Saturday Night at the Observatory
It has been several months since we have had a clear night.
It was clear Saturday night 2/3/2024 into Sunday morning 2/4/2024. Our
Astronomy club’s imaging group assembled at our Dark Sky Observatory. We call
ourselves the Tuesday Night Imagers, but Tuesday night can be any night of the
week. We put my camera (ZWO ASI2600MC
Pro) on the club’s Celestron 14” Edge HD Telescope which is on an Astro Physics
AP-1200 mount. An Optolong L-eXtreme Dual-Narrowband filter was used to target
specific wavelengths of light.
The imaging team (for the club's equipment) was our Observatory Director (Dan), a member named Mike, and me. Our target was Messier 1 (M1) a.k.a. The Crab Nebula. M1 is
a supernova remnant located in the constellation Taurus. We lost some time at the beginning of the night getting things running. The Observatory had not been used (due to poor weather) since mid-December. Programs and drivers needed to be updated and we needed to fine tune the Acquisition software for this new Telescope/Camera combination. We started to acquire images at 8:40 PM and imaged until 11:30 PM when we lost M1 to the Muck near the horizon and the trees. We closed the roof and took our flat frames. Mike removed his camera from the Tele Vue NP-10is that rides on the mount with the 14" Edge HD. We replaced it with an eyepiece to keep things close to balance so Dan and I could go after one more target. We'll cover that in part 2.
We did encounter an issue with aberrations (spikes) on our stars. We were unable to resolve the issue Saturday night. Dan and Mike returned to the observatory Monday evening, and I joined them via Zoom. After some troubleshooting, we believe the issue is caused by the Celestron Dew Heater Ring. Even with the Star spike issue, we managed to collect 13 usable subs at 600 sec each for a total exposure of 130 minutes. Here is the resulting image:
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| M1, The Crab Nebula from 2/3/2024, HOO version. BAA Tuesday Night Imagers. |
Processing:
I did all pre and post processing in PixInsight. Pre-processing: Blink & WBPP. Linear Post-processing: GraXpert, BlurXTerminator (correct only), Spectrophotometric Color Calibration, BlurXTerminator, NoiseXTerminator, and Histogram Transformation. Non-Linear Post-processing: StarXTerminator. Starless: Narrowband Normalization (two methods as described below), Curves (Multiple iterations to increase brightness, contrast, and color saturation), SCNR, Local Histogram Equalization, Unsharp Mask, and Multiscale Median Transform. Stars: Curves (to increase color saturation) and SCNR. PixelMath was used to screen the stars back in.I tried to different methods in the Narrowband Normalization process. Method 2 which produces an HOO result and Method 1, which produces a result that simulates the Hubble or SHO palette. The image above is the HOO version. I prefer this version. Here is the simulated SHO version:
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| M1, The Crab Nebula, simulated SHO Version. BAA Tuesday Night Imagers. |
What is it?
M1 is a supernova remnant. Humans observed the Supernova when it occurred in 1054. It was recorded by Chinese astronomers, and it appears that the event is also depicted in Petroglyphs in Arizona and New Mexico. The Chinese astronomers referred to it as a "Guest Star". it was visible during the day for 23 days and was visible at night for 653 days. The supernova also left behind a stellar remnant known as a Pulsar. The Crab Pulsar rotates 30.2 times per second. The nebula is expanding at a rate of 1,800 km/sec.
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| Annotated image of M1, The Crab Nebula. |
How big is it?
This object has an angular distance of 6 x 4 arcminutes (1 degree is 60 arcminutes) on the night sky. The object is 13 x 11 light-years (ly) across.
How far is it?
It is located about 6,300 light-years (ly) from Earth in the Constellation Taurus.
How to find it?
This object is relatively easy to find. It's very close to the bright star Zeta Tauri in the constellation Taurus. Refer to the finder chart below. This is a great visual target. It can be seen in binoculars and small telescopes. Dark skies help as it is it can get lost in light polluted skies. Larger aperture helps significantly. Although visible in smaller instruments, I believe it is far more interesting to observe in large aperture scopes. Nebula filters can aid in viewing this object.
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| Finder Chart for M1. |
Image Details:
