Tag: Rho Ophiuchi

Rho Ophiuchi cloud complex

The Rho Ophiuchi cloud complex is a dense region of gas and dust located in the constellation Ophiuchus, near the border with Scorpius. It is one of the closest star-forming regions to Earth and contains a number of young, hot stars as well as protostars still in the process of forming. The cloud complex is known for its striking red and blue colors, caused by the presence of ionized gas and reflection of starlight off dust grains. Basically, nearly all the colors of the universe can be seen here.

TelescopeWilliam Optics RedCat 51/250 f4.9
Aperture51 mm
Focal length250 mm
MountiOptron Skyguider Pro
AutoguidingZWO 178MM, QHY Mini Guide Scope 30/130 mm
CameraCanon EOS 6Da
Filtersnone
Exposure60x120s, ISO 1600
Date2022-05-29

Rho Ophiuchi region

Rho Ophiuchi is in my opinion the most beautiful assembly of the nebulae in the universe. Blue, red, and orange colors are combined to create this magnificent cloud complex. The dominant yellow star Antares (Alpha Scorpii) is a red supergiant, one of the largest visible stars. The star Alniyat (Sigma Scorpii) is surrounded by ionized hydrogen gas. Between these two stars is the M4 globular cluster, which I captured on Fuerteventura. The blue nebula is Rho Ophiuchi, also captured by me earlier.

In order to capture the whole beauty, one has to use a relatively short focal length (I used 180 mm), combined with a large sensor area (I used full frame 36×24 mm), and take the shots at a very dark location. This was my primary target during our trip to Crete 2021 and I am very happy that I finally got it framed. However, there is another beautiful nebula called Blue Horsehead in the visual vicinity and if I would turn the camera 90°, I would manage to capture it. So, there is a target for my next expedition.

Technical details:

LensAskar FMA180 F4.5
CameraCanon EOS 6Da
MountiOptron Skyguider Pro
Exposure38x120s, ISO 1600
Date2021-07-07

Milky Way on Kythira

To capture our home galaxy Milky Way properly was my dream for a very long time. A long time ago I started with Canon EOS 40D with Tokina 11-20 f2.8. Then I changed the rig to Olympus PEN-F with Zuiko 12-40 mm f2.8. A year later I upgraded to Zuiko 8 mm f1.8. Recently I purchased a second-hand full-frame camera Canon EOS 6D and I let it modified for astrophotography. All my previous attempts were based on a single photo strategy, following the 500 rule. Basically, you divide 500 by the focal length of your lens and you get maximal exposure time. Of course, you have to crank up the ISO, use as wide aperture as possible, and a tripod. Photos produced by the above-described methods lack the details or they are very noisy, depends how much you de-noise in post-processing.

However, there is another method, which requires a tracker, which is basically a motor with a gear, which makes a full revolution in one day. By other words, it compensates for the Earth’s rotation. This means, you are not limited by a single picture, but you can make as many pictures as the weather allows. Of course, you have to stack the pictures. Therefore the post-processing is a bit complicated, but the signal to noise ratio can be significantly improved. I purchased Baader Nano tracker for my trip to Fuerteventura, but I was struggling with the equipment (shutter release, polar alignment, and lens) and as soon I got familiar with the setup, the weather got really bad, so the outcome was not as expected.

I got a new opportunity to test this set up on Kythira, where the Milky Way was not spoiled by the light pollution, because in direction south, there was nothing else than the Mediterranean sea. The primary target was the Rho Ophiuchi cloud complex. I have to say that I managed to capture it really well:

LensSigma 50 mm f1.4 Art@ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure80x25s, ISO 1600
Date2020-07-11

After collecting 80 photos of Rho Ophiuchi, I pointed the camera to the east side of the Milky Way and I tried to capture the brightest objects in the sky – Jupiter and Saturn (upper left corner). Can you see the dark cloud at the bottom left corner? This is NGC6726 Nebula and NGC 6723 Chandelier Cluster.

LensSigma 50 mm f1.4 Art@ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure40x23s, ISO 1600
Date2020-07-11

The next day I turned the camera 90 degrees and capture the Milky Way again. At the bottom, there is “a line” of red nebulas. From left to right: Cat’s Paw Nebula, Lobster Nebula, Lagoon and Trifid Nebulae, Omega Nebula, and Eagle Nebula. The brightest object at the top right is Jupiter, making some reflections.

LensSigma 50 mm f1.4 Art@ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure47x25s, ISO 1600
Date2020-07-12

Here is another stack of 40 pictures targeting the core of the Milky Way.

LensSigma 50 mm f1.4 Art@ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure40x25s, ISO 1600
Date2020-07-12

Later on, the Milky Way started to submerge into the Mediterranean Sea, so I changed the composition slightly, to capture the constellation Scutum. I also changed the post-processing technique and left bit of the green color. 

LensSigma 50 mm f1.4 Art@ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure47x25s, ISO 1600
Date2020-07-12

I also took a different lens with me – Samyang 24 mm f1.4. This lens is theoretically very fast, but I experienced very ugly stars if it’s fully opened. The reasonable aperture starts at f2.4, but at f2.8 the sharpness is very good, except in one corner. Here is a stack of 55 pictures, 60 second each:

LensSamyang 24 mm f1.4 @ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure55x60s, ISO 1600
Date2020-07-17

Or here is another wide-angle picture, which is a stack of 60 samples, each 24 second long:

LensSamyang 24 mm f1.4 @ f2.8
CameraCanon EOS 6Da
MountBaader NanoTracker
Exposure60x24s, ISO 1600
Date2020-07-13

The last picture I would like to post here is made by the smartphone Xiaomi Mi 10 Pro. The camera has a night mode, but for astrophotography, one would need something better. Google Pixels has a special feature for it. Moreover one can install a non-official port of the Goggle Camera App to third-party Android phones. So I purchased the holder for the phone, placed on a tripod, and pressed the shutter button. The camera collected photons for 3 minutes and made multiple shots and stacked them automatically. The result is, however, not impressive and I have to conclude that smartphones cannot replace the DSLR or mirrorless cameras. There is Milky Way visible in the picture, but it lacks details and stars are elongated. The conclusion: for my next expedition I still cannot leave the camera at home and take only the smartphone.


IC 4304 Rho Ophiuchi Nebula

Rho Ophiuchi is a triple star system (on the left side of the picture) in the constellation Ophiuchus. The light from the stars is partially absorbed by the gas, which makes the blue reflection nebula visible. A smaller reflection nebula called IC 4603 is located on the right. The picture shows just a small frame of the significantly bigger nebula, called the Rho Ophiuchi complex, which combines star Antares, globular cluster M4, and many more reflection, emission, and dark nebulae. In order to capture the whole complex, one has to use a significantly shorter focal length, like 130 – 200 mm.

The picture was taken under the dark skies of Fuerteventura and it’s a stack of 73 pictures, 3 minutes each, which makes the total integration time 219 minutes.

Technical details:

TelescopeNewton 150/600 mm
Aperture150 mm
Focal length570 mm
MountRainbow Astro RST 135
AutoguidingZWO 174MM, Guidescope 30 mm
CameraZWO 071 Pro @-0°C
CorrectorTS MaxField
FiltersNo
Exposure73x180s, Gain 94, bin 1x1,
Date2020-07-21