New Gear for Christmas - let the clouds Roll in!

It never fails.  You get new astro gear and the clouds will roll in, or in this case, never leave!  Most astrophotographers believe that the bubble wrap used in the protective packaging contains cloud seeds and so breaking them causes the issue.

Oh well, so it goes.  Looks like no clear skies until maybe Monday.

New equipment includes a wide field telescope, the William Optics ZenithStar 61, with field flattener/focal reducer and remote auto focuser.  So far I have not had the time to assemble the complete setup, but plan to do so soon.  Although not a Christmas present per se I had ordered a new ZWO Camera, the ASI533MC, to pair up with this scope (as well as my other scopes) but it was backordered for weeks.  It was delivered a few days before Christmas!

So what do you do when the skies won't cooperate?  Well, you process your backlog of images. I posted some of that backlog recently and so am currently working off the remainder of the list. A surprise to me, the list is larger than I thought - currently, six more objects are awaiting processing.

First up is the nebulosity around the star Sadr. The Sadr Region (also known as IC 1318 or the Gamma Cygni Nebula) is a diffuse emission nebula surrounding the bright star Sadr in the constellation Cygnus. Sadr is the central star of Cygnus's cross. The Sadr Region is one of the surrounding nebulous regions which contains many dark nebulae in addition to the emission diffuse nebulae.

Sadr Region - Oct 18 to Nov 4, 2021
WO GT102 and ASI2600mm Pro
73x600sec Ha; 30x30sec RGB Stars

Next is Sh2-155, commonly called the Cave Nebula. The Cave Nebula is an emission nebula with reflection and dark nebula surrounding. It lies in the constellation of Cepheus and is reported to be about 2,400 light years from Earth. Sh2-155 (it's official designation from the Sharpless catalog in 1959) was first noted as a “galactic emission nebula” in the Cepheus molecular cloud. Patrick Moore popularized the common name we give this nebula, “Cave Nebula”, and likely due to photographic images that show this nebula’s curved arc of emission nebulosity resembling the mouth of a cave.

Although not one of my better images, this was taken during a period when I was testing some equipment and decided to take some Ha data along the way.

Cave Nebula - Sep 19-24, 2021
WO GT102 and ASI2600mm Pro
69x300sec Ha; 20x30 RGB stars

Abell 85 in SHO-RGB

I've been working to get my backlog of images processed since comet Leonard has moved into the evening sky and is too low to capture from home. The comet has actually brightened quite a bit since passing around the sun. Our neighbors in the southern hemisphere are now getting some really fantastic views and images of Leonard.

This image is Abell 85/CTB 1, which is a nearby supernova remnant with an apparent diameter of about a half a degree. For perspective that is the same size as a Full Moon. Originally CTB1 was thought to be a planetary nebula, so Abell included it in his catalog of planetary nebulae as Abell 85. This is a full SHO (Hubble Palette), hence the golden color throughout. 

William Optics GT102 and ZWO ASI2600mm Pro
Imaged Sept. 27, 2021 through Oct 2, 2021
HaOiiiSii (600sec exposures) and RGB stars (30sec exposures)
Total time 22.5 hours

Christmas and Science Fiction Geeks

What happens when you mix a diehard Star Trek fan with the Christmas season?  Well for one, you end up with a Star Trek Tree!   

This small tree is decked out (get it?) with a few lights (a single string of 100 - I should have added at least one more string) and the new Hallmark Star Trek ornaments based on the 'Mirror Mirror' episode. 

• Enterprise Tree Topper
• Spock

Here are a couple of videos of how the ornaments work.  With the complete set of five characters you can set it to play the soundtrack of a section of the 'Mirror Mirror' episode.  Only a few seconds are provided in the second video but the full session lasts for a number of minutes.

Of course we have a regular tree as well.  This year we bought a 6.5 foot artificial tree already fitted with 800 lights which have multiple display modes.  We keep it set to slowly alternate between all white and colored. Takes 5 minutes to set up (a bit longer to add the ornaments :) )

Wishing everyone a Merry Christmas and Happy New Year.

The "37"

Been spending some time processing some of my images taken over the past couple of months.  I had imaged this particular star cluster early in November, but something went awry and the result was terrible.  I then re-imaged this on the 30th of November. After looking for a good while in my file directories for the flats that go with this image I was unable to locate them. I guess I had thought I had taken the flats, but seems like I did not. So, since this was just a bright star cluster I decided to process it without any calibration (no darks; no flats) and see what comes out. So here it is. And I guess you have figured out where the nickname for the object came from?

This is NGC 2169, an open cluster in the Orion constellation. It was possibly discovered by Giovanni Batista Hodierna before 1654 and discovered by William Herschel on October 15, 1784. NGC 2169 is at a distance of about 3,600 light years away from Earth. It is nicknamed "The '37' Cluster" due to its striking resemblance to the numerals "37". (Wiki)

NGC 2169 (The "37") - November 30, 2021
EdgeHD11; ASI2600mm Pro RGB
20x60sec each filter

Comet C/2021 A1 (Leonard)

After many nights planning my attempt to capture Comet Leonard, I ended up with two sets of images that turned out really bad - comet head at edge of image frame in both cases. Turns out that Stellarium, my planetarium and telescope pointing application, doesn't precisely calculate comet positions. So, I decided to set up Horizons (part of Astro-Physics APCC-Pro software) to use JPL coordinates in realtime to track the comet. I created a sequence in NINA software to turn on my equipment, slew to the comet and take 20x60sec subs in each filter, R, G and B. Since the image run would start at 5:00AM, I went to bed - the scope was on full automatic. The next morning I checked the images and was pleased to find I got all the images with the comet centered in the frames. Success! But, later, when I started to process the images I found out that there was a problem.

