Hi folks! I know it’s been awhile since I’ve been on here. Back to work full time… for awhile anyway. However I had a chance to do a presentation on amateur spectroscopy for the Astro imaging channel (also known as TAIC) on Youtube this past Sunday.
You can see the presentation in its entirety right here: https://www.youtube.com/watch?v=e3wZos5CMC0
Hope you enjoy it!
As always, thanks for reading!
DrDave
The “Soul Nebula”, more commonly designated by the cluster “Index Catalog” number IC 1848, is a large star forming region toward the constellation Cassiopeia that contains several small open star clusters. The Soul Nebula is about 100 light years across and has an estimated age of 1 million years. It is formed by the stellar winds from the stars embedded within it, a process that leaves behind large pillars of material pointing inwards. These pillars are very dense and have stars forming at their tips. Each pillar spans about 10 light years.
Capture info:
Location: Orion’s Belt Remote Observatory, Mayhill, NM
Telescope: Takahashi 180 ED reflector
Mount: Paramount MX+
Camera: SBIG STXL 16200
Data: 4, 3.5, 4.5 hours RGB respectively
Processing: Pixinsight
Above image shows the location of the Soul Nebula in the northeast sky, northern hemisphere, around 10PM MDT. The blue square shows it’s position just below the constellation Cassiopeia and above and to the left of Perseus. A sign of summer’s ending and autumn beginning! The September Epsilon Perseid meteor shower is active from September 5 to 21, with a peak of activity occurring around September 9. Unlike the August Perseids, the September Epsilon Perseids are not caused by the comet 109P/Swift-Tuttle. Presumably, the parent body of the Epsilon Perseid meteors is an unknown long-period comet. It’s not a particularly noteworthy display. Only about 5 or so meteors per hour are typical.
Thanks for reading!
DrDave
Bad monsoon rising
Hopefully the worst monsoon season here in the Southwest US that I have seen since moving here 8 years ago is finally winding down. Intermittent rain and thunderstorms have shut down Orion’s Belt Remote Observatory in Mayhill NM for the past several weeks. Typically here the rainy months are July and August and it certainly has been that.
Most likely a lightning strike damaged the computer running Pier 2 at the remote observatory and also took down the Sky Roof control board. Both had to be replaced. The whole lightning thing is very strange as everything in the observatory is fully surge protected but apparently it’s not bullet proof. No other major equipment damage occurred.
Recurrent Nova “wakes up”
One of the few recurrent novae, RS Ophiuchi blew up to around 5th magnitude on August 8-9. The recurrence period is around 15-20 years. While remote imaging was shut down because of weather, I did have an opportunity to observe the nova from the spectroscopy observatory in Las Cruces, NM
RS Ophiuchi as mentioned is one of the few observable recurrent symbiotic novae. The binary consists of a red giant and a white dwarf with an orbital period of 454 days. The red giant is the “donor” star and the white dwarf accretes material from it. The accretion produces a very hot source of radiation which ionizes the outer atmosphere of the red giant and produces a constant nebular emission. If the accreted material reaches a critical value then a phenomenon called “thermonuclear runaway” occurs on the surface of the white dwarf and then it blows up many magnitudes brighter. Anyway that’s as much astrophysics as I am able to breakdown.
Due to the clouds I was not able to capture spectra at the peak of the event but was actually able to get a couple nights at around day 10 and 12 and combined them into this short gif. My guess is the nova is around 7th mag by now? Basically there is a very broad emission zone from the nova ejecta from which the hydrogen alpha peak rises up and dominates early but then retreats. You can see the Ha spike (at the 6563 angstrom mark) by itself in the gif animation. At this point it isn’t nearly as prominent (Spikes going upward are emission and going downward are absorption). I also attached a spectrum taken by Olivier Garde from France on day 1 so you can see the evolution, sort of, from the peak and also a raw spectrum of the nova I captured so you can see the bright broad emission zone what that looks like.
Thanks for reading!
DrDave
A hopeful sign of eventual return to normalcy, the Astronomical Society of Las Cruces (ASLC) New Mexico held its’ first live outreach event, since the start of the COVID 19 pandemic, at Leasburg State Park in Radium Springs, NM. The ASLC is celebrating its’ 70th anniversary since the original founding by Pluto’s discoverer, Clyde Tombaugh.
