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Old 03-06-2019, 04:43 PM
Astrovisuals
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Daylight Jupiter Occultation

Am wondering about how much to feature a daylight occultation of Jupiter that will occur on January 23, 2020, in my Astronomy calendar?

The event will occur around noon, but is less than 2 days before new moon, so only about 22 degrees will separate Sun from moon.

So, apart from the danger of accidentally looking at the sun through the telescope, will it be a sight worth looking for, or be too difficult?

Last edited by Astrovisuals; 03-06-2019 at 04:45 PM. Reason: Clarity
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Old 03-06-2019, 08:26 PM
Saturnine (Jeff)
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I would be happy to see it included in the calendar , maybe with the caveat about taking care not to point the telescope anywhere near the sun. The only problem may be that being only 22 deg. from the sun, there may be glare down the dew shield from the sun. would be advised to set up in the shade of a building or tree to prevent the chance of glare being introduced.
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Old 03-06-2019, 09:15 PM
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I think this will be a challenging observation.

I am a experienced daytime observer, chasing Lunar occultations, conjunctions of bright objects, bright stars and double stars and testing just how close to the Sun I can see bright objects, eg Venus and crescent Moon. Back on 18th Oct 2018 I completed a five planet observation in broad daylight. At the time Jupiter was at mag -1.8 and 30 degrees from the Sun. Refer to my Observing Report:

http://www.iceinspace.com.au/forum/s...d.php?t=170943

You can see my observation using a 140mm refractor noted: "Jupiter - faint disc with main bands just visible.” To add to this, my recollection is that Jupiter was certainly faint, but quite easy to see in the FOV.

This time it will be harder:
Jupiter will be closer to the Sun meaning more glare and heightened safety issues given the Sun is following Jupiter across the sky. Jupiter, and indeed the Moon, will be much more difficult to observe.
The Moon will not be visible naked eye. It will require some daytime observing experience to find the Moon with a push to scope. It will be doable, but a challenge.
Alternatively, it will require an aligned goto mount to find the targets. Goto mounts on fixed piers will be fine, but it would take some planning to set up a scope in the field and have it aligned ready to find the Moon and Jupiter. Perhaps set up and align in darkness and leave set up for the daylight observation. Daylight alignment can be done but needs some knowledge and experience
A polarising filter will greatly assist the observation by darkening the bright background sky. Red filters can help too.

Incidentally there was a daytime Lunar occultation of Saturn on 23rd May. Saturn was well placed, perhaps 160 degrees from the Sun. I have not seen any commentary or feedback from anyone seeking to observe this event. Admittedly, Saturn was at mag 0.5, so much fainter. I chased this observation but was thwarted by very thin high cloud. I have observed Saturn in daylight previously at this magnitude, so it was certainly doable.

There is a grazing Lunar occultation of Saturn visible only from southern Tasmania in November - my next daytime observing challenge!
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Old 04-06-2019, 01:35 AM
Saturnine (Jeff)
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Sorry to go off topic a little.
Steve, I was aware of the occultation of Saturn on the 23/5 but when studying the mechanics ! it meant that the moon was only about 15 deg. above the horizon, almost setting behind the hilltops. Being so low and Saturn being quite faint I didn't think it was a viable observing opportunity.
As for the Jupiter occultation on the 23/1/20, if you have the backyard where you can align the mount during darkness and leave it set up so that GoTo can find the target when nearing the time of the occultation, that will take some of the pain out of the exercise. Maybe something like a beach umbrella providing shade may help a well.
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Old 04-06-2019, 11:01 AM
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Seeing Saturn on the 23rd was always going to be problematic. I am a little further west than you so the events were a little higher. Worth a try though - in the end the high cloud won out. The Moon was visible but not Saturn.
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Old 05-06-2019, 06:23 PM
Astrovisuals
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Jupiter occultation

Thanks for the very thoughful replies. Intended target for the calendar has always been a mix of serious astronomers plus interested naked eye or binocular observers, so would like to include it for serious observers. Will have to put warnings as you suggest. Good point about sun following Jupiter, so shade will vanish! Midday mid January... you’d want shade anyway!
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Old 06-06-2019, 11:27 AM
Saturnine (Jeff)
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Glad that we may have been of some use with our thoughts. Love the calendar, have been buying it for quite a while now and find it most useful. Hangs up along side the computer desk so it can be referred to at the turn of the head.
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Old 06-06-2019, 05:39 PM
Wavytone (Nick)
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Set up where the sun is safely blocked from the scope eg behind a building or similar. Test the day before to make sure, using sky safari to work out where tha planet will be respective to the sun.

Last edited by Wavytone; 06-06-2019 at 09:01 PM.
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Old 07-06-2019, 05:16 PM
Astrovisuals
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Yes I thought that would the way to go. Problem is with the waning moon, the sun is following Jupiter, so by the time you wait for Jupiter to reappear an hour later, you might be in the Sun again!
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Old 09-06-2019, 09:17 PM
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In fact for most of Australia, the occultation period is well in excess of an hour - up to 1 hour 20 minutes here in Tasmania. So it will be virtually impossible to place the scope in a building shadow and not have the sun emerge from behind the building before the occultation ends.

This should not really be a problem if the mount and scope are tracking Jupiter as they will remain the 20 degrees away from the Sun. One will just need to be careful.

Using a building will appeal to some. However there are plenty of DIY solutions that can be used to shield the scope from the glare of the Sun.

Irrespective of any shading strategies that I am using at the time, there is one simple safety step that I take every time I am about to look through a scope that is pointing anywhere near the Sun. I simply place my hand infront of the eyepiece to check that the Sun is not in the FOV. If it was, one would have a very bright and hot image of the Sun being projected onto one’s hand.



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Yes I thought that would the way to go. Problem is with the waning moon, the sun is following Jupiter, so by the time you wait for Jupiter to reappear an hour later, you might be in the Sun again!
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