Observing Lunar Occultations with CCD´s by drift-scan imaging

From: Joan Genebriera


I will introduce myself, I’m an amateur astronomer resident in Barcelona, Spain and two month ago a colleague told me about “Scan” and their posterior astrophysical applications.

After some unsuccessful trials, finally last February, 22th I had luck enough to capture two lunar occultation's. It was using the option “Fast Scan” in a lunar occultation and I have been very excited with this awesome results.

With your permission I enclosed this results for your review

Equipment:

SBIG camera model: ST8E
Filter: SBIG "R" color filter.
Telescope type: Cassegrain-Relay
Aperture: 400 mm.
Focal ratio: 6.5
Mount type: equatorial fork
Image processing: dark subtract, average image, vertical profile( CCDOPS and MaximDL).
Control Software: Scan by Christoph Flohr

I found specially suited for this work the use of SBIG "R" color filter.
It has a better peak transmission and small bandwidth
than the normal "R" Johnson / Coussins (Bessell) photometric one.


Observations details:
Long.= 01d 56m 41s East (1,94494d E.)
Lat. = 41° 25´ 09´´ Nord (41,41925° N.)
Altitude= 285m.

Date: 22/02/02 Time: 23:33:44 U.T.C. disappearance of the star: 954kG8 Mag.= 6.1 by
the moon. 75% illuminated. Exposure: 0.002 sec. per line.
total time 40 sec. or 20,000 lines. 20 columns dowloaded (planetary mode).

Note: 954k (8 Gem) is double, magnitudes 6.9 + 6.9 at 0.1´´ separation.


This is a MS excel graph of the light curve. You can see the pre-occultation fringes and also notice the small "bump" on the descending light curve due to double star nature.






Date: 23/02/02 Time: 20:24:19 U.T.C. disappearance of the star: 48 Gem F5 Mag.= 5.8
by the moon. 83% illuminated. Exposure: 0.002 sec. per line.
total time 30 sec. or 15,000 lines. 20 columns download (planetary mode).






As far as I know, the photoelectric photometer systems, using photomultipliers, has been the usual choice as a detector to be considered. But now, CCD’s are a serious alternative to the PEP.



Joan Genebriera
Montserrat,18 Can Margarit (I)
e-mail:
jgenebriera(AT)eresmas(DOT)net  (replace "(AT) " with "@ " and "(DOT) " with ". " )
08757 Corbera SPAIN