Object of the Week - 25 July 2021 - A nebula in the snake's tail

[Clear Skies]

Summer is here and with summer the Objects of the Week move from galaxies to nebulae and star clusters.

This week's object is a nebula in the tail of the constellation of Serpens, the Snake.

Minkowski 1-88 a.k.a. Gum 85
18:17:53 -11d44m00s (http://aladin.unistra.fr/AladinLite/?target=18%2017%2053.000-11%2043%2060.00&fov=0.5003&survey=P%2FDSS2%2Fblue)
Constellation: Serpens (https://en.wikipedia.org/wiki/Serpens) (Cauda)

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15' POSS2 Red & Blue

Dr. R.L.B. (Rudolph) Minkowski (http://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/minkowski-rudolph.pdf) was a German born astronomer who headed the Palomar Observatory Sky Survey (https://en.wikipedia.org/wiki/National_Geographic_Society_–_Palomar_Observator y_Sky_Survey). Minkowski is best known for his planetary nebula research and discoveries. For his work, deemed distinguished services to astronomy, he was awarded the Bruce Gold Medal (https://iopscience.iop.org/article/10.1086/127627/pdf) in 1961. Minkowski discovered almost 200 unknown planetary nebulae in a time when previously only 155 were known.

Minkowski published three papers on nebulae in 1946 (http://articles.adsabs.harvard.edu/pdf/1946PASP...58..305M) (the Minkowski 1- objects), 1947 (http://articles.adsabs.harvard.edu/pdf/1947PASP...59..257M) (Minkowski 2-) and 1948 (http://articles.adsabs.harvard.edu/pdf/1948PASP...60..386M) (Minkowski 3-). A fourth list, the Minkowski 4- objects, was compiled by Perek & Kohoutek in 1965.

Combined (https://clearskies.eu/csog/downloads/nebulae/#minkowski), Minkowski's papers, along with the P-K additions, list 256 objects: 40 emission nebulae, 207 planetary nebulae, 1 galaxy, 1 supernova remnant and 7 stars.

Minkowski 1-88 is a small, irregular emission nebula, approximately 6'x4' in size, with dark rifts crossing its eastern part. Several faint mag. 13+ stars are involved, or superimposed. The nebula is on the northern edge of the much larger and fainter nebula Gum 84 (Sharpless 54 - Lynds 71 & 72) of which it may actually be a brighter part. The larger nebula is at an estimated distance of 6200 ly.

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Click here to download this observing guide (https://clearskies.eu/csog/downloads/dsfootw/).

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2.7 degrees DSS mosaic

Gum 84 contains a small, concentrated, moderately bright open cluster: NGC6604 (https://cseligman.com/text/atlas/ngc66.htm#6604), half a degree to the south of our OOTW.

In the vicinity
Pull out your 1 degree eyepiece and pan exactly two fields of view towards the south, to center Messier 16 (https://www.deepskyforum.com/showthread.php?903-Object-of-the-Week-July-24th-2016-M16-and-the-Pillars-of-Creation&highlight=eagle) (NGC6611) - the "Eagle Nebula".
A bit closer, 1.5 degrees to the southeast is the planetary nebula Sanduleak-Stephenson 156 - the "Red Square Nebula (https://en.wikipedia.org/wiki/Red_Square_Nebula)". Another planetary is 1.7 degrees to the north-northwest and it's another Minkowski object: 3-25 (http://aladin.unistra.fr/AladinLite/?target=18%2015%2016.967-10%2010%209.47&fov=0.2502&survey=P%2FDSS2%2Fblue), stellar and quite faint.
On your way to Messier 16, pause three quarters of the way there to observe the open cluster Trumpler 32 (https://clearskies.eu/csog/downloads/starclusters#trumpler): A small, regular cluster of about 50 faint stars, as Robert Trumpler described it. If a star 13' east-southeast of the cluster appears deep orange to you, it's good to know that it's the carbon star ES Serpentis (http://aladin.unistra.fr/AladinLite/?target=18%2018%2021.511-13%2026%2019.26&fov=0.25&survey=P%2FDSS2%2Fcolor) (CGCS3987). It is a flanked by a mag. 11 star directly west, but the two are not cataloged as a double.

Well, you know what to do: give it a go, let us know!

[obrazell]

Interestingly this nebula is also known as Sh 2-54 which is how it may be found in some software.

Owen

[Clear Skies]

The larger nebula Gum 84 = Sharpless 54 (http://articles.adsabs.harvard.edu/pdf/1959ApJS....4..257S), with a diameter of 140' and described as: Part of II Ser association. Contains cluster NGC6604.

I went with Gum as the primary designation, as Gum's paper (http://articles.adsabs.harvard.edu/pdf/1955MmRAS..67..155G) is from 1955 while the Sharpless (http://articles.adsabs.harvard.edu/pdf/1959ApJS....4..257S) (Sh2-) paper is from 1959. That being said, Sharpless did include it in the 1953 paper (http://articles.adsabs.harvard.edu/pdf/1953ApJ...118..362S) (Sh1-) as nr. 41 with a diameter of 40', noting NGC6604 and describing it as Very bright central portion; cluster.

Well, the view in the eyepiece is what counts :-)

[wvreeven]

Victor, have you observed this emission nebula? If yes, what did you log?

My own observation with my home built 6" Newtonian telescope in August 2005 from Southern France reads:

Around the open cluster NGC 6604 lies a large nebula, Sh 2-54, at with the 40 mm eye piece (25x) and OIII I see it very well. Without OIII it also is visible. The part around NGC 6604 is brightest.

[Clear Skies]

Victor, have you observed this emission nebula?

No, not yet. My most recent (...) visit to the region was eleven years ago. I only have an observation of the open cluster NGC6604 in my database (https://clearskies.eu/astronomy/observing/observations/), but not this week's OOTW Minkowski 1-88, nor the large nebula Gum 84 / Sharpless 54.

[Steve Gottlieb]

I viewed M 1-88 back in July 2001 with my former 17.5". This observation was from a site (Packer Saddle at 7100') I used to regularly observe from in the summer at the Sierra Buttes.

"Picked up at 64x using a UHC filter as a moderately bright glow, slightly elongated N-S and ~3' in length. The eastern side has a sharper, linear border. Also viewed at 220x unfiltered and a N-S string of a half dozen mag 12-13 stars are superimposed near the eastern boundary. This relatively easy nebula is located 30' N of NGC 6604 and Sh 2-54 (a large, faint HII region encasing the cluster)."

An alternate name may be Simeis 3-132, though SIMBAD doesn't recognize that designation.

[Clear Skies]

Thanks for filling in that info, Steve. I have yet to get hold of the complete Simeis catalog, but thanks to Google (searching for Simeis 3-132) I just learned that both Minkowski 1-88 and the large nebula have fitting names: "the egg" and "the nest". Source: https://www.astrobin.com/5d71np/?nc=collection&nce=443

[Uwe Glahn]

I just tried the nebula last new moon period. Even it responded moderate to the UHC filter, the best view gave the view without any filter because of the embedded stars.

sketch: 27", 293x-419x, no filter, seeing III, NELM 6m5+
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home (http://www.deepsky-visuell.de/Zeichnungen/M1-88.htm)