Sh2-284 - Emission Nebula in Monoceros - Astrophotography
Updated: Mar 25
Sh2-284 is a colorful emission nebula in the constellation Monoceros. It does not have a nickname, but is often mistakenly called the Little Rosette Nebula (which is in fact Sh2-270). Because of that, why don't we call it the Portal Nebula? You can see why I decided to give it this nickname later in this post.
Sh2-284 is not often photographed, but is a good target for both beginner and experienced astrophotographers.
Object Designation: Sh2-284, LBN 983
Also Known As: The Portal Nebula (since today)
Constellation: Monoceros
Object Type: Emission Nebula
Distance: 15,000 light-years away
Magnitude: Unknown
Discovery: Unknown
In the northern hemisphere, the best time to photograph the Portal Nebula is in the Winter season.
Sh2-284 Astrophotography from a Dark Site
March 2024
We photographed this target using our refractor telescope at Utah Desert Remote Observatories.
The Bortle 2 skies are fantastic, and you can inquire at UDRO if you'd like to have your scope next to ours!
The image below is the result of 30.5 hours in SHO. I rarely forget to spend an extra couple of hours shooting in RGB to get natural stars, but this time, I completely forgot! This is why the stars look white, magenta, and blue. I am overall happy with the picture, it shows the impressive nebula in the center with lots of wisps of gasses all around.
I have rotated the image in a way that was visually pleasing. Do you see the portal yet? If not, scroll down some more to see an explanation!
Click the image to see it in high resolution!
GEAR USED:
Camera: QHY600M
Telescope: Stellarvue SVX130
Mount: 10Micron GM1000 HPS
Guiding: ZWO ASI 290MM Mini
Accessories: Moonlite Nitecrawler focuser / Pegasus Astro Ultimate Powerbox
Processing: Pixinsight with RC-Astro plugins, final touches in Skylum Luminar Neo
ACQUISITION DETAILS:
Total Exposure Time: 30.5 hours
Exposure Time per frame: 10 minutes
Filters: Chroma 3nm S/H/O
Gain: 56
How to Find Sh2-284
Sh2-284 can be found in Monoceros in the Winter sky. It is not far from the brightest star in the sky: Sirius, as well as Betelgeuse in Orion.
The constellation Monoceros was outlined by the Dutch globe maker Petrus Plancius in 1612. Along with Camelopardalis, Monoceros was only two of twelve proposed constellations to be approved by other astronomers during that year. The story is actually very interesting and you can learn all about it in The Constellations Handbook!
Sh2-284 can be seen from a dark site using a telescope or a pair of binoculars. It looks similar to the Rosette Nebula, but slightly fainter and much smaller.
You can find several other colorful deep sky objects not far from the Portal Nebula, such as:
NGC 2264 - The Christmas Tree star Cluster and Cone Nebula
NGC 2346 - The Butterfly Nebula (The little one, not the huge Butterfly in Cygnus!)
Messier 50 - An open cluster 2,270 light years away.
The entire Orion Region, including Barnard's Loop, the Orion Nebula, M78, the Horsehead Nebula, and the Witch Head Nebula
NGC 2359 - Thor's Helmet Nebula
IC 2177 - The Seagull Nebula
The best time to observe and photograph Sh2-284 is in Winter.
Sh2-284 by NASA and ESO
NASA and ESO only photographed this target a few times, and none of the results are as impressive as what you'd see from the Hubble or the James Webb Space telescopes, but I'm sure they're probably very interesting scientifically speaking.
On June 7, 2023, ESO released the image you see here. It was taken with the VLT Survey Telescope from the Panaral Observatory.
The main goal of this was to capture the object in great detail, including the cluster of stars.
This cluster, visible near the center, is made up of young stars and is known as "Dolidze 25". It is emitting large amounts of radiation in all directions, as well as powerful stellar winds. This is the reason why the nebula seems to have a "hole" in its center.
NASA used the Wide-field Infrared Survey Explorer (WISE) back in 2011 to capture Sh2-284 in Infrared. The green and red colors you see represent the wavelength of infrared light.
Blue/Green shows the light emitted in 3.4 and 4.6 micron wavelengths. They mostly come from the stars.
Green/Red represent 12 and 22 micron light, which mostly comes from the dust.
