51 replies to this topic

[KiwiRay]

Thanks a bunch for the list, Ray. Since it is predicted to be clear at my place on the morning of the 14th, I plan to set up my 16-inch to try and observe Saturn as Titan transits. Maybe I'll see it or just a sliver of its shadow?

 

Scott H.

You won't see the shadow, which will be below the planet, but Titan is darker than Saturn so it will easy to see the transit with your scope. Good luck!

[Bob King]

Hi everyone,

 

How do you set Winjupos up to show a list of Titan transits and shadow transits? Thank you so much for your help!

Bob

[Mike_Kar]

Thanks for sharing this great information Ray. It's very much appreciated!

Mike

[KiwiRay]

Hi everyone,

 

How do you set Winjupos up to show a list of Titan transits and shadow transits? Thank you so much for your help!

Bob

I don't think you can, but because its orbital period is very close to 16 days, once you have one date, you can find the others one at a time. That's all I did for the list above.

[Bob King]

Thanks, KiwiRay. But how do you show a single transit event? When I open WinJUPOS I see CM crossing, etc. but nothing for transits. It must be something very simple I'm overlooking. Thanks for your help.

Bob

[yuzameh]

Thanks, KiwiRay. But how do you show a single transit event? When I open WinJUPOS I see CM crossing, etc. but nothing for transits. It must be something very simple I'm overlooking. Thanks for your help.

Bob

Trial and error, kr probably did a lot of looking till he found the first one then used his sixteen day route to scan about for following ones.

 

Some planetaria software will also show shadows and transits.  I use Guide 9.0 and the game with that is you can lock onto a planet and the sky moves behind it when you are in animation mode, so you could jump daily then pause than go slower till you see one.

 

In other words, kr put in a lot of legwork.

 

I think I gave some clues in this thread somewhere on how to do a look up using a service at paris observatory, but quite rightly few folk read my long and bloated witterings.  'sides which everyone seems to want stuff on a plate nowadays, since web 2.0 took off as smartphones got faster and 4G kicked in.

[KiwiRay]

Thanks, KiwiRay. But how do you show a single transit event? When I open WinJUPOS I see CM crossing, etc. but nothing for transits. It must be something very simple I'm overlooking. Thanks for your help.

Bob

From the graphics tab you can see where Titan is for any date relative to Saturn, which allows you to guess when the next transit might be. Then adjust the day and hour until you get it right. So yes, trial and error for the first one and every 16 days after that.

 

One of yuzameh's links above does contain the information, but it's not completely intuitive (and is in French): https://ssp.imcce.fr...tellites-events

 

If you choose Saturn, and manage to fill in the other fields (I just put in degrees for coordinates - accuracy doesn't matter), it will output a list. You're looking for Corps A to be "606" for Titan transits. Eg, for June 14, you'll see two times with 606, one the start of ingress and the other the start of egress (I assume the time in minutes is how long Titan takes to cross Saturn's edge). I don't see a way to filter for a particular event, but presumably you could download the data and then filter in Excel or similar software. Creating a list of start and end times of any given event wouldn't take much work once the data are downloaded. There is a diagram under Documentation that visually explains what the Type codes mean. So PA.D and PA.F are the beginning of ingress and egress respectively. Other codes refer to shadow transits, occultations and eclipses.

[Bob King]

I see the ephemerides for Saturn and I can create a visual simulation and see the times of Titan's entrance and exit but I don't have any idea where "Corps A" is. This may be a lot to ask but can you write out a step-by-step?

Thanks!
Bob

[RedLionNJ]

Trial and error, kr probably did a lot of looking till he found the first one then used his sixteen day route to scan about for following ones.

 

Some planetaria software will also show shadows and transits.  I use Guide 9.0 and the game with that is you can lock onto a planet and the sky moves behind it when you are in animation mode, so you could jump daily then pause than go slower till you see one.

 

In other words, kr put in a lot of legwork.

