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After having a good deal of success with my last mosaic, M31, I thought I’d give a go at a winter time favorite M42. I’ve been working on my mosaic software, Mosaic Engine, and was stuck in the city as my favorite dark sky site was inaccessible due to several recent snow storms. So with no dark sky site available I decided to try some more urban imaging and do some software testing at the same time. Setting up in my driveway is much easier these days courtesy of a Scope Buggy so all I have to do is wheel out the scope, turn it on and start the alignment procedure.

I’ve made several upgrades to Mosaic Engine including an updated user interface, multi-target imaging for a fully automated system and a calibration window that removes the reliance on Astro Tortilla. The calibration window also adds a unique image based telescope control system that allows one click target centering and framing.

While testing the software I took the opportunity to grab a three by one mosaic of the Orion’s sword region. Each frame is the average of 10 sub-exposures of two minutes each and after a lot of processing to get the light pollution under control I managed to get a reasonable image out of the data.

For more information about the image and a higher resolution version check out my web page.

After having success with my NGC7000 mosaic I found some time to get out to the RASC, Halifax Centre’s dark sky observatory to capture the last frame of my second 3 by 3 effort on the Andromeda Galaxy. One of the issues I’ve been struggling with is matching the camera rotation night to night. After having a few clear nights at home I figured out where zero degrees camera rotation lined up and things fell into place. After a little practice I’m now able to line the camera up with just one plate solve and get close enough to shoot multi-night mosaics.

As evening fell I headed out to the observatory with my gear. After a pleasant 30 minute drive I arrived as a few other club members were setting up. Lugging 200 pounds of gear from my car and setting up gave me my evening workout and soon it was dark enough to align the scope and acquire a guide star. Firing up the computer and recalling the mosaic in Mosaic Engine the scope quickly moved to my target and thanks to some recent software changes Mosaic Engine was able to control PHD and completely automate the session.

Initially I captured eight frames at our cottage over the summer. Unfortunately the Sun came up before I could capture the upper left frame. Since the image was taken at two different times and at two different places I was concerned that stitching in the last frame would be a bit tricky. Turns out I was right to be concerned as the skies at SCO are slightly darker than at my cottage and I had a bit of trouble matching the final frame. Using a lighten blend mode I was able to combine the mosaic with a neutral, dark grey frame with some noise added to flatten the background nicely.

To see a higher resolution version, visit my site web page but keep in mind that clicking on the image to download the high res version will cause a large download.

All in all not a bad image and it’s been several years in the making. One of my first efforts on this target was the combination of a zoom lens shot and a telescopic shot of the core.

This one is a long way from the quality of the mosaic, but it was one of my first digital attempts.

With summer vacation at hand my family and I headed to our cottage and some dark skies. Having some decent skies and a few clear nights I got out to take the last row of my North American Nebula mosaic. In the process I revamped the user interface to Mosaic Engine, fixed numerous bugs and added a hack to keep the scope motion synched to the image capture. In theory you can now run a completely automated mosaic acquisition after setting everything up, but I admit that I haven’t had time to try that out just yet.

The new user interface has had some new functionality added as you can see below.

The controls are now logically grouped and the messages from the application now print in the status portion of the window so there is no longer a need to keep closing message boxes.

The first week of our time at the cottage was a wash out as far as astrophotography was concerned. The days were hot, at least by eastern Canadian standards, and the cloud seemed to move in as soon at the Sun set. Things seemed to clear out on the second week and the neighbours and their kids popped over for a great look at Jupiter and Saturn several evenings. Once everyone left I would polar align and start in capturing the top row of my shot. The first night I was able to get two of the three frames I needed and a few nights later I captured the last frame to complete the mosaic

For a more detailed look please visit my web page which has the exposure details and a much higher resolution version of the image.

NGC7000 has always been a favorite target of mine and I’ve imaged it and the Pelican several times. I’ve got widefield images and telescopic shots but I’ve always wanted to take a telescopic shot of the whole North American and Pelican complex. My problem has always been that the field of view through my scopes was too small and even my Rokinon lenses had too short a focal length to give great detail. For the last several months I’ve been working on a solution, Mosaic Engine is a software package that controls any ASCOM compatible telescope mount to take wide mosaics of my favorite objects. On 7 July I got out to my favorite dark sky site for a test of the system. My plan was to shoot a 3 by 3 frame mosaic, but the Moon rose before I could finish so I still have three more frames to shoot. So far I’m very pleased with the result.

So far the mosaic consists of six frames, each one being a 30 minute stack of five minute subs. The image was captured on a night of very good transparency but only so-so seeing.

My software setup used Mosaic Engine to control the scope, PHD2 guiding software to accurately guide allowing Back Yard EOS to acquire the data from my Canon 60Da. I also use Earth Centered Universe (ECU) to provide scope control and show the position of the scope on the sky. ECU is a great planetarium program that focuses on what observers actually need and less on glitz. AstroTortilla provides precise positioning of the mount and measures the rotation of the camera (required by Mosaic Engine). Mosaic Engine calculates the center position of each frame in the mosaic and executes a goto to move the scope for each frame. It also interfaces with PHD to stop guiding before each goto and to reacquire a guide star after the goto completes.

The image was captured using a SkyWatcher Esprit 120 APO which produces pinpoint stars to the corner of the frame making it easy to assemble the final mosaic. The image was assembled using Microsoft’s Image Composition Editor (ICE), simply the best mosaic and panorama software I’ve used to date. Once the target is centered, Mosaic Engine acts as the central control hub handling the mount motions and controlling PHD to acquire guide stars for each frame.

