1 hour of 8 second lights, plus 100 bias frames.
21 April 2024. Waxing Gibbous moon (12.5 days old)
Skywatcher 350 goto, ZWO ASI2600MC PRO, Starizona Nexus focal reducer, and ZWO Duo-Band filter.
Telescope and camera controlled by N.I.N.A. Image processed on a Mac in Siril, Starnet++, and Affinity Photo 2 (with RC-Astro's NoiseXterminator plugin).

This is cropped quite a bit, as I was seeing a faint halo further out in the image, that I wasn't able to remove in processing. Not sure if this was caused by the moon, a street light, or was a by-product of the vignetting which I am seeing in the corners of my images.

SIMPLE  =                    T / file does conform to FITS standardBITPIX  =                  -32 / number of bits per data pixelNAXIS   =                    3 / number of data axesNAXIS1  =                 2816 / length of data axis 1NAXIS2  =                 1687 / length of data axis 2NAXIS3  =                    3 / length of data axis 3EXTEND  =                    T / FITS dataset may contain extensionsCOMMENT   FITS (Flexible Image Transport System) format is defined in 'AstronomyCOMMENT   and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359HBZERO   =                    0 / offset data range to that of unsigned shortBSCALE  =                    1 / default scaling factorDATE    = '2024-04-21T23:32:33' / UTC date that FITS file was createdDATE-OBS= '2024-04-21T09:39:51.383000' / YYYY-MM-DDThh:mm:ss observation start, INSTRUME= 'ZWO ASI2600MC Pro'  / instrument nameOBSERVER= '        '           / observer nameTELESCOP= 'SkyWatcher 350'     / telescope used to acquire this imageROWORDER= 'TOP-DOWN'           / Order of the rows in image arrayXPIXSZ  =                 7.52 / X pixel size micronsYPIXSZ  =                 7.52 / Y pixel size micronsXBINNING=                    2 / Camera binning modeYBINNING=                    2 / Camera binning modeFOCALLEN=                 1650 / Camera focal lengthCCD-TEMP=                  -15 / CCD temp in CSET-TEMP=                  -15 / Temperature setting in CEXPTIME =                    8 / Exposure time [s]STACKCNT=                  448 / Stack framesLIVETIME=                 3584 / Exposure time after deadtime correctionEXPSTART=         2.46042e+006 / Exposure start time (standard Julian date)EXPEND  =         2.46042e+006 / Exposure end time (standard Julian date)IMAGETYP= 'LIGHT   '           / Type of imageOBJECT  = 'Horsehead Nebula'   / Name of the object of interestCVF     =            0.0242863 / Conversion factor (e-/adu)GAIN    =                  300 / Camera gainOFFSET  =                    1 / Camera offsetSITELAT =               -37.95 / [deg] Observation site latitudeSITELONG=              145.017 / [deg] Observation site longitudeSITEELEV=                   30 / [m] Observation site elevationCTYPE1  = 'RA---TAN'           / Coordinate type for the first axisCTYPE2  = 'DEC--TAN'           / Coordinate type for the second axisCUNIT1  = 'deg     '           / Unit of coordinatesCUNIT2  = 'deg     '           / Unit of coordinatesEQUINOX =                 2000 / Equatorial equinoxOBJCTRA = '05 40 59'           / Image center Right Ascension (hms)OBJCTDEC= '-02 27 30'          / Image center Declination (dms)RA      =              85.3663 / Image center Right Ascension (deg)DEC     =             -2.59876 / Image center Declination (deg)AIRMASS =               2.3261 / AirmassHISTORY mean stacking with winsorized sigma clipping rejection (low=3.000 high=3HISTORY .000), additive+scaling normalized input, normalized output, no image weHISTORY ighting, unequalized RGBHISTORY Background neutralizationHISTORY Color CalibrationHISTORY SCNR (type=average neutral, amount=1.00, preserve=true)HISTORY Crop (x=201, y=161, w=2816, h=1687)HISTORY Background extraction (Correction: Subtraction)HISTORY Histogram Transf. (mid=0.001, lo=0.006, hi=1.000)END

... and this is the same data after going back to the original frames and reprocessing, trying to bring out more detai. Some parts look better, while other areas appear to have been pushed too far. I've still got a lot to learn :-)

