DSO Projects from April 2013 Season

[rcj]

Hi all,

April's collection of imagery captured in the dark skies of Mersing was abit of a hide-and-seek attempt with passing clouds and quickly gathering data during clear spates of weather. It was a challenge trying to obtain clean data (free from thin haze) while we had numerous low cumulus interruptions throughout.

The first image is one in the apparent busy region of the Ara-Norma border (located "below" the familar Scorpius constellation). In this area, there are seemingly complex interactions of glowing Hydrogen gas, all part of a larger molecular cloud, that is filled with massive young stars formed only a few million years ago. These resulted in dark shapes against the emissive clouds together with glowing nebulosity mixed with intense UV radiation (depicted as fainter but visible bluer regions). The NGC6188 region has been described by many as the Fighting Dragons of Ara, Twisted Vortices, etc. It was a lucky attempt to go deep enough to extract the reflective components in a usually "purely" emissive nebulous regions when one observes the area in closer detail.

Within the same FOV, there is also the bipolar planetary nebula (NGC6164-5) represented by two half-lobes. The second photo shows a close-up view that also displays a fainter outer shell beyond these lobes of NGC6164-5.


Fighting Dragons of Ara


Bipolar NGC6164-5


Another image captured during this challenging April period was the area near the Sagittarius north-western border when you have the reflective "eyes" of NGC6589 and NGC6590 coupled with emissive components made up of an assortment of IC objects. An interesting dusty region, plus absorption components make up an interesting portrait all within this FOV.

NGC6589-90


Lastly, this image was done a couple of months back but never processed till now, of the Bubble Nebula and the nearby NGC7635 open cluster located in northern Cassiopeia. Not a lot of data here (two 5min subs per channel), but surprised to see the level of depth being represented here (background wispy nebulosity around the whole area).

Bubble and NGC7635 Open Cluster

[antares2063]

awesome...

"I miss the place where stars shine bright, to gaze upwards in awe of the sight"

regards,
Junwei

[Airconvent]

Awesome Remus! Lots of stars...so many stars...and "gases" too !!!

[cataclysm]

Stupendous images!

[rcj]

thanks guys!

having captured during the last day of April, guess i will include one last (first light) image of the Trifid Nebula under this thread as well.

During the Bedok South SKYWatch session last night, it was a first light attempt and discovery at high focal length DSO imaging done in Singapore. This was also the first time having dabbled in off-axis guiding using the OAG built-in feature in the CCD camera.

It was certainly more challenging doing high f.l. with the following factors that one will encounter (and the effects are augmented):

1) seeing
2) "more" noise
3) small FOV
4) auto-guiding corrections (and getting the right set of parameters)

With the sample setup at hand, the following test luminance image of Trifid was taken at f12.4 with the CN212 8" (cassegrain mode), with 3 groups of 5min subs. Polar alignment should be done properly, but being a test session, i wanted to just explore and evaluate how the subs would look like. There was no reducer/flattener used as well, so one would expect some aberration at the corners, plus errors reflected through poor drift alignment. Seeing last night was below average too - this was reflected in initial auto-guiding process chasing the seeing. During this process, some considerable time was spent fine tuning the guiding exposure, aggressiveness, delay between exposures, etc. Exposures in proper should also be longer (than 5 min) in lieu of the slow focal ratio, and it was also challenging having to find appropriate (or even find one!) guide-star within the restrictive FOV. However, prior to imaging, a one-time focus calibration process was executed to ensure that the focus of the main CCD and the auto-guiding chip should be consistent with each other, which (again) can be further improved as the auto-guiding star was usually blobby and this was made worse with turbulent seeing.

Nevertheless, the un-cropped image below seemed marginally acceptable though with slight ovalish stars. Being at 2630mm, it was really hit or miss with each consecutive sub taken, with a bonus satellite passing thrown in as well (:P).

[Jeremy]

Cracking images from Mersing, Remus.
And your S'pore image of the Trifid really shows what's possible with a long FL in spite of the light pollution. Excellent!

Go well!
Jeremy

[lqx]

the "noooooo!" satellite-moment when that sub came out...

nice images Remus!

[rcj]

thanks Jeremy, QX! will be interesting to attempt an RGB from SG next, at this "favourable" slower focal ratio. Yeah boy! Satellite trailing past this tight sub-1-degree FOV....bingo! lol