Daylight observations of stars

CometGuy · #1 30-08-2009, 04:46 PM

At about 3:30pm this afternoon I was having a look at the moon through a C8 as the transparency was quite good and the contrast good. With the good conditions I tried to see if I could find some stars using a 9mm Plossl (220x). These were my results:

Antares (mg 1.1) : Very conspicious and showing a striking vivid Orange against the blue sky.

Sigma Scorpii (mg 2.3) : Very easy to see.

Lamda Sag (mg 2.8) : Very easy.

TY1 7377-1056 (mg 4.8) : Not spotted immediately, but once located seen with ease.

TY1 7378-3132 (mg 5.2) : Took approximately 5-10 seconds before located, dim, but not hard to hold in constant view.

TY1 7385-659 (mg 5.6) : Difficult and getting close to the threshold of visibility. Interestingly this is the brightest member of the M7 star cluster.

After this cloud moved in and started reducing contrast, but I am confident I could have got close to mag 6.0 some 2 hours BEFORE sunset!

Terry

mozzie (Peter) · #2 30-08-2009, 04:59 PM

there amazing to see in daylight hours i often use my scope and follow stars of a day rigel kent is another fine sight and you can see the 2 have a look at venus during daylight the phases are easy visable
mozzie

Lester · #3 30-08-2009, 05:00 PM

Interesting stuff there Terry, I have always wondered what would be the faintest magnitude stars that could be viewed during daylight.

Once I get my GOTO working I will check it out.

Thanks.

Quark (Trevor) · #4 30-08-2009, 05:47 PM

Hi Terry,

It is possible to observe stars in the middle of the day naked eye.
About 10 years ago, on route to the SPSP we stopped off for a few days in Canberra and went to Mount Stromlo. In the visitors centre, among other things, they had a 8 or 10 inch Schmidt Cassegrain with a CCD camera on it. One of the Stromlo people that was present saw me looking at the screen of the monitor showing what the CCD was imaging, it was quite a bright binary star, Alpha Cent.

They also had a cardboard cylinder, about 2" diameter, taped to the tube of the scope. The operator told me to stand back and look through the cardboard tube, which I did, and there was Alpha Cent visible to the naked eye in the middle of the day. If I fixed my gaze on the star and moved away from the scope without blinking I could still see the star, if I blinked or turned away and then tried to find it again, it was impossible, until I went back to the cardboard tube to find it again.

Regards
Trevor

pgc hunter · #5 30-08-2009, 07:12 PM

That's quite interesting! Well done on your observations. I've only ever seeing Venus in daylight, but seeing wreaks havoc due to the sun blazing upon all the concrete, asphalt, roof tiles and crap.

Alpha centauri seen with naked eye in broad daylight

that's impressive!

DavidU (Dave) · #6 30-08-2009, 07:19 PM

I have reacked down some planets during the day but I must have a go at stars

leon · #7 30-08-2009, 10:17 PM

Although I only do imaging that must be an amazing sight, it is one probably never thinks about, except you guys of coarse.

Leon

byronpaul (Paul) · #8 30-08-2009, 11:17 PM

Terry, how did you align your scope to start with?

Is it a permanent mount, or was it aligned from a prior night?

I've wondered about trying this, but thought I'd have to leave my scope outside one night in the "Park" position.

CometGuy · #9 31-08-2009, 03:54 PM

Paul,

I have a rolloff roof observatory so it was pretty easy to GOTO the objects. I did do some fine tuning on the moon and then did small hops to successively fainter stars. This way I could make any small corrections (I have a custom program that talks to the mount via ASCOM).

Terry

mozzie (Peter) · #10 31-08-2009, 03:56 PM

looked at cent.a arcturas spica today cool sights i have my scope permenate pier and the first star is pretty close to the centre .byronpaul you may have some trouble after coming of park the lx90 and them bloody lnt modules they override the telescope and dont give you a o reading i had lots of trouble with mine but you can try it
mozzie

byronpaul (Paul) · #11 31-08-2009, 09:40 PM

Quote:

Originally Posted by mozzie

looked at cent.a arcturas spica today cool sights i have my scope permenate pier and the first star is pretty close to the centre .byronpaul you may have some trouble after coming of park the lx90 and them bloody lnt modules they override the telescope and dont give you a o reading i had lots of trouble with mine but you can try it
mozzie

Peter, thanks for the heads-up. I'll give it a try ..... but at least you've hinted at a potential flaw in my ability to try this.

Nightskystargaz (Thomas) · #12 01-09-2009, 01:19 AM

Terry,

I've never tried it on stars, but I tried it on the Moon.