SIMPLE  =                    T / file does conform to FITS standardBITPIX  =                   20 / number of bits per data pixelNAXIS   =                    3 / number of data axesNAXIS1  =                 2871 / length of data axis 1NAXIS2  =                 1771 / length of data axis 2NAXIS3  =                    3 / length of data axis 3EXTEND  =                    T / FITS dataset may contain extensionsCOMMENT   FITS (Flexible Image Transport System) format is defined in 'AstronomyCOMMENT   and Astrophysics', volume 376, page 359; bibcode: 2001A&A...376..359HMIPS-FHI=                    1 / Upper visualization cutoffMIPS-FLO=                    0 / Lower visualization cutoffBZERO   =                    0 / offset data range to that of unsigned shortBSCALE  =                    1 / default scaling factorDATE    = '2024-04-30T11:55:35' / UTC date that FITS file was createdDATE-OBS= '2024-04-21T09:39:51.383000' / YYYY-MM-DDThh:mm:ss observation start, INSTRUME= 'ZWO ASI2600MC Pro'  / instrument nameOBSERVER= '        '           / observer nameTELESCOP= 'SkyWatcher 350'     / telescope used to acquire this imageROWORDER= 'TOP-DOWN'           / Order of the rows in image arrayXPIXSZ  =                 7.52 / X pixel size micronsYPIXSZ  =                 7.52 / Y pixel size micronsXBINNING=                    2 / Camera binning modeYBINNING=                    2 / Camera binning modeFOCALLEN=                 1650 / Camera focal lengthCCD-TEMP=                  -15 / CCD temp in CSET-TEMP=                  -15 / Temperature setting in CEXPTIME =                    8 / Exposure time [s]STACKCNT=                  448 / Stack framesLIVETIME=                 3584 / Exposure time after deadtime correctionEXPSTART=         2.46042e+006 / Exposure start time (standard Julian date)EXPEND  =         2.46042e+006 / Exposure end time (standard Julian date)IMAGETYP= 'LIGHT   '           / Type of imageOBJECT  = 'Horsehead Nebula'   / Name of the object of interestCVF     =            0.0242863 / Conversion factor (e-/adu)GAIN    =                  300 / Camera gainOFFSET  =                    1 / Camera offsetSITELAT =               -37.95 / [deg] Observation site latitudeSITELONG=              145.017 / [deg] Observation site longitudeSITEELEV=                   30 / [m] Observation site elevationCTYPE1  = 'RA---TAN'           / Coordinate type for the first axisCTYPE2  = 'DEC--TAN'           / Coordinate type for the second axisCUNIT1  = 'deg     '           / Unit of coordinatesCUNIT2  = 'deg     '           / Unit of coordinatesEQUINOX =                 2000 / Equatorial equinoxOBJCTRA = '05 40 59'           / Image center Right Ascension (hms)OBJCTDEC= '-02 27 30'          / Image center Declination (dms)RA      =              85.3663 / Image center Right Ascension (deg)DEC     =             -2.59876 / Image center Declination (deg)AIRMASS =               2.3261 / AirmassHISTORY mean stacking with winsorized sigma clipping rejection (low=3.000 high=3HISTORY .000), additive+scaling normalized input, normalized output, no image weHISTORY ighting, unequalized RGBHISTORY Crop (x=170, y=176, w=2871, h=1771)HISTORY Background neutralizationHISTORY Background extraction (Correction: Subtraction)HISTORY Background extraction (Correction: Subtraction)HISTORY NL-Bayes denoise (mod=1.000, CC enabled)HISTORY Histogram Transf. (mid=0.000, lo=0.005, hi=1.000)HISTORY SCNR (type=average neutral, amount=1.00, preserve=true)HISTORY Saturation enhancement (amount=0.65)HISTORY DeconvolutionEND

 The Horsehead Nebula is a small dark nebula in the constellation Orion, and is roughly 1,375 light-years from Earth. It is very difficult to see through telescopes in Melbourne because of light polution, but lots of exposures, and a narrowband filter that removes the worst effects of light polution can make it show up in photographs. As Orion is so close to the horizon at dusk now I will have to wait until later in the year to have another opportunity to get a better image.