Friday, March 2, 2018

First lunar images taken with the ZWO camera

After a period of careful deliberation, I chose to purchase a ZWO ASI 290MC astro-video camera. This camera has a CMOS sensor with 1936 X 1036 pixels 2.9 microns across, and is capable of exposures of up to 2,000 seconds duration, or more than half an hour. It is a one-shot color camera that although it isn't cooled, it can be used on deep sky objects as well as the Sun, Moon and planets for which it's designed. The camera also has a tripod socket and an auto-guider port to allow it's use through software as an auto-guider as well as a camera. In addition to the nosepiece, cap, cables and software, the camera also came with an all sky lens with a field of view of at least 150 degrees.
 
The software that came with the camera included Sharp Cap, which is an excellent software suite for controlling the camera and capturing video. The camera can also be used to take still images as well. Along with the camera, I purchased an Agena flip mirror to make locating objects and getting them in the camera's field of view easier and a filter wheel that for now will be mainly used for visual observing with the SCT. Recently I also acquired a atmospheric dispersion corrector and an IR-cut filter. The camera does not have one, and infrared radiation will be recorded along with visible light. That can contaminate the color balance of color images, and blur monochromatic images due to infrared light not being focused by the telescope in the same way as visible light.
 
ZWO ASI-290MC Color Astronomy Camera USB 3.0
The flip mirror has T-threads on the rear port, so I screw the camera directly to the rear of the flip mirror. The front nosepiece is inserted into the telescope's visual back or a Barlow lens when more magnification is needed. The eyepiece drawtube has a helical thread for adjustments to enable the eyepiece and camera to reach the same focal plane. I also bought a short extension tube to ensure I will always be able to get the eyepiece and camera in focus at the same time regardless of what eyepiece I use in the flip mirror. It takes a 6mm eyepiece to approximate the field of view the camera sees through the telescope. I use my laptop to capture the video and still images then transfer them to my more powerful desktop for processing.
 
 
This shot of the craters Cyrillus, Theophilus and Catharina was one of the best astronomical images I have ever taken. In addition to the flip mirror and camera, I used a 2X TeleVue Barlow lens to achieve the needed magnification to frame the scene. Note the numerous small craters and the shallow troughs in the area.

 
This flooded crater is surrounded by rugged terrain saturated with other impact craters. Except from the two other craters that overlap it, the crater's floor is relatively flat and dotted with tiny craters. The central peak is the oblong mound in the center.

 
Although my main interest is imaging the moon and planets, I found this camera is a capable imager of double and multiple stars. This picture is of Epsilon Canis Majoris, or Adhara during poor seeing. The eight magnitude companion is readily visible.
 
 
 
This feature is known as Grimaldi, which lies along the western limb of the moon. It's best seen just before full moon and when the moon is a thin waning crescent. Like the maria of the Moon, it's a lava flooded impact basin.

 
This is a wide area photo of Oceanus Procellarum, Grimaldi and the terminator one day before full moon. Like most of the photos, this one was taken at the full 1936 X 1036 pixel resolution.
 
 
These craters are also visible in the wide area photo above. Numerous shallow rilles abound, including two straight rilles nearly at right angles in the larger crater, as though they're runways at a major airport.
 
 
This image was taken during first quarter moon a week before of the terminator along the southern highlands.
 
 
This wide scale image of the southwestern limb includes the craters Wargentin and Schiller. Note that basaltic magma has flooded some craters in the area.

 
The closer image of Wargentin shows the crater was filled to the brim with lava until it overflowed onto the surrounding landscape. Because of this, it is now a circular mesa or plateau.
 
 
This is a close up of the double star Sirius and it's white dwarf companion. I have seen this star visually, but with difficulty under anything less than very good seeing and larger apertures. Through my 8-inch Celestron and this video camera, it appears readily even though the seeing was poor that night.
 
 
This image shows the rilles Rimae Hyuginus and Triesnecker. The pits along Rimae Hyuginus are not impact craters, they are volcanic collapse pits. They have no raised rims while the impact craters do. These rilles were formed by volcanism and tectonic forces.
 
