Monday, 27 July 2020

Comet Neowise from a Chennai terrace part 2

Author: Ravi Kailas (ficustours@gmail.com)

After making a post on my first sighting of Comet Neowise, on Thursday, 23rd July, the sky was clear enough (relatively speaking, but not before a typically dramatic (see video below), July evening cloud build-up in the western sky, threatening a black-out) for another attempt at imaging the comet, on Friday, 24th July. 


While, in the earlier post, I might have suggested that this comet is comparable to Hale-Bopp, that visited three decades ago, I understand that it is barely (although higher in the sky) a naked eye object of late, with a visual magnitude of over 7 (unlike in early July, while it was, reputedly, much brighter in morning sky) and its fuzzy spread of light (unlike pin-point sources like stars), makes it all the more difficult to spot without visual aids. Light polluted city skies, as in Chennai, with veil of high clouds, and additional light from the first quarter moon, do not particularly help matters either and it required a bit of effort, looking through binoculars in the section of the sky, west of Ursa Major, before I can locate a faint greenish-blue blob, with vestiges of a tail. Fortunately these conditions stayed, more or less the same, through a prolonged imaging effort (for an hour or so from about 1920), and I managed a series of multiple images, with a combination of settings (see table below and associated images), all untracked, with an m43 camera (Olympus O-MD E-M5II) and a M. Zuiko 40-150 2.8 lens. 

Image no.     Focal Length                     Settings
1                    150mm                                     ISO 1250 2.5s f 2.8 Stack of 21 Images
2                    150mm                                     ISO 3200 1.6s f 2.8 Stack of 21 images
3                    150mm                                     ISO 1600 3.2s f 2.8 Stack of 18 Images
4                    150 mm                             ISO 2000 1.6s f 2.8 Stack of 21 Images


While the results, after much post processing (alignment and stacking to start with) with Lightroom 6.0 and Nebulosity 4.0, were a tad better at eking out some of the faint tail, than my first effort, the resultant images were riddled with unattractive artefacts from the pp effort of pushing the image data to reveal the fainter details of the comet. But, I will let you decide, whether or what you like, or otherwise, from the images below!

Image 1


Image 2

Image 3


Image 4

I suspect that this will be among the last of my imaging efforts of Comet Neowise, with the brightening moon promising to interfere with what little is visible of the comet as it is, while it is still predicted to remain in our view until the end of the month, after which the comet will disappear, on its travels to other parts of the solar system, for over 6000 years. 


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