in Scuti, on 2009 November 09.08 we performed some follow-up of this object through a 0.25-m, f/3,4 reflector + CCD, from GRAS Observatory (near Mayhill, NM).

We can confirm the presence of an optical counterpart with unfiltered CCD magnitude about 8.5 (UCAC-2 Catalogue reference stars) at coordinates:

R.A. = 18 43 45.57, Decl.= -07 36 42.0

(equinox 2000.0; UCAC-2 catalogue reference stars).

Our confirmation image:


A bigger version is available here:

The extreme stellar crowding due to nearby field stars makes this measurement rather difficult. A comparison with a DSS red plate(limiting magnitude about 20), obtained on 1996, Aug. 13, fail to show a clear unambiguous pre-outburst precursor.

This is an animation showing of our image and the DSS plate:

More details about the discoverer have been provided on the Cbet circular No. 2008, issued of 2009 November 09. The cbet announces the discovery of Hideo Nishimura(Japan) of a possible nova (mag 8) on two 10-s CCD frames (limiting magnitude 11.5) taken on Nov. 8.3699 and 8.3700 UT using a Canon EOS 5D camera (+ Minolta 120-mm f/3.5 lens).


by Ernesto Guido and Giovanni Sostero