We have had a very active ‘monsoon’ season which runs from July through about mid-September. Very few clear nights have been had unfortunately, but the forecast for last evening was for partly cloudy skies. While setting up we were able to witness the colorful sunset shown above, actually typical for this part of the country!
The showcase platform for these sessions is the 16″ Schmidt-Cassegrain reflector. The Leasburg Dam State Park Observatory was a joint venture between the New Mexico State Parks and the Astronomical Society of Las Cruces. The Park funded the observatory construction in exchange for the ASLC providing regular outreach programs there. Sounds like a reasonable arrangement to me! It was completed before I arrived in NM. The 16″ telescope was donated to the club by New Mexico State University located in Las Cruces, NM which is only about a 15-20 minute drive from the park. The telescope optics are great and especially after I recollimated it not too long ago, after the mirror cools down for a couple of hours and focusing stabilizes, the views are really second to none for a reflector of that size.
As mentioned, the weather was not very good at the start but gradual clearing enabled viewing of some of the usual fan favorites for the summer. The turnout for this month’s event was not particularly robust but for those that were there, about 15 or so, there was a lot of excitement. The following objects viewed through the 30mm eyepiece on the 16″ telescope did not disappoint!:
2. M57, the Ring Nebula, is always a great target, one of the most well known of the planetary nebulae, located in the constellation Lyra. The image above is about how it looked through the 16″. It was exactly like a smoke ring with not any visible color at the time. Normally the central white dwarf star is visible on a clear night but with the high clouds it was obscured.
3. Saturn! This is a must for these public viewing events if the planet is visible. Everyone who looks is mesmerized by the ring structure that can be seen especially through a larger scope. There are always several “wows” and “ooh’s and ahh’s” with one or two “that’s incredible”s. The seeing last night was actually very good and the image above is not too far off from what it actually looked like. The planet rose about an hour after sunset so it was fairly low in the sky and considering that, the viewing was exceptional.
4. M22, one of the brighter globular star clusters we can see, in the constellation Sagittarius, was spectacular! In fact, next to Saturn, the globular clusters I find most captivating in a large telescope. Way better than any image you can capture, these compact spheres of stars in the hundred thousands look like tiny jewels you can almost reach in there and grab!
5. And finally the prize for the most “wow’s, ooh’s and aah’s” goes to M13, the Great Hercules Cluster! It is the largest globular star cluster visible from the northern hemisphere. Located in the constellation Hercules, M13 contains several hundred thousand stars and measures about 145 light years across at a distance of around 25,000 light years from us. We ended with this object since it took a while for people to get enough looks at it!
And that’s it for now. It was really great to be able to actually get out finally for a live public viewing event. Everyone had a fantastic experience and are looking forward to next month, weather permitting!
Thanks for reading!
DrDave
IC 1318, The Sadr Region, is the diffuse emission nebula surrounding Sadr (γ Cygni) at the center of Cygnus’s cross (left of center in this image). It contains many dark nebulae in addition to the emission diffuse nebulae. The brighter emission feature in the center with associated dark region is often referred to as the “Butterfly Nebula”. The intricate patterns in the bright gas and dark dust are caused by complex interactions between interstellar winds, radiation pressures, magnetic fields, and gravity.
The image was taken through the three narrow band filters Hydrogen alpha, Sulfur II and Oxygen III. Readers can refer to a detailed explanation of narrow band imaging I covered beginning in this post, the first of a 3-part series on the subject. Really the main issue with narrowband images is that the individual channels have to be “mapped” to the broadband channels Red, Green and Blue to yield a color image. In other words it is false color. It is usually described though as “mapped color” or “tone mapping” . That sounds like a really complex process but it’s really the wild west when it comes to this because you can make the colors anything you wish. Typically we amateurs use the “Hubble palette” which is derived from how the Hubble Space Telescope handles its’ images. The sulfur is mapped to red, hydrogen to green and oxygen to blue. The challenge arises with the hydrogen mapped to green because it is by far the strongest of the three in terms of signal. Therefore at first you have a bright green nebula which looks awful, but you can easily manipulate it to taste. After processing a few of these, this color palette kind of grows on you and you can begin to see how these colors can be manipulated and blended to yield a nice result.