Although the mount tracked on the comet fairly well, it wasn't good enough - there was some drifting in DEC. The result made it impossible to properly register the images as the stars trailed a little on each exposure (as expected) but so did the comet. I was then forced to manually register the frames. With elongated stars I was not able to process an RGB stars only image so I had to settle for the star trails. 

To make matters worse the position of the comet (in the east, south-east) placed it right over Baltimore's light dome, at a fairly low altitude. I didn't have the LP filter installed (I forgot) and so had to process out as much of the skyglow as I could and still get a decent image. But here it is. With the comet dropping lower in the east I doubt I'll have another attempt to capture it in the future.

Comet C/2021 A1 (Leonard)
GT102 f/5.6
ASI2600mm 18x60sec R, 18x60sec G, 20x60sec B

I plan to spend some time experimenting with Horizons to determine why I was getting drift in the comet's position as this software was designed to make these type of image runs. More on this in a future blog.

Lunar Eclipse - November 19, 2021

It wasn't until the evening of November 18th that I remembered there was going to be a partial (almost total) lunar eclipse early on the morning of November 19th. I guess the rain earlier in the day and the busyness of my schedule was the culprit. Of course, age might also be a factor.

I am still processing all the images I took, but here is the moon at mid-eclipse which occurred at 4:02AM.  

Mid-eclipse - November 19, 2021, 4:02AM
GT102 (562mm; f/5.5) - Canon 50D; ISO 200; 4 sec

A Lion, an 'E' and some Dark Nebulae

The first eleven days of September offered me some excellent seeing conditions for a change and so I was very busy taking lots of subs for a number of new and interesting deep space objects. 

First up is Sh2-132 which is a relatively faint emission nebula about 10,000 lightyears distant in the constellation of Cepheus the King. Commonly known as the 'Lion Nebula' due to its shape (you can make out the head at the upper left, tail to the right, with four legs below). It features a conspicuous dark lane in the "head" section. 

This image was taken over five nights, with a total integration time of about 16 hours; 14 of those hours in narrowband and the remaining in RGB to capture the stars. 

Sh2-132 - Lion Nebula in SHORGB
William Optics GT102 (f/5.5) with ZWO ASI2600mm Camera
September 3, 6-9 2021

Next is LDN 688 & 694 (B142 & B143), collectively known as Barnard's 'E' nebula; gets it's name from the distinctive 'E' shape of the dark nebula that obscures the dense background of stars. The pair is also known as the Triple Cave Nebula. Although it appears that the two nebula are part of the same structure, they are, in fact, two distinct objects. It is our brain that wants to combine them into a familiar symbol, and so it appears as a single object.

LDN 688 & 694 in LRGB
William Optics GT102 (f/5.5) with ZWO ASI2600mm Camera
September 9 and 10, 2021

The bright star to the left is Gamma Aquilae (Tarazed). Gamma Aquilae is a relatively young star with an age of about 270 million years, estimated to be 3.5 times the mass of the Sun and about 92 times the Sun's radius. Shining at over 2100 times the luminosity of the Sun this K-type star glows with an orange hue. The image is a combination of twenty, 60sec exposures of RG and B with 40 x 60sec of luminance.

Finally, we have LDN 900 which is a Dark Nebula in the constellation of Cygnus.  It is approximately 8 arc-minutes (0.133 degrees) in size.  

LDN 900 in HaLRGB
William Optics GT102 (f/5.5) with ZWO ASI2600mm Camera
September 10 and 11, 2021

Dark nebulae are interstellar clouds that contain a very high concentration of dust. This allows them to scatter and absorb all incident optical light, making them completely opaque at visible wavelengths.  The nebula (centered in the image and running top to bottom) obscures the background of dust and ionized gas.

The blue regions are vdB 131 (upper) and vdB 132 (lower). These are both reflection nebulae, regions of what have been dark nebulae if not for the fact that the dust reflects the light from nearby bright stars that is not hot enough to ionize the cloud's hydrogen. This scattered light generally appears blue since the typical size of dust grains in the cloud are comparable to the wavelength of blue light.

This image is 5 hours of Hydrogen-alpha (Ha) and 4 hours of LRGB.

Project "Final Cut" - an awesome rocket

It's not often that I blog about amateur high power rocketry in this space since I essentially have just about ended (but not entirely!) my efforts in that hobby as of late. Between the time (and expense) of running my telescope(s) and doing all other manner of hobby and hobby-like activities rocketry has taken back stage. It was getting really difficult to lug around all the equipment to the rocket field on the eastern shore of Maryland, not knowing if the weather conditions were going to be suitable for launch until the last minute. And add to that, taking the better part of an entire day prepping my large rocket(s) and then having to chase them down when they drift to the edge of the launch site and carry them back to the launch area. Some of my largest rockets weigh in at 50-150 lbs. plus. Gets to be problematic in the summer heat, and almost equally so in the winter chill at my age. I still plan to continue in the hobby, but only building and flying small to mid-size rockets.

However, in the most recent Sport Rocketry magazine is a feature article on Project Final Cut, an amazing rocket built and flown by Doug Gerrard of Socorro, New Mexico. This incredible project is an 8" diameter rocket with a 98mm central motor mount and six 54mm strap-on boosters. It is over 15ft tall and weighs in at just under 190lbs at liftoff. Doug's passion is launching rockets and capturing photographic footage and stills. For the last 33 years nearly all his rockets carried camera payloads and all of them were named after photography/movie terms. This project, likely his last, is appropriately named "Final Cut". On board there are 13 cameras, 12 altimeters/timers and 7 motors. The central motor is a 15-second burn N1000 and the outboards are six K270 long burn motors. All seven were planned to ignite at once to lift the massive rocket into the sky. Then at about T+7.5 seconds, the strap on boosters would separate in pairs while the main motor continues it's burn. Although the flight had a few issues, the rocket reached an altitude of 11,000 ft. and landed successfully not far from the flight line. 

