Grazing Occultation of Saturn
Friday 2nd March 2007
Observers' Reports
I would like to offer my congratulations to all SPA members who observed the early morning
occultation of Saturn by the Moon on
March 2nd. Without a doubt, this has been one of the most widely observed occultation
events, and many timings and images have been made. My thanks to all who contributed in
any way.
From the numerous reports still coming in to the SPA Occultation Section, it seems that the weather
over much of the UK was kind to us this time, many amateur astronomers were able to enjoy this
night-time spectacular. Which is just as well because although we have a couple of daylight events
(extremely difficult indeed!), the next Lunar Occultation of Saturn at night will not take place
until the early hours of August 21st 2024.
Jon Harper
SPA Occultation Section Director
I have made two short animations from the event, one showing the ingress phase 02:28-02:45 UT,
and one showing the egress phase 02:54-02:59 UT. These animations are approximately centred on
Saturn (to within the tracking accuracy of the mount going at siderial rate), so the Moon
appears to move.
I have left these videos "natural" and minimally-processed. Exposure is for Saturn with no
attempt to hide the consequent over-exposure of the Moon. This is what was really seen on the
screen. There is some loss of quality in the conversion to GIF animations. There are also some
twigs visible in the foreground as the scene was going behind a tree.
Each frame is a stack of 100 frames (10 second AVI files), taken with a standard ToUcam Pro
through a 10" Dall-Kirkham-Dall Cassegrain at approx. f15. (These are the first
publicly released images from this telescope following its optical re-work).
More of David's work can be found on his website.
Click anywhere on the images below to see the animated versions
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Managed to get a few images of the occultation - we had a
lovely clear night here. Pity it was almost a full Moon because, as predicted, it
is a real challenge to the camera - these shots are no where near as good as
the ones I got in 2002. These images are all 'single shot' i.e. not
composite but had some processing for sharpness and contrast. I did get some
at the closest approach, but they were very poor. Camera used was Canon Powershot A20,
used afocally through my 10inch Newtonian. The image on the left was taken at 02:32 UT
and the one on the right at 02:57 UT (the closest approach where the image was a tolerable
standard).
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Posted via the SPA Observing Forum
Richard submitted the following image from the event:
More of Richard's work can be found on his website.
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Posted via the SPA Observing Forum
David submitted the following images from the event. The image on the left was captured at 12:12 UT
and the image on the right at 02:57 UT.
More of David's work can be found on his website.
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Posted via the SPA Observing Forum
Not a cloud in the sky (for a change) had wonderful
views of the event. Did not bother taking images or timings,
simply wanted to take it all in at the eyepiece.
Reappearance saw Saturn shining with a ghostly light, but
features on the planet easily seen.
Just as I was shutting the observatory roof at about 03:20 UT,
a really bright meteor was seen going from Alkaid down to
Coma Berenices.
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Conditions were perfect with not a cloud in the sky. To start with I used 12 x 50 binoculars to be
able to see both objects within the same field of view. At 19:40 UT they were about 4 degrees apart and
at 20:40 UT about 3 degrees. I recommenced observing at midnight and the Moon was followed as it moved
closer and closer to the planet until at 01:30 UT when they were about a lunar diameter, half a degree,
apart. An hour later I switched to using a 50mm zoom spotting scope hand-held but supported against
the window frame and at about 15x magnification. I noted how much paler the planet was when compared
to the lunar surface. At this time, 01:30 UT, Saturn was much closer to the terminator than Tycho. The
terminator here had an apparent bite out of it, which I guessed was the crater Bailly. Saturn seemed
to skim along the edge of the Moon, getting closer and closer and so I zoomed up to high power, about
40x. However even at this, by 02:52 UT the tiny remaining bit of Saturn was very hard to see. By 03:00 UT
Saturn was back to full brightness and clear of the Moon and quite close to the limb near Mare
Australe.
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I attempted to get some pictures on a mobile phone, with some limited grainy success. I missed the
last contacts while I was poking around with the phone, but reckon that these were about 02:50.
This is backed up by the said grainy pictures, which show coverage still in progress at 02:49:39 UT,
but a distinct gap between Saturn and the Moon by 02:54:16 UT. So my best estimates for last contact
would be: planet 02:50:30, edge of ring 02:51:30 UT, but the uncertainty could be plus or minus a
minute or more.
