Object of the Week, October 10, 2021 - IC 59 + IC 63 - "The Ghosts of Cassiopeia"

[Uwe Glahn]

Sh 2-185 (LBN 623, "Gamma Cassiopeiae Nebula")

= IC 59 (LBN 620)
RA: 00 57 28.5
DEC: +61 08 37
Size: ~10'x5'

= IC 63 (LBN 622)
RA: 00 59 29.0
DEC: +60 54 40
Size: ~10'x3'

According to Seligman and Steve G. the discovery of the faint nebulae itself is an adventure like many IC discoveries. To make it short - both nebulae were discovery independently on photographs taken by Max Wolf and E.E. Barnard around 1893/1894. For us visual observer, the most interesting part is the visual observation of Barnard. He was able to see both nebulae (without any filter!) with the 12-inch Lick at 80x (EP 3.75mm) with a field of 42'. He made a precise sketch with stunning accuracy.

Physically, both parts are bound to the near variable (+1.6mag and +3.0mag) ? Cassiopeiae which makes it easy to find but difficult to observe the faint glows. The massive star itself is rapidly spinning and transforming into a giant star. The main and bright component is itself a spectroscopic binary. Beside this, there are two more bounded companions, B (2.1", 10.9vmag) and C (~1", 13mag).
Both nebulae are listed as emission and reflection nebula. Colourful photographs shows blue and red colours within the nebulae. While the northern IC 59 shows more blue parts, the western IC 63 is shining more in the red colours from the emission of ? Cas.

The colours are already a indication of using nebula filters. Most observers with mid size telescopes reported a somewhat brighter IC 63 with and without filters. While my experiences were the same, I made an opposite observation with a 4-inch binocular telescope. While I could not spot IC 63, I could barely see IC 59 directly west of a faint 12mag star group. Reason could be the very small magnification of 14x, which shows the larger blue parts of IC 59. But what are your experiences? What details could you see and what was the smallest aperture to see the nebulae?

DSS red, 60'x60'
IC59_IC63_60r.jpg

---

DSS blue, 60'x60'
IC59_IC63_60b.jpg

---

sketch: 16", 75x, no filter, NELM 7m0+, Seeing II
IC59_IC63.jpg
home

Give it a go, and let us know!

[lamperti]

Saw both of these with a 22" at 90x + an Ultrablock filter back in December of 2015. Seeing = 5/10; transparency 7/10; SQM = 20.6 (NELM=5.9)
IC-63 was quite spread out and dim.
IC-59 was also dim with embedded stars
(a half hour earlier Einstein's Cross was resolved!)

[akarsh]

Haha, Uwe, you "stole" my next OOTW! I was telling Jimi earlier over the phone that the gamma Cas nebulae had not featured as OOTW, and so I had made sure to observe them in detail last week in preparation for a OOTW in December. Anyway, the good news is I have one more candidate, I think, and I get to post my observations here.

These nebulae are combination emission + reflection nebulae:
https://apod.nasa.gov/apod/ap181026.html
I imagine that the emission is more prominent in the regions "facing" gamma Cas, as the UV radiation from the star is able to ionize the hydrogen there. I wonder if only the "outline" of the nebula remains with an H-beta filter.

IC 63
I first observed IC 63 on October 16--17 2020 from the Modoc National Forest near Likely, CA in north-eastern California. This is a very dark site, and on this particular night, I assessed the seeing as poor and the transparency as "not so great", with the sky being maybe between Bortle 2 or 3.

With a 10mm Delos (207x), I logged "Beautiful cometary nebulosity" and drew a sketch of a "nucleus" with two "tails" nearly perpendicular to each other, one long and the other marked as faint. I also logged "No UHC response".

I was then unaware of IC59, so I did not observe it.

More recently, at the Okie-Tex Star Party 2021, I observed this object on 2021-10-06, once again using the same 10mm Delos eyepiece. The conditions on that night were with good seeing but moderate sky darkness. My description reads "Rocket-head shaped nebulosity, almost entirely obliterated by [Lumicon] UHC [fiter]. Reminiscent of Hubble's Variable Nebula. After UHC, the tip alone remains as an extremely faint glow that can only be discerned [after] knowing exactly where to look". I estimated the diameter of the nebula as about 15'. Here is my sketch from this night:
IC63.jpg

IC 59
I observed this, also on 2021-10-06 at the Okie-Tex Star Party with a 10mm Delos eyepiece (207x). My notes read "Wisp of nebulosity roughly 25' [sic] in length, reminiscent of the Witch Head Nebula. [Lumicon] UHC [filter] makes it too dim to see. The visually brighter segment is a band that roughly runs E-W with a size of about 25'x10' [sic]. The fainter arm running NE is hard to discern due to presence of stars. The E end of the main arm is the thickest segment."
My sizes were estimated using my 10mm Delos FOV, which I had miscalculated as 30'. In reality, it is 20' (72°/207), so my size estimates for IC59 should have instead read as ~16' x 7'

Unlike your observations, somehow I found that the Lumicon UHC filter was detrimental to the observation. I'm not sure why. My rationale for this was that the ionized region must be thin, and the rest of it must be reflection nebulosity -- or perhaps it was an artifact of the amount of power I was using and I must have lowered it after the filter enhanced the contrast. With IC 63, after introducing the filter, I was only able to see a vestige of the "nucleus" of the cometary nebula or the "head" of the ghost if you like, after sincere attempts at averted vision. I agree with the majority of observers in that I found IC63 much brighter than IC59.

Clear Skies

Regards
Akarsh

[j.gardavsky]

Hello Uwe,

and thank you very much for reminding these nebulae, and thanks to you and Akarsh for the great sketches!

I have just 2 entries in my observing log book: Of August 10th, 2016, and of October 10th, 2018:
6" F/5 achro
Leica L 32mm, Leica HC Plan S 25mm, Hensoldt 15mm
blue(RGB)CCD 400nm - 510nm filter, H-Beta 12nm filter
Erlanger Oberland, Bortle 3-4

H-Beta: both nebulae very faint and well separated
Blue(RGB)CCD: both nebulae brigther, faint bridge between them.

The better view through the blue(RGB)CCD filter is expalaind by a mix of HII and of the Rayleigh scattering in the nebulae.
Unfortunately, I have made no sketch for the documentation.

This area of skies is generally worth of a closer inspection.
The IC 59 and IC 63 belong possibly to a band of faint light extending south to Theta-Mu Cassiopeiae, and this band has been visible through the 15x85 binoculars with the H-Beta filters on other observing sessions.

Clear skies,
Jiri