A Tale of Two Supernovae ... Part 2

 Saturday Night Turned into Sunday Morning ...

Picking up where we left off in part 1, we removed the L-eXtreme filter from the imaging train because we planned on imaging a broadband target, and the dual-narrowband filter would detrimentally impact the results. Dual-narrowband filters are effective for emission nebulae like H2 regions, supernovae remnants, and planetary nebulae but are not recommended when imaging targets like galaxies, star clusters, and reflection nebulae. Since we changed the imaging train, we took a second set of flats to be used with this target. It was after midnight at this point, and we agreed to image to 1 am. We opened the roof and slewed the telescope to Virgo, which was rising above the eastern horizon. Our target was a recent supernova that had occurred in the Galaxy NGC 4216. The supernova was discovered on January 4, 2024 by Japanese astronomer Koichi Itagaki, who has discovered 170 supernovae! This supernova has a designation of, SN 2024gy. 

We imaged until the agreed upon time of 1 am. We ended up rejecting the last few subs (short for sub-exposure) as the image quality was degrading due to the poor transparency. Had to be some very high thin cloud or haze, even though the sky looked clear, guiding, focus, and image quality indicated we were losing the skies. We managed to collect 7 subs at 180 sec each. The supernova, the dust lanes in NGC 4216, and many smaller background galaxies were visible in the individual exposures. Here is the resulting image: 

SN 2024gy in NGC 4216 captured on 2/4/2024 from the BMO.

An annotated version of the image indicating the location of supernova SN 2024gy.

An animated GIF of SN 2024gy in NGC 4216

Processing:

All pre and post processing was performed in PixInsight. Pre-processing: Blink & WBPP. Linear Post-processing: GraXpert, BXT (correct only), Color Calibration, BXT, NXT, & Histogram Transformation. Non-linear Post Processing: SXT. Stars: Curves (saturation) and SCNR. Starless: Curves (contrast & saturation), SCNR, LHE (3x's), Unsharp Mask, MMT, and PixelMath (to screen the stars back in).

Magnitude Estimate:

Disclaimer: I'm not an experienced variable star observer. There is a decent probability that the following methodology is flawed.

The BAA had our monthly meeting for February on 2/9/2024. After the meeting, I joined the Astrophotography breakout room, and we discussed estimating the magnitude of the supernova from the images we collected on 2/4/2024. This ended up as a fun activity for the small group of us left in the meeting. Since imaging supernova SN2023ixf in M101 in May of 2023, I've made an effort to try to learn how to estimate the magnitude of the supernova from my images. I recently joined the AAVSO and managed to cobble together and idea on how to estimate the magnitude of the supernova from stars with known magnitudes in the same field of view. The manner in which we captured images was optimized for "pretty pictures" not photometry, but the value we ended up with is pretty close to other reported values of the supernova from the same date. 

One of the other members generated a star chart from the AAVSO website. This chart depicted stars in the field of view, of which several were labeled with known magnitudes. It took some trial and error to the chart correct so it matched the field of view of our image. The first chart was off, we had used RA & Dec coordinates from Sky Safari. When we used RA & Dec coordinates from The Sky X, it finally matched the image. We think the difference may be the epoch used by each software (J2000 vs. Jnow). We visually estimated the brightness to be somewhere between 13 and 15th magnitude. Another member pulled a light curve from the AAVSO website. This light curve was compiled from member reports and indicated that the magnitude was around 13.5. We identified a star in the field with a known magnitude of 13.1. I took one of the calibrated and debayered individual sub exposures and extracted the RGB channels in PixInsight. The image was still linear, only a display or screen stretch was applied. Using the green channel, we measured the flux of the known star and the supernova using PixInsight's Dynamic PSF process. We put the resulting values into this formula:

Mag(supernova) = Mag (star) - 2.5Log(FluxSN/FluxStar)

We came up with a magnitude of 13.4 which closely matches reported values!!!! 

What is it?

SN 2024gy is a Type 1A Supernova in the Galaxy NGC 4216. It was discovered on 1/4/2024 by Japanese astronomer Koichi Itagaki. Type 1A supernovae occur when a White Dwarf syphons material from another star that it is in a binary pair with. Once the White Dwarf reaches 1.4 times the mass of the Sun, it goes Supernova. This type of Supernova is used as a standard candle and is important in determining the distance to objects in the universe.

Annotated image of the field of view.

How far is it?

It is located about 45 million light-years (ly) from Earth in the Constellation Virgo.

How to find it?

SN  2024gy is located in the Galaxy NGC 4216 which is located in the Constellation Virgo. Refer to the Finder Chart below. The tiny red rectangle in the center of the image marks the position of NGC 4216. It is very near M86, in the bowl of Virgo.

Finder Chart for NGC 4216. 

Image Details:

Capture Date: 02/04/2024

Location: Beaver Meadow Observatory (North Java, NY)

Telescope: Celestron 14" Edge HD w/0.7x Reducer

Camera: ZWO ASI2600MC Pro

Filter: none

Mount: Astro Physics AP-1200

Exposure: 7 exposures at 180 sec / Gain 100 / Offset 50 / -10°C each for a total exposure of 21 minutes

Software: NINA, PHD2, and PixInsight

Clear Skies!

Ernie

A Tale of Two Supernovae ... Part 1

 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:

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:

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.

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.

Finder Chart for M1.

Image Details:

Capture Date: 02/03/2024

Location: Beaver Meadow Observatory (North Java, NY)

Telescope: Celestron 14" Edge HD w/0.7x Reducer

Camera: ZWO ASI2600MC Pro

Filter: Optolong l-eXtreme 

Mount: Astro Physics AP-1200

Exposure: 13 exposures at 600 sec / Gain 100 / Offset 50 / -10°C each for a total exposure of 130 minutes (2.2 hours)

Software: NINA, PHD2, and PixInsight

Clear Skies!

Ernie

Experimenting at the Club's Observatory

 First off, it's been a while ... 

The last clear night that I was able to image was on October 3rd. So, apologies for taking so long between posts. The weather has been horrendous and travel for work forced me to miss the one clear night we had in November. I was super excited to see a clear forecast for Thursday night (December 14th). Our astronomy club has an imaging group, we're called the Tuesday Night Imagers. the leader of our group posted on the forum of our website that Tuesday would be Thursday this week. One advantage of winter is I can make it out to the observatory after work and get a few hours of imaging in and still get home at a reasonable time. 

We made our plans ahead of time. The plan was to try my personal camera, the ZWO ASI2600MC-Pro on the club's Celestron 14" Edge D Telescope. Our club has the 14" and a Tele Vue NP-101is mounted on an Astro Physics AP-1200 mount. We have an Atik 383L+ Color camera for the 14". A great camera, but it is an older CCD camera and is starting to show it's age. We are actively discussing what camera to get to replace it. We wish to stick with a One-Shot Color (OSC) camera for simplicity and convivence. Technically, my camera is a great match for the NP-101is but not for the 14". Even with the 0.7x focal reducer, the 14" has focal length of 2,738 mm. Therefore, my camera's small pixels result in a very over-sampled image scale with the 14". This is typically not desirable. However, we have seen some great results from similar setups and decided to give this a try. 

I got to the observatory around 5:30 pm. The observatory director, the leader of our imaging group, was unable to make it out to the observatory due to a last minute issue. Typically, the observatory director and another member of our group are the main operators of the telescope. The other telescope operator and I got the telescopes going. My camera on the 14" and the other telescope operator put his ZWO ASI1600MC-Pro on the NP-101. The observatory director and a couple of other members of our imaging group joined us via Zoom. 

The skies were not great. lots of high/thin clouds or haze especially towards the western horizon. Of course, that's exactly where we wanted to image. We wanted to get data on Comet 12/P Pons-Brooks which is near the bright star Vega. We tried for about an hour, but the data was not looking good. Autofocus was struggling and there was little signal from the comet. I have not tried to process the data from the 14" yet but the other telescope operator managed to get a nice image (especially considering the conditions). 

