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Anyone Seen Sirius Naked-Eye in the Daytime?

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#1 SNH

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Posted 15 November 2018 - 04:59 PM

Back in September, Stephen O’Meara challenged me to see Mars naked-eye before sunset. After doing much better than I thought possible on it, I got to wondering what other planets might be visible in daytime. Since Mars was magnitude -1.6 at the time, I realized that Sirius, the night sky’s brightest star, isn’t much fainter at -1.45! So on the morning of October 8th, after failing to see a 16-hours-from-new moon, I turned my attention to watching Sirius as sunrise got closer. While keeping an eye on it, I decided to move my folding chair to a spot where I could just see Sirius above the dark treetops of trees only 20 yards away. As the sky continued to brighten, I used my binoculars to keep an eye on it and keep it in a little “pocket” of a treetop. To my surprise, I was able to keep it in sight and got my last one second view of it exactly 7 minutes after sunrise! A week or so later I repeated the experiment and got the same result -- 7 minutes. I did get a little ambitious one day and tried for Capella, though I lost it 2.5 minutes before sunrise. I hope to try Arcturus in the spring, but until then I might try Sirius a little more this fall. I mentioned my feat to TieDyeAstronomer - and lets just say that she blew my numbers away when she tried it. So has anyone else seen Sirius naked-eye in the daytime?

 

Scott


Edited by SNH, 15 November 2018 - 05:18 PM.

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#2 nicoledoula

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Posted 15 November 2018 - 05:11 PM

I haven't, but believe it can be done. 1st one must know where to look for it. Find it in binoculars and then move the binoculars away. Venus can be found and seen naked eye the same way, although it's brighter.



#3 goodricke1

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Posted 15 November 2018 - 05:25 PM

I think focus is the critical factor. I've found it much easier to see Venus in daytime when wispy clouds are floating by, as these can then be focused on. Or a slender moon, although that won't get close enough to Sirius.


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#4 TOMDEY

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Posted 15 November 2018 - 06:06 PM

I DO, very fondly recall... 1960-ish. We were waiting at the bus-stop for school. Right around dawn, and Venus was shining BRIGHTLY. We kept watching it until the sun was up... and rather pleased that we could just keep seeing it! We were kids, so undoubtedly enjoyed eyes not-yet degraded by the Grim Reaper dulling our senses and sapping our enthusiasm.

 

I know, I know... that's really NOT such a feat. But, to have discovered it ourselves, without some mentor trying to turn us into vicarious little prodigies... now THAT untutored discovery was, by far, By FAR... the BEST!

 

Now, lens implants, PRK, etc. have returned my vision to quite good, again. A peculiar bonus of those procedures... I cannot focus AT ALL. My eyes are "stuck on infinity." The Bonus part of that... If I'm scanning a blank daytime sky... my eyes ARE focused on infinity! I have found that makes it especially easy to see stars, typically long before my friends.

 

I DO practice a lot. Going for the planets and 1st mag ones starting just before sunset. That's usually standing outside the airing-out observatory. Knowing exactly where to look, and being "stuck on infinity" help tremendously!  Tom


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#5 TieDyeAstronomer

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Posted 16 November 2018 - 02:06 AM

Hi Scott!

That was a fun challenge! I'll go ahead and share my observation.



After Scott challenged me to hold Sirius for as long as I could after sunrise while I was "nearby" in Arkansas, I set my alarm for 7am the next day (Oct 22nd) and kept my eye on Sirius. The transparency had been excellent the night before, but that morning there were cirrus clouds over Sirius which thickened as time went by, and I think I would have been able to get a longer time if there had been no cirrus clouds over it. Still, I was quite happy with the time I got!

I recorded many descriptions of the conditions and visibility of Sirius periodically, using my pocket voice recorder, which I record all of my observations on. Because I wasn't sure how accurate the voice recorder's timestamps would be, I had time.gov open on my phone (and later my mom's phone, after mine died), and read out the precise time on many of the voice logs. I was able to determine that my voice recorder is slow by just about exactly 33 seconds.

Local sunrise was at ~07:26am according to the NOAO computational definition, which is what I use to keep my observations standard. (It is, however, interesting to note that the apparent sunrise would have been noticeably earlier due to observing from a mountain at an altitude of 2180ft above sea level: SkyTools estimates apparent sunrise would have been 07:21am.) My last record of "a couple of good pops" has them occurring at about 8:13am, before I lost it completely in the clouds. Therefore, I was able to see Sirius for 47 minutes after sunrise!



Here's a timeline of my observation that morning:

-16 min - 7:10 - easily visible, I immediately abandoned my "post" to go watch the sunrise.