Using ECU I was able to verify the position of each frame. This allowed me to check on the progress of the mosaic as Mosaic Engine stepped through the entire mosaic. Stay tuned, with summer vacation approaching I’m planning on finishing the mosaic and starting one of M31.

After getting proper calibration frames the night before I was able to measure the scale in my images which ended up being 0.315 arc-seconds/pixel. Armed with this and a good image of Rigel which has similar separation to Sirius A & B I headed back out into the cold on February 19, 2018 to try my luck again. This time around I used a sub-exposure of 0.1 seconds which I calculated from the Rigel image below and the difference in brightness between the Rigel and Sirius components.

Rigel Image (taken for reference)

Knowing roughly where to look for Sirius made all the difference. After collecting 122, 0.1 second sub-frames and stacking them to produce a stacked image in Images Plus, an arcsinH stretch was used to bring out the dwarf. Sirius B was just visible in the correct spot so the image was enhanced with sharpening and more contrast stretches. Finally the image was combined with my previous effort to show some field stars along with the resolved binary.

Sirius A & B

Measurements made from the image show that the stars have a separation of 11.3 arc-seconds with a PA of 72 degrees. This compares very well with the RASC Observer’s Handbook value of 10.94 arc-seconds with a PA of 72 degrees.

It is interesting to note that the star that I originally thought was Sirius B has been mistaken in several images and sketches I’ve seen, including some on the RASC Sirius B observing challenge page. I’d like to thank Dr. Roy Bishop, a mentor to the whole Halifax RASC Centre, for prompting me to re-examine my original data and to calculate the separation and position angle. If it were not for his coaching I would have made the same mistake as many others and reported the faint, blue star a little less than half way between Sirius A and the bottom of the cropped frame as the white dwarf.

Imaging Sirius B has been on my astrophotographical bucket list for some time now. Several years ago I tried with an old Meade SN8, but the scope had some optical issues and although it was a reasonable wide field imaging platform, it just wasn’t up to the task of resolving close binary stars.

My next attempt was with a classic 8 inch SkyWatcher Newtonian. I’m still convinced that this system may be able to resolve Sirius B, but I’ve been stymied by the bright halo around the bright A component. The f/5 scope has a large secondary so diffraction is an issue.

These days I’m using an Esprit 120 APO refractor and I thought I’d give it another try. The scope is a joy to use with a very stable focuser and great optics. February 15, 2018 around 7:00 PM I rolled the scope on a ScopeBuggy out of our garage and set it up to cool in the driveway. It wouldn’t be until around nine before Sirius cleared the trees so I went back in to watch the news and plan the evening’s attempt. I had downloaded several images that all supposedly showed the dwarf, including one from the national RASC site on the Sirius observing challenge that I was going to use as a reference. Around 8:30 I went back outside and polar aligned the scope, pointed it at Sirius and started up the autoguider, not that easy a task at -12 degrees!

Heading back inside I have the advantage of using a VNC connection to my tablet running the scope so I could stay warm for the rest of the evening. Since I had no idea of what exposure would work I tried a variety starting at 30 seconds and reducing in two second increments until I saw something close to Sirius A three frames in a row. I was able to see a faint star with exposures from 10 to 5 seconds so I settled on 8 seconds and shot 64 frames. There was a slight breeze so I used the best 42 and stacked them to produce the image below.

Sirius (full field)

Zooming in on the main target

Central Crop

Now things were getting exciting, in close to Sirius A is a faint blue star, slightly elongated due to the breeze moving the scope in some of the subframes. This was the same star labelled as the dwarf in all of the images I had downloaded. From here is where everything went wrong.

I took a couple of calibration frames where I used a planetarium program to send the mount one arcminute north and took a quick image so I would be able to determine direction in the image. I took another image after sending the scope another arcminute north thinking that the first would run out any backlash in the gearing system and I could use this image to measure scale. Finally I took another image with the north button held down and the shutter open, trusting the mount to move north at the sidereal rate. After working through the math I came up with a position angle of 68 degrees (actual is 72) so I was in the right ballpark. When I checked the separation I got almost 17 arcseconds which was off by quite a bit. This was puzzling so I decided to sleep on it and retake my calibration images on the next clear evening.

The next night I planned to take new calibration frames and image Rigel. Rigel is a binary with close to the same separation as Sirius at the moment, but the stars are closer in brightness so resolving the system is much easier. The idea was to use a sequence of images to home in on the correct exposure for the next attempt at Sirius. It turns out that my initial attempts were done with much too long an exposure, saturating the entire area where the dwarf would be located. After determining that two seconds was correct for Rigel, I was able to image and easily resolve Rigel. I took some proper drift shots by exposing for ten seconds with the mount turned off allowing the star to drift through the frame in order to calculate the correct value for the image scale.

Rigel

With the new drift calibration the image scale was found to be 0.315 arcseconds per pixel. I checked the separation on Rigel and got an answer of 9.8 arcseconds with the real value being around 9.5. Much better agreement!

Using the correct image scale of 0.315 arcseconds per pixel I went back to the Sirius image to find that the faint star was definitely not the dwarf. The central crops of Sirius and Rigel, shown above, are both to the same scale. The separation of the two stars in the Rigel system is close to the spacing between Sirius A & B so it is obvious from the two images that the actual dwarf is still within the saturated area of the brighter star. It is interesting to note that the star I had mistaken for the dwarf has been labelled as Sirius B in several images online, including one on the RASC Sirius Observing Challenge page so I’m not alone in my error.

Stay tuned as I’m not ready to give up on this one just yet. Since the target is bright, I can keep trying from home whenever it is clear.

A fellow astro-imager and I decided to head out to the club observatory for a little photon capturing. As the Sun set we got to work setting up our gear. For a change, the