At the end of last nights imaging session, I tried to capture comet C/2023 P1 Nishimura with the C14 Hyperstar. Unfortunately, the comet was only 8° above the horizon at my location here in Northern Germany. An almost 80% moon, the nautical twilight and some haze near the horizon lead to mean brightness values between 13000  - 14000  of the raw subs. Looking back, using the R instead of the L filter might have increased the contrast relative to the blue sky background. Furthermore, I made the mistake to use 30 s exposures, which  clipped the brightness values in the comets coma, making it impossible to use comet alignment in PI. Therefore, I applied some simple processing to the 40 raw subs and compiled them into a short time-lapse movie. For the animation, I used a strong crop around the brighter parts of the comet tail.

Revision B shows the whole FOV after an image integration of 4 x 30 s subs. Some details in the fainter parts of the tail become visible including a possible disconnection event. However, without proper comet alignment and a darker sky background, the details remain fairly fuzzy.

04.09.2023, 02:20 UT - 02:46 UT

Equipment

ZWO ASI 1600 MM Pro @ -20°C
+ C14 & Starizona Hyperstar v2 @ 675 mm (f/1.9)
+ Baader 2" L filter
+ Celestron EF
+ Tempest Cooler
+ Omegon Dew Heater
+ Astrozap Dew Shield for C 14 Hyperstar
on CGE-Pro mount

Cable managment to mitigate Hyperstar diffraction spikes.

Autoguiding:
Artesky 70 mm Guidscope (f=400 mm)
ZWO ASI 120 MM mini
PhD2 (Multistarguiding)
Dither every 4 subs

light frames:
L (gain=75, offset=15)

acquired with N.I.N.A.

Remaining Issues
- coma is overexposed, so comet alignment in PI fails

Post-Processing

PixInsight

L

- image calibration (darks only) & image registration with WBPP script
- dynamic crop
- DBE
- Fast Rotation -> Horizontal & Vertical Mirror
- AutoHistogram in Blink
- Blackpoint definition GHS (linear)
- GHS tweaks
- export tiffs

LRTimeLapse

- create time lapse movie

Revision B

Post-Processing

PixInsight

L

- image calibration (darks only) & image registration with WBPP script
- image integration of 4 x 30 s subs using sigma clipping pixel rejection
- DBE
- dynamic crop
- Fast Rotation -> Horizontal & Vertical Mirror
- strong GHS

Location: Schwentinental (Germany)

- CS Daniel