The Skull and Crossbones Nebula (NGC2467,Sh2-311,RCW16) WMBNC 13

WMBNC 13: Catalog of large nebulae in the winter Milky Way 13
I took this photo from my backyard in East Pattaya three years ago, and I remember it was mostly Ha Signal, with only a 30-minute exposure appearing between the palm trees.
I was planning to edit this time with HOO, but there was something in the center of the RGB of the 25 minutes I shot for the stars that wasn't in HOO, so I also edited the Target with HOORGB.
I didn't create the color intentionally, but perhaps because I mixed RGB, the blue looked like the blue-green of Oiii, which was a color I hadn't seen in a while, so I continued with it.
I wanted to take a detailed shot of the center with a long focal length.
By the way, what is that star cluster-like thing that looks like a horizontal Y in the upper left? I looked everywhere but couldn't find anything. If anyone knows, please let me know.

P.S.: Watanabe-san from Niigata told me that this star cluster is numbered
Rumpler 9 or Collinder 168.
Thank you Watanabe-san

WMBNC 13: 冬の天の川の中にある大きな星雲のカタログ13
3年前にEast Pattayaの裏庭から撮影したことがあるが、椰子の木と椰子の木の間に出てくる30分だけの露出でほとんどHaのSignalだった記憶がある。
今回はHOOで編集しようと思っていたが星のために撮影した僅か25分のRGBの中心部にHOOにはないものがあったので、HOORGBでTargetも編集して見た。
特に意識的に作った色ではないが、RGBを混ぜたせいか青がOiiiの青緑の様で久しぶりの色だったで恋しかったのでそのまま進めて見た。
中心部の詳細を長焦点で撮りたくなった。
ところで左上のYの字を寝かせた様な星団みたいなものはなんなのだろう?色々調べたが見つからなかった。ご存知の方がいましたら教えてください。

追記:新潟の渡辺さんが教えていただきました。この星団は
Rumpler 9又は Collinder 168.
と付番されているとのことです。
渡辺さんありがとうございます

Place: Astropical@CSky Observatory (Bortle Class 3, Moon Phase 64.1%)
Shot1 Date:20th / Jan / 2025 20:33 (UTC+7)

William Optics Z61 WIth JSSS  (61mm F/5.9 f/360mm)
Filter: Optolong L-Ultimate,Baadar SemiAPO
L-Ult: 18X 600Secs Total 180 minutes
SemiAPO: 5X 300Secs Total 25 minues

Total 3 Hours 25 Minutes

Palette: Target HOORGB
Star RGB
Gain: 2600, Offset 60
CCD: QHY294C Pro 11Mega Mode BIN1
Mount :iOptron CEM70G
Guide: OAG Z61 61mm F/5.9, QHY290C.
Controler: NINA Dither, PHD2
Pre-Processing APP Drizzle None
Post-Processing PI,PS
Shot By Taro Seki Astropical.uk

Skull-RGB-SemoAPO-crop-Edit01-Finish