Ryderscope
02-10-2023, 11:35 AM
Whilst this may not be the most jaw dropping image that I've published it does have a moderately interesting back story so is worth sharing. The reason being is that I accidentally imaged the same field twice, three years apart. As it transpires, the galaxy in the centre of the image has duplicate NGC numbers i.e. NGC4517 and NGC4437 which caught me out. There is a discussion on the error resulting in the duplicate designation here (https://cseligman.com/text/atlas/ngc44.htm#4437). In addition to the duplicate designation, I had rotated the camera on the OTA by 90 degrees in between the projects so didn't recognise the field as the data were coming in from the camera. It wasn't until I was processing the second data set that I noticed the error.
So what to do with two data sets of the same field taken three years apart? Throw the lot in together of course and see what happens :). I finished up combining 19.5 hours of data from 2020 with 17.5 hours of data from 2023 using the Weighted Batch Preprocessing Script in Pixinsight (along with the requisite calibration frames) to produce four nice new masters for Luminance, Red, Green and Blue. Given the amount of data that I had I also used drizzle integration to improve the resolution of the image. This was particularly useful as I had to crop down the field quite a bit.
In reviewing the final image when compared to the original one from 2020 (https://astrob.in/ev2lct/0/), I can see that I've managed to bring out more detail and (to me at least !) the result was worth the effort. I was very surprised though as to how much chromatic noise I had to deal with given that the amount of data.
Click here for access to the image on Astrobin. (https://astrob.in/xyu2ls/C/)
(Acquisition and equipment details can be found in the Astrobin post).
Clear skies,
Rodney
So what to do with two data sets of the same field taken three years apart? Throw the lot in together of course and see what happens :). I finished up combining 19.5 hours of data from 2020 with 17.5 hours of data from 2023 using the Weighted Batch Preprocessing Script in Pixinsight (along with the requisite calibration frames) to produce four nice new masters for Luminance, Red, Green and Blue. Given the amount of data that I had I also used drizzle integration to improve the resolution of the image. This was particularly useful as I had to crop down the field quite a bit.
In reviewing the final image when compared to the original one from 2020 (https://astrob.in/ev2lct/0/), I can see that I've managed to bring out more detail and (to me at least !) the result was worth the effort. I was very surprised though as to how much chromatic noise I had to deal with given that the amount of data.
Click here for access to the image on Astrobin. (https://astrob.in/xyu2ls/C/)
(Acquisition and equipment details can be found in the Astrobin post).
Clear skies,
Rodney