 

I think I gave some clues in this thread somewhere on how to do a look up using a service at paris observatory, but quite rightly few folk read my long and bloated witterings.  'sides which everyone seems to want stuff on a plate nowadays, since web 2.0 took off as smartphones got faster and 4G kicked in.

Another Guide 9.x user here. Been using Guide for at least 25 years and Bill Gray (author) has done a remarkable job in keeping it accurate beyond any reasonable expectations, particularly for planetary moon and "surface" feature events.

 

BTW, I'm going to pin this thread for a few weeks. If I've had to dig for it more than once this month, I'm sure others have, too.  Nice work, Ray - much appreciated.

[KiwiRay]

I see the ephemerides for Saturn and I can create a visual simulation and see the times of Titan's entrance and exit but I don't have any idea where "Corps A" is. This may be a lot to ask but can you write out a step-by-step?

Thanks!
Bob

I probably wasn't clear. The second half of my post was referring to the link to the French emphemerides site, not WinJUPOS. For WinJUPOS, you just have to manually change times and watch the graphics change (or play at high speed and watch for a long time).

[Bob King]

Thank you all! I appreciate the several options.

Bob

[RedLionNJ]

Here's another prediction option I forget from time to time.

 

Don Carona (Texas A&M) put together a web page which computes satellite events around Saturn. It's quite flexible and may serve as a reference (as well as a predictor) when someone records what looks like a bright spot or a dark spot on Saturn's rings or southern hemisphere this apparition:

 

https://doncarona.ta...du/apps/saturn/

[Robert Lunsford]

I managed to photograph the Titan transit Sunday morning using my 9.25in SCT at f20 and f12.6. While the sky was clear east of San Diego, CA, the seeing was poor. I could not see Titan's disk through the eyepiece at 235x, but it was easy to see on the laptop screen once I connected my camera to the scope.

I look forward to the next two transits plus the shadow transits in November!

 

Clear Skies,

Bob Lunsford

 

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[RedLionNJ]

Member cotts started a thread over in Solar System Observing, devoted to the Titan shadow transit predictions for 2024 and 2025:

 

https://www.cloudyni...4-5/?p=13532739

[yuzameh]

From the graphics tab you can see where Titan is for any date relative to Saturn, which allows you to guess when the next transit might be. Then adjust the day and hour until you get it right. So yes, trial and error for the first one and every 16 days after that.

 

One of yuzameh's links above does contain the information, but it's not completely intuitive (and is in French): https://ssp.imcce.fr...tellites-events

 

If you choose Saturn, and manage to fill in the other fields (I just put in degrees for coordinates - accuracy doesn't matter), it will output a list. You're looking for Corps A to be "606" for Titan transits. Eg, for June 14, you'll see two times with 606, one the start of ingress and the other the start of egress (I assume the time in minutes is how long Titan takes to cross Saturn's edge). I don't see a way to filter for a particular event, but presumably you could download the data and then filter in Excel or similar software. Creating a list of start and end times of any given event wouldn't take much work once the data are downloaded. There is a diagram under Documentation that visually explains what the Type codes mean. So PA.D and PA.F are the beginning of ingress and egress respectively. Other codes refer to shadow transits, occultations and eclipses.

As probably noticed in another thread here, I did use the documentation button at imcce recently and then something called reverso (online) to get a better idea of the column headings (cut and paste then translate).  Still not entirely sure on some aspects (the flux ratio value for instance) but others work.

