C49 Rosette Nebula – photons from 2016-12-30
Rosette Nebula (Caldwell 49)
In the freezing cold I imaged the C49 Rosette Nebula with my usual equipment: Canon 1100D mod, 23x135sec, ISO 1600, Canon 200mm f/2.8 @ f/3.5, HEQ5, from Dângău Mare. I can say the session was a success. I used my star handling program to reduce the stars’ dominance over the nebulae.
The curious thing in the frame is the crown shaped denser star field at 6h39′, N2°3′ in the upper left corner. It lies near the open cluster NGC 2262, at 11.3m which is just outside of this frame. I included some Google Sky and SIMBAD images for comparison, and also did an astrometry.net plate solving. With some help from a fellow amateur astronomer, known as nr74 (Németh Róbert), I identified it as Collinder 110, at 10.5m. Noteworthy that the cluster is not listed in other obvious places. See [simbad]
In this frame, open cluster NGC2236, at 8.5m is on old friend, known from the previous attempt to image the Rosette Nebula. It is about 9600 light years away, ie about twenty times further than the Pleiades.
A Glimpse into Auriga
M38 and the Flaming Star Nebula
It was a very cold night, -8 degress Celsius at the observation site near Dângău Mare, although the car’s thermometer indicated -14 at some places on the road back. While contemplating the beauties of the southern vs the northern sky, I imaged this vista in Auriga, which to my surprise turned out to look very nice with my setup. The frame contains, among others:
- M 38 or NGC 1912 [open cluster] 6.4m
- NGC 1893 [open cluster+nebula] 7.5m
- IC 405 or C 31 Flaming Star nebula 10m
- IC 417 and NGC 1931 (the Spider and the Fly)
Technical data: 26×2 min, ISO 1600, Canon 1100D mod, Canon 200mm f/2.8 @ f/4, HEQ5, Dângău, Cluj. One step of the processing was my star reducer.
California Nebula, Pleiades Cluster
California nebula and the Pleiades
Two nebulae and a cluster – perhaps the cluster – in one frame, this is the NGC 1499 California emission nebula and the M45 Pleiades open cluster with the reflection nebula it is passing through. Parts of the complex nebula system are also visible, with a hint of the LBN 777 Baby Eagle Nebula being there too. This picture was a challenge due to less than ideal transparency, odd gradients on the sky and the approaching moonrise. My starheal program did a great job. California Nebula and the Pleiades, 10×2 min, ISO 1600, Canon 1100D mod, Canon 50mm f/1.8 @ f/3.5, HEQ5, Dângău Mare, 2016-11-20
Her Majesty, Queen Cassiopeia
Cassiopeia, 23×3 min, ISO 1600, Canon 1100D mod, 50 mm f/1.8 @ f/4, HEQ5, Dângău Mare
elliptical
I recently composed this one:
StarHeal – how I handle the dense star fields
Left: the original. Right: the automated output: less prominent stars, no panda eyes.
The Milky Way offers some great wide angle views for the astrophotographer. But there is a catch: the dense star field. While in theory stars are point like, ie subpixel sized, in practice the seeing, some worse than ideal transparency, lens errors, bad focus, a not that parallel lens and sensor, a bit of dew – all work against the astrophotographer.
While I can’t solve all the problems, I sure can try. So I wrote a program. I found that I can mitigate some of the problems: the blown up stars, the panda eye image artifact around stars with middle range luminosity and the overall visual impact of the star field. I continued to develop the previous version of my software, so here’s what I’ve got now.
The program
I wrote the program in PHP because it is the language I mainly use. It is not the best choice, by far. But it does the job I expect it to do. All you need is a webserver, some storage space, memory and time. You may download it from here. (tovább…)
Heart and Soul, reprocessed
Heart and Soul in Cassiopeia
This time I used two old data sets of IC 1805 and IC 1848, one from when the camera has not been modified yet and one from last summer, both under fair skies.
(1) 41×2 min, ISO 1600, Canon EF 200mm f2.8L II USM at F/3.5, Canon 1100D unmod, EQ3 (see article)
(2) 8×3 min, ISO 1600, Canon EF 200mm f2.8L II USM at F/4, Canon 1100D mod, HEQ5 (see article)
I reduced the stars with my own program.
Galaxies Maffei 1 and Maffei 2 are also in the frame, the yellow patches on the bottom. Both galaxies are in the zone of avoidance, ie in the plane of the Milky Way where the dust adds up to be almost opaque. Wiki says 99.5% of the light of Maffei 2 is obscured. In a crop below I emphasize these objects with infrared data from WISE. The dust is mostly transparent at infrared wavelengths.
NGC 1499 California Nebula
The sky allowed only very few exposures on this object, and the -8°C temperature was somewhat unforgiving. In order to cancel out a known lens error (the lens seems to be off a bit from the ideal perpendicular), I rotated the gear 180 degrees at half of the session.
Canon 1100D mod, 14×2 min, ISO 1600, Canon EF 200mm f/2.8L II USM at f/4, HEQ5, Dângău Mare
