NGC 6888 Crescent Nebula, 50×45 sec
I found some forgotten raw material I collected during the summer. Tech details show the frames were more like tests than a serious attempt at photographing this object. Nevertheless it was worth the shot.
NGC 6888, also known to amateurs as Caldwell 27, the Crescent nebula is a faint, 10m deep sky object in Cygnus, near the well known Sadr (γ Cygni) region. The nebula is blown by the Wolf-Rayet star WR 136 (HD 192163).
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
I recently composed this one:
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.
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 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.
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
I reprocessed the data obtained in Namibia, processed a few times before.
Two pictures this time, both featuring Crux. Differences in processing technics and regarding the invested amount of time are visible.
alpha and beta Centauri, the Coalsack and Crux, 20x240s, ISO 800, 50 mm, F/5
The Coalsack, Crux and the Carina Nebula, 43x135s, ISO 800, 50 mm, F/4
The Milky Way around M6 and M7
An image of the Milky Way around open clusters M6 and M7. Many other deep sky objects are also visible. Of particular beauty is the pair on the left formed by a star, G Sco and a globular cluster, NGC 6441. Hints of red nebulosities are also visible.
Canon EF 200mm f2.8L II USM at F/4, Canon 1100D mod, 60×180 sec, ISO 800, HEQ5 pro.
The raws were taken on two nights during my expedition in May of 2016, Namibia.
