Adding to the Sharpless Sh 129 image.. and failing
Category: Astronomy Images
Posted by: Tom How
Last night was murky, but I could see some stars, so I decided to try taking some more frames of Sh 129 in Cepheus to add to the previous image.
However, it didn't turn out very well.
First of all the RA drive on the telescope decided to start playing up. It was jumping around very faster forward in RA. It did all the usual things, such as checking the power to the telescope mount and re calibrating the Meade LXD55 mount, but it wasn't working. So I took the entire motor and circuit board apart, cleaned it, touched all the solder connections with a soldering iron, and put it back together. After this is worked fine. I do not know what went wrong, but I seem to have fixed it!
I then got about 7 frames of 15 minutes each, however after that, the guider must have mislaid the guidestar, and the remaining frames were unguided junk. This could be an artifact of the high angle of this object in the sky.
This evening I've spent about an hour stacking the images from last night with the images from the night before and not doing very well. Last night’s images stacked together make a good image, but adding them into the dataset from earlier in the week didn't give any visible improvement.
I blame the murk for this. The background in the frames from last night were consistently 50ADU brighter than the data from earlier. The light pollution reflecting off the clouds finds its way into the sensor via the Hydrogen Alpha filter and gives a tiny increase in the background of the image - and this was enough to make most of the frames useless compared to the previous dataset.
This goes to show two things. If you want to image in poor conditions then narrowband filters are fantastic. They cut out the increased skyglow and make it possible to get some kind of image where none was possible.
On the other hand, if you want an image of the highest quality then you still need to image on a perfect night, regardless of the filters!
However, it didn't turn out very well.
First of all the RA drive on the telescope decided to start playing up. It was jumping around very faster forward in RA. It did all the usual things, such as checking the power to the telescope mount and re calibrating the Meade LXD55 mount, but it wasn't working. So I took the entire motor and circuit board apart, cleaned it, touched all the solder connections with a soldering iron, and put it back together. After this is worked fine. I do not know what went wrong, but I seem to have fixed it!
I then got about 7 frames of 15 minutes each, however after that, the guider must have mislaid the guidestar, and the remaining frames were unguided junk. This could be an artifact of the high angle of this object in the sky.
This evening I've spent about an hour stacking the images from last night with the images from the night before and not doing very well. Last night’s images stacked together make a good image, but adding them into the dataset from earlier in the week didn't give any visible improvement.
I blame the murk for this. The background in the frames from last night were consistently 50ADU brighter than the data from earlier. The light pollution reflecting off the clouds finds its way into the sensor via the Hydrogen Alpha filter and gives a tiny increase in the background of the image - and this was enough to make most of the frames useless compared to the previous dataset.
This goes to show two things. If you want to image in poor conditions then narrowband filters are fantastic. They cut out the increased skyglow and make it possible to get some kind of image where none was possible.
On the other hand, if you want an image of the highest quality then you still need to image on a perfect night, regardless of the filters!