Capture info:
Location: Orion’s Belt Remote Observatory
Telescope: Takahashi FSQ106N
Camera: SBIG STXL 16200
Mount: Paramount MX+
Data: SHO 10,11,12 hours respectively
Processing: Pixinsight
Full resolution image can be viewed, as always, via the link on the right under “My astro-images”
IC 1318 is visible now in the northern hemisphere right as it gets dark. If you are in a dark enough sky to see the Milky Way, just trace the star cloud north to the “Northern Cross” which is the the central part of the constellation Cygnus the Swan. The brightest star there is Deneb, but the second brightest star which is quite bright at just over 2nd magnitude is gamma Cygni. This is the star at the right lower corner of that blue square in the image above. That is the location of the nebula! The nebulosity should be visible in small telescopes under a reasonably dark sky.
Thanks for reading!
DrDave
Just north of the Gila National Forest along the western edge of New Mexico lies the town called Pie Town. Its’ name comes from a bakery that specialized in dried apple pies back in the 1920’s. Today, continuing that “pie” tradition, it is still known for the popular Pie Town Annual Pie Festival held the second Saturday each September. While I certainly wouldn’t turn down a great homemade apple or cherry pie once in a while, my interest in the region is of course not about that, but about the fact that 15 years ago a couple of guys established the SkyPi Observatory and that gradually became one of the several telescope hosting sites in New Mexico. You could probably imagine that with a whopping census of under 200 people and sitting at an altitude of close to 8000 feet it might have potential for an observing site! Not to mention the famous Very Large Array radio telescope complex is very close by. That is a great sign if an outfit like the National Radio Astronomy Observatory found the area to be suitable for their observing needs!
I decided to pay a visit to Pie Town to see what their set-up was about. As I mentioned in previous posts, the seeing at my observatory is a challenge for my large telescope platform and after researching the various hosting sites, it appeared that the seeing at SkyPi, in particular, was consistently almost a full arc second better.
The drive from my home is not bad at all. If you live out here, driving 3-4 hours is nothing. Interestingly Pie Town is about the same distance from my house as it is from my remote observatory in Mayhill (image above).
It was a fantastic crystal-clear day with just some high thin clouds when I made the trip. I drove north on I-25 and got off at the Socorro exit after about 2 hours. Heading west on highway 60 I went through the town of Magdalena and right after entered the Plains of San Agustin. This is a flat stretch of desert far away from everything! The plains are ringed by mountains which kind of looked like a natural fortress of rock. It was really a majestic view while driving through there.
After another 20 minutes or so I looked toward the south and suddenly the iconic Y configuration of VLA’s telescopes came into view! It was much bigger than I imagined. Of course, I stopped at the lookout point to take these images. Unfortunately, the visitor center is still closed due to COVID 19. The Very Large Array is a collection of 28 radio telescopes, each about 25 meters in diameter, arranged in a Y shape along rails. That allows for 3 long arms of 9 telescopes each with one at center. Their position can be adjusted as needed. The VLA is one of the most active radio astronomy observatories in the world!
From there it was not far to my ultimate destination. After about an hour I drove into Pie Town, but there was not much of a town. A welcome center and general store was all I could see. The SkyPi facility was only about a mile from there, take a right onto a dirt road up a series of hills and I had arrived!
SkyPi is a very modest sized facility. It is run basically by two guys, the owner and the “technical expert” with the help of the owner’s daughter. The owner was off site so I had scheduled a meeting with Michael who was the one in charge of keeping the roll-off observatories running smoothly. They host about 10 telescopes currently, so not many, but plenty for the staffing that they have. Unfortunately for me they had just rented out their last available pier, but they are planning to expand once they have the necessary help. Michael told me that he and the owner John are “just getting too old for this sort of thing”. I could understand that. There is quite a bit that goes into running these types of facilities. I have enough to deal with just two telescopes let alone 10 or more!
I got the grand tour of the facility, the roll-offs and the equipment they were hosting as well as a couple of visual observing decks used for Dobsonian telescopes. There was also a privately owned 40” Dobsonian housed in a large roll-off at the bottom of the hill, and an observing site that was used for star parties where they had a few cement piers with power for anyone doing portable imaging.
After the tour we sat out on the deck of the main house which is where the two of them stay. There is a guest room for anyone needing to spend the night setting up equipment, etc. I had a great afternoon there with Michael. I had come there with a huge list of questions regarding setting up, operating logistics and other technical matters, but I could see that my host was a little weary probably from the previous night and since they didn’t have any available piers anyway, I decided to let the conversation just flow naturally. We talked about the community and the astronomers who lived there. It turns out they are going to host the Magdalena Astronomy Club’s annual Enchanted Skies star party which is in October.