 
This image shows the Alpine Valley to the left, and a flooded impact crater to the right with two more craters within its rim.
 
 

Bought a ZWO camera and flip mirror

Two weeks ago, I took delivery of a ZWO ASI290MC one-shot color camera, and just before that I bought an Agena flip mirror, extra nose piece and extension tube. I also purchased an Orion five position filter wheel, which I have tried out on deep sky objects with my Orion and Lumincon Ultrablock, O-III, H-beta and comet filters. It was impossible to install the filters without opening up the filter wheel, but once the filters were inserted and the filter wheel re-assembled, it works well for visual observing with the 8-inch SCT. It would not however work with the Dobs, not without altering them so eyepieces would focus with the filter wheel in place. Since I opted for a one-shot color camera instead of the monochromatic camera I was considering, I'll use it for visual observing for now.
 
As for the camera, I am very favorably impressed with it. Build quality is second to none, and it's small size and light weight makes using it as simple as using an eyepiece. With the camera a 1.25-inch nosepiece, an all-sky lens, a driver and software disk, a USB 3.0 cable and a cable for using the camera as an auto-guider. No external power is required, and the camera is not cooled. It does have a tripod socket, which proved useful for some sorts of astronomical imaging that this category of camera is uniquely suited for.
 
 
This image is of the night sky from my front yard using the all-sky lens, my lap top and my old camera tripod. Using the full resolution of the 1024 X 1936 pixel chip's two million three micron pixels, I recorded a view of the sky from the northern to the southern horizon in one view. The washed out areas and green hue are from the streetlights that pervade the area. The constellations Orion, Canis Major, Taurus, Auriga and others were recorded with passing clouds. This camera is very sensitive, stars fainter than I can see with the unaided eye appear in video and still images taken with an eight second exposure per frame. Because the camera is a video camera, I've also recorded a time lapse video of the sky that shows the movement of the stars and the clouds over time. One was of the same scene shown here, this is a frame from that time lapse video. The other was a two hour time-lapse video of the winter sky taken over a two hour period. When  I can get to a dark site, I can do some imaging of the night sky, meteor showers and aurora displays with this camera, which can take exposures minutes long if called for. This camera is not a CCD camera, it used a CMOS chip instead.
 
 
This image is of the core of M-42, the Orion nebula taken at prime focus through my Celestron. It is an unguided 2 minute exposure. At the full 1936 by 1096 pixel resolution, many deep sky objects will fit comfortably in the field of view possible with an 8-inch EdgeHD SCT.
 
 
This image is of the bright multiple star Castor, with the dim red dwarf to the left of the bright stars.
 
 
This is a 45 second unguided exposure of NGC-2392, the Eskimo Nebula in Gemini. Like the image of M-42, the stars are not round because I did not have an auto guider. The noise in the image is dark current, electronic noise. It's presence is due to the camera not being cooled, but that is not a problem because this camera is mainly designed for imaging the Sun, Moon and planets. Long exposures are possible, but dark and flat field frames are needed to remove dark current from images. 
 
 
This is a 45-second exposure of the planet Uranus and it's largest four moons Titania, Oberon, Umbriel and Ariel. The planet itself was completely overexposed due to the very long exposure time needed to record the moons. The brightest two of them are at magnitude 14.5, and I barely seen them from my home with a 10-inch and 15-inch Dob. Because of the tiny apparent size, I used a resolution of 800 X 600 pixels for this image and the planet itself.
 
 
This image shows Uranus alone during a period of poor seeing. The planet at high power is merely a turquoise disk just under 4-arc seconds across. It was bright enough to be recorded with a 50 second millisecond exposure time.
 
