SOLAR
SYSTEM DEPARTMENT 
Instituto de Astrofísica de Andalucía Tel: 34 958 121311 Apdo. 3004, 18080 Granada, Spain Fax: 34 958 814530
The large telescopes could not be
used because clouds were completely blocking the moon most of the time,
and humidity was so high that we were not allowed to open the domes, but
three of the small telescopes that could observe the moon through gaps
in the clouds and fog WERE SUCCESSFUL!. Fortunately we could use special
equipment purchased for our lunar impact search programme which turned
out to be pivotal. After the video-tapes were inspected on November 21,
a few flashes were evident.
The images that follow are low-resolution versions of the images digitized
from the tapes by using a frame grabber:
The brightest impact flash
was recorded on Nov. 18th at 18:27:46 UT, in VHS video tape, by means of
a Celestron C-8 telescope which was equipped with a focal reducer plus
one of our sensitive Watec black and white CCD cameras. The observations
were carried out by Jose-Antonio Quesada at his own observatory in Huétor
Santillán, Granada, Spain. The impact flash occurred at a preliminar
lunar latitude of -23 degrees and longitude of 16 degrees W, with an accuracy
of approximately +/-1 degree. This means that the impact was nearly grazing
at that location, if our knowledge of the sublunar Leonid radiant point
was correct. The other two telescopes that could observe had a smaller
field of view, so this impact flash did not appear in any other of our
video tapes. We are 100% confident that this flash is not an artifact for
a number of reasons: It has some coma and it is slightly defocused, which
rules out electronic noise or cosmic rays. In addition, we have accumulated
more than 100 hours of video recordings with the same equipment in previous
training runs and never got anything like this. A satellite is also ruled
out as it would have been trailed and should appear on other frames.
A rough calibration of the peak intensity is m_v=5.17+/-0.10. The lightcurve
as well as a movie will be posted soon.
The second brightest impact
on Nov. 18th was at 18:10:36 UT and was detected by two different telescopes
within the same second at the same lunar location of 39degrees North, 15degrees
E. The two telescopes were the previously mentioned C-8 and a f/3.0 0.4m
telescope, both in Quesada's observatory. Therefore, the impact nature
of this flash is clear. The first image below was taken with the C-8
telescope and the other one with the 0.4m telescope. Note that the fields
of view are different.
A third flash detected on
Nov 18th at 18:29:07 with Quesada's C-8 telescope is likely another impact
flash.
Two more flashes were recorded
in video tape by means of a f/6.3 10" Meade telescope equipped with a Watec
camera. This was located at the Instituto de Astrofísica de Andalucía
main building in Granada's downtown and operated by F. Aceituno and J.
Aceituno. These occurred on Nov. 18th at 17:58:41 and 18:20:15. These ones
cannot be confirmed by Quesada's observations because he was likely
clouded out at that time. Their characteristics are also compatible with noise
in the VHS tape, so these are not confident detections. The field
of view of this camera was smaller than that of the previous images.
Another
impact flash was observed on Nov 19th by J.A. Quesada at 19:43:28UT, but again
this was through clouds and was recorded in just one videotape (the
Moon was completely blocked by clouds at his other telescope due to paralax
of the low-altitude clouds). This flash was also very bright and shows
similar features as the first one presented here, so there is little doubt
that this is real.
When this page was being finished we learnt about other impact flash detections
made in the USA somewhat later than those reported here, as it was still
daytime there a the time of our impacts. The observations were made by a group of amateur astronomers
and at least one of the impact flashes was detected by 3 independent observers
and recorded on video tape. A description can be found at D.
Palmer's web page.
Members of the team were:
J.L. Ortiz, J.A. Quesada, J. Aceituno, F. Aceituno, P. Sada, V. Costa, P. Gutiérrez, L. Lara, P. Amado, A. Castro-Tirado, L. Bellot and Ángel López.
This research was supported by the Instituto de Astrofísica de
Andalucía, CSIC.
Comments or questions:
ortiz@iaa.es