-8 min - 7:18 - Still easy with direct vision, light patchy clouds begin to form, I leave again to see if I can spot the fog in the valley from my vantage point.

-5 min - 7:21 - Still easily visible, I dash inside for more cold gear.

-3 min - 7:23 - Still holdable with direct vision. Gauzy clouds now covering Sirius.

Sunrise - 7:26 - Still 100% holdable with direct vision, but with "little, insignificant notches" where it rarely seems to flicker instantaneously.

3 min - 7:29 - Getting faint, and starting to need to know where to look. I lose it when I move my eye off of it, but when I have my eye on it, it's 100% of the time with direct vision.

6 min - 7:32 - Seeing appears bad, and Sirius is now 90% of the time with direct vision, as staring too long causes it to go away.

8 min - 7:34 - The cirrus clouds passing in front of it are thickening, but so far it has remained visible through them.

8.5 min - (30 seconds later) - Sirius starts to disappear behind the thicker sections of the clouds.

11 min - 7:37 - I can now see the sun if I turn around. Note to self: Don't turn around!

12 min - 7:38 - I keep losing Sirius behind the still-thickening cirrus, but when it appears in a gap, it's still mostly visible with direct vision.

15 min - 7:41 - Easily visible with direct vision 100% of the time when a cloudless patch appears.

18 min - 7:44 - Sirius is holdable with direct vision, however, I have to be careful to keep my eyes directly on target.

22 min - 7:48 - Sirius is now difficult with direct vision, and with slightly averted vision, it's pretty much holdable.

31 min - 7:57 - Cirrus clouds are now causing long gaps in visibility, but when visible, while it's not easy, it's not at the edge of visibility yet.

33 min - 7:59 - 50%-40% of the time with averted vision, when viewed through a relative gap in the clouds.

36 min - 8:02 - Still got it, but man, it's getting hard! Starting to look more ghostly, like a phosphene or visual artifact, but 95% sure it's not in my vision, as it follows the sky when I move. 

38 min - 8:04 - Very slight, and getting to the point where the pops have to be very long in order for me to be sure I'm seeing something. "At that ghostly threshold now." Cirrus clouds nearly constant.

47 min - 8:13 - Only a few pops since 8:04, and the last few good pops were at this time. Cirrus clouds remain thick.



Here's a photo taken in the direction of Sirius around 8:00am, showing those infernal cirrus clouds:

M7TFh10.png



I've added an article about my observation to my website, complete with the original voice logs and full transcript, if you'd like to check it out:

https://tiedyeastron...during-daytime/

Clear Skies!
Lauren Herrington


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#6 Arcticpaddler

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Posted 16 November 2018 - 11:24 AM

Nice job!  I've gotta try it.  I've seen Venus and Jupiter with the naked eye with the sun above the horizon.


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#7 TOMDEY

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Posted 16 November 2018 - 11:36 AM

Nice job!  I've gotta try it.  I've seen Venus and Jupiter with the naked eye with the sun above the horizon.

I should also add... dawn seems a LOT easier, because pre-dawn... there they all are! So, as I'm leisurely closing up the dome, etc. I keep going out on the deck and looking at the "remaining" stars. Then stay out there as the sky is getting bright, sometimes even sitting in a chair!

 

I think knowing exactly where to look must also help tremendously: Like, I have a great feel for Polaris, from various points on my property, especially the dome and other favorite observing spots. At sunset, I'll often snag Polaris Before the others (Altair, Vega, Capella...), just because I know Exactly where it is. One very early dusk I was doing the 2-star initialization, using the Telrad 1x Reflex Finder to get on Polaris, and my buddy asks, "WHAT are you doing?!"  Tom


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#8 timokarhula

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Posted 16 November 2018 - 12:39 PM

Good catches!  I have been able to follow Sirius naked eye after sunrise on two mornings from Western Australia, on 29 August 2006 and 17 December 2009.  Sirius was seen up to 6 minutes after sunrise.  Mars (magnitude -1.66) was visible before sunset on 15 October 2003.  I have also logged Jupiter 24 times and Venus 117 times (and stopped counting) in daylight with naked eyes.  Yes, and comet C/2006P1 (McNaught) in January 2007!

 

/Timo Karhula


Edited by timokarhula, 16 November 2018 - 12:40 PM.