Thanks,

Tom

Outbackmanyep · #13 04-09-2009, 06:44 PM

Hi Terry!
I had a group of school kids at Copeton Dam recently, we didnt see much the night before (clouded out) but i managed to roughly polar align my C8 using a compass, then i used my Astronomy 2009 Ephemeris to find Geocentric positions of the Sun (as i don't have GOTO). I used an indirect method to find the sun in the finder (hand over the eyepiece of finder; with cap on the main scope of course) then used my setting circles to set posi to the Sun, then found Venus position in the book, swung the scope to position and found it in the finder, Voila!
The kids had a good look, and i even showed them with the naked eye, and then i went on to find Sirius then i had to go to work! They all enjoyed it pretty well!

It's always fun finding stars in daytime!

jjjnettie (Jeanette) · #14 04-09-2009, 07:03 PM

I'll sometimes, if I've left the TOT in Park from the night before, track down Venus and Jupiter.
Taking great care re. Sol. of course.
Next time I'll have a go at some stars.

CometGuy · #15 01-11-2009, 07:30 PM

I attempted some more "extreme" daylight observations today including a daytime observation of the planet Uranus! Transparency was not too bad (good for this time of year) so armed with the C8, 220x and a GOTO I started looking late in the afternoon with the Sun up around 5 degrees from the horizon.

Jupiter was a spectacular sight with obvious cloud detail and all 4 Galilean moons visible. IO and Europa, mag 5.6 and 5.9 respectively, were rather easily visible possibly due to proximity to the planet itself. After locating Ganymede, I then moved onto spot Callisto at only mag 6.4. I would never have though I would be able to see something at mag 6.4 with sun shining brightly against the side of my face!

With the Galilean moons under my belt I then moved onto something more challenging - Uranus. Uranus being lower in the sky, non-stellar and not located near a bright object was going to be tough. To ensure I got accurate Goto I star hopped down from Jupiter in the sky to various stars of around mag 4. These stars were all clearly visible, and I could centre the star and update the Goto pointing. My first attempt failed to find Uranus but I hopped across to a mag 5.5 star and found it, then a nearby mag 5.9 star and also found that. Perhaps because the sun was getting lower, on my second attempt the planet Uranus was finally visible (with the sun a calculated 2.7 degrees above the horizon!). In the daytime sky the Planet's tiny limb darkened disk seem to give it a vague diffuse appearance - it was visibly non-stellar.

As the sun neared the horizon I then slewed back to Jupiter. How faint could I go with the sun still up. Well I succeeded in getting a mag 7.1 star just before the sun touched the horizon, and then a 7.4 star as the sun was setting!

Don't ask me why the fascination with seeing stars by daytime, but it is certainly a "cool" experience. I also find the star colour seems to be more obvious in daylight, perhaps because colour sensitive vision is fully activated and perhaps because of the contrast against the blue sky.

Terry

Lester · #16 03-11-2009, 10:48 AM

I enjoyed reading your daytime star hunt, plus Uranus. Good stuff Terry.

CometGuy · #17 14-11-2009, 06:28 PM

Today, setting up my C8 again for some comet hunting I tried even harder for stars in daylight and set a new benchmark! As a hint I've now managed to see all 8 planets during the daytime

The seeing and transparency seemed quite good - although a bit of haze in the west - and I could plainly see Jupiter and its 3 brightest moons around 5:30pm. Mag 6.5 callisto was a bit harder, especially since it was well away from Jupiter itself, but once found it was seen with ease.

However, with the sunset getting closer I decided to go for a harder target, mag 7.9 Neptune! I centred the scope on a nearby mag 5.9 star, which was plainly visible, and at that point - judging by how easy the star was to see - I went for the planet. To my amazement at 6:10pm I succeeded in finding Neptune! From my location I calculated the centre of the sun to be 0.5 of degree above the horizon and local sunset to be around 2-3 minutes later.

NOTE: I am going to try to make a metal pointer/reticle at the field stop in the eyepiece (this allows the eye to be trained more readily at infinity) so perhaps its possible to see fainter still

Terry

Outbackmanyep · #18 16-11-2009, 05:16 PM

Interesting development Terry, are you going to try for SOHO comets visually or something?

Domol (Domenic) · #19 17-11-2009, 03:25 PM

Sounds like a great way to spend a sunny afternoon. I think you just opened up a new branch of Astronomy! Thanks

CometGuy · #20 18-11-2009, 06:15 PM

Chris,

I think your on to my thinking! However, at SOHO distances the limiting magnitude is much higher, maybe its possible with a videocam. The most impressive daylight observation I've seen (made 2.5 hours before sunset) is this image of M57:

http://mallincam.tripod.com/sitebuil...dayfinal3w.jpg

When you stretch the image you can see mag 12-13 stars quite easily. 8 Degrees from the sun WILL be a different story, however, and I think you would loose several magnitudes so I do think it is good enough against SOHO!

Terry