- First contact with outer edge of rings: 02:42:45 UT
- First contact with planet: 02:43:55 UT
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Posted via the SPA Observing Forum
Great view of the occultation from Chelmsford this morning. Seeing conditions were very
good with a slight hint of frost. I was able to track the whole event through my 80mm
short focus Celestron 'scope. I did not bother timing it but would suggest both the
disappearance and reappearance of Saturn lasted about one minute, whilst the 'total'
phase lasted about ten. It was quite fascinating seeing first the ring gradually reappear,
then the main planet followed by the otherside of the ring again. It's an event I will
remember for a long time.
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Posted via the SPA Observing Forum
Gregger submitted the following image from the event:
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Clear views here of the disappearance of the planet at 02h 33 UT, but rather cloudy at emersion
02h 53 UT, however the clouds were thin and Saturn looked smashing above Mare Australe as the
moon left the planet behind. It was interesting to note how the Inverse Square Law applied,
making Saturn dull and yellow-ish-grey compared with the brilliance of the moon's southern
uplands. The picture was taken with a hand-held canon Ixus 300 at the 9mm eyepiece of a 9" f/6
Newtonian reflector. Antoniadi seeing conditions fluctuated between 3 and 4.
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OCCULTATION OF SATURN - 2007 March 2 02:30 - 03:10 UT
Setting the alarm for 02:00, the sky was clear but frosty. The telescope used was the Celestar-8 at
x50 and x200 Seeing was unsteady and it was windy.
- 02:35 UT Saturn close to the Moon's limb
- 02:39 UT Saturn in contact with limb
- 02:40 UT Saturn looks grey against the much brighter Moon
- 02:41 UT Limb bisects globe
- 02:42 UT Almost gone
- 02:43 UT Fraction of ring visible
- 02:44 UT Gone
Some broken cloud around now and some thin cloud dimming the Moon slightly.
- 02:50 UT First sight of rings re-appearing but may have been there half a minute or so earlier - image very dim
- 02:52 UT Limb bisects globe
- 02:54 UT Globe in contact with limb
- 02:55 UT Planet now clear of limb
- 03:00 UT Planet a ring diameter from limb
The planet was occulted for approximately 6 minutes from this location.
LOCATION - 52° 54' 03" N, 01° 15' 18" W
Elevation 30 metres
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Lovely clear night, air was very steady and seeing conditions were very good. Amazing to watch the whole event
on 2 Telescopes, a Meade ETX 125AT and a Celestron C9.25. I used the ETX to watch the event and the C9.25 for
astrophotography purposes. It's very hard to get a bright Saturn unless you over-expose the Moon, however, on a
setting of 1/125th of a Second, my Nikon 4300 Digital Camera did a great job.
The Close up of Saturn and the Moon was taken by 2 Separate AVI Videos, Saturn was done at 1/30th Sec and the
Moon at 1/500th and the composed into this composite image.
Technical information:
- Telescope: Celestron 9.25
- Imager: ToUcam Pro 2
- Processed: Registax 4/Paint Shop Pro 7
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Posted via the SPA Observing Forum
I have just come in from watching Saturn disappear behind the Moon!! I didn't manage to get any
timings as the cloud in front of the Moon was too thick to see Saturn clearly, but before it
disappeared I managed to get some photos using my digital camera. If there are any decent ones,
I shall post them later today.
Subsequent posting via the SPA Observing Forum
Just seen Saturn reappear, about 02:52:25 UT or there about. Got some images, but cloud is still a
problem! Not going to be able to have a look around tonight as it's really thickened up! So its
back to bed!! Got work in a few hours.
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Just thought you might like to see the picture I've made up from
still frames from a video I took last night (02/03/2007) The frames were
picked at 2 minute intervals between 02:39:00 UT and 03:01:00 UT. I was
at the Ashdown Forest (N51° 02" 25.1" E00° 04' 53.4") where the
prediction seemed to be for a graze, however, it looked to me as though
Saturn disappeared completely for a couple of minutes, perhaps the
graze path was slightly further west.
I've gone through the tape and got some timings, which due to atmospheric
effects, lumpy Moon etc., could be out by 30 seconds or so.