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#9 TOMDEY

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Posted 16 November 2018 - 07:14 PM

Hi Scott!
That was a fun challenge! I'll go ahead and share my observation.
...
Clear Skies!
Lauren Herrington

Wow! Your experiment was ambitious! You might be the most likely person to try something like THIS>>> ... if it hasn't been done yet >>>  Tom

 

There are stories from the Early Cold War, where Venus was reported as "Incoming ICBM." And, earlier, during WWII, oft forward spotters reporting Venus as unidentified "bogie" (enemy) aircraft.

 

HERE'S A THOUGHT! >>>

 

Wouldn't we expect linearly-polarizing glasses to greatly enhance the contrast of an (unpolarized) planet or star against the (polarized) sky? The sky can be 75% polarized 90-deg from the sun. So, it follows, that polarizing glasses, appropriately oriented, would Greatly enhance the contrast of star/planet vs sky... especially if they are made to block out extraneous light from around the edges. One might argue that is cheating... or NOT!

 

Postulate: Use that and maybe (?) even detect such star(s) during the day. Seems worth a try?!  Like Vega at zenith Well before sunset? I'm guessing that Contrast matters more than raw intensity, when it comes to detecting star vs sky...  Tom


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#10 TieDyeAstronomer

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Posted 16 November 2018 - 08:29 PM

Wow! Your experiment was ambitious! You might be the most likely person to try something like THIS>>> ... if it hasn't been done yet >>>  Tom

 

There are stories from the Early Cold War, where Venus was reported as "Incoming ICBM." And, earlier, during WWII, oft forward spotters reporting Venus as unidentified "bogie" (enemy) aircraft.

 

HERE'S A THOUGHT! >>>

 

Wouldn't we expect linearly-polarizing glasses to greatly enhance the contrast of an (unpolarized) planet or star against the (polarized) sky? The sky can be 75% polarized 90-deg from the sun. So, it follows, that polarizing glasses, appropriately oriented, would Greatly enhance the contrast of star/planet vs sky... especially if they are made to block out extraneous light from around the edges. One might argue that is cheating... or NOT!

 

Postulate: Use that and maybe (?) even detect such star(s) during the day. Seems worth a try?!  Like Vega at zenith Well before sunset? I'm guessing that Contrast matters more than raw intensity, when it comes to detecting star vs sky...  Tom

Hi Tom!

Excellent idea! In fact, I am aware of the effects of polarizing glasses on the sky, and I have experimented with them on sighting daytime objects before... however, only casually, and not successfully, as I was trying not too long before sunset, when polarizing effects seem greatly diminished. Now that you mention it, I should try again, this time much earlier and around the time I usually notice the dramatic effects when tilting my head. The daytime transparency around here has been excellent recently, and the sky gets quite dark indeed with sunglasses around noon- dark enough that it takes effort to perceive entoptic blue-field phenomena... based on my past observations, that means SOMETHING ought to be visible. Food for thought... The only issue is that it will be nigh-impossible to locate the object ahead of time without binoculars, and I'll need to be very careful not to accidentally sweep those near the Sun!

As an aside, tilting your head while wearing linearly-polarizing sunglasses has a dramatic effect on rainbows. It allows me to see supernumerary bows on even more mediocre rainbow fragments! I usually get weird looks when I proffer someone my sunglasses and tell them to look at whatever kind of atmospheric optical effect is visible at the moment, but rarely is the reaction anything other than "Oh, WOW!!"!

My opinion on using sunglasses to increase contrast during the day is the same as for using them to increase contrast at night (by allowing greater dark adaptation): it's not cheating if you mention it in your log. :) 

Thanks for the suggestion, I'll let you know how my attempts go!

Clear Skies!

Lauren Herrington



#11 MEE

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Posted 18 November 2018 - 04:56 PM

Hi Scott!

That was a fun challenge! I'll go ahead and share my observation.



After Scott challenged me to hold Sirius for as long as I could after sunrise while I was "nearby" in Arkansas, I set my alarm for 7am the next day (Oct 22nd) and kept my eye on Sirius. The transparency had been excellent the night before, but that morning there were cirrus clouds over Sirius which thickened as time went by, and I think I would have been able to get a longer time if there had been no cirrus clouds over it. Still, I was quite happy with the time I got!

I recorded many descriptions of the conditions and visibility of Sirius periodically, using my pocket voice recorder, which I record all of my observations on. Because I wasn't sure how accurate the voice recorder's timestamps would be, I had time.gov open on my phone (and later my mom's phone, after mine died), and read out the precise time on many of the voice logs. I was able to determine that my voice recorder is slow by just about exactly 33 seconds.

