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Comet C/2022 E3 (ZTF) - The "Green Comet" | Astrophotography Tips & Pictures

Updated: May 19, 2023

Comet C/2022 E3 (ZTF) is a bright long-period comet that was discovered in early March of 2022 by the wide-field survey camera at the Zwicky Transient Facility in California.


Object Designation: C/2022 E3 (ZTF)

Also known as: The Green Comet

Constellation: Taurus, Cameleopardalis, Ursa Minor...

Object Type: Long-period Comet

Distance: 26 million miles (closest), 103 million miles (farthest)

Magnitude: 6

Discovery: March 2nd 2022, Zwicky Transient Facility


We were visiting family overseas when the comet became visible to amateur astronomers, and we did not have time to capture it until February 1st, 2023. Luckily, the comet still looked bright and beautiful, as you will see in our image below!


 

Comet 2022 E3 (ZTF) with a Refractor Telescope and Monochrome Camera

February 10, 2023


My first ever mosaic! It was cloudy in Las Vegas but I was able to take this image from the clear skies of Utah Desert Remote Observatories.


This 2-panel mosaic shows the C/2022 E3 ZTF "Green Comet" on its closest visual approach to Mars for northern observers.

Mars is obviously very bright and the comet is still looking nice with a defined tail as of February 10.


I am very happy with how this turned out, the processing was very long and difficult because of the three filters used and the 2 panels, but the result was worth it. Please click the image for the high-resolution version!


Green Comet and Planet Mars

GEAR USED:

Camera: QHY600M

Telescope: Stellarvue SVX130

Mount: 10Micron GM1000 HPS

Accessories: Moonlite Nitecrawler focuser / Pegasus Astro Ultimate Powerbox

Processing: Pixinsight, final touches in Lightroom and Topaz Suite

ACQUISITION DETAILS:

Total Exposure Time: 18 minutes for each panel

Exposure Time per frame: 30 seconds

Gain: 56


 

Comet 2022 E3 (ZTF) with a Refractor Telescope and Monochrome Camera

February 2023


Despite the near-full moon being high in the sky, I decided to aim my 655mm refractor telescope (hosted by Utah Desert Remote Observatories ) at the comet and start shooting using R, G, and B filters.


Because I was on vacation for the holidays, I did not have any knowledge about the comet's position, number of tails, and best angle to capture it. I did a quick Google Image search to look at recent pictures of the object and tried my best to align it right in my field of view. Looking back, I wish I had off-centered it more to the bottom of the frame, to have a full view of the upper tail.


Green Comet C/2022 E3 ZTF astrophotography

Want to process your images following our own workflow? Get our Comet Processing Guide!


GEAR USED:

Camera: QHY600M

Telescope: Stellarvue SVX130

Mount: 10Micron GM1000 HPS

Accessories: Moonlite Nitecrawler focuser / Pegasus Astro Ultimate Powerbox

Processing: Pixinsight, final touches in Lightroom and Topaz Suite

ACQUISITION DETAILS:

Total Exposure Time: 15 minutes

Exposure Time per frame: 30 seconds

Gain: 56


 

How to find the Green Comet C/2022 E3 (ZTF)?

Comet C/2022 E3 ZTF trajectory path map
Comet path - Credit: Don Machholz / EarthSky

Comets move each day, so it can be difficult to know where to point your telescope when you are finally ready to image. The image above shows the path the comet has been following since it became visible, and the path it is expected to follow throughout February.


TheSkyLive comet information and coordinates
The information you can find on TheSkyLive

The easiest way to slew your telescope to the exact location of the comet is to input its current coordinates, either in your mount's hand controller, or your laptop program. To find the comet's exact coordinates at any given time, you can look up the comet's page on the website "TheSkyLive".


On that page, you can see the Righ Ascension (R.A) and Declination (Dec) coordinates. It also shows you the current visual magnitude and more information about the comet.


When you are ready to slew your telescope, be sure to refresh the page one final time to get the latest coordinates on the comets, as it might have moved from the last time you opened the page.


 

Comet C/2022 E3 (ZTF) Information


The Green Comet, as the media calls it, gets its color due to the sunlight hitting gasses such as diatomic carbon and cyanogen. Its color is nothing special though, as pretty much all comets are green.


Comet E3 ZTF comes from the Oort Cloud, a cloud of icy objects that orbits the sun at a distance of approximately 0.03 to 3.2 light-years, beyond the orbit of our main planets. Long-period comets have orbits that are so far away from the sun that they are believed to come from the Oort Cloud.