 

One thing I did notice is that Guide 9 for the first Oct 2 eclipse event differed by quite a few minutes, which was a bit weird because the June event matched within seconds (I also figured out the leap second situation, the version I've got goes back to before the 2017 leap second, and states that future values of TD-UTC will be extrapolated, so Guide is likely using 70.4 seconds (at least on my system) difference (delta T consists of a fixed TD to TAI (atomic clock) difference of 32 and a bit seconds and then you add the leapseconds to that), whereas it's only 69 and a bit because they stopped adding leap years (the planet also sped up recently and at one point they were worried about how to fit in a negative leap second, a lot of modern interactive stuff nowadays needs time not to be played with so much, so they haven't used a leap second in ages and are thinking of ditching it in 2035, as all it does is make little Y2K type issues for firmware)

 

ANYWAY, the real point is that when you've got your list of predictions up from IMCCE you will see at top right of the table just generated (NOT the page, the table) is a little cog wheel symbol, which usually means "settings".  I bravely clicked it and found a pleasant surprise.

 

A list of the names of the objects generated in the table appears with little tick boxes next to them.  So if for instance you unticked all bar Saturn and Titan you'd only end up with the predictions for Titan.  I just unticked Saturn to narrow it down to the satellite mutual phenomena at first, but suck it and see is likely the way to go.

 

NB it turned out that on 2nd Oct 2024 there was another partial eclipse around my local noon, and I think at just about Saturnset in most of USofA, so not much use.  However, I wanted to check Guide 9's accuracy on that one given the time offset compared to IMCCE for the one early in the UT day.  Tried it, couldn't find the Satellites, zoomed out, and found why.  They were behind Saturn (at least relative to the Earth).  I'll play with it more another day, but as all events here are not due until maybe 2025 (as in mostly daytime ones here until that time) last time I checked, and highly unlikely visually observable, especially in my kit (even Titan transits), the interest for me is more academic.

 

SUMMARY : IMMCE results tables have a little cog wheel to to top right, press on that and you can select specific satellites or Saturn, toggling them on or off, to customise targets shown in the table.

[yuzameh]

I managed to photograph the Titan transit Sunday morning using my 9.25in SCT at f20 and f12.6. While the sky was clear east of San Diego, CA, the seeing was poor. I could not see Titan's disk through the eyepiece at 235x, but it was easy to see on the laptop screen once I connected my camera to the scope.

I look forward to the next two transits plus the shadow transits in November!

 

Clear Skies,

Bob Lunsford

Aha, not just meteors then!

 

Good stuff!

[yuzameh]

Here's another prediction option I forget from time to time.

 

Don Carona (Texas A&M) put together a web page which computes satellite events around Saturn. It's quite flexible and may serve as a reference (as well as a predictor) when someone records what looks like a bright spot or a dark spot on Saturn's rings or southern hemisphere this apparition:

 

https://doncarona.ta...du/apps/saturn/

That is indeed a lovely website, I saw it the other day when you or someone else linked it in another thread.  Wish you could zoom in and out of the graphics though.  I thought I got them to animate first time I looked at it but today I think I got it confused with something else.

[yuzameh]

Here's a years worth of Titan set for Geocentric (idealised Earth Centre) for what I think are just the occultations and shadow transits.  Occultations are called PASSAGE (the type which is given as occultation are occultations of the satellite by the planet, similarly eclipses are eclipse of the satellite whilst ombre sounds like umbra ie shadow transits).  D is start and F is Final

 