Sh2-284 Nickname: The Portal Nebula
Why did I come up with the nickname "Portal Nebula"?
While doing research for this write-up about this nebula, I realized that several people call this "the Little Rosette Nebula". This is not true, as the Little Rosette Nebula is Sh2-270.
Just like the IFN vs ISM terms, we have to be careful not to blindly share false information online because it spreads quickly! If I did not already suspect the Little Rosette Nebula to be a different object, I could have also used that term in this blog after my research and contribute to spreading this sick, terrible, outrageous lie!
Either way, this nebula does not have a name, so I decided to call it the Portal Nebula. Yes, I have no right to name this nebula, and it will never be official, but it looks like a portal to me in the orientation I ended up with, so I named it the Portal nebula.
Single Shot and Processing of Sh2-284
Below you can see what a the master files for each narrowband channels (H - S - O) looked like before being combined into one color image. As you can see, like it is the case for pretty much all emission nebulae, the Hydrogen Alpha channel is the one showing the most gas! It is followed by the OIII channel, and then the weakest of the three, the SII channel.
You can see the same type of comparison for many other targets on our Narrowband Expectation page.
Processing Sh2-284 was not too difficult but can be a bit tricky if you're trying to reveal as much of the fainter outer gas as possible. Make sure to not make the bright areas within the nebula too bright as you increase the visibility of the dimmer gas.
I had some gradients on my image, which I took care of with the GradientCorrection tool in PixInsight. After following my usual nebula processing workflow, I imported the image into Skylum Luminar Neo for some final touches.
Sh2-284 FAQ
In which constellation is Sh2-284 located?
You can find the Sh2-284 Nebula in the constellation Monoceros.
How big is Sh2-284?
The nebula has a diameter of 150 to 200 light-years.
How far is Sh2-284?
The Portal Nebula is located about 15,000 light-years away from Earth.
How long should my exposure times be when photographing Sh2-284?
We suggest doing 10-minute exposures for this object.
Should I use a filter to image Sh2-284?
Sh2-284 is a good narrowband target. As you saw in our comparison shots about the different channels, the H and O channels show a lot of signal. You probably could skip SII and do a bicolor HOO combination.
Sh2-284 Astrophotography - Final Thoughts
The Portal Nebula is a beautiful nebula in Monoceros. I love how colorful it looks, and that it is not too difficult to capture. Make sure to capture this object before the Winter season is over, although if you are a beginner, we suggest starting with the Rosette Nebula first.
Do you like the name "The Portal Nebula"? What would you have named it?
Clear Skies,
Antoine & Dalia Grelin
Galactic Hunter
GALACTIC HUNTER BOOKS
Description: Discover 60 Deep Sky Objects that will considerably improve your Imaging and Processing skills! Whether you are a beginner, intermediate, or advanced astrophotographer, this detailed book of the best deep sky objects will serve as a personal guide for years to come! Discover which star clusters, nebulae, and galaxies are the easiest and most impressive to photograph for each season. Learn how to find each object in the night sky, and read our recommendations on imaging them in a quick and comprehensive way. Each target in this guide contains our advice on imaging, photos of expected results, and a useful information table. We've also included a few cool facts about each target, a map to find it in the night sky, and more!
Description: The Astrophotographer’s Journal is a portable notebook created for the purpose of recording observations, cataloguing photographs, and writing down the wonderful memories created by this hobby. This book contains more than 200 pages to memorialize your stargazing and imaging sessions, as well as a useful chart on the last pages to index exciting or important notes. Read back on the logs to see how much progress you have made through the months, the problems you overcame, and the notes taken to improve in the future. Just as the pioneers of astronomy did in their time, look up and take notes of your observations as you are the author of this star-filled journey.
Description: The Constellations Handbook is a logical guide to learning the 88 constellations. Learning the constellations is difficult. Remembering them is even harder. Have you ever wanted to look up to the night sky, name any pattern of stars and be able to tell their stories? This book groups the constellations in a logical order, so that the reader can easily learn them by their origin, and see how their stories interact with one another as a group. The last pages of this book include an index of all 88 constellations, each with a slot where you can write your own personal tips and tricks in order to memorize them with ease. The Constellations Handbook is not just another guide listing all the constellations from A to Z and their location, it is the perfect companion for stargazing, and a learning journey through the ages.
