PixInSight workflow to get starless and star separated masters by Starnet2 from SHO channel combination integration, this latter used as luminance level; files not stretched hereby available:
NGC 1365 JWST MIRI mosaic, filters f770W, f1000W, f1130W and f2100W
According to James Webb Space Telescope official documentation (cfr. https://jwst-docs.stsci.edu/jwst-mid-infrared-instrument) the JWST Mid-Infrared Instrument (MIRI) provides imaging and spectroscopic observing modes from 4.9 to 27.9 μm. These wavelengths can be utilized for studies including, but not limited to: direct imaging of young warm exoplanets and spectroscopy of their atmospheres; identification and characterization of the first galaxies at redshifts z > 7; and analysis of warm dust and molecular gas in young stars and proto-planetary disks.
MIRI imaging filter curves and wavelenght are resumed below
From Mikulksky Archive for Space Telescopes I downloaded raw calibrated .tif data focused about NGC 1365 Great Barred Spiral Galaxy, a double-barred spiral galaxy about 56 million light-years away in the constellation Fornax.
Among all data available I picked-up 3 sessions: a wide field MIRI mosaic by filters f770W, f1000W, f1130W and f2100W, a small field MIRI mosaic by the same filters f770W, f1000W, f1130W and f2100W a small NIRCAM field mosaic by filters f200W, f300M, f335M and f360M.
NGC 1365 JWST MIRI mosaic, filters f770W, f1000W, f1130W and f2100WNGC 1365 JWST NIRCAM mosaic, filters f200W, f300M, f335M, f360M
After and according to Warren Keller intro and divulgation paper focused about James Webb Space Telescope raw data availability from MAST Portal, archive named after Barbara Mikulski fulls of tons and tons of data including Hubble Space Telescope’s .fits calibrated frames, I’ve downloaded a couple of sets focused on NGC 3132 and NGC 3324 to begin an attempt of post-processing.
Browsing mast portal is kinda experience within a state of art information retrieval system: filters options permits to produce precise queries for matching desired set of data.
JWST target session produce .zip archives tagged, among other criteria, by NIRCAM, MIRI and NIRSPEC instrument label.
suggestions and guidelines about JWST raw data elaboration and post production, most convenient and useful data for an Astrophotographic approach come from NIRCAM sensors and filters.
NIR camera JWST official documentation guidelines specifies and classifies the following filters wheels clusters:
and resumes microns wavelength of filters set as pictured below :
Wavelength and filters label specification, assigned to visible spectrum compass, as confirmed by Keller and Carver tributes, suggests and permits two approach as attempt of post-production and elaboration of JWST NIRCam available data:
a “simplified” RGB or LRGB image integration by channel combination
a “more complex” image integration by available channel combination
An RGB or LRGB approach is “simple” as it consists essentially in identifying proper NIRCAM filter most representative data for RGB channels and integrate them by simple melting channel combination in – for instance – PixInSight: Process > Channel Management > Combination.
NGC 3324 NIRCAM filters available data are f090W, f187N, f200W, f335M, f444W and MIRI f770W, f1130W, f1280W, f1800W.
MAST portal retrieved data for NGC3324 filter by JWST mission
Letting MIRI data to further investigation, I focused on NIRCAM range records download them all.
Each .zip archives exploded out as follow:
file of interest is the _i2d.fits file, generally speaking the biggest among all records.
Opening it in PixInSight generate 8 preview:
A quick autostretch easily let us identify the proper image which I always found as the first, thus the downer pop-up opened.
In the name of .fits file are indicated which filter belongs to, thus it’s very easy to select.
Among JWST data from NIRCAM records focus about NGC 3324 I thought the lowest and more representative for blue channel could be f090W, whilst f444W for red and middle f335M for green.
Before channel combination I did proceed for a star registration of the whole masters, choosing f444W as reference.
I thus integrated all registered frames in percentile clipping and saved the .xifs integration as luminance.
“Simple” [L]RGB is about to end by:
RGB final integration by Process > Channel Management > Channel Combination
LRGB final integration by Process > All Process > LRGB Combination
About more “complex” 6 channel integration I just stretched very lightly by manual Histogram Transformation and export each filter master registered file as .tiff.
Using luminance as bg layer, I thus imported as layer each filter, according to Carver tutorial in screen mode blending with 50% opacity, by adjustment layer/saturation colorizing and boosting/decreasing saturation and luminance trying to respect NIRCAM wavelenght filters charts; take care to change Image > Mode to RGB from greyscale as very first step after luminance opening in Photoshop.
Finally applying an adjustment/curves layers to each filter and retouching pertinent saturation I try to obtain the most balance and well colored images, imho absolutely subjective pov.
Region of SH2-157 and NGC7635 in narrowband filters, SHO palette. From Bortle 6th degree sky in Livorno, Italy – home balcony. William Optics Redcat 51 and ASI1600mm Pro cooled at -20 Celsius. Mount SW EQM35 Pro, setup ground on Asiair Pro.
A mosaic composition of IC1805 and IC1848 in SHO palette
Strumentazione Telescopi O Obiettivi Di Acquisizione William Optics RedCat 51 Petzval APO Camere Di Acquisizione ZWO ASI 1600MM-Cool Pro Montature Skywatcher EQ35M Filtri astronomic Oiii 6nm · Astronomic SII 6nm 1.25 · Astronomic 1,25″ Luminance · Astronomik H alpha 12 nm 2 inch Astronomik Accessori ZWO 8x 1.25″ Filter Wheel (EFW) Software ZWO ASIair Pro · Pleiades Astrophoto PinInsight · Lightroom · Photoshop · Astroberry Telescopi O Obiettivi Di Guida QHYCCD QHY Mini Guide Scope Camere Di Guida ZWO ASI120MM Mini
Telescopi O Obiettivi Di Acquisizione William Optics RedCat 51 Petzval APO Camere Di Acquisizione ZWO ASI 1600MM-Cool Pro Montature Skywatcher EQ35M Filtri astronomic Oiii 6nm · Astronomic SII 6nm 1.25 · Astronomic 1,25″ Luminance · Astronomik H alpha 12 nm 2 inch Astronomik Accessori ZWO 8x 1.25″ Filter Wheel (EFW) Software ZWO ASIair Pro · Pleiades Astrophoto PinInsight · Lightroom · Photoshop · Astroberry Telescopi O Obiettivi Di Guida QHYCCD QHY Mini Guide Scope Camere Di Guida ZWO ASI120MM Mini
Dettagli d’acquisizione Date: 28 Ottobre 2021 · 01 Novembre 2021 Pose: Astronomic SII 6nm 1.25: 153×180″ (7h 39′) (gain: 139.00) -20°C bin 1×1 Astronomik H alpha 12 nm 2 inch Astronomik: 170×180″ (8h 30′) (gain: 139.00) -20°C bin 1×1 astronomic Oiii 6nm: 298×180″ (14h 54′) (gain: 139.00) -20°C bin 1×1 Integrazione: 31h 3′ Dark: 33 Flat: 33 Dark dei flat: 33 Giorno lunare medio: 23.80 giorni Fase lunare media: 34.21% Scala del Cielo Scuro Bortle: 6.00 Dettagli astrometrici di base Astrometry.net job: None