Date de début (UTC)                 Dur.min sat   Type    Δf% DistRad Distarcsecs
2024-07-16T06:18:01.669 24.87 606 PA.D   0 -0.06  8.66
2024-07-16T10:13:16.062 24.99 606 PA.F   0 -0.06  8.61
2024-08-01T04:56:30.154 37.77 606 PA.D   0 -0.08  8.63
2024-08-01T07:31:02.263 38.02 606 PA.F   0 -0.08  8.6
2024-11-20T19:38:41.483 38.02 606 OM.D   0  1.29 20.33
2024-11-20T22:12:09.030 38.67 606 OM.F   0  1.87 25.48
2024-12-06T18:29:13.728 27.43 606 OM.D   0  1.17 18.71
2024-12-06T22:02:57.176 27.68 606 OM.F   0  2.00 25.88
2024-12-22T17:25:41.880 22.95 606 OM.D   0  0.93 16.26
2024-12-22T21:41:41.004 23.07 606 OM.F   0  1.94 24.74
2025-01-07T16:26:05.548 20.42 606 OM.D   0  0.60 13.14
2025-01-07T21:14:20.138 20.47 606 OM.F   0  1.74 22.46
2025-01-23T15:29:13.890 18.80 606 OM.D   0  0.20  9.66
2025-01-23T20:42:44.848 18.82 606 OM.F   0  1.41 19.36
2025-02-08T12:59:14.231 36.58 606 PA.D   0 -0.08  7.31
2025-02-08T14:34:27.504 17.70 606 OM.D   0 -0.19  6.44
2025-02-08T15:41:47.744 36.58 606 PA.F   0 -0.08  7.31
2025-02-08T20:07:43.957 17.70 606 OM.F   0  0.98 15.73
2025-02-24T12:27:29.749 19.00 606 PA.D   0 -0.03  7.64
2025-02-24T13:41:18.402 16.94 606 OM.D   0 -0.33  5.23
2025-02-24T17:40:26.824 19.00 606 PA.F   0 -0.03  7.64
2025-02-24T19:29:41.963 16.94 606 OM.F   0  0.50 11.8
2025-03-12T12:41:02.338 16.21 606 PA.D   0  0.0   7.82
2025-03-12T12:49:32.166 16.42 606 OM.D   0 -0.05  7.46
2025-03-12T18:47:56.835 16.21 606 PA.F   0  0.0   7.81
2025-03-12T18:48:55.199 16.42 606 OM.F   0  0.0   7.86
2025-03-28T11:59:00.682 16.09 606 OM.D   0  0.43 11.23
2025-03-28T13:20:20.181 16.23 606 PA.D   0  0.00  7.84
2025-03-28T18:05:39.920 16.09 606 OM.F   0 -0.43  4.51
2025-03-28T19:26:28.573 16.23 606 PA.F   0  0.00  7.84
2025-04-13T11:09:43.784 15.92 606 OM.D   0  0.93 15.28
2025-04-13T14:18:17.248 18.78 606 PA.D   0 -0.03  7.72
2025-04-13T17:20:07.108 15.92 606 OM.F   0 -0.51  3.9
2025-04-13T19:34:30.837 18.78 606 PA.F   0 -0.03  7.73
2025-04-29T10:21:42.287 15.90 606 OM.D   0  1.38 19.17
2025-04-29T15:34:52.415 29.18 606 PA.D   0 -0.07  7.5
2025-04-29T16:32:24.732 15.90 606 OM.F   0 -0.2   6.47
2025-04-29T18:58:15.727 29.18 606 PA.F   0 -0.07  7.51
2025-05-15T09:34:57.134 16.02 606 OM.D   0  1.76 22.64
2025-05-15T15:42:34.832 16.02 606 OM.F   0  0.16  9.54
2025-05-31T08:49:35.030 16.30 606 OM.D   0  2.03 25.44
2025-05-31T14:50:43.421 16.29 606 OM.F   0  0.46 12.24
2025-06-16T08:05:40.857 16.76 606 OM.D   0  2.17 27.33
2025-06-16T13:56:47.574 16.75 606 OM.F   0  0.65 14.21

 

(I wish people would remember to put leading and trailing zeroes in their tables!!!).

 

I've checked first occultation and first eclipse with Guide and they tally as to type and approx time.

 

Now, even if, like me, you can't parlez the old Francais, or barely can, this link will help

 

https://ssp.imcce.fr...ites-events/doc

 

just scroll down to the diagram which graphically depicts what the types represent.

 

And I've just found they have a list of mutual events here

 

http://nsdb.imcce.fr...t/nsszph6he.htm

 

dans Anglais!

 

It's set for 500, geocentric, click "see the list" and you can pick a station number in a city near you.

