Object Of The Week December 18, 2022 - The Ghost of Cassiopeia

[wvreeven]

Sh2-185, LBN 623, Ghost of Cassiopeia, Gamma Cassiopeiae Nebula, parts of which are
IC 59, LBN 620
IC 63, Ced 4b, LBN 622

Reflection Emission Nebula

Cassiopeia

RA: 00 57 42.40 / 00 59 01.37
DEC: +61 04 59.8 / +60 53 17.8

This week's Object Of The Week brings us north to Cassiopeia. On the winter evenings of the northern hemisphere Cassiopeia culminates well after astronomical twilight ends, albeit well before midnight. It is where the northernmost part of the Milky Way crosses the sky.

The Ghost Of Cassiopeia is an extensive nebula of which the brightest parts lie close to the magnitude +2.18 star Navi or Gamma Cassiopeiae. Navi is a double star and its magnitude +10.90 component lies a mere 2.1" from the main star.

Probably a well known fast is that the Milky Way is riddled with hydrogen clouds of greater or lesser brightness. The advent of small band astrophotography has shown that these clouds can be imaged literally anywhere in the Milky Way using a narrow band Ha filter. How much this is true can be seen on this wide field image of Cassiopeia.

cassiopeia_wide_field.jpg

Navi is at the center of the image and Sh2-185 is the bright, upper and most right part of the nebula that curls around it. The two brighter condensations in Sh2-185 are IC 59 (the blue part) and IC 63. Here is an image zoomed in on both nebulae.

cassiopeia_detail.jpg

If you open the AstroBin link and hover your mouse over the image, you'll see which parts are IC 59 and IC 63.

Being such a low surface brightness nebula, it is visually challenging. I am curious to see if anyone was able to pick up the fainter parts of the nebula. My observation of this area with my 20" on Sept 20, 2015, was logged by me only as

"At 83x I can see IC 59 and IC 63 together in the same field of view close to Gamma Cas. IC 59 is oval, IC 63 is triangular."

No notes of using a filter and, if yes, which one. I suspect I didn't given that IC 59 is a reflection nebula. Unfortunately my 20" is in Chile so I won't be able to use it to have another look at these nebulae. I might try with a smaller instrument at some point though.


As always,

"Give it a go and let us know!
Good luck and great viewing!"

[Clear Skies]

Please allow me to set the record straight on the designations of these objects:

gamma cassiopeiae nebulae_1.jpg gamma cassiopeiae nebulae_2.jpg gamma cassiopeiae nebulae_3.jpg

The guide is available as a (large) pdf here.

The Hubble designation applies to only the two IC nebulae. Struve & Elvey at McDonald Observatory used Gamma Cassiopeiae as a guidestar for their slit-spectrography survey; they did note the "fan shaped nebulae" in the vicinity and as for so many of their other entries, they describe a region. Cederblad (4)'s designations A & B apply to the IC nebulae, but he too noted more nebulosity. So did Gaze & Shajn with their addition of Simeis 111. Three of their papers include description for the nebulae. Sharpless and Lynds (both two entries) and Van den Bergh noted a significantly larger region.

There's only a single entry in my log and it's only for the brighter southeastern nebula IC63. October 2017, 14" SCT @ 110x / 45', unfiltered:

A part of the SE nebula IC63 is visible, the NW nebula IC59 is not visible. The part of IC63 that is visible, is a WSW-ENE elongated part. To the east thereof, with AV, a faint, slightly fanning out part is subtly visible, at the limit of visibility without AV. On the northern side the nebula ends quite suddenly on a line from SW to NE.

Is just over 1/2 FoV to the ENE of the star Gamma Cassiopeiae.

I wonder what aperture it would take to tease out the faintest parts..!

[Skyheerlen]

Nice choice!

Both IC59 and IC63 are not easy to catch. I succeeded with my 13" from La Palma last month and in 2018, as well as with my C14 (with improved optics) from Northern France (Talma Grandpré) in 2017. In all cases, I used no filter; a filter did not help.

In all cases, IC63 was easiest (or better: less difficult); last month on La Palma, the parts of the nebula I saw were smaller than the outline shown in de IDSA. The southern sections are brightest; eastern edge fades away into nothing.

IC59 is more difficult, with some brighter stars close. The nebula is not much more than a brightning of the dark background; eastern sections are brightest.

Eyepiece used was XW14; in combination with SIPS, a magnification of 118x.


Very nice objects, but not easy.

[wvreeven]

Please allow me to set the record straight on the designations of these objects

Thanks for the useful additional info. At least it shows that I got the Sh2, IC and Ced designations correct, even if they weren't complete.

[ScottH]

Good one there, Wouter! I actually had not seen such images where IC 59 and IC 63 were connected to so much more nebulosity (which Victor was kind enough to give us more on). Before I give my own observation from two nights ago, I will just add that these nebulae were covered just over a year ago by Uwe Glahn as an OotW: Object of the Week, October 10, 2021 - IC 59 + IC 63 - "The Ghosts of Cassiopeia" . That being said, I think you both did a fine job.

12/17/22 IC 59, 63
In my 6” at 56x (1.5° TFoV), both IC 59 and IC 63 are faintly visible while brilliant Navi is still in the field. With time and study, I’m able to detect IC 59 slightly easier than IC 63. My ability to detect them doesn’t seem to change with the addition of my NPB filter. But with my recently acquired Baader B-CCD (blue) filter, I am able to see them a little bit easier.

Scott H.

[wvreeven]

Scott, thanks for finding that Uwe already covered these objects. I actually searched this forum for these nebulae and didn't find any reference to them. Sorry for my sloppy research!

[j.gardavsky]

As Scott also reported above,
I have been observing these both nebulae through my 6" F/5 achromatic refractor in 2016 and 2018,
https://www.deepskyforum.com/showthr...ull=1#post8663

They are a mix of the molecular clouds and HII emissions, and hence the blue(RGB)CCD filter is a good companion to the H-beta filter.

Best regards,
Jiri

[Steve Gottlieb]

I didn't post on the earlier OOTW, but these observations were using my 18-inch f/4.3 many years ago.

IC 59: best view was unfiltered at 108x. Appears as a faint, large, irregular glow, roughly 8'x5'. Elongated E-W and extends to a group of a half-dozen stars at the NE end. This group of stars is also possibly involved with the haze. There is a slightly brighter patch on the south side.

IC 63: unusual triangular or wedge-shaped nebula just 20' NE of Gamma Cas. At 115x appears fairly large, elongated SW-NE, ~6' diameter, with the brighter vertex at the west end. The southern edge, which extends towards the SW, is slightly brighter and more sharply defined. The interior of the wedge is slightly weaker with subtle brightness variations. OIII and UHC filters dimmed the objects.