OSC-Imaging with heavy light pollution 

Usually I use every clear night around the new moon period for driving at dark sites of the Black Forest, to collect as much clear data as possible. I combine this data with narrowband Data which I collect from my city balcony. The light pollution map shows for my hometown a Bortle 5-6 sky. It also shows a Bortle 4 Sky for the darkest places in the Black Forest. But the difference is very huge. Especially in my case, cause my balcony is straight above a bright illuminated parking space. Additionally the orange lights are in the hight of my telescope, cause due to my roof I can only see targets that are standing low above the horizon. 

Cause of these little problems I usually collect only H-Alpha from home with special narrowband Filters and edit these images to the data that I collect outside the city.

Due to a leck of clear nights for a long time, I used the last new moon period in May for a new image of NGC 7000, the Nort-America Nebula. The target was a little bit low in May, but after a long time of "Galaxy-Season" with my EdgeHD 800, I was very happy to use the RASA8 for some nebula imaging. The problem in this session was wind. I have used my little iOptron CEM40EC Mount, which handle the RASA very well, but it is a little bit wobbly in windy situations. After a frustrating test on the field I decided to take some balcony images. This time i have tried a new strategy. I would do a complete image only with data from my balcony. For this test I didn't choose a narrowband Filter only for H-Alpha. I chosed a Filter with wider bands to collect more than H-Alpha. 

For this I have chosed the Hutech IDAS NB1 Filter. I have made many positive experience with IDAS NB Filters on the RASA8. Cause of bandshifting with fast telescopes, it is important that the Bands are controlled for every Filter by the manufactory, what Hotech do. So you can predict if the filter will work on a fast system or not. Of course this gets more important, if you use narrow bands, so it is not so important for a filter like the NB1, but I could say, that it is working very fine at the RASA. The only disadvantage of nearly every filter which you use with the RASA produces halos around bright stars. In my case you can see it around the bright star under NGC 7000.

For my final image I have collected 149 frames, some 60sec, 75sec and 120sec frames over 3 nights (the target was only visible for some hours and nighttime in May is already short).

Celestron RASA 8

iOptron CEM40EC

ZWO Asiair Plus

ZWO ASI 2600MC Pro

bin 1x1

-10° temp

high gain modus.

30 darks, 30 flat darks, 30 bias, 30 flats

Hutech IDAS NB1 Filter

Let me know in the guestbook how you think about it.