- 2:43:10 Rings first contact
- 2:43:40 Ball first contact
- 2:46:40 Ball second contact
- 2:48:10 Rings second contact
- 2:51:10 Rings third contact
- 2:53:50 Ball third contact
- 2:57:20 Ball fourth contact
- 2:58:40 Rings fourth contact
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Keith submitted the following images from the event:
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Dear friends,
As I reported before the clouds were coming in after the observation of
the occultation by (265) Anna last night.
Anyway I waited for the occultation of Saturn and hoped for a gap in the
clouds.
20 minutes to go...
There were some gaps and I prepared my SAC IV attached at the 10" LX200.
Settings: 320x240 Pixel, 8 fps. Unfortunately clouds crossed the Moon
just in the moment of the disappearance of Saturn behind the dark limb.
The camera shutter was set to a fixed value and the image changed fast
between "overexposed" and "underexposed". Just for a little bit more
than a second the exposure of Saturn was just right. The next moment the
clouds had dimmed the picture again. Saturn was not visible anymore but
the surface of the Moon was recorded with the correct exposure at the
AVI file.
Today I have stacked the few frames of Saturn (about 14 frames) and the
frames with surface of the Moon with "Registax 4". At "Corel
Photo-Paint" I combined these two images to one final image and
resampled it with the factor of 1.5.
The image is still very noisy but not bad for an image through thin
clouds and with bad seeing conditions.
The reappearance at the bright lunar limb 30 minutes later was lost
behind clouds.
So I you had not the opportunity to see the occultation, enjoy this image.
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The main Saturn shot was taken with a C-14 @f/33 using a Lumenera SKYnyx 2-0M camera and Astronomik RGB
filters. The final result is an LRGB with L= to an average of the R and G channels. Seeing was 7/10 and
transparency 7-8/10.
More of Pete's work can be found on his website.
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Iain produced the following video sequence using a Meade LPI + 2x Barlow on a 10" LX200R. Click on the link below
to visit the SPA Gallery Forum, where Iain's clip is available to view.
Occultation of Saturn - Ian Melville
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The occultation of Saturn by the Moon event 2007-03-02; I was not sure how to tackle this one,
with the timing of the event a bit past my bedtime, and the sky having been so cloudy recently,
I wondered if it was worth bothering.
Well, the weather forecast was good and my two mates Ken Irving and Tony O'Sullivan were both very
keen (and still working as well) so I decided that I had to try! But how to do it? There seemed to be
a variety of options, one being just to visually observe the event through a scope, another being to
image, but what with? I decided to keep things fairly simple, rather than set up an array of
instruments and make a mess of everything. So I opted to use my 8 inch "classic" LX200 (which might
be better described as a clapped out LX200 - although it works in a fashion) with my trusty Philips
ToUcam Pro.
I was organised well in advance, having set up the scope about 20:00 UT. I then took it easy
organising for the main event rather than tiring myself out before the main event. I spent ages
polar aligning the LX200, which as usual was being difficult. By
then, the Moon and Saturn appeared above the house tops. The LX200 did not find Saturn, but
fortunately I did! I rather visually observed Saturn and the Moon casually, using the telescope, without
making any sketches. Dare I say it, but with the unaided eye Saturn looked a long way from the Moon, "Surely it
was happening tonight? Or is it tomorrow?" I had a few odd spells "relaxing indoors" nipping out
to see if the sky was still clear, and that the scope was tracking on Saturn. Not that the planet
stayed on the centre of the ToUcam chip monitor image, but it was pretty good (so the
LX200 is not going in the bin just yet).
Approaching 01:00 UT (yes, tomorrow had arrived) I went out, thinking it was then getting time to start
getting serious. Blow me down (you guessed it, a broad band of mackerel type cloud cover came in.
Oh! No! That's IT! For a few minutes things looked bad, but then within a quarter of an hour the
sky largely cleared, with just the odd small patch of drifting cloud remaining. A final check, and the
telescope was tracking Saturn and the ToUcam was working. The difficult thing was deciding on what
exposure to use. I had decided that rather than take two sets of alternate separate
ToUcam images clips, one exposed for Saturn, the other (much shorter) for the Moon, I would gamble on
sticking to one exposure level and hope to sort things out in the processing. When Saturn
and the Moon eventually appeared on the same ToUcam frame (LX200 at f 10). I adjusted the ToUcam exposure, gain
and brightness levels, such that I could just (and only just) see Saturn on the PC monitor image.
