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It‘s Gegenschein Season

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#1 project nightflight

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Posted 21 February 2020 - 12:47 PM

Here is a challenge for your local night sky: can you spot the gegenschein?

 

Currently there are quite favorable conditions for observing the sun‘s counterglow. On Sunday, February 23, we have new moon phase so the moon won‘t interfere. The gegenschein itself is placed nicely in the constellation Leo. Regulus is a convenient pointer, the counterglow is a few degrees southeast of the 1.4mag star.

 

Here is an image of the gegenschein we made last autumn on La Palma island. A 6-page article about our imaging efforts, the origin of the counterglow and tips for visual observations can be downloaded from our website here: https://project-nigh...rojects013.html

 

projects013.jpg

 

 

We would be very interested in your own observations. Please post your results here, along with some info about your sky quality (SQM, NELM, Bortle, whatever).

 

Good luck!
Erwin


Edited by project nightflight, 21 February 2020 - 03:54 PM.

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#2 Mel Bartels

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Posted 21 February 2020 - 12:56 PM

My poor attempt at sketching the Gegenshein, depicted as a glow to the east of Capricorn with the Milky Way to the west.

I usually can see the Zodiacal Light stretching to the zenith, crossing the Milky Way, at my home under SQM 21+ skies. Occasionally I'll spot the Gegenshein.

One time at the Oregon Star Party a couple of people wondered over to my scope,  confused between the Milky Way and Zodiacal Band that stretched across most of the sky. The Gegenshein is commonly viewable after midnight at OSP. I've been able to point it out to a number of participants.

 

Gegenshein.jpg

 

Mel Bartels


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#3 Dave Mitsky

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Posted 21 February 2020 - 02:45 PM

Articles on the gegenschein appear at the following URLs:

 

https://www.skyandte...ge101420151410/

 

https://www.atoptics...hsky/zodim2.htm

http://www.as.wvu.ed...h/skw9810h.html

https://apod.nasa.go...d/ap140114.html

 

There's an image that shows the zodiacal light, the gegenschein, and the elusive zodiacal band posted at https://www.atoptics...hsky/zodim3.htm


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#4 Rich (RLTYS)

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Posted 29 February 2020 - 02:18 PM

I've only seen the Gegenschein once on 9-31-90, while observing in South Hampton NY. After the Moon had set, I noticed a soft ill-defined glow high in the east, around 4 AM just south of Auriga near Taurus and north of Orion. It was an amazing sight.



#5 project nightflight

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Posted 29 February 2020 - 03:18 PM

I've only seen the Gegenschein once on 9-31-90, while observing in South Hampton NY. After the Moon had set, I noticed a soft ill-defined glow high in the east, around 4 AM just south of Auriga near Taurus and north of Orion. It was an amazing sight.

 

Rich, thank you for your contribution, but you might want to check your data:

1. There is no such date as 9-31-90
2. The antisolar point (where the gegenschein is located) always culminates around local midnight. So it is impossible for the gegenschein to be in the east around 4 a.m.



#6 Dave Mitsky

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Posted 29 February 2020 - 04:56 PM

I've seen the gegenschein a number of times at the Winter Star Party in the Florida Keys and at Cherry Springs State Park in Pennsylvania and on a couple of occasions at Cherry Springs I've been able to see the very faint zodiacal band.



#7 Cotts

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Posted 01 March 2020 - 11:00 AM

Seeing the G.  (and the zodiacal band) is reliant on dark, transparent skies, of course, but also on technique.

 

1.  Find the anti-solar point on a star atlas or planetarium program.......  e.g. Sun right now is at 22h 50m and -7º 21'.   For the Antisolar point subtract 12h from the RA (or add if this causes a negative number...) and reverse the sign of the Dec.  Thus tonight's anti-solar point is at 10h 50m and +7º 31'.   This is about 10º ESE of Regulus (α Leonis...)

 

2. Observe at or near local midnight.  The important thing is NOT to go out and look for some sort of glowing cloud.  Instead,  look at the anti-solar point and make a mental note of the sky darkness in that immediate area. then move your gaze north or south of that area (perpendicular to the ecliptic, actually) and watch what happens with the sky background. It will appear slightly darker.... Now sweep your gaze back to the anti-solar point. Sky background gets lighter again.  Now sweep to the opposite side.  Gets darker.  The change in the sky background darkness IS the Gegenschein...

 

3.  This technique also works for the Zodiacal Band which is somewhat more subtle than the G.  Need truly dark, Bortle 1-3 skies...

