NGC 3718
Posted: Tue Apr 05, 2022 10:57 am
Being not sure if it's worth sharing, but here's my take at NGC 3718 in Ursa major:
It's really a cool looking object but my data is aweful. Lots of different gradients, banding and stuff. Just not an even field. I pushed the gradient aggressiveness and gradient falloff almost to the max. Synthetic bias finally ironed out the field. That may not have been ideal for the galaxy but I think in general the signal remained intact. I also masked out the galaxy for Wipe which I usually don't. In the end IMHO it's an okay result given the problems the data set has.
By the way, I stacked in Siril for the first time by using Scripts. That worked nicely. Usually I use ASTAP. But no matter the parameters the stacks always had a strange pattern of hot pixels repeating over the image. I wasn't able to spot these in the single subs and they remained if the subs were stacked without calibration frames. So it should be a problem of the lights... The problem did not occur with Siril or DSS (but the DSS stack had almost no galaxy in the image...DSS just doesn't work in my hands). Maybe a similar problem with ASTAP like the one @Carles reported a while back? Or just indicative that my data was inferior in that case.
Anyway, next time I will have a look at an easier target
Regards
Stefan
PS. See https://www.astrobin.com/l9ms4t/ for technical details.
It's really a cool looking object but my data is aweful. Lots of different gradients, banding and stuff. Just not an even field. I pushed the gradient aggressiveness and gradient falloff almost to the max. Synthetic bias finally ironed out the field. That may not have been ideal for the galaxy but I think in general the signal remained intact. I also masked out the galaxy for Wipe which I usually don't. In the end IMHO it's an okay result given the problems the data set has.
By the way, I stacked in Siril for the first time by using Scripts. That worked nicely. Usually I use ASTAP. But no matter the parameters the stacks always had a strange pattern of hot pixels repeating over the image. I wasn't able to spot these in the single subs and they remained if the subs were stacked without calibration frames. So it should be a problem of the lights... The problem did not occur with Siril or DSS (but the DSS stack had almost no galaxy in the image...DSS just doesn't work in my hands). Maybe a similar problem with ASTAP like the one @Carles reported a while back? Or just indicative that my data was inferior in that case.
Anyway, next time I will have a look at an easier target
Regards
Stefan
PS. See https://www.astrobin.com/l9ms4t/ for technical details.