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The Rosette Nebula and Cluster ( NGC 2237 and 2244 ) in the constellation Monoceros edit: updated 30th Dec with improved colour balance and slightly increased brightness ... ...... original: ( please click / tap on image to see larger and sharper ) Still a work-in-progress really... with only 10 x 4min exposures for the main 'lights' before the clouds came over. I will try to add some more data when the moon has gone I am still experimenting with how to get the best out of the D7500. With the very warm nights ( low to mid 20s all night ) the 'warm pixels' are very noticeable so I reverted to my old practice of in-camera dark subtraction. This worked quite well and produced a nice smooth noise floor in the integrated images - albeit at the expense of more exposures. ................. Identification: The Rosette Nebula ( NGC 2237 ) is a large, circular emission nebula in the constellation Monoceros. It surrounds a cluster of hot, young stars known as the Rosette Cluster ( NGC 2244 ). ( SkySafari ) NGC 2237, 2244 Caldwell 49, 50 North is up. .................. Capture Details: Telescope: Orion Optics CT12 Newtonian ( mirror 300mm, fl 1200mm, f4 ). Corrector: ASA 2" Coma Corrector Quattro 1.175x. Effective Focal Length / Aperture : 1400mm f4.7 Mount: Skywatcher EQ8 Guiding: TSOAG9 Off-Axis-Guider, Starlight Xpress Lodestar X2, PHD2 Camera: Nikon D7500 (unmodified) (sensor 23.5 x 15.7mm, 5568x3712 @ 4.196um pixels) Location: Blue Mountains, Australia Moderate light pollution ( pale green zone on darksitefinder.com map ) Capture ( 23 Dec 2017 ) 9 sets of sub-images with exposure duration for each set doubling ( 1s to 240s ) all at ISO400. 10 x 240s + 5 each @ 1s to 120s imaged ~ +/- 1.5hrs either side of meridian maximum altitude ~ 51.3 deg above north horizon Processing ( Pixinsight ) Calibration: master bias, master flat and in-camera dark subtraction Integration in 9 sets HDR combination Image Plate Solution =================================== Resolution ........ 0.633 arcsec/px ( full size image ) Rotation .......... 0.181 deg Focal ............. 1367.90 mm Pixel size ........ 4.20 um Field of view ..... 58' 59.4" x 39' 15.0" Image center ...... RA: 06 31 55.638 Dec: +04 56 30.84 ===================================
The Great Barred Spiral Galaxy ( NGC 1365 ) in the constellation Fornax edit: new version with new long exposure data ( 52 x 240sec ) and better dark subtraction / dithering to remove streaks in the noise and amp glow. This also allowed for a greater stretch revealing more faint data in the galaxy and small faint fuzzies in the image .. The Great Barred Spiral Galaxy ( NGC 1365 ) in Fornax ( please click / tap to see larger ) and below I have added a 100% crop of new version: ........ original image: NGC 1365 ( please click / tap on image to see larger ) ............... The Great Barred Spiral Galaxy ( NGC 1365 ) in the Constellation Fornax Below the equator, not seen from much of the Northern hemisphere, NGC 1365 passes very nearly directly overhead an observer situated near Cape Town, as Sir John Herschel was in November of 1837, or near Sydney, as I was, almost exactly 180 years later, when I photographed this “remarkable nebula” that is numbered 2552 in his book of observations from the Cape. Not called a “nebula” now, of course, this striking object is one of the nearest and most studied examples of a barred spiral ( SB ) galaxy that also has an active galactic nuclei resulting in its designation as a Seyfert galaxy. At around 60 M light years from Earth, NGC 1365 is still seen to occupy a relatively large area ( 12 by 6 arc minutes ) due to its great size; at some 200,000 light years or so across, NGC 1365 is nearly twice as wide as the Milky Way and considerably wider than both the Sculptor and Andromeda galaxies. This High Dynamic Range ( HDR ) image is built up from multiple exposures ranging from 4 to 120 seconds with the aim of capturing the faint detail in the spiral arms of the galaxy whilst also retaining colour in the brightest star ( the orange-red 7th magnitude giant, HD 22425 ). Also, scattered throughout the image, and somewhat more difficult to see, are numerous and far more distant galaxies with apparent magnitudes of 16 to 18 or greater. Mike O'Day ................. Identification: The Great Barred Spiral Galaxy New General Catalogue - NGC 1365 General Catalogue - GC 731 John Herschel ( Cape of Good Hope ) # 2552 - Nov 28, 29 1837 Principal Galaxy Catlogue - PCG 13179 ESO 358-17 IRAS 03317-3618 RA (2000.0) 3h 33m 37.2 s DEC (2000.0) -36 deg 8' 36.5" 10th magnitude Seyfert-type galaxy in the Fornaux cluster of galaxies 200 Kly diameter 60 Mly distance .................. Capture Details: Telescope: Orion Optics CT12 Newtonian ( mirror 300mm, fl 1200mm, f4 ). Corrector: ASA 2" Coma Corrector Quattro 1.175x. Effective Focal Length / Aperture : 1400mm f4.7 Mount: Skywatcher EQ Guiding: TSOAG9 Off-Axis-Guider, Starlight Xpress Lodestar X2, PHD2 Camera: Nikon D7500 (unmodified) (sensor 23.5 x 15.7mm, 5568x3712 @ 4.196um pixels) Location: Blue Mountains, Australia Moderate light pollution ( pale green zone on darksitefinder.com map ) Capture ( 22 Nov 2017 ) 6 sets of sub-images with exposure duration for each set doubling ( 4s to 120s ) all at ISO400. 70 x 120s + 5 each @ 4s to 60s total around 2.5hrs Processing ( Pixinsight ) Calibration: master bias, master flat and no darks Integration in 6 sets HDR combination Image - Plate Solution ========================================== Resolution ........ 1.328 arcsec/px Rotation .......... -0.008 deg ( North is up ) Field of view ..... 58' 8.6" x 38' 47.5" Image center ...... RA: 03 33 41.182 Dec: -36 07 46.71 ==========================================
Finally a clear night and no need to get up (too) early tomorrow !! Seen the weather report on the Clear Skies app and immediately informed the missus shed be going to bed alone tonight. Got all my kit up and running in the garden and prepared myself for a few hours of viewing. First thing i noticed was how much id forgotten... so just keeping it simple and going for some obvious targets like double stars and the moon to get used to the equipment again (this is only my fith outing). Want to use my new phone adapter to grab some simple pictures but a bad back has left me unable to contort myself into some precarious positions to view the screen and nab a decent shot so you all will have to wait until the next clear night before i can try it out for real. Heading up to the very north of scotland for work tomorrow so will take all my gear along with me in the hope i get a calm clear night to get some awesome stargazing ! Clear skies everyone and we can finally get this show on the road for another season.