It can get pretty cold up there in Pie Town. He called it “Canadian cold”. I certainly know what that is! The conversation then moved into music and electric guitars. They had a couple of instruments in the main house. It turns out John, the owner, is a bassist and Michael plays guitar. I told Michael next time I came out I could bring my own Fender Stratocaster which I play periodically. The afternoon wrapped up with a discussion of UFOs! All in all, a most enjoyable afternoon! The VLA, SkyPI Observatory and some very stimulating conversation all in one day. Perhaps the window for equipment moving has closed at least for now, but I have a place I can go for jam sessions and spectacular dark sky observing!
Thanks for reading!
DrDave
Located in Tucson, AZ in the US, the International Dark Sky Association (IDA) was incorporated in 1988 for the purpose of “preserving and protecting the night time environment and our heritage of dark skies through quality outdoor lighting.” It does this via many education and public outreach strategies as well as partnering with local businesses and municipalities. Despite the fact that the scourge of light pollution does not seem to be going away any time soon, the good news is the IDA remains the recognized authority on worldwide light pollution and the leading organization combating it. It has an International Dark Sky Places program that aims “to encourage communities, parks and protected areas around the world to preserve and protect dark sites through responsible lighting policies and public education”.
There are currently five types of designation (see below) for International Dark Sky Places which the IDA “awards” to those regions which have accomplished the goal of developing, preserving and protecting the night sky. While I am well familiar with the IDA (since I am only four hours away from their main headquarters!), I was not familiar with the specific categories of Dark Sky Places, and in fact did not know there were more than one!
The following information is courtesy of darksky.org, the IDA’s website:
And now the envelope please for the Dark Sky Designation recent winners!
International Dark Sky Parks: Zion National Park, Utah USA; Florissant Fossil Beds National Monument, Colorado USA
International Dark Sky Communities: Nucla and Naturita, Colorado USA
To learn more and see if an area near you has been designated as one of the IDA’s Dark Sky Places, visit the IDA website
Thanks for reading!
DrDave
The latest from Orion’s Belt Remote Observatory in Mayhill, NM includes this narrowband project just completed on IC 1318. This is a fairly large and rich emission and dark nebula region surrounding the bright 2nd magnitude star Gamma Cygni at the center of the “Northern Cross” (brightest star in the image). The region is often referred to as the “Sadr Region” referring to the proper name of the star gamma Cygni . IC 1318 is also known as the “Butterfly Nebula”. It is a fascinating region of the Milky Way and I look forward to the fully processed result which I hope to have within the next couple weeks.
IC 1318 was taken with this platform shown above including an FSQ106N, SBIG STXL 16200 camera and Paramount MX+ mount. No sooner had I completed the OIII channel when the filter wheel sensor failed and had to be sent off for repairs. Luckily I am not missing anything soon because the weather has turned for the worse and we are anticipating our “Monsoon Season” to start up in July. Typically during that time there are frequent thunderstorms but generally off and on so you might get a window of good viewing here and there!
Pier 1 has been very quiet unfortunately. The combination of bad weather and bad seeing has rendered this platform barely usable to be honest. I have been at this location for 3 1/2 years and the seeing just isn’t consistently good enough to support this platform. The 16″ scope has a focal length of 2800mm. The local seeing here is average. It’s plenty dark enough yes, but for long focal length optics that’s not going to be enough. I have looked at these seeing monitors here in this astronomy community forever and I’m going to say it’s about 2.5 arc sec average over the year. That’s a tough ask for anything with over perhaps 1500 to 2000mm FL. In contrast my equipment on Pier 2 is only 5-600mm and it doesn’t care what the seeing is. My solution will be to move this scope to a telescope hosting site about 3+ hours from here where the average seeing is close to a full arc sec better. That would be a town called Pie Town, New Mexico located in the far western part of the state and also further north (more on Pie Town in a future post). I will then install most likely an imaging newtonian on Pier 1 with a focal length of only about 1300mm. That should be compatible I would think with the local conditions here. Hopefully all of this happens in the next year or two. In the meantime I will try to finish a couple more projects here on the 16″, weather permitting.
That’s about it for now from Orion’s Belt Remote Observatory.
Thanks for reading!
