Sh 2-68, the Flaming Skull Nebula in Serpens

Sh 2-68 is a planaetary nebula found in the constellation

Serpens.  Located about 1140 ly from us, it appears

to be screaming past us.  It looks that way because

it has the highest proper motion of any PN.

Hover over the picture for an annotated version

Date:  7 July 2026

FOV:  approximately 30' × 20'; the angular size of Sh 2-68 is about 19'

Rotation:  90.000°

Telescopes:  Orion Apex Mak-Cass (1382mm, nominally 1540mm, f/12.1)

and Celestron 9.25" EdgeHD 925 SCT (1678.39mm, nominally 1645mm, f/7

with Celestron's 0.7 x reducer)

Guiding:  ZWO ASI120MM mini mono guide cameras,

SVBony SV165 Mini 40mm f/4 guide scopes

Computer:  ASIair pro Raspberry Pi

Mount:  iOptron CEM40 2022, ZWO AM5 2025

Camera:  ZWO ASI071MC Pro Cooled (-10°C) Color CMOS with gain 90 (Mak-Cass)

and a ZWO ASI6200MC Pro Cooled (-10°C) Color CMOS with gain 100 (C-9.25")

Pixel size:  4.78 μm (Mak-Cass, 3.76 μm, (C-9.25")

Resolution:  0.713 arcsec/pixel (Mak-Cass), 0.462 arcsec/pixel (C-9.25")

Filter:  none for the Mak-Cass, Optolong L-Ultimate for the C-9.25"

Calibration frames: 20 dark, 20 flat, 20 dark flat

Total Time:  2 hours and 25 minutes

Processing:  Pixinsight

preprocessing → NoFilterx9 and L-Ultimatex20

LUlt:  MGC, DBE, SPCC, BXT, NXT, StarXT → LinearLUlt

MStr, MAS, GHS, HST,

PixelMath MStr + MAS + GHS + HST → LUlt

CurvesTransformation → Starless

NoFilter:  MGC, SPCC, DBE, BXT, NXT → LinearStars

MultiscaleAdaptiveStretch, Sat → Stars

PixelMath ScreenBlend(Stars, Starless), DynCrop/Scale

Location:  Darling Hill Observatory near Vesper, NY