“To them, I am a nursery, serene and timeless, yet they cannot fathom the chaos within. Their lives are but sparks, quick to fade, yet they look upon us and see eternity.”
NGC 7822 – Cosmic Question Mark – HaRGB
Description
NGC 7822 is a star forming HII region in the constellation Cepheus.
The image is showing the bright central region named Cederblad 214 (Ced 214).
There is also a young cluster of star named Berkeley 59 (bottom part of the center of image).
Research and Observations
The complex also includes one of the hottest stars discovered within 1 kpc of the Sun, namely BD+66 1673, which is an eclipsing binary system consisting of an O5V that exhibits a surface temperature of nearly 45,000 K and a luminosity about 100,000 times that of the Sun.
Acquisition Details
This image was captured over the course of two nights:
Aug 27th 2022
– 2.5 hours (15 X 10 min. exposures via Hydrogen Alpha filter)
Sep 1st 2022
– 2 hours (20 X 2 min. exposure via R, G and B filters)
– 1 hour 50 minutes (10 X 10 min. exposures via Hydrogen Alpha filter)
Total Integration Time: 6 hours 10 minutes
Acquisition Start Time: 21h10
Acquisition Stop Time: 02h30
Image Information
| Object(s) Catalog No: | NGC7822 |
| Object Type | Nebula |
| Constellation | Cepheus |
| Size | 100′ |
| Magnitude | 10.03 |
| Distance | 3300 LY |
| Field of View | 2.06° x 1.55° |
Conditions
| Date | August 27th, 2022 |
| Astronomical Dusk: | 21h22 EDST |
| Moon Age | 0.2 |
| Moon Phase | New Moon |
| Temperature | 16.7º |
| Transparency | Below Average |
| Seeing | Above Average |
| Wind | 6 km/h |
| Dew Point | 14º |
| Sky ADU | 1550 |
| Sky Flux (e/min) | not calculated |
Equipment
Software
| Mount | Retrofitted CGEM (OnStep) |
| Imaging Scope | Orion ED80T CF |
| Guiding Scope | APM 60mm Image Master |
| Imaging Camera | SBIG ST-8300M |
| Guiding Camera | QHYCCD: QHY5L-II-M |
| Additional Optics | SharpStar Field Flattener – 2.5″ |
| Filters | Ha, R, G, B |
| Acquisition | Sequence Generator Pro |
| Auto-Guiding | PHD2 Guiding |
| Processing | Pixinsight |
| Planetarium | Sky Planetarium |
Subframe Details
| Filters | L | R | G | B | Ha | OII | SII |
| Camera Temperature | -10° C | -10° C | -10° C | -10° C | |||
| Binning | 2×2 | 2×2 | 2×2 | 1×1 | |||
| Number of sub-frames | 20 | 20 | 20 | 25 | |||
| Sub-frames duration (sec) | 120 | 120 | 120 | 600 | |||
| Number of good sub-frames | |||||||
| Number of Flats | 20 | 20 | 20 | 20 | |||
| Flats Duration (sec) | 0.42 | 0.31 | 0.48 | 31.13 | |||
| Number of Darks | 11 | 11 | |||||
| Darks Duration (sec) | 120 | 600 | |||||
| Number of Bias | 51 | 51 |
Auto-Focuser Position: 2882
Autoguiding Average : 0.6″ RMS
Acquisition Notes
Increase the plate solve (“until error is less than”) from 50 to 125 to avoid failure.
Focuser slippage interrupted the first night of acquisition.
Processing Notes
R, G and B subframes where shot using Bin2x2. This was probably too under sampled for the ED80T CF at 480mm F6.0 and created square stars. With researches and trial/error, Bicubic B-Spline pixel interpolation for the image registration was found to resolve the issue.
Not enough therefore very noisy R, G and B sub-exposures.
Gradient was difficult to remove on R, G and B sub-exposures because most of the image is filled with nebulosity.
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