DrDave
Deconvolution is one of the most confusing and poorly understood algorithms in all of image processing. Most of the time I think people get frustrated with the bad results in terms of image artifacts that they just forget about it altogether. While it is true for sure that it doesn’t always help and for lower resolution wide field images it probably isn’t applicable, I think it is a mistake to avoid it entirely. You may have a great data set for it and that is really the time in the workflow to address distortion issues.
Before getting into this further just a word about image “enhancement” in general. I am certainly no expert but have been doing this long enough to realize that when it comes to image processing I am a firm believer in a “less is more” approach. I see so many folks trying desperately to create a great image from bad data and that just isn’t possible. All you get from that is overprocessed bad data. However I have sadly also seen overprocessing of good, even superb data. This is the worst combination of all. When you have excellent data you really do not have to do much at all. Just let the data “breathe” and preserve the natural beauty of the object. Don’t crush the life out of it with all kinds of sharpening tools, artificial intelligence apps etc.
The above image is a full resolution sample from a superb data set of Omega Centauri, that from an amateur hosting facility in Chile. You can see especially when you click on the image the stars are peppered with a myriad of processing artifacts, in essence destroyed by overzealous application of sharpening and other enhancement tools.
What is deconvolution? This is a class of algorithms that attempts to correct for atmospheric distortion. It’s kind of a focusing algorithm. It technically is not “sharpening” but the effect is essentially similar. It cannot create resolution in an image that isn’t there, meaning if you examine a raw image at full resolution and your galaxy dust lane is lacking detail, it’s not going to add detail in there but it can certainly decrease the distortion of the detail that is present. To accomplish this the average point spread function or PSF of the stars in your image is determined so that the overall degradation of the entire image can be measured. This can only be applied to an image that has not been stretched yet and is still in the “linear” stage. When an image is linear the brightness value of every pixel is proportional to the photons received at the sensor’s corresponding pixel. Any “sharpening”, focusing etc you can do at this stage will be far better than after the image is stretched which is why when deconvolution works it is a great tool.
This is the case of the “Needle Galaxy” I recently processed where deconvolution was applied with great success which is why I decided to post this. Now I am using the program Pixinsight for this which is very popular but certainly not the only option out there. That’s ok because I still think you can see the approach and basic ideas which will be similar for other applications.
The basic plan let’s say for a galaxy is to enhance the galaxy’s features and perhaps tighten the stars without creating star or background artifacts. So we have to protect the stars and background from “collateral damage”. The workflow in Pixinsight is:
1) Create a star mask to protect stars
2) Create a mask to protect the background, in this case what is called a luminance mask
3) Create a point spread function or PSF so the entire image can be modeled
4) Apply the deconvolution process, adjusting a couple of variables to create the desired result
In Pixinsight you can apply “star mask” to your linear image to produce good star protection of the brighter stars during deconvolution. Just use the default settings for this purpose. You don’t have to change any parameters.
You then want to make the star protection more efficient by brightening the stars, increasing the contrast. I use the “auto clip highlights” button in the histogram transformation process to do this. This mask is not going to be applied directly to the image but will be used as a reference image for the process.
Next step is to create a mask to protect the background by first making a copy (steps shown above), then applying a permanent stretch to the copy to make it non-linear
The PSFImage script is able to create the PSF for image modeling as shown above
Open the PSF script, click on “evaluate”, wait until it’s done, and then click the “create” button to the right of it to produce the PSF which is basically a star image.
The PSF is shown above. The deconvolution process will use this file to model the whole image.
When you open the deconvolution process you’re going to click on “external PSF” at the top and select the PSF file in the drop down when it pops up.
The steps above show how to configure deconvolution to minimize artifacts. The star “support” mask is not directly applied to the image but the software refers to it internally to get the info it needs to carry out the “masking”. The other settings are left as default, so under “algorithm” you should see Regularized Richardson-Lucy selected. The other option is Van Crittert which we typically do not use for deep space images but is better suited for planetary images. Deconvolution is a wavelet based algorithm so “wavelet regularization” should be checked. I have not found adding additional layers beyond the default of 2 to be of any additional benefit. Also note the default iteration value of 10. This is a good starting test point. Typically I might do 15-25 for the finished product but not more.
Last thing to do before actually starting is to protect the background. This is a mask directly applied to the image so we take our stretched copy that we made earlier and apply it as shown above to mask the background. Remember this is a stretched non-linear copy applied to the linear original image. A linear mask will not be effective. I have not typically made any adjustments to this with histogram transformation etc. Just apply as is.
