Sunday, September 24, 2023

LDN 1235 - The Dark Shark Nebula

 Smile you Son of a ...

LDN 1235 - The Dark Shark Nebula captured on 9/14/2023 & 9/15/2023

This never happens!!! Two clear nights in a row at New Moon!!! Thursday (9/14) and Friday (9/15) were predicted to be clear, with no Moon. Therefore, wanted to go after something that was a challenge or stretch target for me and my Bortle 4/5 location, The Dark Shark Nebula. This target is very faint and requires dark skies and lots of exposure. I have pretty good skies, around Bortle 4 or 5, darker skies would be better, but figured I would give it a go. 

Wednesday, I framed up the image using Telescopius (telescopius.com) because I wasn't able to find this object in the NINA Sky Atlas. One advantage of Telescopius is that it allows you to adjust the brightness of the image being displayed. Increasing the brightness made the Shark visible, an advantage when framing the image. I imported the coordinates into the NINA Framing Assistant and then created a Sequence so I would be ready to go Thursday night. I still use the Legacy Sequencer, although I'm preparing to give the Advanced Sequencer a try. Will use a night with a bright Moon to experiment (not risking clear nights at New Moon). 

Thursday, after getting home from work, I quickly set up my imaging rig. Things went smoothly. Polar aligned with SharpCap Pro and calibrated the guiding software (PHD2) once skies were dark enough. Started collecting subs at 8:43 PM. Individual 2-minute sub exposures (subs) did not show any hint of the Shark, even with a screen stretch. I decided to keep collecting exposures without a change because I was shooting to the North, there's lots of light pollution to my North. Examining the subs and looking at the histogram led me to the decision to keep exposure as is. My hope was by getting enough exposures, I would be able to get the Shark. I stopped imaging at 2:23 AM, when the target would be lost to the trees. Was able to collect 130 subs on night 1. NINA parked my scope and warmed the camera. I got up earlier the next morning to bring in my laptop and cover my rig with a tarp. 

A single 2-minute exposure (calibrated and debayered) with an unlinked auto stretch applied (no other processing). Do you see the Shark? 

I got a later start on Friday night as I tried (unsuccessfully) to catch Comet C/2023 P1 Nishimura at sunset. Started capturing exposures at 8:54 PM. Conditions were very good again and the imaging session went smoothly. The session ended at 2:31 AM. A total of 139 exposures were captured. NINA parked the scope and warmed the camera. Retrieved my laptop in the morning and waited until late morning to put my equipment away, as everything was covered in dew. Saturday was forecast to be cloudy. Even if it was clear, I would not have been able to image due to family a commitment. 

Image Processing

All pre and post processing was done in PixInsight. All 269 sub exposures were evaluated with Blink and the Subframe Selector process. After this evaluation, 36 sub exposures were discarded. The remaining 233 subs were loaded into the Weighted Batch Pre-Processing Script (WBPP) along with the associated calibration (Darks, Flats, & Flat Darks) frames. This represents a total of 7 hours and 46 minutes of total exposure. I enabled 2X Drizzle Integration. This is the resulting Master Light unlinked auto stretch applied (no other processing). 

Master Light from WBPP. Can you start to see the Shark now?

Linear Processing: Automatic Background Extraction (ABE), Sprectrophotometric Color Calibration (SPCC), RC-Astro's BlurXTerminator (BXT), RC-Astro's NoiseXTerminator (NXT), and the image was made non-linear with Histogram Transformation (HT). 

Non-Linear Processing: RC-Astro's StarXTerminator (SXT). Stars: Saturation was enhanced with Curves Transformation (CT) and Green Noise was removed with SCNR. Starless: Another application of NXT, the Image was brightened, and contrast was enhanced with multiple applications of CT. A mask was applied, and Saturation was enhanced with CT. Mask was removed and SCNR was applied. Local Histogram Equalization (LHE) was applied at 3 different Kernel sizes followed by Multiscale Median Transform (MMT). Dark Structure Enhance script (DSE) was used and the Stars were screened back in with pixel Math. The image was resampled down by 50% with the Resample process (making the file size a little more manageable). The image was processed 6 different times using the above process/scripts with slightly different setting each time, until the final (for now) image at the beginning of this post was obtained.  