Final Cut launch

With cameras in the main rocket, in the strap-on boosters and on the launch tower, the footage captured was incredible. Looking to the rear of the main body tube was a special high-speed Chronos 1.4 camera with a 1" sensor that records at 1080P at 1000 frames per second. Video of the launch can be found on Vimeo (https://vimeo.com/558878230) - a must see!! One thing to keep in mind while watching the video is that all the clips are played back in slow motion. This makes the rocket appear to take a long time to take off and the sound of the motors is a thundering roar. In real time amateur rockets accelerate rather quickly; usually in excess of 5gs, the lowest recommended acceleration for safe launch since these rockets are fin stabilized and need to move at 30 -45 ft per second to achieve flight stability. Because all of the motors used in Final Cut were long burn motors, the rocket only accelerated at a max acceleration of 4.5gs, and therefore the team constructed a special launch rail that was twice the normal 12ft length to keep the 'pointy-end' pointing up until the rocket reaches the required minimum velocity for fin stabilization.

It's projects like Final Cut that make me want to get out there and get another one of my birds in the air. Maybe even design a similar rocket. We'll see :)

Final Cut launched at NAR's National Sport Launch (NSL 2021) in Alamosa, CO, during the last weekend of May. Additional details can be found at: NSL 2021 and NSL 2021 - Facebook, as well as in the Sept/Oct 2021 issue of Sport Rocketry.

WR 134 - A Wolf-Rayet Star with Nebulosity

Oh my gosh, what a terrible summer season for astrophotography. There was maybe 5 relatively clear nights since July 12 when I completed the tandem telescope setup. I had expected to image my favorites by now - the Trifid, the Lagoon, etc., with my new ASI2600 camera, but alas, that's probably not going to happen now as they are slowly receding in the southwest. I may have another couple of weeks to give them a try while the moon is out of the picture, but if the weather doesn't cooperate soon I may need to wait until next year. 

However, I did point my scope to an object I have never imaged before. It is well placed in the sky, high and to the SE allowing me to run long series of narrowband images throughout the entire evening. This object is WR134, a Wolf-Rayet star with surrounding nebulosity. A tough one for sure, but I wanted to give it a try. The star itself is nondescript, but because of the intense radiation it spews forth, the surrounding gas, excited by the star's radiation, glows brightly.

Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionized helium and highly ionized nitrogen or carbon. The spectra indicate very high surface enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. The surface temperatures of known Wolf-Rayet stars range from 20,000 K to around 210,000 K, hotter than almost all other kinds of stars. (Wiki)

WR 134 is a variable Wolf-Rayet star located around 6,000 light years away from Earth in the constellation of Cygnus, surrounded by a faint bubble nebula blown by the intense radiation and fast wind from the star. It is five times the radius of the sun, but due to a temperature over 63,000 K it is 400,000 times as luminous as the Sun. (Wiki)

Over the nights of August 2, 3 and 6, I captured both Ha and Oiii narrowband data, 65 subs of 300 sec exposures for each, and a series of RGB subs to get the star colors correct. I had planned to get Sii data as well (to complete the standard SHO Hubble Palette) but the clouds moved in and stayed for awhile! So, with what I had, I processed a HOO palette, the results shown in the image below.

WR134 and Nebulosity (August 2021)
WO GT102 f/5.6  -  ASI2600mm Pro
65x300s Ha; 65x300s Oiii; 10x30s RGB Stars

WR134 is the brighter star in the small group of four stars at the center of the image. The enlarged central region clearly shows the star (reddish-white at center) with the bubble nebula surrounding it. The upper region of the bubble, bluish in color, is the Oiii ionized gas. 

Then, some clear skies presented themselves on and about August 25th. I had to setup and try to get the missing Sii data, which I was able to do over two evenings. I managed to get 67 subs of 300sec. I added this new data into the mix and with some re-processing of the original data with the new Sii data I created the final image using a modified SHO Hubble palette.

WR134 and Nebulosity (August 2021)
WO GT102 f/5.6  -  ASI2600mm Pro
65x300s Ha; 65x300s Oiii; 67x300s Sii; 10x30s RGB Stars

Full resolution images can be found at XCalRocketMan's Astrobin page

So, I have at least one new image to add to my collection from the 2021 summer season. Hopefully I'll capture some other deep space summer gems before they move out of view until next year.

 

Grand Slam of Jupiter Moons

On the night of August 15, 2021, a very rare alignment of Jupiter's moons occurred. On this night a triple transit on Jupiter with the moons Callisto, Ganymede and Europa in transit was visible from some parts of the world.  After the triple transit there was very rare event when Ganymede occulted Europa followed by Ganymede eclipsing Europa!  

Although I have tried my best to capture images of the planets the seeing at my location in Maryland is usually awful - and good seeing is an absolute 'must have' in planetary imaging. This event would have been one that I would have certainly tried for, but the weather conditions (clouds, go figure) nixed that.

However, Christopher Go, one of the handful of the best amateur planetary photographers, had excellent conditions at his location in the Philippines. He was able to capture the entire series of events with his 14" Celestron SCT.

Here is the NASA Astrophoto of the Day that he was awarded.

For a more complete review of Christopher's imaging, including this event, point your browser to his web page at http://astro.christone.net

Mars Drilling Didn't go Quite as Expected

Last week, NASA’s Perseverance rover shot for a new milestone in the search for extraterrestrial life: drilling into Mars to extract a plug of rock, which will eventually get fired back to Earth for scientists to study. Data sent to NASA scientists early on August 6 indicated a victory—the robot had indeed drilled into the red planet, and a photo even showed a dust pile around the borehole.