Now we are ready to begin deconvolution, but first we notice that the temporary screen stretch applied to the original image is a little overstretched as you can see in the right side image. We want to be able to clearly see the effects of what we are doing. You can dial it down a tad in the screen transfer function shown at the top (white circle) until you get a level that you are comfortable with just by moving the midtone and black point sliders and arrive at the result on the left. Remember this is NOT a permanent change and the image is still linear. This is just a way to see what you need to see.
Next step is to finally run deconvolution! At this point it is really about experimentation. Always select a small preview of an area of interest (Alt-N keys in Pixinsight). This will make the process much faster when you are testing your settings. The only setting you are going to change is “Global dark” at first. I start around 0.01. If you get the so-called “racoon eyes” around stars your setting is too low. If you get ugly bright artifacts in multiple areas your setting is too high. Once you have a result you are happy with you can increase iterations until you see problems. Remember it is very tempting to overdo it . If you get a nice result with lets say 15 iterations, doing 30 or more is likely to create a problem that you may not necessarily detect until much further in the processing flow when it will be much harder to correct. Quit while you’re ahead!
And the final result is shown above! Before deconvolution is on the left and after is on the right. I think the key is producing a good star support mask and background protection with the stretched luminance copy, dialing in the correct global dark setting and not going too crazy. Remember less is more!
And finally it’s nice to be able to quantitate what improvements we made and these are shown above. Deconvolution reduced the average FWHM by close to 1.5 arc sec which is the most I have ever seen doing this! Typically it’s around maybe 0.5 to not more than 1.
Anyway quite a bit to unpack here in this post! I hope at the very least you can get a sense of how deconvolution can work when it does work.
Thanks for reading!
DrDave
Sh2-155 or Sharpless 155 is a diffuse nebula in the constellation Cepheus, within a larger nebula complex containing emission, reflection, and dark nebulosity. It is widely known as the Cave Nebula, presumably derived from photographic images showing a curved arc of emission nebulosity corresponding to a cave mouth (roughly center of the image). Sh2-155 is an ionized H II region with ongoing star formation activity, at an estimated distance of 725 parsecs (2400 light-years) from Earth. (Courtesy Wikipedia)
The original “Sharpless” catalog was created by Stewart Sharpless in 1953 when he was on the observatory staff at the US Naval Observatory in Flagstaff, Arizona. He surveyed HII regions in the Milky Way which are regions of ionized hydrogen gas. A second catalog edition appeared in 1959 which contains some southern hemisphere objects but most are above around -30 declination.
Sh2-155 lies at the edge of the Cepheus B cloud (part of the Cepheus molecular cloud), and is ionized by young stars in the region. The energy from these stars is absorbed by electrons within the hydrogen gas and when these electrons release this energy, the result is emission of discrete wavelengths of light.
Hydrogen gas emits predominantly red light in the visible spectrum but there is also a component of blue and ultraviolet. Hydrogen alpha emission is what we are all used to seeing in deep space nebula images, namely the deep red corresponding to 6563 angstroms. However emission also occurs at shorter wavelengths, particularly H beta which is around 4860 angstroms. This is an aqua color which is actually fairly close to the emission line of doubly ionized oxygen or OIII, and also fairly weak compared to the H alpha line .
This is why we don’t apply hydrogen beta filters to our imaging because there is very little signal to be gained. However what we can do, since we are using a narrow band hydrogen alpha filter and that signal is quite strong, is to borrow some of it and apply it to the blue channel we obtain through the broad band blue filter, thus “simulating” H beta in the image. In this image I applied maybe 7% to blue. The net result is a slight pinkish hue in certain areas. Mind you there is no scientific basis to this per centage! It is simply “dialed in to taste”, meaning personal taste 😊. If you like more purple in the image or none, just increase or decrease the per centage accordingly. No law against that!
The full resolution image can be seen as usual by clicking on the thumbnail at lower right under “My astroimages”
Capture info for Sh2 155:
Location: Orion’s Belt Remote Observatory, Mayhill NM
Telescope: Takahashi 180ED
Mount: Paramount MX+
Camera: SBIG STXL 16200
Data: 4.75,4.25,4,4.75,4.5 hours LRGB , Ha respectively
Processing: Pixinsight 1.8.8.7
Thanks for reading!
DrDave