Needless to say the monitor image of the Moon was brighter than I would have liked,
but I decided to stick to my plan.
The other problem was how long should I make the ToUcam image clips? Recently I have got round to
taking in excess of 2 minute clips for individual higher magnification images of planets or the Moon.
But, I decided that the different movements of Saturn, relative to Moon, would be a problem
using long clips. I decided to compromise on about 30 second clips, (but in the event, just to edge
my bets in case they failed completely, I did take a 10 second clip and a 60 second clip). I
had thought about taking my ToUcam clips at exact time intervals, but when it came down to it, since
I wanted to get as many clips as I could (within reason), I tended to take clips as quickly as I
could, recording times and writing file references as I went along. It worked out mostly at about
one minute intervals, with the odd gap (snatching a very brief visual observation in between).
Soon after Saturn was well clear of the Moon I went to bed. The next day, the task of image processing using RegiStax
3 initially began as a bit of another nightmare. I was beginning to
think my gamble with exposure settings had been a complete failure. Then, with a bit a judicious use
of RegiStax "wavelets" numbers, I managed to salvage things to my reasonable satisfaction. To get
Saturn to a reasonable brightness level I needed to use very high wavelet numbers. The resulting
colours of Saturn are questionable, but I am reasonably happy, and Saturn is noisy, but my pictures do
show an acceptable amount of detail (e.g. Cassini's Division, globe shadow and a belt). I hope my
attached images help explain most of the basic things related to my pictures. I processed some images
twice (i.e. one to get the best of Saturn, the other for the Moon) then I combined those two RegiStax
results in Paint Shop Pro. Some images I only processed once in RegiStax (i.e. for Saturn) I accepted
a poor Moon because those particular pictures do not show much lunar detail anyway. As viewed from Manchester (or more
specifically for me here in Prestwich!) was this a graze event, or was it a full occultation of Saturn and all
of its rings as well? I was expecting a graze, and analysis of my images so far suggest it was a graze.
However, as yet my analysis is relying on two rather crudely joined images, which suggest that
the tip of Saturn's rings was never fully occulted.
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Not very good night last night - this picture was just before the clouds
came, and that was it. I've been waiting for one of these for a long
time. Here's waiting for the next.
The picture is a frame from a 22 second webcam movie taken at 02:24 UT using a Philips
ToUcam Pro.
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Posted via the SPA Observing Forum
Commenced observing at 01:50 UT. Using a combination of the Mewlon (12" Cassegrain)
and a 4" Vixen Fluorite piggy-backed to the main scope. Nice wide field in the Vixen at
x36 showing a bright Moon and a tiny Saturn in the same field. In the Mewlon, using
bino-viewer, initially at about x190. Nice crisp image (my local seeing is not
normally that good in the west) could see 3 Moons laid out in a triangle, Cassini,
Crepe ring, equatorial zone, a darker band in the southern hemisphere, then a
lighter zone, then a darker polar band. The northern hemisphere was darker with a
bluish tint to it. Shadow of globe on rings, wasn't sure if it was shadow, Crepe,
or combination that I was seeing between the B ring and the globe. Hint of structure
in the B ring. Did push the power up to x300 but a bit fuzzy at times, best was
about x250. Couldn't see Encke's/Keeler Gap - seeing wasn't good enough.
This was looking to be a promising event, seeing a reasonable level of detail this
close to a bright Moon with not a cloud in sight.
02:10 hrs, x250, Saturn in centre of FoV, Moon at edge (7 or 8 O'Clock in my inverted
view). Cassini still well defined, Crepe ring and banding on the globe still visible
- beautiful sight.
02:17 UT: Pleasant view in the Vixen at x120 but with the bright Moon so close the
image of Saturn just wasn't bright enough to give the detail visible in the 12".
The Moon is looming.
02:30 UT: Cloud approaching, would you believe it!!!! Only thin stuff at the moment
but it's taking the edge of the contrast of the image.
02:32 UT: Thicker cloud covering now, occultation imminent and I'm having to reduce
power to x190 - British weather !!!