NASA

But, while data indicated that Perseverance had transferred a sample tube into its belly for storage, that tube was in fact empty, driving Katie Stack Morgan, deputy project scientist of the Mars 2020 mission, to call it “the case of the missing core.”

While this is not the 'hole in one' we hoped for, there is always risk with breaking new ground," Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate in Washington, said in a statement. (Perseverance's mission is the first step in a Mars sample-return campaign, which has never been done before.)

Read the full story at ARS Technica

Get Ready for the Perseids Meteor Shower

On the nights of August 11-13, 2021, the most famous of all annual meteor showers, the Perseids, will take place. And this year conditions are right for an optimal show, since there’ll be no moon to ruin our view.

Perseid meteors scream through our atmosphere at nearly 40 miles per second, so they often leave behind long, glowing, persistent trains. The shower gets its name from the point in the sky where the meteors appear to originate - the radiant. When the radiant is high in the sky you can capture the most meteors. As typical of most meteor showers, this occurs in the early morning hours - and this year that would be on Thursday, August 12 around 2 A.M when up to 100 meteors per hour can be seen (in dark suburban skies). Since this particular shower is so plentiful, it's possible to spot the meteors as early as 9 p.m.

Although that is the best time to view them, don't worry if you miss the peak as this shower typically builds up and winds down slowly, so you can head out on any of the few days before and after the 12th as well.

JASON WEINGART / BARCROFT MEDIA

Observing the Show

In order to achieve the best views avoid artificial light as much as possible when viewing the shower. This doesn’t necessarily mean you need to travel to a dark-sky site. Just try to keep nearby street and house lights out of your line of sight.

Pick a comfortable location where the view to the north-east is unobstructed. Lie back so that a large swath of the sky is visible and you are not straining to keep you head looking up. A lounge chair or recliner works well. Look for Perseid meteors at an altitude around 60˚ in any direction. If you want to see the most faint meteors be prepared to spend about 20-30 minutes to allow your eyes to get dark-adapted. 

Where do the Perseids come from?

Meteors are fragments of periodic comets, the dust and debris that they leave behind in their orbits. In the case of the Perseids, that comet would be Swift-Tuttle, which orbits between the Sun and beyond the orbit of Pluto once every 133 years. Every year, the Earth passes near the path of the comet, and the debris left behind by Swift-Tuttle shows up as meteors in our sky as they burn up in our atmosphere.

Visit to the International Latitude Observatory

Yesterday my wife and I needed to drop off our aging poodle Lucy for dental surgery at the Center for Veterinary Dentistry and Oral Surgery in Gaithersburg. The surgery was to take about 3-4 hours, and so after we arrived at around 7:45AM, we had some time to kill. Our ultimate location was Capital Quilts (directly across the parking lot from the Veterinary Center), but it didn't open until 11:00.

So we headed over to the Silver Diner RIO in the new RIO Lakefront Mall where we had a wonderful breakfast/lunch. We then took in the sights of the small lake/pond, this after I spent 15-20 minutes searching for my car in the parking garage. Turns out I entered from a different side and got disoriented. This is what happens when you reach the senior years!

But just prior to getting to the quilt shop, we headed to a small park that Joan had researched as a possible site to visit - an interesting astronomy related site called the International Latitude Observatory. Nestled right in the middle of a small area called Observatory Heights lies the Observatory Park, just across from Gaithersburg High School. A small park, with only about eight parking spaces on the small street, surrounds the International Latitude Observatory. 

Built in 1899 the Gaithersburg Latitude Observatory became part of an international project to measure the earth’s wobble on its polar axis. The Observatory operated from 1899 to 1982, when satellites replaced human observers. It is still active, however, with GPS systems using survey markers installed on these grounds to make periodic course corrections. Fully restored in the 1980s, the observatory building, the meridian mark pier, and the five geodetic monuments scattered throughout the park are listed on the National Register of Historic Places.

Unfortunately (or maybe not) the observatory building was gated off and locked, but it was a nice place to visit. 

View along the Meridian line

The Observatory

Meridian Mark Pier
used to align the telescope

Markers representing one of the other four locations

We finally got to the quilt shop where we both spent some money (amateur astrophotography is not the only hobby that can drain your budget!). I needed some supplies for items I'm designing and sewing for sale in my shop, Maryland Fiber Arts, LLC. Joan picked up some nice yardage as you can never have enough fabric. She creates quilts for sale in the shop.

Lucy was picked up around 1:00 or so, and we headed back home. She is doing fine considering she had ALL her teeth extracted! But she is not a happy camper!! We continue to remind her that recovery will take some time and then all will be good. I'm not sure she is convinced.

Hubble is Back!

NASA's Hubble Space Telescope is back in business, exploring the universe near and far. The science instruments have returned to full operation, following recovery from a computer anomaly that suspended the telescope's observations for more than a month.

New images have been downloaded showing some interesting odd galaxies.

See Phys Org for more details on the fix and the new images.

Adding the WO GT102 to the EdgeHD - Tandem Scopes

With the summer nebulae making their return I need to switch to my wide field refractor to capture these colorful deep space objects. Problem is, removing the 11" Edge from the mount requires a bit of effort and then the mounting plates need to be readjusted. Once the plates are done and the GT102 mounted I need to rebalance the scope. If I then decide I need to photograph planets this summer, or even some small planetary nebulae, the whole process repeats, as I remove the GT102 and add the Edge.

Ever since I got the new AP1100 mount I've been toying around the idea of mounting both OTAs in tandem. The mount can handle up to 110 pounds and I figured the two scopes would come in around 60 pounds including the camera and guide scope. That way I could just cover the two scopes when not being used and leave them on the mount. I could then image from either one just by moving the camera from one OTA to the other. A little bit of rebalancing may be needed, but that shouldn't be too hard.