 
 

Monday, January 29, 2018

Nineteen day old waning gibbous moon

 
The past few weeks saw two artic cold snaps that left sleet and ice behind, along with cloudy skies and bad seeing. One Friday night however turned out to be decent and so I set up the Celestron in the driveway and proceeded to observe deep sky objects until the moon was high enough to get a good look at. After observing lunar craters and other features on the Moon, I replaced the eyepiece with the Nikon and exposed a roll of Fujicolor 200 color print film using shutter speeds from 1/250th to 1/15th of a second. After each series of exposures, I refocused the telescope to ensure at least one frame will be sharply focused. The DW-3 finder I use on my Nikon F-3 has a magnifier that greatly aids in getting accurate focus, and so does the entirely fine matte focusing screen used in place of the standard focusing screen equipped with central split image rangefinder and micro-prism array. After processing, I scanned the film as usual with my Canon flatbed scanner and filmstrip adapter. The image was stretched, converted to grayscale and cropped in Adobe Photoshop.

Wednesday, December 27, 2017

Three day-old moon

Winters has finally arrived, and so has the clouds and rain, even snow on one occasion in my area. Until last Thursday, I saw no reason to set up the Celestron up with either of the cameras I using. That night turned out to be clear and steady enough for photography, so I drove off to a nearby site where a hospital once stood to set up and photograph the three day-old moon then do some visual observing.
 
 
As usual, I set up the 8-inch EdgeHD on the AVX mounting, using an extra counterweight on the declination axle to balance it in right ascension and another counterweight on the dovetail to balance the telescope in declination. Then I used my Nikon to take a series of photos with exposure times ranging from 1/30th to 1/4 second, then additional photos with exposure times of 4, 8 and 16 seconds to record the night side of the moon. The picture above was a 16 second exposure. The film as before was Fujicolor 200 print film.

 
This picture was exposed for 1/15th of second on the same film. In both cases, I used the mirror lock up and cable release to eliminate vibrations that would blur the picture. I also used vibration suppression pads under the tripod's feet. Once I had exposed an entire roll of film, I removed the camera and replaced it with my 2-inch mirror star diagonal and eyepieces and observed some objects before taking the telescope down and returning home.
 
After picking the developed film from the lab, I used my flatbed Canon scanner and film strip adapter to scan the film and import it into Photo Shop. Then I adjusted the brightness levels, removed dust and corrected the color balance. Light sharpening was used after I created a lower resolution, smaller image from the original high resolution scans.

Sunday, December 3, 2017

Latest lunar close ups

Last Sunday night I had the Celestron set up in the driveway for gathering more video imagery of the moon. The areas of interests this time were the craters Arazchel, Ptolamaeus and Alphonsus, Rupes Recta or the Straight Wall, and a curious chevron like feature I cannot recall noticing before. Instead of using the 3X TeleVue Barlow, I opted to use the 2X Barlow because the wider field of view was needed and the seeing was okay but not great. It also made finding the area I wanted to image easier. The moon was higher up in the sky, which also lessened the prism like color fringing that appears when it's close to the horizon.
 
 
The craters Ptolemaeus and Alphonsus nicely fit in the field of view. While both were flooded by mare lavas that erupted through faults onto the crater floors, Alphonsus still has a visible central peak while Ptolemaeus' central peak is buried under lava flows, if it exists at all. In 1965 the Ranger 9 probe crashed in the Alphonsus crater near it's central peak at 6,000 mph at the conclusion of it's successful mission. The probe was sent to take and images of the lunar surface back to mission control until impact. The goal of the Ranger lunar probes were finding out what the nature of the lunar surface was and to see if manned spacecraft could land there. Small craters are scattered across the floor of Ptolemaeus.

 
Along the terminator eight days after new moon I spied this strange chevron like feature that resembles the rim of a crater, but has two curiously straight sides. It almost looks like the layout of the two LIGO arrays in the United States that have been detecting gravity waves.

 
The trio of craters Cyrillus, Theophilus and Catharina are one of the most recognizable features on the moon even through binoculars.
 
 
The crater Arazchel was rapidly flooding with sunlight while sunrise is taking place at Rupes Recta or the Straight Wall at the right side of the image. The low sun angle at the site accentuates the rugged topography in the area around Rupes Recta, which led to the ground dropping 1,300 feet or 400 meters on one side of the fault relative to the other. The Straight Wall is not actually a wall at all, it's a 70 mile or 110-kilometer long thrust fault. Along it's length the slope is only about ten degrees or so, an astronaut can hike from the bottom to the top with ease. Hidden in the shadow is a shallow rille through which very fluid basaltic lava flowed. As the sun angle rises higher at the site, it becomes visible through small telescopes.