02:34 UT: Saturn less than a globe's diameter from Moon and almost greyed out due to
a thick dollop of cloud, can't see it in the Vixen at all!
02:35 UT to 02:37am: Saw just rings and then finally disappeared behind the Moon. The
occultation was visible but only just, due to the cloud.
02:38 UT: Cloud completely cleared away from Moon!!! But stayed clear thereafter,
left scope tracking on Saturn, watching the Moon move through the FOV, upped power again
to x250 whilst keeping an eye on things through the lower powered Vixen (just in case).
02:59 UT: Rings just starting to poke out from behind Saturn. Awesome sight, a planet
rising from behind the Moon's limb. Could see both rings and Cassini as they appeared,
and the globe, but didn't see the Crepe ring (not expected this close to the Moon).
This sight more than made up for the earlier frustration and disapointment. It was
just awesome seeing this ringed planet in detail and a respectable size rising edge
on from behind of the Moon.
03:15 UT: Seeing deteriorating, Jupiter rising in the SE, time to call it a night.
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For once down here in London we had perfectly clear skies and after getting up at 02:00
I rushed outside and saw the whole thing. Managed to get a few shots with the webcam,
although had terrible trouble with the difference in brightness
between Saturn and the Moon. Other half thought I was mad getting up so early to see it,
but it was well worth it. I was too busy trying to image to remember exact times, but did
note that the occultation was much more complete than my StarryNight Pro predicted (it
said rings would still be visible) - and was longer than I expected. I estimate that the
disc of Saturn dissappeared about 02:48 and reappeared about 02:53.
As a relative beginner it was my first occultation, and as the weather gods were more
than kind I thoroughly enjoyed the whole thing. I am determined that next time I will try
to sort out exposure problems and get better pictures of Moon and Saturn.
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I'd set up fairly early for this event, at 23:55 UT, using an ETX 90 at 100x magnification.
Apart from a very slight haze, the sky was fairly clear. I had some lovely views of Saturn,
and by 02:08 UT I had the lunar limb and Saturn in the same telescopic field of view.
At 02:35 UT, with only 10 minutes to go, the patchy cloud began to roll in, and the view
became intermittent. Despite this, in fleeting moments, I had some beautiful views as the
lunar limb encroached upon Saturn. Alas, I missed the crucial moment when the lunar limb
made contact with Saturn's ring system. For about 30 seconds, at about 02:46 UT, during a
slight break in the cloud, I had a stunning view of an approximately 55% occulted disk of
Saturn - and a real sense of the motion of the Moon. After that it was solid cloud until
I had a last brief glimpse of Saturn at 02:57 UT, when the occultation was over. A few
seconds later and everything was covered in cloud again.
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The skies were clear and it was possible to follow the occultation from start to finish. I have a
small Meade (ETX90), so the view of Saturn is very small indeed! I used a standard Moon filter to
cut down the glare, and so it was possible to follow the occultation right through, but once the
main bulk of the planet became occulted I found it was extremely difficult to see any part of the
rings at all - especially at maximum occultation. My impression, therefore, was that more than 50%
must have been occulted.
This was the first time I had attempted anything like this!
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Posted via the SPA Observing Forum
The evening started out fine and clear, but up here in Dunvegan, Isle of Skye, you also expect the
worst. By 11:30 UT it didn't disappoint, the clouds came rolling over. Stayed up hoping until 01:30 UT,
but no luck. Maybe next time !!
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Brian submitted the following images from the event:
More of Brian's work can be found on his website.
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Observed with an ETX 90 OTA mounted on a parallelogram mount (meant I could easily switch viewing
postions and powers using the flip mirror).
Observed from 02:30 UT to 03:05 UT. Clear but breezy.
02:30 UT - Saturn not visible to naked eye since 2:00am, due to lunar glare. Approaching limb of Moon.
Brown/tawney colour. Not easy to see detail given size of scope. Rings prominent.
First contact of outer ring noted at 02:41:20 UT. Fully immersed about 3 mins later but I
mis-hit the stop watch, so I don't have an exact time of full immersion. Saturn fully reappeared
(all rings clear) at 02:58:30 UT. Start to end time 17 mins 30 seconds.
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Maintained by
Jeff Stevens. Last modified 7th March 2007.