So this past week I ordered a new 18lb counterweight. It arrived last Friday. I then mounted a dovetail plate on top of the Edge, and with two ADM clamps on the WO GT102 it was mounted on top of the Edge. The 50mm guide scope sits atop the GT102. With all the camera equipment attached I needed the new 18lb counterweight as well as my 5lb one to get the whole system balanced. Now all I need is some clear nights to check everything out. 

The only other issue that needs addressing is the cover. The existing Telegizmo 365 cover could work, but it would be a tight fit and would not reach to the bottom of the pier. I contacted Telegizmo to see about ordering a custom fitted cover. I await their response. Based on my measurements a new cover would allow me to keep ALL the equipment (Power supplies, computer, dew controllers, power distribution panel, etc.) out covered and protected.

So it goes. Hopefully, new summer nebulae images will soon be on the way.

My Attempt at the Pillars of Creation

Back in July and August of 2020 I imaged M16, the Eagle nebula, which contains, at it's center, what has become one of the Hubble telescopes famous images - the Pillars of Creation. I used my EdgeHD11 telescope to close in on the central portion of the nebula where the pillars reside.

The processing of the image took much effort, and every time I completed the final image I was not pleased with the results. 

Last week I tried a new technique for processing these images and together with some new software I was finally able to get a good result. So here is my version of the Pillars of Creation, in narrowband, Hubble palette.

M16 - Pillars of Creation - July/August 2020
EdgeHD-11 at f/11 with ASI1600mm pro
13 hours Ha, O3, S2 Narrowband w/RGB stars added

Complete details can be found at Astrobin

Hubble Space Telescope in Trouble

June 13, 2021, the Hubble Space Telescope shut down after an issue with a 1980s-era payload computer.
Team members continue to work on the issue to get the telescope operational once again.  (Image credit: NASA)

The Hubble Space Telescope, which has been peering into the universe for more than 30 years, has been down for the past few days, NASA said Friday. The problem is a payload computer that stopped working last Sunday, the US space agency said. "There is no definitive timeline yet as to when this will be completed, tested, and brought back to operational status," the Hubble operations team said.

Full story at Phys.Org and Space.com.

Juno Visits Ganymede

Up close and Personal

The Juno spacecraft flew closer to Jupiter’s largest moon than any other in more than two decades, offering dramatic glimpses of the icy orb.

Credit: NASA/JPL-Caltech/SwRI/MSSS

The first two images from NASA Juno’s June 7, 2021, flyby of Jupiter’s giant moon Ganymede have been received on Earth. The photos – one from the Jupiter orbiter’s JunoCam imager and the other from its Stellar Reference Unit star camera – show the surface in remarkable detail, including craters, clearly distinct dark and bright terrain, and long structural features possibly linked to tectonic faults.

Full story/article at JPL.

M90 - Galaxy in Virgo

M90 - Spiral Galaxy in Virgo

M90 - May 13-15, 2021
EdgeHD-11 Telescope - ZWO ASI2600mm Pro Camera
LRGB

Messier 90 (also known as NGC 4569) is an intermediate spiral galaxy with a weak inner ring structure. It lies about 60 million light-years away in the constellation of Virgo. The star formation in Messier 90 appears to be tapering off as evidenced by the galaxy's spiral arms appearing smooth and rather featureless. Galaxies with active star formation have knots and trails of knotted groups in their arms. However, the central region does show some significant activity where there exists around 50,000 stars of spectral types O and B (blue to blue-white hot stars) that formed around 5 to 6 million years ago (young).

This image was created by combining 24 blue, 18 green and 17 red subs, each 120 seconds exposure, to get the master color image (RGB). To the RGB image I added 54, 120 second luminance subs (monochrome) for the detail. I had planned to use 30 of each color, but the Maryland weather this year has been giving me fits!

Remember, complete technical details on all my photos can be found on my Astrobin site.

Creating Starless Images

Astro imaging using narrow band filters (Hydrogen alpha, Ha; Oxygen-iii, O3 and Sulphur-ii, S2) is a popular part of imaging. Not only does it enable amateur astro-photographers like me to take images comparable to the Hubble Space Telescope and other land based observatories but they are a great weapon against the ever increasing light pollution we are all experiencing. They are very effective against light pollution because they only allow a very small range of light to pass (hence, narrowband). The NB images are false color as you assign the three colors of the RGB palette to each NB filter. The Hubble palette (SHO) assigns red to the S2 filter, green to the Ha filter and blue to the O3 filter. Another palette I use is the HOO - a bicolor palette as it assigns red to the Ha and both green and blue to the O3 (no S2 data). 

An obvious down-side to NB imaging is that the stars appear highly tinted in largely purple hues because the full range of color is not processed in NB treatment. So, not only is the nebula rendered in false color so are the stars, which makes them somewhat unappealing.

To correct for this I usually image the main subject using the three NB filters and then run a set of short exposure subs using the standard broadband filters to capture the true color of the stars. Then, in post-processing I create two images, one that has all the stars removed, and another that contains only the RGB stars. Then the two images are combined resulting in a NB nebula but with stars of their proper color and brightness. 

Extracting the stars is a fairly easy process that works well. Removing them to create a starless image is much more difficult. Some of the tools I use to remove the stars leave behind artifacts that must be manually corrected, and sometimes not all the stars get removed - especially bright ones that appear bigger on the image.

Recently, a fellow forum member, Steve, over at The Sky Searchers (TSS) forum posted about a multi-step process to remove stars from an image leaving no unsightly artifacts. Although I haven't fully tested it out on multiple images the results are thus far impressive.

Here are the pre- and post- star removal images of the Rosette nebula.

Unfortunately I don't have a set of RGB stars for this image so I couldn't add them back for the final photo (some folks like star-less images standalone). 