What is it?

The Dark Shark is located in a section of the Milky Way that contains a lot of interstellar Dust and Gas. This object is comprised of interstellar dust and gas. Powerful winds radiating from massive stars create the "structure" or shape of this object. 

An annotated version of the image

How big is it?

This Shark is about 15 light-years (ly) from head to tail.

How far is it?

It is located about 650 light-years (ly) from Earth in the Constellation Cepheus.

How to find it?

I'm honestly not sure if this object can be observed visually, if it can be observed, assuming this would be a very challenging target. My gut says this can't be visually observed. This object is located in the Constellation Cepheus. To me, it looks like a house. The Dark Shark Nebula is location is indicted by the red rectangle in the finder chart below. 

Finder Chart for Dark Shark Nebula

Image Details:

Capture Date:09/14/2023 and 09/15/2023
Location: Eden, NY
Telescope: Explore Scientific ED80 Essential Series Air-Spaced Triplet Refractor
Camera: ZWO ASI2600MC Pro
Filter: None
Mount: Sky-Watcher USA EQ6-R Pro
Exposure: 9/14: 104 exposures at 120 sec each; 9/15: 129 exposures at 120 sec each for a total exposure of 7 hours 46 minutes. Gain 100 / Offset 50 / -10°C for both nights.
Software: NINA, SharpCap Pro, PHD2, and PixInsight

Clear Skies!
Ernie

Saturday, September 16, 2023

M27 with a Dual Narrowband Filter

A return to M27


Friday September 1st was a clear night, a clear night with a very bright (nearly full) Moon. I decided to use my Optolong L-eXtreme dual narrowband filter on M27. I imaged M27 without a filter under moonless skies back in May (click here for the related post). The L-eXtreme has 7 nm band passes in both Ha and Oiii. It would be interesting to see how it would perform with an almost full Moon. This is the resulting image.


M27 imaged with a dual narrowband filter on 9/1/2023.

Setup went relatively smoothly. Started collecting images at 9:14 PM and stopped at 1:56 PM when clouds started to roll in (I wouldn't have been long until I lost the target to the trees anyways). I collected a total of 52 subs at 300 sec each. All pre and post processing was performed in PixInsight. A total of 45 subs were used after inspecting the frames with blink and using the Subframe Selector process. Processes used: Blink, Subframe Selector, WBPP (enabled2x Drizzle Integration and Autocrop), DBE, SPCC, BlurXTerminator, NoiseXTerminator, HT, and StarXterminator (unscreen stars). Stars: Curve Transformation (saturation), SCNR, and Correct Magenta Stars Script. Starless: Curve Transformation with mask (RGB/K), Curves Transformation with mask (saturation), SCNR, LHE, MMT, and Pixel Math to Screen stars back in. Finally, the image is significantly cropped in as this object is very small in my setup.

What is it?

Messier 27 (M270, also known as the Dumbbell Nebula, is a form of Emission Nebulae known as a Planetary Nebula. It has the distinction of being the first planetary Nebula ever discovered.  A Planetary Nebula is the remnant of a star, like our Sun, that is too small to end its life as a Supernova. Instead, as the star reaches the end of its life, no longer capable of fusion, the star will lose its outer shells. A hot and very dense remnant known as a White Dwarf is left behind. Even though it is no longer capable of fusion, it is hot enough to ionize the expelled shells of gas.

How big is it?

This object has an angular distance of 8.0 x 5.7 arcminutes (1 degree is 60 arcminutes) on the night sky.

How far is it?

It is located about 1,400 light-years (ly) from Earth in the Constellation Vulpecula.

How to find it?

This object is relatively easy to find in a pair of binoculars, optical finder scope, or telescope with a wide field of view. It is located in the Constellation Vulpecula which is a dim constellation located within the Summer Triangle. A nebula filter (like UHC or Oiii) filter can help improve contrast and make the nebula stand out more from the background sky. Use the finder chart below to help you locate it.

