ASTRO: NGC 3726 under good skies

I recently have spent quite a lot of nights on fields somewhere near Berlin,
hoping to get better images than from the city.
Unfortunately technical problems (mostly related to the lack of mains power)
and gusty winds combined with bad seeing have kept me from getting good
results in all nights but one.
From this only really good night is this image of NGC 3726 in UMa. I lost
quite a lot of time because of dew on the corrector plate at the time when
the galaxy was at it's highest, but apart from that conditions were good
(more like mag 6 than mag 7, but I won't complain ;-) , especially seeing
was very good.

Actually I will always prefer my bright city skies in a night of good seeing
to country skies with bad seeing.

I took the colour frames without binning, planning to add them to the
luminance (even did a lum image from them), but later forgot to include them
in the luminance and was too lazy to start from scratch when I noticed the
omission.

Taken from a defunct airfield near Klein Köris (you are excused if you have
never heard of the village of "Klein Köris" ;-) with a 10" Meade ACF at
f/7.8 (image scale 0.68 arcseconds/pixel), G11 mount, SXV-H9 camera, 26x5
minutes for L, 12x5 min R, 9x5 min G und 11x5 min B, all unbinned.

The image can be found at
http://ccd-astronomy.de/temp2/3726colourgut.jpg
and b/w version:
http://ccd-astronomy.de/temp2/3726-26x5gut.jpg

Stefan

Stefan Lilge wrote:
I recently have spent quite a lot of nights on fields somewhere near Berlin,
hoping to get better images than from the city.
Unfortunately technical problems (mostly related to the lack of mains power)
and gusty winds combined with bad seeing have kept me from getting good
results in all nights but one.
From this only really good night is this image of NGC 3726 in UMa. I lost
quite a lot of time because of dew on the corrector plate at the time when
the galaxy was at it's highest, but apart from that conditions were good
(more like mag 6 than mag 7, but I won't complain ;-) , especially seeing
was very good.

Actually I will always prefer my bright city skies in a night of good seeing
to country skies with bad seeing.

I took the colour frames without binning, planning to add them to the
luminance (even did a lum image from them), but later forgot to include them
in the luminance and was too lazy to start from scratch when I noticed the
omission.

Taken from a defunct airfield near Klein Köris (you are excused if you have
never heard of the village of "Klein Köris" ;-) with a 10" Meade ACF at
f/7.8 (image scale 0.68 arcseconds/pixel), G11 mount, SXV-H9 camera, 26x5
minutes for L, 12x5 min R, 9x5 min G und 11x5 min B, all unbinned.

The image can be found at
http://ccd-astronomy.de/temp2/3726colourgut.jpg
and b/w version:
http://ccd-astronomy.de/temp2/3726-26x5gut.jpg

Stefan

That certainly is clearer than my shot from two years ago. Better color
as well. It was taken in my "blue" period when I wasn't compensating
for the blue sensitivity of my camera correctly. Somehow I'd reversed
the red and blue labels on my spreadsheet for how to compensate
depending on altitude and thus for blue extinction. Result was too
little red and too much blue. I need to go back and reprocess them but
I don't have time to process the new ones coming in let alone redo old ones!
http://www.spacebanter.com/attachmen...ntid=739&stc=1

When I was working in the field with film all my mounts were AC motors.
They drew lots of power compared to today's DC motors. I built a 200
watt inverter to power everything from a couple deep cycle batteries.
Worked well but now I doubt I could carry that weight 100 yards into a
cow pasture like I used to! Since everything ran exactly the same as
from the power mains (I used the inverter when home as well as that
controlled guiding on the RA axis) it made for an easy night in the
field. Spent the next day recharging the batteries however.

I still have the inverter though doubt I'll ever use it again. It was a
home designed device. Commercial ones for scopes were far too low power
and tended to lack frequency stability due to temperature and often
falling voltage. I used a different oscillator that allowed for a
temperature compensating capacitor and of course voltage regulation on
the oscillator circuit. Commercial units didn't do either that I saw.
But without PEC you had to keep glued to the guiding eyepiece at all
times. A pain in the neck and much lower as well. I really don't miss
those "good old days."

Rick

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

"Stefan Lilge" wrote in message
...
I recently have spent quite a lot of nights on fields somewhere near
Berlin, hoping to get better images than from the city.
Unfortunately technical problems (mostly related to the lack of mains
power) and gusty winds combined with bad seeing have kept me from getting
good results in all nights but one.

Nice Image Stefan

too bad you had the technical problems

I have felt your pain many times Stefan. I have tried using three
high-capacity marine grade lead-acid batteries in an attempt to get a full
night's of imaging: no luck on a consistent basis.

I finally settled on two solutions: mains power and a small Honda EU2000i
"whisper" generator

http://www.hondapowerequipment.com/p...elid=EU2000IAN

the generator is an inverter type so it actually provides sinewave outputs.
It is well mufflered so the generator is very quiet. You can still hear it
of course but it is quite tolerable compared to the standard run of the mill
type generator using a lawnmower engine

I believe the 1/4 load Sound Pressure Level is about 53dBm

It will run all night on one tank of gas with the electrical load of my
system. I've run two systems in parallel with it before as well as powered a
buddy's rig and only used 1.5gal of gasoline for the night's imaging

anyway it is a great way to go to have reliable power: I figured I invest a
lot of time and effort and driving to get to a place to image so I want
reliable power. For what it is worth when they have the big Maverick's Surf
Competition in Half Moon Bay here in NORCAL, the Japanese TV Crews all use
them for powering their digital recorders etc....



From this only really good night is this image of NGC 3726 in UMa. I lost
quite a lot of time because of dew on the corrector plate at the time when
the galaxy was at it's highest, but apart from that conditions were good
(more like mag 6 than mag 7, but I won't complain ;-) , especially seeing
was very good.

Actually I will always prefer my bright city skies in a night of good
seeing to country skies with bad seeing.

I took the colour frames without binning, planning to add them to the
luminance (even did a lum image from them), but later forgot to include
them in the luminance and was too lazy to start from scratch when I
noticed the omission.

usually I didn't bin my color although it does give fine results as Rick
demonstrates time and again.


Taken from a defunct airfield near Klein Köris (you are excused if you
have never heard of the village of "Klein Köris" ;-) with a 10" Meade ACF
at f/7.8 (image scale 0.68 arcseconds/pixel), G11 mount, SXV-H9 camera,
26x5 minutes for L, 12x5 min R, 9x5 min G und 11x5 min B, all unbinned.

The image can be found at
http://ccd-astronomy.de/temp2/3726colourgut.jpg
and b/w version:
http://ccd-astronomy.de/temp2/3726-26x5gut.jpg

Stefan