Below you can see an annotated image of the comet, done by Maskrem Larnaout. On that graph, you can clearly see what the comet is made up of:


  • The Nucleus

The main body of the comet, and its brightest part

  • The Dust Tail

The tail is millions of miles long and is made up of small rocks that reflect the sunlight

  • The Ion Tail

The Ion Tail is always in the opposite direction of the sun

  • The AntiTail

The AntiTail, unlike the Dust Tail, is made up of much larger rocks and particles


Comet C/2022 E3 (ZTF) Informational graph
Graph by Makrem Larnaout

 

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Processing Comet E3 ZTF


Processing comets is tricky, and can be very difficult for beginners who do not have much experience processing astronomical objects. Luckily, stacking raw data of comets now is much easier than it used to be. For example, you now only need to select the nucleus on the first and last image of your data set, instead of every single frame like it was the case during the events of Comet NEOWISE.


The workflow for stacking and processing comets goes like this:

  • Calibrate and stack all your files as you would for any deep sky object

  • Use the Master file for the stars only

  • Use the Comet Alignment tool to add all the registered files. Double Click on the first and last frames and select the nucleus

  • Open StarXTerminator's Process Batch to remove the stars of all comet-aligned files

  • Use ImageIntegration to stack all the starless files, without pixel rejection or weights

  • Process both the starless file and the stars-only file as you would any deep-sky object


Processing Comet C/2022 E3 ZTF in PixInsight

Above you can see what my PixInsight dashboard looked like near the beginning of the process. The three images on the left are the R, G, and B masters. The "rainbow" image is what it looked like when the three monochrome channels were combined, and the one on the right is the starless comet image.


Using a monochrome camera makes the processing a bit more difficult, as you have much more files to deal with and filters to combine, so you can expect the workflow to be pretty simple if you use a one-shot-color camera or DSLR.


If you'd like to learn how to capture and properly process comet data, get our guide dedicated to comets!

Comet processing guide pixinsight


 

Comet C/2022 E3 ZTF with a Small Remote Telescope


Because I was unable to capture the early phases of the Green Comet, I wanted to download a set of raw frames on the comet from a remote observatory. I sometimes like to download raw data of transient objects I missed or of southern hemisphere targets from Telescope Live.

For just a few credits, I was able to download approximately 35 minutes of data on the comet, taken from Spain with one of the best widefield telescopes out there, the Takahashi FSQ-106.



If you'd like to try TelescopeLive, you can use the discount code "TL4GH" when signing up!

The Green Comet with a widefield telescope

GEAR USED:

Camera: FLI PL16083

Telescope: Takahashi FSQ-106

Mount: Software Bisque Paramount MX+

Processing: Pixinsight

ACQUISITION DETAILS:

Total Exposure Time: 35 minutes

Exposure Time per frame: 30 seconds

Filters: LRGB


 

Comet C/2022 E3 (ZTF) FAQ



How did the Green Comet get its name?

The Green Comet got its nickname from the media, who don't seem to know that almost all comets are green by default.

The scientific name (C/2022 E3 (ZTF)) got its designation because "C" means it is not a periodic comet, "2022" means it was discovered in 2022, "E3" means it is the third comet discovered that year, and "(ZTF)" because it was found using the Zwicky Transient Facility.


  • Who discovered the Green Comet and when?

Comet E3 ZTF was discovered on March 2nd, 2022 by astronomers Bryce Bolin and Frank Masci using the Zwicky Transient Facility (ZTF).


  • How far is the Green Comet?

The perihelion of the comet was 166 million km/103 million miles/1.11 AU. This was on 12 January 2023. The closest the comet has ever been to Earth was 42 million km/ 26 million miles/0.28 AU on February 1st, 2023


  • How long should my exposure time be when photographing the Green Comet?

To image C/2022 E3 (ZTF), and most other comets, we recommend an exposure time of 30 to 60 seconds. The exposure time will depend on your focal length, but 30-60 seconds is a safe bet for most telescopes around 300-700mm of focal length. You don't want your exposures to be too long or you might notice that the comet is slightly moving, creating a blur around the object.


  • Should I use a filter to image the Green Comet?

Comets are broadband objects and so can be photographed with a simple DSLR camera or one-shot camera without filters. If using a monochrome camera, using just RGB filters is enough.


  • What equipment do I need to photograph the comet?

You can capture most large comets with just a DSLR/mirrorless camera and tripod. This comet is large and bright, so you can easily photograph it with just a tripod and camera lens. You can also get a nice close-up view of the object using a telescope. In this case, the comet has such a long tail that it is best captured with a small telescope.



 

Final Thoughts


This is the third comet we have had the chance to photograph since starting this hobby, and is number #2 on our list of favorite comets! You can probably guess who #1 is... Comet NEOWISE of course! I was very afraid that the comet would disintegrate before getting back home from the holiday travels, but it was still glowing strong and in one piece which made for a beautiful image!



Have you imaged the comet? If so, upload your picture in the comments! We'd all love to see your work :)



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Clear Skies,

Galactic Hunter





 

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