Local sunrise was at ~07:26am according to the NOAO computational definition, which is what I use to keep my observations standard. (It is, however, interesting to note that the apparent sunrise would have been noticeably earlier due to observing from a mountain at an altitude of 2180ft above sea level: SkyTools estimates apparent sunrise would have been 07:21am.) My last record of "a couple of good pops" has them occurring at about 8:13am, before I lost it completely in the clouds. Therefore, I was able to see Sirius for 47 minutes

 

Nicely done! I've seen:

 

Mars at magnitude -1.5 8 minutes before sunset- sky transparency below average (sky color washed out blue)

Sirius 8 minutes before sunset- sky transparency below average (sky color washed out blue)

Sirius 8 minutes after sunrise- sky transparency average (sky color medium blue) but had to stop observation because my family and I were going somewhere

Jupiter ~90 minutes before sunset

Venus basically naked eye for the entire day

 

My method: scan around for it. If I can't see it after a few moments, lower my head and take a break. Try again. When I think I see it, try to hold it for a few seconds. Once it's held for a few seconds, it's a "maybe". Lower my head and try again.  3 "maybes" equals a positive sighting.

 

I think it's a good idea for people to perhaps post a "shades of blue" palette such as https://graf1x.com/s...-color-palette/ next to their report and mention which shade of blue the sky was.

 

I've seen it mentioned that Sirius can't be seen with the naked eye in the day. Ok, so you got it 47 minutes after sunrise on a day of not particularly transparent skies.

 

If several very experienced observers try for Sirius in the mid-morning or mid-afternoon on a very transparent, Sapphire blue sky at high altitude and STILL don't see it- then I MIGHT be convinced.



#12 SNH

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Posted 20 November 2018 - 05:27 PM

WOW! Really glad to see that others of done the feat!

 

MEE writes that he has seen "Jupiter ~90 minutes before sunset". I'm going to have to try to do that feat also!

 

 

Scott



#13 Keith Rivich

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Posted 21 November 2018 - 10:16 AM

Back in September, Stephen O’Meara challenged me to see Mars naked-eye before sunset. After doing much better than I thought possible on it, I got to wondering what other planets might be visible in daytime. Since Mars was magnitude -1.6 at the time, I realized that Sirius, the night sky’s brightest star, isn’t much fainter at -1.45! So on the morning of October 8th, after failing to see a 16-hours-from-new moon, I turned my attention to watching Sirius as sunrise got closer. While keeping an eye on it, I decided to move my folding chair to a spot where I could just see Sirius above the dark treetops of trees only 20 yards away. As the sky continued to brighten, I used my binoculars to keep an eye on it and keep it in a little “pocket” of a treetop. To my surprise, I was able to keep it in sight and got my last one second view of it exactly 7 minutes after sunrise! A week or so later I repeated the experiment and got the same result -- 7 minutes. I did get a little ambitious one day and tried for Capella, though I lost it 2.5 minutes before sunrise. I hope to try Arcturus in the spring, but until then I might try Sirius a little more this fall. I mentioned my feat to TieDyeAstronomer - and lets just say that she blew my numbers away when she tried it. So has anyone else seen Sirius naked-eye in the daytime?

 

Scott

Years ago from west Texas I was able to follow Sirius through most of the day. At the time I did a lot of daytime planet observations (venus, mars, jupiter) so my eyes were well trained to focus at infinity during the day. 

 

I did cheat a little bit, though. Before sunrise I centered my scope on Sirius and let it track throughout the day. I just had to look in the Telrad to get Sirius' location. 

 

As far as seeing conditions it was cold and very clear with good seeing. 



#14 masterdrago

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Posted 21 November 2018 - 09:23 PM

It's been many years since I did this. It was the late 80s. I don't remember the date but it was late summer but very cool and I had finished an all nighter just on the north side of Lake Conroe (55 miles north of Houston). The last objects we observed in my sharp 10" f/5.6 were Maffei I & II. As the sky began to brighten, we noticed Sirius up about 30 degrees to the east so decided to try and split it. At the time, it was about 3 arc seconds separation from its Pup. We had heard that others had done it with smaller scopes during that time. After failing that task due to the seeing getting ratty, we decided to see how long we could hold it naked eye. We did loose it just after sunrise but had held it about 30 minutes and the light of the sun was just hitting the treetops on the west side of the lake. I remember the night so well because we had a local sheriff visit us around 10pm. We were on a small dirt undeveloped road and we think someone heard us in awe of the sights. We were able to showcase Saturn for the deputy so he understood that the 10" Dob was not a mortar or rocket launcher.


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#15 SNH

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Posted 15 January 2019 - 06:02 PM

I recently got a chance to view Arcturus naked-eye for nine minutes after sunrise! That was insane, and really proves TieDye's observation.

 

Scott




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