As it was also the peak of the Geminids meteor shower, we did try to get outside and see if we could see meteors. We saw about four or five. We also noticed skies were better towards the Southeast, where the constellation Orion was rising. We decided to give up on the comet and slew to the Horsehead Nebula (Barnard 33). We slewed to B33 and got both telescopes framed as best as we could. We were feeling the pressure to get imaging quickly, so we didn't rotate the camera or refine (manually) the relative pointing of the telescopes to one another, a disadvantage of two scopes on one mount. We dialed in our exposure settings, 120 sec subs at Gain 100 with an Offset of 50 for me and started collecting exposures. The results looked really good. The stars were nice and round. We imaged for little over an hour. It was a work night, skies weren't the best, and both of us had a pretty good drive home. This is the resulting image from the night's work. Pretty encouraging results!

The Horsehead Nebula (B33) from the BAA's Beaver Meadow Observatory on 12/14/2023.

Processing

There was a lot of conversation in our club's forum leading up to Thursday night and again afterwards regarding how to capture and process images with this scope/camera combination. We are lucky to have some talented imagers in the group, one in particular who is both very talented and technically knowledgeable. This person was a key participant in those discussions and I'm personally very grateful for his mentoring.

All pre and post processing was performed in PixInsight. Pre-processing: All 34 images were examined in Blink, 2 were rejected. The remaining 32 images were calibrated, registered, and stacked in WBPP with 1X Drizzle integration, astrometric solution, and auto-crop enabled. 

Linear Post-processing: Gradient was removed with the GraXpert script (AI mode), initial deconvolution with BlurXT in Correct Only mode, color calibration SPCC, second deconvolution with BlurXT, noise reduction NoiseXT, and the image was made non-linear with HT. Non-linear Post processing: Stars were removed with StarXT. Stars: Saturation curve applied with CT and green noise removed with SCNR. Starless: Multiple iterations of CT were applied to increase brightness and contrast, Saturation was added with CT, green noise was removed with SCNR, and noise reduction was further reduced with NoiseXT. The image was sharpened with LHE at 3 different kernel sizes and MMT. Dark structure was enhanced with the DSE script and stars were screened back in with Pixel Math. No down sampling was performed. 

What is it?

The Horsehead Nebula (Barnard 33) is a small dark nebula silhouetted against the emission nebula IC434. B33 resembles the profile of the head of a horse. It is a concentration of dust and non-luminous gas that blocks light of the nebula behind it. 

Annotated image of the Horsehead Nebula

How big is it?

This object has an angular distance of 6.0 x 4.0 arcminutes on the night sky. The object is 2.8 light-years (ly) across. 

How far is it?

It is located about 1,600 light-years (ly) from Earth in the Constellation of Orion.

How to find it?

It is located close to Alnitak, one of the 3 belt stars in Orion. This makes it easy to find. However, it is much easier to photograph than visually observe. To give you the best chance of success in visually observing it, use a large aperture telescope, use an H-beta nebula filter, and get to dark skies. It is tiny and it is essentially like trying to find a black fingerprint on a black tablecloth. Try to find the emission nebula IC 434 and look for the absence of the nebula. Photographically, this target shows up relatively easily and can be captured with and without the use of filters. 

Finder Chart for B33

Image Details:

Capture Date: 12/14/2023

Location: North Java, NY (BAA's Beaver Meadow Observatory

Telescope: Celestron 14" Edge HD w/0.7x Focal Reducer

Camera: ZWO ASI2600MC Pro

Filter: N/A

Mount: Astro Physics AP-1200

Exposure: 32 exposures at 120 sec / Gain 100 / Offset 50 / -10°C each for a total exposure of 1 hour and 4 minutes.

Software: NINA, PHD2, and PixInsight

Clear Skies!

Ernie