  1. Find the Summer Triangle (Vega, Deneb, & Altair).
  2. Method 1: 
    1. Find Albireo (a beautiful visual target itself) which is the head of Cygnus the Swan or the base of the Northern Cross. 
    2. Find Altair. 
    3. M27 is the vertex of a imaginary triangle with Albireo and Altair as the other two vertices.
  3. Method 2: (Darker skies may be required)
    1. Find 13 Vulpeculae.
    2. Find Gamma Sagittae.
    3. M27 is the vertex of a imaginary triangle with 13 Vulpeculae and Gamma Sagittae as the other two vertices.

Finder Chart for M27

Image Details:

Capture Date:09/01/2023
Location: Eden, NY
Telescope: Explore Scientific ED80 Essential Series Air-Spaced Triplet Refractor
Camera: ZWO ASI2600MC Pro
Filter: Optolong l-eXtreme 
Mount: Sky-Watcher USA EQ6-R Pro
Exposure: 45 exposures at 300 sec / Gain 100 / Offset 50 / -10°C each for a total exposure of 3.75 hours.
Software: NINA, SharpCap Pro, PHD2, and PixInsight


Clear Skies!
Ernie


Sunday, September 10, 2023

The Coathanger Asterism - A Great Target for Binoculars

 

Things have been a little crazy

It's been a while since I've posted. In addition to poor weather and smoke, the last couple of months have been crazy (both at work and at home). Catching up on the few opportunities I had to image since July.

The Coathanger - captured on 8/19/20232 with the open star cluster NGC 6802 just to the left of the horizontal portion of the Coathanger.

The Coathanger is one of my favorite visual targets, especially for binoculars (this isn't the first target or the last that I will describe in that way). I love to observe with binoculars. I have a pair of 8 x 40 and a pair of 10 x 50. The 8 x 40's are perfect handheld and the 10 x50's are best on a tripod. The Coathanger is located in the Summer Triangle, so it is almost directly overhead at dark. If you're interested in astronomy and don't have a telescope (or even if you do), but have a pair of binoculars, grab them at dark and try finder this object. 

August 19th was a Saturday night. Although clear, the transparency was poor and clouds were predicted later in the night. Only a brief window to image. Knowing the window would be short, figured I would go after The Coathanger as lots of integration time would not be needed. Ended up with 92 subs at 30 secs each. I started collecting subs at 9:55 PM and stopped at 11:23 PM when the clouds became more frequent. I collected 119 subs but had to discard a large number due to passing clouds / poor sky conditions. Given the circumstances, the resulting image isn't that bad. 

What is it?

The Coathanger is known as Collinder 399 (Cr 399) or Brocchi's Cluster. This object is an Asterism (a prominent or recognizable pattern of stars). It is not a true open star cluster, it is a chance alignment of 10 bright stars. There are about 30 more stars that some consider to be a part of the asterism. 


An annotated version of the image of The Coathanger.

How big is it?

This object has an angular distance of 89 arcminutes (1 degree is 60 arcminutes) on the night sky.

How far is it?

It is located about 4,200 light-years (ly) from Earth in the Constellation Vulpecula.

How to find it?

This is object is relatively easy to find in a pair of binoculars, optical finder scope, or telescope with a wide field of view. It is located in the Constellation Vulpecula which is a dim constellation located within the Summer Triangle.  Use the finder chart below to help you locate it.

  1. Find the Summer Triangle (Vega, Deneb, & Altair).
  2. Method 1: 
    1. Find Albireo (a beautiful visual target itself) which is the head of Cygnus the Swan or the base of the Northern Cross. 
    2. Find the star Alpha Vulpecula and draw an imaginary line from Albireo through Alpha Vulpecula. The Coathanger is roughly the same distance from Alpha Vulpecula as Alpha Vulpecula is from Albireo. 
  3. Method 2:
    1. Find Vega and Altair and draw an imaginary line between them.
    2. The Coathanger is roughly between both stars (it's a little closer to Altair).


A finder Chart for The Coathanger

Image Details:

Capture Date:08/19/2023
Location: Eden, NY
Telescope: Explore Scientific ED80 Essential Series Air-Spaced Triplet Refractor
Camera: ZWO ASI2600MC Pro
Filter: none
Mount: Sky-Watcher USA EQ6-R Pro
Exposure: 92 exposures at 30 sec / Gain 100 / Offset 50 / -10°C each for a total exposure of 46 minutes.
Software: NINA, SharpCap Pro, PHD2, and PixInsight


Clear Skies!
Ernie

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