I will certainly add in the RGB session on my next NB project.

Darks vs no darks

One of the features of my new ASI2600mm camera is the low noise levels compared to other cameras. Recall that the 2600's dark frames typically have median ADU values of about 500 (Test of the 2600). And that is consistent over the typical range I use for exposures in my imaging (60-600sec).

Earlier this week I imaged some RGB and Lum subs of M98. Clouds rolled in and ruined the complete set of 60 Luminance subs so all I got was the 20 each of RGB. Not a whole lot of subs to work with, and with short 60sec exposures the amount of data was really low - in fact, only about 20-80 ADU over the noise level of 500.

To make matters worse, my attempts at taking the flat calibration frames produced odd horizontal banding on the images so I couldn't use any flats in my post-processing. Later I found out in my research that the 2600 doesn't like short exposures using a flat panel for illumination. If I had reset the camera gain to 0 (from the 100 I used for imaging) I would have had better results.

So I decided to run a little experiment. I processed each set of 20x60sec RGB subs, one with darks (but no flats) and one without darks (again, no flats). Darks are typically used in processing to calibrate the subs by removing the camera's inherent noise from the images. Since the 2600 has very little noise I wanted to see what I would get if I didn't use dark calibration in the processing.

The results are shown below. The image on the left is the 20x60 sec RGB stack processed normally, but without darks. The one on the right is with dark frames. Neither, of course, had flats, but I cropped the images to remove the vignetting and the dust bunnies weren't obvious in these short exposure images. They look pretty much the same don't they? And indeed, I was just a little surprised at the fact that they did look very similar. The low noise is really a great feature of this camera.

M98 - No darks vs darks
20x60 sec subs EdgeHD11/ASI2600

Now, if we zoom in on the images you can see that the image processed without the darks starts to show some significant noise. The image with the darks is much cleaner. (these images have been lightened to show the background noise better.)

So, I will continue to process with darks and flats. But it was an interesting experiment nonetheless. As for the final image of M98 - although I really want to retake this one with proper exposure times and processing to bring out all the lacking detail and brightness, this image will be used in the M110 contest (award on TSS for imaging all 110 Messier objects). I only have eight more to go!

M62 - Globular Star Cluster

Messier 62 is located in the southern constellation of Ophiuchus. It was discovered by Charles Messier in 1771. It lies at a distance of about 22,000 light years from earth and has a diameter is 110 light years. Its estimated mass is one million solar masses and it contains over 200 variable stars. In 2013, astronomers discovered a stellar-mass black hole in M62, one of the first to ever be found in a globular cluster.

M62 - May 21, 2021
Celestron EdgeHD11 f/10 and ASI2600mm camera
20x30sec RGB subs and 33x30sec Lum

With a Declination of -30 degrees, this was a difficult object for me to capture as it never gets more than 25 degrees above the southern horizon and I have very limited view in that direction to boot. I wanted to capture at least 40-60 luminance subs, but with the limited view and not very ideal weather conditions I settled for only 33 good ones to go with the 20 RGB subs.

This one deserves much better treatment (and longer integration time) but it is on my list for the M110 award at TSS and I don't want to wait another year to complete that contest.

NGC 6229 - Globular Cluster in Hercules

NGC 6229 is a very distant globular star cluster in the constellation Hercules. At about 100,000 light years away it is one of the furthest clusters from earth (that is, cluster in our galaxy) sitting at the very edge of our Milky Way. The Stellarium planetarium software identifies it as the "Prize Comet Globular Cluster" - possibly because of its distance, and hence small size, it would look like a faint comet head in smaller amateur telescopes.

NGC 6229 - May 21, 2021
EdgeHD-11 f/10 ZWO ASI2600mm
30x30sec RGB; 60x60sec Lum

This image was taken with a 9.8 day old moon blaring in the west and cirrus clouds covering most of the sky. Not ideal conditions, but whenever you get a mostly clear night here in Maryland you try to take advantage of the opportunity as best as you can. Globulars are ideal for image objects in these conditions as they tend to hold up well to the sky brightness and LP. 

The Lunar-X

While testing out the new adjustments I made to my mount software and camera hardware, I took a quick image of the moon. Wasn't really interested in keeping them, they were just for testing focus points, But then I noticed that I had captured the famous Lunar-X (and Y). They are optical features on the moon, visible when the moon’s terminator, the position between light and dark on the moon, is located in just the right place, you can see what appears to be the letters "X" and "Y". A serendipitous capture, I post-processed a single frame and posted here.

Lunar X and Y
EdgeHD-11; ASI2600; 0.002 seconds f/10
May 18, 2021 - 8:10 PM

Close up

For more information on the Lunar-X see the article in EarthSky.

The Blowdryer Galaxy (M100)

No, I didn't name this galaxy. It is one of the popular names for M100. But it does look a little bit like a blowdryer.

Names aside, this is one of the Messier objects on my list to image. I'm trying to get the final Messier Award, the M110 Award, for photographing all 110 Messier objects. With eleven more to go it may be a challenge to complete the series this season if the weather doesn't cooperate soon. 

This image of M100, also known as NGC 4321, is a spiral galaxy in the constellation Coma Berenices. One of the largest and brightest galaxies in the Virgo cluster, it is 55 million light years from earth, and spans 107,000 light years across.

Taken over two nights, May 1 and 2, 2021, it was a difficult imaging run as clouds interfered throughout both nights - more than half of the exposures had to be discarded because of either low signal (clouds) or equipment failure. My new Off Axis Guider is giving me fits trying to get the image focused sufficiently for the guide system. But I'll get it sorted out someday :) It was, nonetheless, a good test of my new camera, the ZWO ASI2600mm Pro. 