 

4.  If the G. is in or near the Milky Way or low in the sky it is harder to virtually impossible to make out.  This time of year, from late January through April the G. moves from Cancer to Leo to Virgo with little interference from the Milky Way and is well up in the sky.  The other 'season' for the G. is in September through November when the Anti-solar point moves from Eastern Capricorn through Aquarius and into Pisces, Aries and western Taurus...

 

Using this technique I have seen the G. at many sites, not all of which are Bortle 1 or 2.....e.g the winter Star Party where there are significant light domes from Big Pine and Marathon and oodles of car headlights.  

 

Dave


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#8 Cotts

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Posted 01 March 2020 - 11:07 AM

I've only seen the Gegenschein once on 9-31-90, while observing in South Hampton NY. After the Moon had set, I noticed a soft ill-defined glow high in the east, around 4 AM just south of Auriga near Taurus and north of Orion. It was an amazing sight.

Assuming you mean Sept 30...  The anti-solar point at that time of year is in Pisces.  The area you describe is in the winter Milky Way so that's probably what you saw....

 

Dave



#9 Redbetter

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Posted 01 March 2020 - 03:35 PM

At moderate latitudes the only time it isn't gegenschein season is when it passes through the Milky way, about 1/4 of the year total.  If you are familiar with it, you can still see it as it begins merging into/emerging from the Milky Way on either side, particularly in early Winter.  When it is furthest south (Summer) it is also on the brightest part of the Milky Way, so at least the more northern viewers are not missing much due to latitude when that happens.  

 

I expect to see it on any dark and transparent night in Bortle 2/3 conditions, assuming it isn't buried in the Milky Way.  The zodical band is more demanding of transparency and generally requires Bortle 1/2 conditions to trace it from the gegenschein to the zodiacal light, although Bortle 3 works at times.  Both suffer greatly from any reduction in transparency or increase in light pollution.

 

A lot of this is familiarity.  If you observe from truly dark skies regularly, then it becomes easier to trace it night-after-night, month-to-month.  If you only get to truly dark skies a few nights every several months, then it is more difficult to recognize what has changed.  Even though I knew what it was and had seen it brightly in Bortle 1 conditions, it wasn't until I started maximizing dark sky observing in Bortle 2 conditions that I finally began to realize that I could see both the gegenschein and the zodiacal band regularly.  


Edited by Redbetter, 01 March 2020 - 03:41 PM.

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#10 Rich (RLTYS)

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Posted 01 March 2020 - 04:20 PM

Assuming you mean Sept 30...  The anti-solar point at that time of year is in Pisces.  The area you describe is in the winter Milky Way so that's probably what you saw....

 

Dave

Sorry, I really messed up on the date foreheadslap.gif it was 8-30-90. There were three other observers with me and they saw the same thing, an illdefined, faint, roundish glow that wasn't part of the winter Milky Way. scratchhead2.gif



#11 Cotts

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Posted 01 March 2020 - 04:40 PM

Sorry, I really messed up on the date foreheadslap.gif it was 8-30-90. There were three other observers with me and they saw the same thing, an illdefined, faint, roundish glow that wasn't part of the winter Milky Way. scratchhead2.gif

August 30?   The sun is at 10h 38m and + 8º 35 so the Anti solar point is 22h 38m , -8º 35.  About 2 degrees west of λ Aquarii.  

 

Dave



#12 Rich (RLTYS)

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Posted 01 March 2020 - 04:46 PM

August 30?   The sun is at 10h 38m and + 8º 35 so the Anti solar point is 22h 38m , -8º 35.  About 2 degrees west of λ Aquarii.  

 

Dave

I wonder what we did see?question.gif



#13 Crusty99

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Posted 03 March 2020 - 01:36 AM

Here is a copy of a Zodiacal Light art print from years past.


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#14 project nightflight

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Posted 10 March 2020 - 07:12 AM

Today, Doborah Byrd's site EarthSky re-published our story about the gegenschein: 

 

https://earthsky.org...the-gegenschein

 

We are still highly interested in your observations. The moon will be out of the way soon and in the next weeks the counterglow will be placed conveniently between Spica and Regulus.

 

May the starlink miss you
project nightflight


Edited by project nightflight, 10 March 2020 - 01:56 PM.


#15 Rich (RLTYS)

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Posted 12 March 2020 - 04:17 PM

Here is a copy of a Zodiacal Light art print from years past.

Beautiful work! drool5.gif



#16 calypsob

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Posted 12 March 2020 - 04:59 PM

Awesome work, I have always wanted to try and spot this as well as the zodiacal light.




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