Abell 2152 observation of gravational lens arc

[Jimi Lowrey]

On Larry Mitchell (Advanced observing List ANYTHING ABELL) from the Texas Star party. Larry put on the list AGC 2152 lens arc as a challenge.

The lens arc is near the cD galaxy MCG +3-41-95. On Monday night of TSP Alvin Huey and I tried for the Arc on a night that I rated above average transparency. There is a faint star that is near the lens arc that when the star would come to a sharp point with the seeing the lens arc would pop into view This would repeat time and time again. It was very exciting to see the arc as I have been trying to see one for the last four years with the 48"

The best view that night was with A 6MM ZAO II 813X. Last Monday night I did a drawing of the arc that I will post below.

I hope Alvin will jump in and share his observation of this illusive object.

208

[Uwe Glahn]

Congrats to you Jimi and Alvin for the spectacular observation. Next to the gravitation images of quasars for sure one of the holy grails for the visual amateur astronomy. Never thought that this detail could been a target for visual amateurs. Thanks for sharing the observation with us.

[MarcE]

Hi all,
Sunday night after TSP 2012 i also had the chance to observe the lens arc near MCG +3-41-95 with Jimi's 48" (Jimi - thanks for the spectactulare views in your scope during these days!). I also made a rough sketch in the night, which is similar to Jimi's. The lens arc was not seen 100% of the time with indirect vision, but it just pops up sometimes. Very tough object, but as Uwe said: one of the holy grails for the visual observer!
A really great experience!
Clear skies
Marc

[Dave Tosteson]

In regard to the Arc in AGC 2152, I was at Larry Mitchell's 36" scope at TSP 2012, after a few people had just viewed the area and successfully seen the arc. But I tried for 3-4 minutes and could not see it. Possibly conditions had changed in a short time.

A note on two other arcs that are visible in larger scopes. The bright blue arc in AGC 2667 in Sculptor was visible from Okie-Tex in 2008 using my 32" scope on a a night of very good seeing.

And the object called "The Cosmic Eye", or LBG J213512.73-010143, was seen in a 30" scope in central Minnesota on an excellent night in August, 2011. Here is a short description: It iis a gravitationally lensed galaxy located in Aquarius, just 30’ southeast of the globular cluster M2. At magnitude 20.3 and redshift 3.07, it is 11 billion light years away. This galaxy was discovered during a search for bright lensed galaxies in X-ray emitting clusters in 2006 by Dr. Ian Smail of England’s Durham University, and was reported in the January 1, 2007 Astrophysical Journal. Magnified by a foreground galaxy at a redshift of 0.73 designated “G1” in this paper, which is the yellowish object seen in the Hubble Space Telescope image that centers the “eye”, the lensed galaxy forms two nonconcentric arcs with a size of only 3 arcseconds. The intervening galaxy cluster MACS J2135.2-0102, is at redshift 0.325. Without the lensing, the background galaxy would appear close to 24th magnitude, as the magnifying factor is about 28: over three and a half magnitudes.

Using a 6 mm Ethos and averted vision, this was seen 4-5 times in 30 seconds with a 30" f4.5 Obsession. Its overall impression was a faint, round smudge a few arcseconds across, with the central lensing galaxy not differentiated from the surrounding arcs. They appeared conjoined as one confluent mass. I classified it as faint, but not extremely difficult; a bit surprising given its magnitude. My impression was confirmed when five other observers came to the eyepiece, each seeing it several times in less than a minute. I estimated it could be seen 40-50 percent of the time. Three galaxies, from 18.5-19.0 magnitude, could be seen in the surrounding MACS cluster within a minute or so, and I suspect several more could have been teased out given extra time.

Dave Tosteson

[FaintFuzzies]

On Larry Mitchell (Advanced observing List ANYTHING ABELL) from the Texas Star party. Larry put on the list AGC 2152 lens arc as a challenge.

The lens arc is near the Cd galaxy MCG +3-41-95. On Monday night of TSP Alvin Huey and I tried for the Arc on a night that I rated above average transparency. There is a faint star that is near the lens arc that when the star would come to a sharp point with the seeing the lens arc would pop into view This would repeat time and time again. It was very exciting to see the arc as I have been trying to see one for the last four years with the 48"

The best view that night was with A 6MM ZAO II 813X. Last Monday night I did a drawing of the arc that I will post below.

I hope Alvin will jump in and share his observation of this illusive object.

208

I sorry I have been pretty busy lately. I echo Jimi's observation. The key was steady seeing. Once the reference star, the one at 3:30, in Jimi's sketch is a sharp point (indicating that the seeing steadied up) the arc would pop in and out during those moments. We've also seen it in Larry's 36" reflector at TSP. Pretty high powers is also needed, at least 500x.