M100 - May 1 and 2, 2021
EdgeHD11 2800mm f/10, ASI2600 Camera
LRGB 3.2 hrs total integration
Full details at: Astrobin

Final Test of the ASI2600

M63 - Comparison ASI2600 vs. ASI1600

As a final test of the ASI2600 I decided to compare the results I obtained imaging M63, the Sunflower galaxy using the ASI2600 with the same object using the ASI1600.  Both images had pretty much the same number of subs, all taken with 60sec exposures. Each was calibrated and processed using the same workflow. 

First, a comparison of the field of view (FOV) of each camera. Note that both images were cropped a bit during postprocessing as needed to account for slight shifting of the masters among the multiple filters and to eliminate vignetting at the corners. As reported in my previous post, I was pleased that the vignetting due to the use of 31mm filters was minimal. The ASI2600 has a wider FOV, mainly in the long axis. The images below are not exactly to scale; the ASI1600 had more cropping than the ASI2600, so the change in FOV is a little bit exaggerated. The actual sensor sizes are:

ASI1600:  4656x3520
ASI2600:  6248x4176

Next, with some cropping of the ASI2600 image to bring the scale of each closer to 1:1 we can examine each for actual image details. Please note that the sky conditions were not completely identical in each session and so there may be some differences due to quality of subs, not the actual difference in the sensors.

However, some of the 'promised' improvements in the ASI2600 over the ASI1600 can be seen. First, the artifacts due to the microlens light scattering in the ASI1600 are completely gone in the ASI2600 (see bright star just to the right and above the galaxy). Second, the overall brightness of the galaxy is greater in the ASI2600, likely due to the greater quantum efficiency of the 2600 over the 1600 (91% vs. 60%).

In addition, but not obvious in these quick comparisons, is the much lower noise in the ASI2600. Dark frames were consistently measured as 500ADU, across all typical durations (30sec - 1200sec)! And, the total absence of any amp glow makes post-processing even easier.

One thing that is noticeable in the 2600 image is the size of the stars - they are bigger than the ones in the 1600 image. This might be due to slightly different post-processing. Another contributing factor may be the lower full well capacity of the ASI2600 at gain of 100.

Overall, I am very pleased with the performance of this new camera. 

ASI2600 Testing Continues

Test of new OAG spacing

You may recall in my last post I had discussed the plan to reset the spacing of the ZWO OAG on the scope to help with the strong vignette of the guide scope camera image. I moved the 15mm spacer in front of the OAG, mounting the OAG flush with the filter wheel. A thin 0.5 mm spacer was used between the nose piece and the 15mm spacer to act as a stop when the assembly was attached to the Moonlite 2" adapter. As expected, the pick-off prism is now rotated a bit from the center of the sensor's long axis.

Although this did improve the guide image, there is still an obvious vignetting present. The ZWO prism and light guide are just very small compared to the Celestron OAG.

Gain Settings

Early Friday morning I imaged the Sunflower galaxy, M63, so that I could compare the results of the ASI2600 with the image I took with the ASI1600 back in March. I ran a similar set of LRGB subs, 60sec exposure, but I used Gain 0. It turns out that these subs are essentially useless as I needed either a longer exposure time, or higher gain setting. The images did look rather nice, but they couldn't be stretched in postprocessing since they lacked sufficient dynamic range.

The darks at Gain 0 on the ASI2600 produce frames of 500ADU average at -10C. The 60sec lights of M63 came in at 520-560ADU. This means that once the dark frame data is subtracted from the light frames the net result will be only 20-60ADU. This is extremely low signal content, especially with a camera that has a 16bit ADC (0-65535). Any amount of stretching to bring out the faint details will produce a final image that is extremely 'posterized'.

To illustrate the point, I took a few subs of the Blackeye galaxy, M64, last evening during a very short period of clear skies in that direction. Clouds interfered with the 60sec gain100 sub so I couldn't do a comparison with the 60sec subs.

Three subs, 60secGain0, 120secGain0 and 120secGain100, are shown in the image below. A quick stretch of each was made to bring out the details. As you can see, the images themselves seem pretty nice. But this is misleading as each stretch is a different relative strength, normalized so that they all appear with the same relative level of brightness and contrast. When a background model (ABE) is created for each sub the underlying problem is made apparent. Notice the model of the 60 sec gain0 sub. There are only 11 levels of dynamic range in this image. Once stretched and processed the result will be very blotchy and posterized - there simply isn't enough data in the sub to work with. Note that one of the reasons I purchased this camera was to get higher dynamic range, 16bit vs the 12bit of the ASI1600. At gain0, 60sec, the result is worse than that of the 1600.

However, when setting the gain to 100 and increasing the exposure time to 120sec the dynamic range is greatly improved. At Gain100_120sec the mean ADU of the image is 1071, twice that of the comparison dark frame.

Reviewing the specs of the ASI2600 suggests that Gain100 should be the optimum setting as there is lower read noise at gain 100 than at gain 0, and the dynamic range is almost the same. The down side is that the full well capacity is greatly reduced (16000 down from 49000). So, for long exposures, the lower gain provides some safety in protecting from blown out star images as the camera can hold far more electrons that at gain 100. Since my general process is to take more, shorter exposure subs, the higher gain is the obvious first choice. 

Since my earlier M63 subs suffer from the low dynamic range, I will need to retake that series once the weather clears and the moon is out of the sky - probably next month - and then do the comparison. Stay tuned!

More ASI2600 Testing

The ZWO OAG finally arrived this past Monday and I was able to do some initial testing of the 2600 on the EdgeHD11.

Getting the spacing just right was a challenge but I had ample spacers in my shop, and ZWO provided a good variety with their cameras. 