[RedLionNJ]

 

It's set for 500, geocentric, click "see the list" and you can pick a station number in a city near you.

I should think 500 would suffice for events at Saturn's distance.  Be a little different if we were talking about a close pass by an NEO

[John Asztalos]

I was lucky enough to see the 6/30 event.  The sky was steady, and Titan was a clean round disk (480x on 12-1/2"), with shading towards it's limb.  Then on Mon. morning, 7/8, there was a Tethys (moon and shadow) transit,  so just for grins I went for it.  It was steady again, couldn't see anything, but the shadow is only ~0.15 arc-sec.  But wait there's more.  Titan was just coming out of occultation, and it brightened on Saturn's edge over a roughly 3-5 minute period.   Enceladus was fairly easy being at "eastern elongation".  Mimas, not so much.  I sort-of suspected it.  What I've been doing is checking out the seeing forecast, then getting on Stellarium to see what events (if any) are coming up.  Steady skies, all!

[Robert Lunsford]

John,

 

Thanks for sharing your experience. I was out the same night and photographed Titan an hour or two after your observation.

 

I'm looking forward to tonight's transit and I'm hoping that the stratus deck will stay away long enough for me to get a couple of photos. This occurs earlier so that favors clear skies, but the elevation will not be quite as favorable as the 6/30 event.

 

Here is a photo of Saturn on the morning of July 8th.

 

Bob Lunsford

 

[yuzameh]

I've been playing

 

A years worth of events from IMCCE Paris's online prediction generator from 28th August set at Greenwhich's location.

 

I forgot to save a copy before trimming the Sun below horizon and Saturn below horizon bits so likely not much use to extreme east and west or southern individuals, but on those long winter nights some might be available.

 

I've translated the French column headings, with the most non-obvious columns being :-

 

0cntr-1poor - not clear myself, but 0 means transit/shadow transit centred on target with 1 being worst case scenario.

 

MaxFluxDrop - maximum drop in flux (not magnitude, flux, unclear if decimal fraction or amount, probably former, thus would need 2.5*log10(satellite_mag) to turn to magnitudes, only given for satellite on satellite action.

 

MaxSatRadDist - max distance in Saturnian radii.

 

Moon Phase - no idea what 0 to 180 is supposed to mean,  left it in anyway.

 

Moon Dist is in degrees.

 

 

[RedLionNJ]

Resurrecting to pinned status, as we still have some shadow transits to go.

[yuzameh]

For those of you of a UK disposition don't forget

 

Date UTC Duration min Cause Obj Phenomenon Affect Obj 0cntr-1poor MaxFluxDrp MaxSatRadDist ang sep " Obj Alt Sun Alt Moon Phase Moon Dist
2024-11-20T19:38:41.483 38.02 Titan Shadow.Begn Saturn   1.29 20.33 28.5 -35.8 64.3 141.3

 

that's Greenwhich Mean Time (as opposed to Greenwhich Nice Time).  Note altitude ain't great.  If you a high flying imager maybe you'll get a bit of Enceladus eclipse ending about an hour earlier.

 

For those of a European persuasion bung an hour on those times.

 

For the rest of you, you had your turn earlier in the year.

 

Next most bestest Titan ones 6/12/24 and 22/12/24 about an hour earlier each so Saturn alt about the same (NB 9/11/24 was a week ago).

 

As far as I can tell that's our British lot for Titan shadow transits, with none in 2025 nor 2026 despite other phenomena occurring here then, upto and including late August 2027.

 

Also, for UK peeps, I saw some things the other day, I was told they were called "the Sun" and "blue sky" from people old enough to remember when last they were visible.  Frosts are hinted for next week in forecasts, but so is cloud cover, so we may just be getting a lump of polar air as opposed to clear skies, especially in central to southern England and all of Wales.  Bugger!

[YossiZ]

I intend to image the transit tomorrow with a 6" Maksutov on an equatorial mount.
What is the maximal video length without smearing the shadow?