Wednesday, November 29, 2017

Fall objects round up

 Poor weather when skies are dark, bright moonlit skies when they are clear have been a maddeningly consistent pattern for the past couple of months, so when a couple of opportunities came alone to observe deep sky objects from the airstrip I would have otherwise passed up, I took them.
 
One idle evening in the driveway included a side trip to the usually neglected and very scattered open cluster Collinder 463 in northern Cassiopeia. This is really more suited to bigger binoculars than a telescope due to it's very large apparent size. A 30mm Explore Scientific 82 degree eyepiece was the perfect way to view this scattered but quite obvious and isolated open cluster. It occupied much of the nearly two degree true field of view my 10-inch Dob delivers with that eyepiece. The light pollution at home doubtlessly diminished the cluster's appearance compared to how it looks from a dark site.

 
The first night was getting cloudy so no sooner than I arrived I had the 10-inch Dob set up and ready for observing. I opted for the galaxies in eastern Cetus because there's some fairly bright galaxies I wanted to sketch. NGC-955 is fairly small, bright, very elongated with a tiny bright core. Despite the milky skies, it was easily located and observed at 149X through the 10-inch Dob.

 
Pointing the telescope a few degrees away took me to the larger and fainter galaxy NGC-958. Larger and with a weak central brightening, this galaxy has a lower surface brightness but is still an easy mark for a 10-inch. Not quite as elongated as NGC-955, NGC-958 has a more lens like shape surrounded by abundant field stars.
 
 
During the holiday weekend, a very clear night came along, and despite the presence of a 5-day-old moon, I drove back to the airstrip with the 15-inch to observe some faint fall objects I wanted to sketch. One of them was the old, and very faint open cluster NGC-136 I have observed before, but did not sketch until now. Through the 15-inch at 142X, it appeared as a faint patch of light that brightens towards the center, sprinkled with very faint stars at the limit of visibility.
 
 
Also observed was the larger and brighter open cluster NGC-189 also in Cassiopeia. Fairly large and scattered, this star cluster lies in the thick Milky Way star fields yet stands out well from them. Its member stars are fairly bright and vary in color.

 
One of many galaxies available to amateur astronomers in Pisces is NGC-670, a spiral galaxy that shows a tiny bright core and a very elongated shape. The galaxy also rapidly brightens towards the center and has a fairly high surface brightness.

 
NGC-7076 is one of a number of faint planetary nebulae within the constellation Cepheus that revealed itself through the 15-inch despite interference from the moon. It was barely visible without a filter, but adding an O-III filter made the nebula much more apparent at 181X. Also known as Abell-75, this planetary nebula was a nearly featureless round disk a little smaller than Jupiter in apparent size. No central star was visible with or without the O-III filter.

 
The open clusters NGC-7788 and 7790 proved to be a treat through the 15-inch at 111X. Both open clusters are small, rich and fairly concentrated, making them obvious against dense Milky Way star fields. It resembled a fainter and poorer version of the Double Cluster.
 

Wednesday, November 8, 2017

Occulatation of Aldebaran


Last Sunday night the 17-day-old moon occulted, or passed in front of the bright star Alpha Tauri or Aldebaran. This star is an orange giant star 65 light years away and un-related to the Hyades star cluster that's twice as far away from Earth. It marks the bull's angry eye as it charged Orion, who stands ready with his club and skin. The disappearance occurred behind the moon's bright limb and because I was a little too far west it happened when the moon was too low to see above the tree line. An hour later Aldebaran re-appeared from behind the dark limb, which I missed but soon after that I began watching the moon move away from it for a few minutes.

Then it was time to replace the star diagonal and eyepiece with the camera. Once all was ready, I shuttered exposures for the moon alone from 1/250th to 1/60th of a second, then I took some exposures one full second long to record the star. Both images were taken at the 8-inch EdgeHD SCT's prime focus.

After getting the developed film back from the lab, I scanned one negative that shows the moon alone, another that shows the star, then combined the two in Adobe Photoshop.