My final configuration is as shown in the pic below; from left to right - nosepiece to mount to the Moonlite Focuser on the EdgeHD, ZWO OAG, 15mm spacer, ZWO Filter Wheel, 2mm adapter and ZWOASI2600. The placement of the 15mm spacer behind the OAG was chosen to allow the guide camera mounting to clear the filter wheel so that it could be rotated to get the pick-off prism to be centered over the long axis of the sensor. 

Initial test exposures yielded very good results, as can be seen in the following images. Since these are single, unprocessed images (except for stretching), the dust motes and vignetting are obvious.

Starfield 300sec

M82 in Ha 300sec

I was very pleased that the f/10 focal length of the Edge produced even less vignetting at the corners than with the f/5.7 WO GT102. Since I had already verified that proper post processing with good flats eliminated the vignetting with the GT102, I should have no problem with the edge images!

However, the placement of the spacer behind the OAG caused serious vignetting in the guide camera view, so much so that finding guide stars became a big problem.

What I had forgot to account for was the longer path of the light cone entering the guide camera. I needed to add 24mm of spacer to the camera. Now the ZWO's pick-off prism is fairly small, and coupled with the guide camera's sensor distance being a bit excessive the effect is like 'looking through a straw'. This needs to be corrected. I decided to move the 15mm spacer in front of the OAG, mounting the OAG flush with the filter wheel. A thin 0.5 mm spacer was used between the nose piece and the 15mm spacer to act as a stop when the assembly is attached to the Moonlite's 2" adapter. The pick-off prism will be a bit rotated from the center of the sensor's long axis but should still be out of the light cone. Now all I have to do is wait for clear skies to test this out.

Additional Info on the ASI2600 and Small Filters

With the cloudy skies, or clear skies with a near full moon and/or other activities keeping me real busy (Easter choral group rehearsals as choral director at Crosslife Bible Church) I haven't been able to continue with my testing of the new ASI2600mm, and I'm still waiting for a new OAG to arrive so that I can mount it on my EdgeHD-11.

As I mentioned in my previous blog, I was worried that the 31mm filters would cause serious vignetting on my subs. My first experiment showed that cropping the subs about 10-15% yielded very good results. However, it turns out that with good flats I was able to use the entire sensor and achieve rather excellent results. Here is a simple post-processed image of the Seagull Nebula in Ha.

Seagull Nebula - 4x300sec Ha
GT102 f/5.5

This is very promising. Of course, more testing is needed with all the various filter types, LRGB and the full NB set. And, I still need to test on the Edge.

ZWO ASI2600mm Pro Camera - Initial Tests

After waiting for almost 2 years the new ZWO ASI2600mm Pro camera was finally announced back in early January. The baby brother to the ASI6200 (which has a full frame sensor) the 2600 is the APS-C version, with a Sony IMX 571 sensor. I pre-ordered mine in mid-January, and received one this past Tuesday. 

ZWO ASI2600mm Pro

First step was to power up the camera and get the settings dialed in with SGP. Once I was confident that SGP was controlling the camera I ran the camera for 16 hours taking the all important dark frames, 40 in each set of 30s, 60s, 120s, 180s and 300s duration at -10 degrees Celsius. Since I was interested in the two key gain settings (0 and 100) I took two complete sets of darks. As promised by ZWO, the dark frames showed no amp glow at all! My ASI1600 was able to reach 40-45 degrees below ambient; the 2600 can only muster 35 so I settled on -10 as a good operating temperature. This gets me to 0.00075e/s/pix, which in other words means that a 300 sec exposure will only produce about 0.225 e of dark current noise, well below the 1.0-3.3e of readout noise. Hot summer nights might be a bit of a problem as the limit to run the camera at -10 degrees C is about 77 degrees F. 

On Thursday night I loaded the camera up on the GT102 to get some initial images while I had some clear skies. The moon was out, more than 3/4 full and there were still some high level thin clouds, so results weren't great, and I really couldn't take any broadband images. So I decided to just take a few 300 sec and 600 sec Ha subs on the California nebula.

My biggest concern prior to setting up the camera was that my existing set of filters were only 31mm in size. Calculations indicated that 30-32 mm was the minimum for the GT102 optical configuration so I was really expecting some serious vignetting of the images. I'm not sure yet if the EdgeHD11 (my larger telescope) would fair even worse (will test that scope later), but replacing the filter wheel and filters with all new 36 mm ones is not an option at this time as the cost is prohibitive (well in excess of $4500).  

The initial test images did show the vignetting, as can be seen in the picture below.

Since the aspect ratio of this sensor is much greater than the 1600mm, I could easily accept a 15% crop of the image in the longer dimension and still end up with an image size a bit larger than the 1600mm was able to produce. Cropping the image to 5200x4176 from the original 6248x4176 gives a pleasing, more 'square-ish' result that eliminates the vignetting. 

So far the results look very good. The images hold up to some aggressive stretching in the post processing since the 2600 has a 16 bit ADC, whereas my 1600 had only 12 bits. This is a huge improvement in dynamic range output of 14 stops, which will significantly improve the image sharpness and contrast, and also create smoother and more natural color transitions.

Download times are on par with the 1600, about 6 seconds per image. File size is much larger of course, coming in at 51 Meg per sub.

Once the skies clear up and the moon is out of the way I'll take a complete run of Ha subs on this object so that I can fully calibrate the images with darks and flats. I'll report on that in a future post.

 

M42 - Orion Nebula

Two weeks ago I posted a blog about the interference from the Starlink satellites on my astro imaging sessions. In that article I explained how the post processing software effectively removes the satellite trails from the images. 

Well here is the final result of those evenings of imaging M42 and the Running Man nebula. I was going to add in some Ha subs, but the result didn't look as good as the standard LRGB.

M42 and the Running Man Nebula - Jan 10-13, 2021
WO GT102 and ASI1600 MM Pro
148x30sec L; 89x30sec R and G; 94x30sec B